L-Carnosine / beta-alanyl-L-histidine

evidence_access

Primary abstract

experimental_model

Human oral administration and urine sampling.

limitations

Urine recovery is not the fraction retained in tissues.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Some intact carnosine crosses the intestine.

primary_references

Intestinal absorption of the intact peptide carnosine in man, and comparison with intestinal permeability to lactulose. · 1991 · https://pubmed.ncbi.nlm.nih.gov/1910085/ · DOI 10.1113/jphysiol.1991.sp018673

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human oral administration and urine sampling. · source_derived_draft · unverified_draft

## carnosine-absorption Some intact carnosine crosses the intestine. After oral carnosine, healthy volunteers excreted intact peptide over five hours, with recovery reaching 14% of the dose in some participants. Model: Human oral administration and urine sampling. Limitations: Urine recovery is not the fraction retained in tissues. Evidence access: Primary abstract Intestinal absorption of the intact peptide carnosine in man, and comparison with intestinal permeability to lactulose. · 1991 · https://pubmed.ncbi.nlm.nih.gov/1910085/ · DOI 10.1113/jphysiol.1991.sp018673

evidence_access

Primary abstract

experimental_model

Mechanically skinned human muscle fibers.

limitations

Enhanced calcium-induced release was inferred; no demonstrated oral caffeine-carnosine synergy.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Calcium release may contribute in one fiber type.

primary_references

Effects of carnosine on contractile apparatus Ca²⁺ sensitivity and sarcoplasmic reticulum Ca²⁺ release in human skeletal muscle fibers. · 2012 · https://pubmed.ncbi.nlm.nih.gov/22174397/ · DOI 10.1152/japplphysiol.01331.2011

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 196–202

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Mechanically skinned human muscle fibers. · source_derived_draft · unverified_draft

## carnosine-caffeine-response Calcium release may contribute in one fiber type. Adding 8 mM carnosine increased caffeine-evoked force; type I potentiation exceeded that explained by measured calcium sensitization alone. Model: Mechanically skinned human muscle fibers. Limitations: Enhanced calcium-induced release was inferred; no demonstrated oral caffeine-carnosine synergy. Evidence access: Primary abstract Effects of carnosine on contractile apparatus Ca²⁺ sensitivity and sarcoplasmic reticulum Ca²⁺ release in human skeletal muscle fibers. · 2012 · https://pubmed.ncbi.nlm.nih.gov/22174397/ · DOI 10.1152/japplphysiol.01331.2011

evidence_access

Primary abstract

experimental_model

Human vastus lateralis biopsy fibers ex vivo.

limitations

Bath exposure does not establish an oral supplementation effect.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Muscle fibers responded more strongly to the same calcium signal.

primary_references

Effects of carnosine on contractile apparatus Ca²⁺ sensitivity and sarcoplasmic reticulum Ca²⁺ release in human skeletal muscle fibers. · 2012 · https://pubmed.ncbi.nlm.nih.gov/22174397/ · DOI 10.1152/japplphysiol.01331.2011

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human vastus lateralis biopsy fibers ex vivo. · source_derived_draft · unverified_draft

## carnosine-calcium-sensitivity Muscle fibers responded more strongly to the same calcium signal. Adding 8 or 16 mM carnosine increased contractile-apparatus calcium sensitivity in mechanically skinned human type I and II muscle fibers. Model: Human vastus lateralis biopsy fibers ex vivo. Limitations: Bath exposure does not establish an oral supplementation effect. Evidence access: Primary abstract Effects of carnosine on contractile apparatus Ca²⁺ sensitivity and sarcoplasmic reticulum Ca²⁺ release in human skeletal muscle fibers. · 2012 · https://pubmed.ncbi.nlm.nih.gov/22174397/ · DOI 10.1152/japplphysiol.01331.2011

evidence_access

Primary abstract

experimental_model

Biochemical catecholaldehyde comparisons.

limitations

No universal antioxidant ranking follows.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Different scavengers favor different aldehydes.

primary_references

Biochemical characterization of the catecholaldehyde reactivity of L-carnosine and its therapeutic potential in human myocardium. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30191330/ · DOI 10.1007/s00726-018-2647-y

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Biochemical catecholaldehyde comparisons. · source_derived_draft · unverified_draft

## carnosine-dopal Different scavengers favor different aldehydes. Carnosine reacted with DOPAL and DOPEGAL; glutathione showed little DOPAL reactivity under the tested conditions. Model: Biochemical catecholaldehyde comparisons. Limitations: No universal antioxidant ranking follows. Evidence access: Primary abstract Biochemical characterization of the catecholaldehyde reactivity of L-carnosine and its therapeutic potential in human myocardium. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30191330/ · DOI 10.1007/s00726-018-2647-y

evidence_access

Primary abstract

experimental_model

Buffered chemical reactions; adducts also detected in oxidized rat muscle homogenate.

limitations

Reaction chemistry does not measure clinical protection.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The peptide can chemically trap a lipid-derived aldehyde.

primary_references

Carnosine is a quencher of 4-hydroxy-nonenal: through what mechanism of reaction? · 2002 · https://pubmed.ncbi.nlm.nih.gov/12419310/ · DOI 10.1016/s0006-291x(02)02545-7

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Buffered chemical reactions; adducts also detected in oxidized rat muscle homogenate. · source_derived_draft · unverified_draft

## carnosine-hne-adduction The peptide can chemically trap a lipid-derived aldehyde. Carnosine reacted with HNE to form a stabilized Michael adduct and an imine macrocycle in a pH-dependent equilibrium. Model: Buffered chemical reactions; adducts also detected in oxidized rat muscle homogenate. Limitations: Reaction chemistry does not measure clinical protection. Evidence access: Primary abstract Carnosine is a quencher of 4-hydroxy-nonenal: through what mechanism of reaction? · 2002 · https://pubmed.ncbi.nlm.nih.gov/12419310/ · DOI 10.1016/s0006-291x(02)02545-7

evidence_access

Primary abstract

experimental_model

Cell-free comparison.

limitations

This molecular comparison is not proof of supplement synergy.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The joined peptide has properties its separate parts do not reproduce.

primary_references

Carnosine is a quencher of 4-hydroxy-nonenal: through what mechanism of reaction? · 2002 · https://pubmed.ncbi.nlm.nih.gov/12419310/ · DOI 10.1016/s0006-291x(02)02545-7

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Cell-free comparison. · source_derived_draft · unverified_draft

## carnosine-hne-intact-peptide The joined peptide has properties its separate parts do not reproduce. At pH 7.4, intact carnosine quenched HNE more effectively than histidine or N-acetylcarnosine, while beta-alanine was inactive. Model: Cell-free comparison. Limitations: This molecular comparison is not proof of supplement synergy. Evidence access: Primary abstract Carnosine is a quencher of 4-hydroxy-nonenal: through what mechanism of reaction? · 2002 · https://pubmed.ncbi.nlm.nih.gov/12419310/ · DOI 10.1016/s0006-291x(02)02545-7

evidence_access

Primary abstract

experimental_model

Overweight adults; 2 g/day for twelve weeks.

limitations

Urinary adducts do not quantify total tissue detoxification; plasma carnosine/adducts were not detected.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Human urine provided evidence of aldehyde trapping.

primary_references

A carnosine intervention study in overweight human volunteers: bioavailability and reactive carbonyl species sequestering effect. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27265207/ · DOI 10.1038/srep27224

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Overweight adults; 2 g/day for twelve weeks. · source_derived_draft · unverified_draft

## carnosine-human-acrolein Human urine provided evidence of aldehyde trapping. Oral carnosine increased urinary carnosine-acrolein adduct excretion, with substantial differences between individuals. Model: Overweight adults; 2 g/day for twelve weeks. Limitations: Urinary adducts do not quantify total tissue detoxification; plasma carnosine/adducts were not detected. Evidence access: Primary abstract A carnosine intervention study in overweight human volunteers: bioavailability and reactive carbonyl species sequestering effect. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27265207/ · DOI 10.1038/srep27224

evidence_access

Primary abstract

experimental_model

Human cardiac mitochondria ex vivo.

limitations

Not evidence of benefit in patients or a substitute for aldehyde-metabolizing enzymes.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The peptide intercepted damage in an isolated mitochondrial preparation.

primary_references

Biochemical characterization of the catecholaldehyde reactivity of L-carnosine and its therapeutic potential in human myocardium. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30191330/ · DOI 10.1007/s00726-018-2647-y

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human cardiac mitochondria ex vivo. · source_derived_draft · unverified_draft

## carnosine-human-heart-adducts The peptide intercepted damage in an isolated mitochondrial preparation. Adding carnosine reduced catecholaldehyde-protein adduct formation in isolated human cardiac mitochondria exposed to norepinephrine. Model: Human cardiac mitochondria ex vivo. Limitations: Not evidence of benefit in patients or a substitute for aldehyde-metabolizing enzymes. Evidence access: Primary abstract Biochemical characterization of the catecholaldehyde reactivity of L-carnosine and its therapeutic potential in human myocardium. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30191330/ · DOI 10.1007/s00726-018-2647-y

evidence_access

Primary abstract

experimental_model

Atrial tissue from cardiac-surgery patients, ex vivo.

limitations

No oral intervention or clinical cardiac benefit established.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A chemical difference translated into protection in sampled heart tissue.

primary_references

Biochemical characterization of the catecholaldehyde reactivity of L-carnosine and its therapeutic potential in human myocardium. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30191330/ · DOI 10.1007/s00726-018-2647-y

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Atrial tissue from cardiac-surgery patients, ex vivo. · source_derived_draft · unverified_draft

## carnosine-human-heart-respiration A chemical difference translated into protection in sampled heart tissue. Carnosine pretreatment attenuated DOPAL suppression of ADP-stimulated respiration in permeabilized human atrial fibers; GSH and cysteine did not. Model: Atrial tissue from cardiac-surgery patients, ex vivo. Limitations: No oral intervention or clinical cardiac benefit established. Evidence access: Primary abstract Biochemical characterization of the catecholaldehyde reactivity of L-carnosine and its therapeutic potential in human myocardium. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30191330/ · DOI 10.1007/s00726-018-2647-y

evidence_access

Primary abstract

experimental_model

Mouse cerebral ischemia with Hdc knockout.

limitations

Preclinical intervention; not stroke treatment guidance.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Protection in this model did not require histamine synthesis.

primary_references

Carnosine protects against permanent cerebral ischemia in histidine decarboxylase knockout mice by reducing glutamate excitotoxicity. · 2010 · https://pubmed.ncbi.nlm.nih.gov/20043985/ · DOI 10.1016/j.freeradbiomed.2009.12.021

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Mouse cerebral ischemia with Hdc knockout. · source_derived_draft · unverified_draft

## carnosine-ischemia-hdc Protection in this model did not require histamine synthesis. Carnosine treatment reduced infarct size in both wild-type and histidine-decarboxylase-null mice after permanent MCAO. Model: Mouse cerebral ischemia with Hdc knockout. Limitations: Preclinical intervention; not stroke treatment guidance. Evidence access: Primary abstract Carnosine protects against permanent cerebral ischemia in histidine decarboxylase knockout mice by reducing glutamate excitotoxicity. · 2010 · https://pubmed.ncbi.nlm.nih.gov/20043985/ · DOI 10.1016/j.freeradbiomed.2009.12.021

evidence_access

Primary abstract

experimental_model

Astrocyte ischemia-like and rotenone experiments; culture species not resolved from the accessed abstract.

limitations

Species must be verified before projecting this cellular result onto a species-specific pathway; complete causal mediation was not isolated.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The cellular response included mitochondrial protection.

primary_references

Carnosine protects against permanent cerebral ischemia in histidine decarboxylase knockout mice by reducing glutamate excitotoxicity. · 2010 · https://pubmed.ncbi.nlm.nih.gov/20043985/ · DOI 10.1016/j.freeradbiomed.2009.12.021

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Astrocyte ischemia-like and rotenone experiments; culture species not resolved from the accessed abstract. · source_derived_draft · unverified_draft

## carnosine-ischemia-mitochondria The cellular response included mitochondrial protection. Carnosine reduced mitochondrial ROS and membrane-potential loss under oxygen-glucose deprivation in astrocytes. Model: Astrocyte ischemia-like and rotenone experiments; culture species not resolved from the accessed abstract. Limitations: Species must be verified before projecting this cellular result onto a species-specific pathway; complete causal mediation was not isolated. Evidence access: Primary abstract Carnosine protects against permanent cerebral ischemia in histidine decarboxylase knockout mice by reducing glutamate excitotoxicity. · 2010 · https://pubmed.ncbi.nlm.nih.gov/20043985/ · DOI 10.1016/j.freeradbiomed.2009.12.021

evidence_access

Primary abstract

experimental_model

Mouse permanent MCAO; separate cultured-astrocyte results are not used here to assign culture species.

limitations

Preservation does not establish direct binding to GLT-1.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Glutamate handling offered another downstream connection.

primary_references

Carnosine protects against permanent cerebral ischemia in histidine decarboxylase knockout mice by reducing glutamate excitotoxicity. · 2010 · https://pubmed.ncbi.nlm.nih.gov/20043985/ · DOI 10.1016/j.freeradbiomed.2009.12.021

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Mouse permanent MCAO; separate cultured-astrocyte results are not used here to assign culture species. · source_derived_draft · unverified_draft

## carnosine-ischemia-transporter Glutamate handling offered another downstream connection. In the mouse ischemia study, carnosine treatment preserved astrocytic GLT-1 expression and decreased glutamate levels. Model: Mouse permanent MCAO; separate cultured-astrocyte results are not used here to assign culture species. Limitations: Preservation does not establish direct binding to GLT-1. Evidence access: Primary abstract Carnosine protects against permanent cerebral ischemia in histidine decarboxylase knockout mice by reducing glutamate excitotoxicity. · 2010 · https://pubmed.ncbi.nlm.nih.gov/20043985/ · DOI 10.1016/j.freeradbiomed.2009.12.021

evidence_access

Primary abstract

experimental_model

Cell-free metal-catalyzed oxidation.

limitations

Millimolar assay; does not show safe systemic metal chelation.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Its chemical protection depended on the oxidation system.

primary_references

Antioxidant properties of carnosine re-evaluated with oxidizing systems involving iron and copper ions. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15853927/ · DOI 10.1111/j.1742-7843.2005.pto_03.x

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Cell-free metal-catalyzed oxidation. · source_derived_draft · unverified_draft

## carnosine-metal-dna Its chemical protection depended on the oxidation system. At 10 mM, carnosine reduced DNA damage caused by copper- or iron/peroxide/ascorbate systems. Model: Cell-free metal-catalyzed oxidation. Limitations: Millimolar assay; does not show safe systemic metal chelation. Evidence access: Primary abstract Antioxidant properties of carnosine re-evaluated with oxidizing systems involving iron and copper ions. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15853927/ · DOI 10.1111/j.1742-7843.2005.pto_03.x

evidence_access

Primary abstract

experimental_model

Cell-free lysine-MG AGE preparation.

limitations

The study does not demonstrate removal of established tissue AGE deposits.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Protection was tested against secondary reaction products too.

primary_references

Carnosine protects proteins against methylglyoxal-mediated modifications. · 1998 · https://pubmed.ncbi.nlm.nih.gov/9675080/ · DOI 10.1006/bbrc.1998.8806

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Cell-free lysine-MG AGE preparation. · source_derived_draft · unverified_draft

## carnosine-mg-secondary Protection was tested against secondary reaction products too. Carnosine also inhibited protein modification caused by products formed by incubating lysine with methylglyoxal. Model: Cell-free lysine-MG AGE preparation. Limitations: The study does not demonstrate removal of established tissue AGE deposits. Evidence access: Primary abstract Carnosine protects proteins against methylglyoxal-mediated modifications. · 1998 · https://pubmed.ncbi.nlm.nih.gov/9675080/ · DOI 10.1006/bbrc.1998.8806

evidence_access

Primary abstract

experimental_model

Cell-free protein incubation.

limitations

Clinical glucose lowering is not established by this assay.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Another reactive carbonyl had less opportunity to modify proteins.

primary_references

Carnosine protects proteins against methylglyoxal-mediated modifications. · 1998 · https://pubmed.ncbi.nlm.nih.gov/9675080/ · DOI 10.1006/bbrc.1998.8806

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Cell-free protein incubation. · source_derived_draft · unverified_draft

## carnosine-mg-trapping Another reactive carbonyl had less opportunity to modify proteins. Adding carnosine inhibited methylglyoxal-driven protein modification in electrophoretic assays. Model: Cell-free protein incubation. Limitations: Clinical glucose lowering is not established by this assay. Evidence access: Primary abstract Carnosine protects proteins against methylglyoxal-mediated modifications. · 1998 · https://pubmed.ncbi.nlm.nih.gov/9675080/ · DOI 10.1006/bbrc.1998.8806

evidence_access

Primary abstract

experimental_model

Forty-three adults with prediabetes or T2D; 2 g/day for fourteen weeks.

limitations

Hepatic glucose-output suppression was a proposed explanation, not directly demonstrated.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Another trial found lower glucose after a glucose challenge.

primary_references

Carnosine supplementation improves glucose control in adults with pre-diabetes and type 2 diabetes: A randomised controlled trial. · 2024 · https://pubmed.ncbi.nlm.nih.gov/38172006/ · DOI 10.1016/j.numecd.2023.10.012

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Forty-three adults with prediabetes or T2D; 2 g/day for fourteen weeks. · source_derived_draft · unverified_draft

## carnosine-ogtt Another trial found lower glucose after a glucose challenge. Carnosine lowered 90- and 120-minute OGTT glucose and glucose AUC versus placebo. Model: Forty-three adults with prediabetes or T2D; 2 g/day for fourteen weeks. Limitations: Hepatic glucose-output suppression was a proposed explanation, not directly demonstrated. Evidence access: Primary abstract Carnosine supplementation improves glucose control in adults with pre-diabetes and type 2 diabetes: A randomised controlled trial. · 2024 · https://pubmed.ncbi.nlm.nih.gov/38172006/ · DOI 10.1016/j.numecd.2023.10.012

evidence_access

Primary abstract

experimental_model

Same randomized trial.

limitations

Preserve null endpoints alongside positive findings.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The glucose response did not imply improvement in every endpoint.

primary_references

Carnosine supplementation improves glucose control in adults with pre-diabetes and type 2 diabetes: A randomised controlled trial. · 2024 · https://pubmed.ncbi.nlm.nih.gov/38172006/ · DOI 10.1016/j.numecd.2023.10.012

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Same randomized trial. · source_derived_draft · unverified_draft

## carnosine-ogtt-insulin-null The glucose response did not imply improvement in every endpoint. The same trial found no significant change in insulin levels or the measured body-composition outcomes. Model: Same randomized trial. Limitations: Preserve null endpoints alongside positive findings. Evidence access: Primary abstract Carnosine supplementation improves glucose control in adults with pre-diabetes and type 2 diabetes: A randomised controlled trial. · 2024 · https://pubmed.ncbi.nlm.nih.gov/38172006/ · DOI 10.1016/j.numecd.2023.10.012

evidence_access

Primary abstract

experimental_model

Cell-free LDL oxidation.

limitations

Cannot distinguish all contributions of trapping and oxidation suppression.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Aldehyde availability changed in an oxidizing lipid preparation.

primary_references

Dietary carnosine prevents early atherosclerotic lesion formation in apolipoprotein E-null mice. · 2013 · https://pubmed.ncbi.nlm.nih.gov/23559625/ · DOI 10.1161/ATVBAHA.112.300572

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Cell-free LDL oxidation. · source_derived_draft · unverified_draft

## carnosine-oxidized-ldl Aldehyde availability changed in an oxidizing lipid preparation. Adding carnosine lowered free HNE formation during copper-driven LDL oxidation. Model: Cell-free LDL oxidation. Limitations: Cannot distinguish all contributions of trapping and oxidation suppression. Evidence access: Primary abstract Dietary carnosine prevents early atherosclerotic lesion formation in apolipoprotein E-null mice. · 2013 · https://pubmed.ncbi.nlm.nih.gov/23559625/ · DOI 10.1161/ATVBAHA.112.300572

evidence_access

Primary abstract

experimental_model

Chemical analysis, mouse tissues and human neuroblastoma cells.

limitations

Product formation is distinct from simple removal of oxidants.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

An oxidation product can retain biological activity.

primary_references

2-Oxo-histidine-containing dipeptides are functional oxidation products. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30504220/ · DOI 10.1074/jbc.RA118.006111

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Chemical analysis, mouse tissues and human neuroblastoma cells. · source_derived_draft · unverified_draft

## carnosine-oxo-product An oxidation product can retain biological activity. Oxidation of carnosine produced 2-oxo-carnosine; mechanistic analysis supported imidazole-radical formation followed by oxygen addition. Model: Chemical analysis, mouse tissues and human neuroblastoma cells. Limitations: Product formation is distinct from simple removal of oxidants. Evidence access: Primary abstract 2-Oxo-histidine-containing dipeptides are functional oxidation products. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30504220/ · DOI 10.1074/jbc.RA118.006111

evidence_access

Primary abstract

experimental_model

Thirty overweight/obese adults; 2 g/day for twelve weeks.

limitations

Pilot outcomes do not establish diabetes prevention; linked carbonyl paper may use the same trial.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A small human trial reported a metabolic signal.

primary_references

Effects of carnosine supplementation on glucose metabolism: Pilot clinical trial. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27040154/ · DOI 10.1002/oby.21434

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Thirty overweight/obese adults; 2 g/day for twelve weeks. · source_derived_draft · unverified_draft

## carnosine-pilot-insulin A small human trial reported a metabolic signal. Carnosine supplementation attenuated the rise in fasting insulin and insulin-resistance indices relative to placebo. Model: Thirty overweight/obese adults; 2 g/day for twelve weeks. Limitations: Pilot outcomes do not establish diabetes prevention; linked carbonyl paper may use the same trial. Evidence access: Primary abstract Effects of carnosine supplementation on glucose metabolism: Pilot clinical trial. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27040154/ · DOI 10.1002/oby.21434

evidence_access

Primary full text, methods and protonation results

experimental_model

Purified dipeptides at 310.15 K and 0.15 M ionic strength.

limitations

Chemical buffering does not establish how much a supplement changes exercising muscle pH.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Reversible proton binding gives the molecule buffering capacity.

primary_references

Species-specific acid-base characterization of carnosine and homocarnosine using nuclear magnetic resonance · 2022 · https://doi.org/10.1016/j.cplett.2022.140128 · DOI 10.1016/j.cplett.2022.140128

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AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Purified dipeptides at 310.15 K and 0.15 M ionic strength. · source_derived_draft · unverified_draft

## carnosine-proton-buffer Reversible proton binding gives the molecule buffering capacity. NMR and potentiometric titration measured reversible protonation of carnosine, including its imidazole site near physiological pH. Model: Purified dipeptides at 310.15 K and 0.15 M ionic strength. Limitations: Chemical buffering does not establish how much a supplement changes exercising muscle pH. Evidence access: Primary full text, methods and protonation results Species-specific acid-base characterization of carnosine and homocarnosine using nuclear magnetic resonance · 2022 · https://doi.org/10.1016/j.cplett.2022.140128 · DOI 10.1016/j.cplett.2022.140128

evidence_access

Primary abstract

experimental_model

Metabolomic screening and uptake assays in transfected human cells.

limitations

Higher Km for ergothioneine, carnitine and carnosine than their established carriers; substrate sharing does not prove competition at dietary exposures.

nutrient_topic

Ergothioneine collection; molecular form, preparation, species, exposure and manipulation remain explicit. · L-Ergothioneine

plain_language

An additional carrier connects carnosine to the transport network.

primary_references

Deorphaning a solute carrier 22 family member, SLC22A15, through functional genomic studies. · 2020 · https://pubmed.ncbi.nlm.nih.gov/33124720/ · DOI 10.1096/fj.202001497R

transport_effect

raises Expression enabled uptake in HEK293 substrate assays.

transport_pool

the expressing cell Expression enabled uptake in HEK293 substrate assays.

Ergothioneine: transport, redox chemistry and cross-nutrient mechanisms (2026-09-19) · lines 56–62

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Metabolomic screening and uptake assays in transfected human cells. · source_derived_draft · unverified_draft

## ergothioneine-slc22a15-carnosine An additional carrier connects carnosine to the transport network. Human SLC22A15 expression enabled uptake of carnosine in HEK293 substrate assays. Model: Metabolomic screening and uptake assays in transfected human cells. Limitations: Higher Km for ergothioneine, carnitine and carnosine than their established carriers; substrate sharing does not prove competition at dietary exposures. Evidence access: Primary abstract Deorphaning a solute carrier 22 family member, SLC22A15, through functional genomic studies. · 2020 · https://pubmed.ncbi.nlm.nih.gov/33124720/ · DOI 10.1096/fj.202001497R

evidence_access

Primary abstract

experimental_model

Purified human protein expressed in CHO cells.

limitations

Kinetic constant is not a plasma threshold.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A separate enzyme breaks the peptide down.

primary_references

Sequence identification and characterization of human carnosinase and a closely related non-specific dipeptidase. · 2003 · https://pubmed.ncbi.nlm.nih.gov/12473676/ · DOI 10.1074/jbc.M209764200

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 44–50

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Purified human protein expressed in CHO cells. · source_derived_draft · unverified_draft

## carnosine-cndp1-hydrolysis A separate enzyme breaks the peptide down. Recombinant human CNDP1 hydrolyzed carnosine, with a reported Km of 1.2 mM. Model: Purified human protein expressed in CHO cells. Limitations: Kinetic constant is not a plasma threshold. Evidence access: Primary abstract Sequence identification and characterization of human carnosinase and a closely related non-specific dipeptidase. · 2003 · https://pubmed.ncbi.nlm.nih.gov/12473676/ · DOI 10.1074/jbc.M209764200

evidence_access

Primary abstract

experimental_model

Purified recombinant protein.

limitations

Do not assume CNDP2 is an equally active carnosinase at normal cytosolic pH.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The similarly named enzyme behaved differently.

primary_references

Sequence identification and characterization of human carnosinase and a closely related non-specific dipeptidase. · 2003 · https://pubmed.ncbi.nlm.nih.gov/12473676/ · DOI 10.1074/jbc.M209764200

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 52–58

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Purified recombinant protein. · source_derived_draft · unverified_draft

## carnosine-cndp2-ph The similarly named enzyme behaved differently. Human CNDP2 hydrolyzed carnosine only under alkaline assay conditions, with an optimum near pH 9.5. Model: Purified recombinant protein. Limitations: Do not assume CNDP2 is an equally active carnosinase at normal cytosolic pH. Evidence access: Primary abstract Sequence identification and characterization of human carnosinase and a closely related non-specific dipeptidase. · 2003 · https://pubmed.ncbi.nlm.nih.gov/12473676/ · DOI 10.1074/jbc.M209764200

evidence_access

Primary abstract

experimental_model

Human transporter expressed in Xenopus oocytes.

limitations

Transporter expression system, not whole-body bioavailability.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A peptide transporter can carry intact carnosine.

primary_references

The bioactive dipeptide anserine is transported by human proton-coupled peptide transporters. · 2010 · https://pubmed.ncbi.nlm.nih.gov/20067523/ · DOI 10.1111/j.1742-4658.2009.07528.x

transport_effect

raises Applying carnosine produced electrogenic proton-coupled inward transport currents.

transport_pool

the expressing cell Applying carnosine produced electrogenic proton-coupled inward transport currents.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 68–74

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human transporter expressed in Xenopus oocytes. · source_derived_draft · unverified_draft

## carnosine-pept1 A peptide transporter can carry intact carnosine. Applying carnosine to oocytes expressing human PEPT1 produced electrogenic proton-coupled transport currents. Model: Human transporter expressed in Xenopus oocytes. Limitations: Transporter expression system, not whole-body bioavailability. Evidence access: Primary abstract The bioactive dipeptide anserine is transported by human proton-coupled peptide transporters. · 2010 · https://pubmed.ncbi.nlm.nih.gov/20067523/ · DOI 10.1111/j.1742-4658.2009.07528.x

evidence_access

Primary abstract and full-text enzyme methods

experimental_model

Human enzyme expressed in HEK293T cells.

limitations

An enzyme assay does not define dietary requirements.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Two building blocks are assembled by a specific enzyme.

primary_references

Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1). · 2010 · https://pubmed.ncbi.nlm.nih.gov/20097752/ · DOI 10.1074/jbc.M109.095505

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 20–26

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human enzyme expressed in HEK293T cells. · source_derived_draft · unverified_draft

## carnosine-synthesis Two building blocks are assembled by a specific enzyme. Purified recombinant human CARNS1 joined beta-alanine and L-histidine to form carnosine in an ATP-containing assay. Model: Human enzyme expressed in HEK293T cells. Limitations: An enzyme assay does not define dietary requirements. Evidence access: Primary abstract and full-text enzyme methods Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1). · 2010 · https://pubmed.ncbi.nlm.nih.gov/20097752/ · DOI 10.1074/jbc.M109.095505

evidence_access

Primary abstract

experimental_model

Apoe-null mouse feeding experiment.

limitations

The administered compound was an analog, not ordinary L-carnosine; no human efficacy inferred.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A synthetic derivative showed an effect in a mouse disease model.

primary_references

Dietary carnosine prevents early atherosclerotic lesion formation in apolipoprotein E-null mice. · 2013 · https://pubmed.ncbi.nlm.nih.gov/23559625/ · DOI 10.1161/ATVBAHA.112.300572

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 332–338

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Apoe-null mouse feeding experiment. · source_derived_draft · unverified_draft

## carnosine-analog-atheroma A synthetic derivative showed an effect in a mouse disease model. Oral octyl-D-carnosine reduced aortic-valve lesions and lesion aldehyde-protein adducts in Apoe-null mice. Model: Apoe-null mouse feeding experiment. Limitations: The administered compound was an analog, not ordinary L-carnosine; no human efficacy inferred. Evidence access: Primary abstract Dietary carnosine prevents early atherosclerotic lesion formation in apolipoprotein E-null mice. · 2013 · https://pubmed.ncbi.nlm.nih.gov/23559625/ · DOI 10.1161/ATVBAHA.112.300572

evidence_access

Primary abstract and full-text nucleotide analysis

experimental_model

Chicken muscle enzyme and nucleotide analysis.

limitations

Use ADP rather than the older inferred AMP assignment; no clinical magnesium-depletion threshold was measured.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The synthesis reaction spends ATP and produces ADP.

primary_references

Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1). · 2010 · https://pubmed.ncbi.nlm.nih.gov/20097752/ · DOI 10.1074/jbc.M109.095505

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 28–34

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Chicken muscle enzyme and nucleotide analysis. · source_derived_draft · unverified_draft

## carnosine-atp-product The synthesis reaction spends ATP and produces ADP. Purified chicken carnosine synthase formed ADP stoichiometrically during carnosine synthesis with MgATP. Model: Chicken muscle enzyme and nucleotide analysis. Limitations: Use ADP rather than the older inferred AMP assignment; no clinical magnesium-depletion threshold was measured. Evidence access: Primary abstract and full-text nucleotide analysis Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1). · 2010 · https://pubmed.ncbi.nlm.nih.gov/20097752/ · DOI 10.1074/jbc.M109.095505

evidence_access

Primary abstract

experimental_model

Human supplementation with muscle biopsy.

limitations

Response size is protocol-specific.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The precursor can build the muscle pool over weeks.

primary_references

Influence of beta-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity. · 2007 · https://pubmed.ncbi.nlm.nih.gov/16868650/ · DOI 10.1007/s00726-006-0364-4

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 204–210

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human supplementation with muscle biopsy. · source_derived_draft · unverified_draft

## carnosine-ba-loading-performance The precursor can build the muscle pool over weeks. Beta-alanine feeding increased muscle carnosine by 58.8% after four weeks and 80.1% after ten weeks. Model: Human supplementation with muscle biopsy. Limitations: Response size is protocol-specific. Evidence access: Primary abstract Influence of beta-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity. · 2007 · https://pubmed.ncbi.nlm.nih.gov/16868650/ · DOI 10.1007/s00726-006-0364-4

evidence_access

Primary abstract

experimental_model

Human cycling and muscle-biopsy study.

limitations

Parallel changes do not isolate proton buffering as the sole cause.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

One trial linked loading with improved high-intensity work.

primary_references

Influence of beta-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity. · 2007 · https://pubmed.ncbi.nlm.nih.gov/16868650/ · DOI 10.1007/s00726-006-0364-4

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 212–218

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human cycling and muscle-biopsy study. · source_derived_draft · unverified_draft

## carnosine-ba-work One trial linked loading with improved high-intensity work. Beta-alanine supplementation increased cycling work at 110% maximum power alongside muscle carnosine loading. Model: Human cycling and muscle-biopsy study. Limitations: Parallel changes do not isolate proton buffering as the sole cause. Evidence access: Primary abstract Influence of beta-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity. · 2007 · https://pubmed.ncbi.nlm.nih.gov/16868650/ · DOI 10.1007/s00726-006-0364-4

evidence_access

Primary abstract

experimental_model

Peptide-array and cellular methylation profiling.

limitations

Zinc-finger identity does not establish regulation by zinc intake.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A shared enzyme creates another testable connection.

primary_references

Identification of substrates and sequence requirements for CARNMT1-mediated histidine methylation of C3H zinc fingers. · 2025 · https://pubmed.ncbi.nlm.nih.gov/40473212/ · DOI 10.1016/j.jbc.2025.110335

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 164–170

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Peptide-array and cellular methylation profiling. · source_derived_draft · unverified_draft

## carnosine-carnmt1-new-target A shared enzyme creates another testable connection. Substrate profiling identified RNF113A as a CARNMT1 histidine-methylation target. Model: Peptide-array and cellular methylation profiling. Limitations: Zinc-finger identity does not establish regulation by zinc intake. Evidence access: Primary abstract Identification of substrates and sequence requirements for CARNMT1-mediated histidine methylation of C3H zinc fingers. · 2025 · https://pubmed.ncbi.nlm.nih.gov/40473212/ · DOI 10.1016/j.jbc.2025.110335

evidence_access

Primary abstract

experimental_model

Human cellular extracts, recombinant-enzyme assays and mass spectrometry.

limitations

This does not show that carnosine supplements alter RNA processing.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The carnosine methylating enzyme also acts on proteins.

primary_references

Identification of substrates and sequence requirements for CARNMT1-mediated histidine methylation of C3H zinc fingers. · 2025 · https://pubmed.ncbi.nlm.nih.gov/40473212/ · DOI 10.1016/j.jbc.2025.110335

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 156–162

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human cellular extracts, recombinant-enzyme assays and mass spectrometry. · source_derived_draft · unverified_draft

## carnosine-carnmt1-protein The carnosine methylating enzyme also acts on proteins. CARNMT1 methylated histidine-containing C3H zinc-finger substrates including U2AF1; cellular mass spectrometry supported these modifications. Model: Human cellular extracts, recombinant-enzyme assays and mass spectrometry. Limitations: This does not show that carnosine supplements alter RNA processing. Evidence access: Primary abstract Identification of substrates and sequence requirements for CARNMT1-mediated histidine methylation of C3H zinc fingers. · 2025 · https://pubmed.ncbi.nlm.nih.gov/40473212/ · DOI 10.1016/j.jbc.2025.110335

evidence_access

Primary abstract

experimental_model

Human neuroblastoma expression model.

limitations

Does not isolate 2-oxo-carnosine as the only protective mediator.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Increasing synthesis changed the cellular response to an oxidant.

primary_references

2-Oxo-histidine-containing dipeptides are functional oxidation products. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30504220/ · DOI 10.1074/jbc.RA118.006111

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 348–354

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human neuroblastoma expression model. · source_derived_draft · unverified_draft

## carnosine-carns1-cell-protection Increasing synthesis changed the cellular response to an oxidant. Stable carnosine-synthase expression in human SH-SY5Y cells was associated with 2-oxo-carnosine formation and less peroxide cytotoxicity. Model: Human neuroblastoma expression model. Limitations: Does not isolate 2-oxo-carnosine as the only protective mediator. Evidence access: Primary abstract 2-Oxo-histidine-containing dipeptides are functional oxidation products. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30504220/ · DOI 10.1074/jbc.RA118.006111

evidence_access

Primary abstract and PMC full-text Figure 2 and CRISPR methods

experimental_model

Human RT4 cell knockout and 25 mM lactate treatment for 24 hours; Figure 2.

limitations

This is a shared-enzyme connection, not proof that carnosine changes appetite.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The peptide-processing enzyme also participates in another metabolic pathway.

primary_references

An exercise-inducible metabolite that suppresses feeding and obesity. · 2022 · https://pubmed.ncbi.nlm.nih.gov/35705806/ · DOI 10.1038/s41586-022-04828-5

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 172–178

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human RT4 cell knockout and 25 mM lactate treatment for 24 hours; Figure 2. · source_derived_draft · unverified_draft

## carnosine-cndp2-lacphe The peptide-processing enzyme also participates in another metabolic pathway. Deleting CNDP2 in human RT4 bladder epithelial cells reduced Lac-Phe production; extracellular lactate stimulated production in the control cells. Model: Human RT4 cell knockout and 25 mM lactate treatment for 24 hours; Figure 2. Limitations: This is a shared-enzyme connection, not proof that carnosine changes appetite. Evidence access: Primary abstract and PMC full-text Figure 2 and CRISPR methods An exercise-inducible metabolite that suppresses feeding and obesity. · 2022 · https://pubmed.ncbi.nlm.nih.gov/35705806/ · DOI 10.1038/s41586-022-04828-5

evidence_access

Primary abstract

experimental_model

Recombinant human CNDP2 characterization.

limitations

This does not show that manganese supplements lower carnosine in people.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Manganese supports the enzyme’s measured activity.

primary_references

Sequence identification and characterization of human carnosinase and a closely related non-specific dipeptidase. · 2003 · https://pubmed.ncbi.nlm.nih.gov/12473676/ · DOI 10.1074/jbc.M209764200

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 60–66

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Recombinant human CNDP2 characterization. · source_derived_draft · unverified_draft

## carnosine-cndp2-manganese Manganese supports the enzyme’s measured activity. Adding Mn2+ was required for full recombinant CNDP2 dipeptidase activity. Model: Recombinant human CNDP2 characterization. Limitations: This does not show that manganese supplements lower carnosine in people. Evidence access: Primary abstract Sequence identification and characterization of human carnosinase and a closely related non-specific dipeptidase. · 2003 · https://pubmed.ncbi.nlm.nih.gov/12473676/ · DOI 10.1074/jbc.M209764200

evidence_access

Primary abstract

experimental_model

Same biochemical study.

limitations

Context difference from DOPAL chemistry, not a contradiction.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The preferred scavenger changed with the target molecule.

primary_references

Biochemical characterization of the catecholaldehyde reactivity of L-carnosine and its therapeutic potential in human myocardium. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30191330/ · DOI 10.1007/s00726-018-2647-y

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 284–290

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Same biochemical study. · source_derived_draft · unverified_draft

## carnosine-gsh-hne The preferred scavenger changed with the target molecule. Glutathione reacted more readily than carnosine with HNE in the comparative assay. Model: Same biochemical study. Limitations: Context difference from DOPAL chemistry, not a contradiction. Evidence access: Primary abstract Biochemical characterization of the catecholaldehyde reactivity of L-carnosine and its therapeutic potential in human myocardium. · 2019 · https://pubmed.ncbi.nlm.nih.gov/30191330/ · DOI 10.1007/s00726-018-2647-y

evidence_access

Primary abstract

experimental_model

Same 23-day study.

limitations

Physiological consequences of the declines were not established.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Making more carnosine can draw on another amino-acid pool.

primary_references

Effects of Histidine and β-alanine Supplementation on Human Muscle Carnosine Storage. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28106620/ · DOI 10.1249/MSS.0000000000001213

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 116–122

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Same 23-day study. · source_derived_draft · unverified_draft

## carnosine-histidine-cost Making more carnosine can draw on another amino-acid pool. Beta-alanine supplementation lowered free histidine in muscle by 31.6% and plasma by 30.6%; simultaneous histidine prevented these declines. Model: Same 23-day study. Limitations: Physiological consequences of the declines were not established. Evidence access: Primary abstract Effects of Histidine and β-alanine Supplementation on Human Muscle Carnosine Storage. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28106620/ · DOI 10.1249/MSS.0000000000001213

evidence_access

Primary abstract

experimental_model

Thirty adults; 23 days; BA 6 g/day, histidine 3.5 g/day or both.

limitations

Study exposures, not personal dosing guidance.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

More of one precursor helped; adding the other did not further raise carnosine.

primary_references

Effects of Histidine and β-alanine Supplementation on Human Muscle Carnosine Storage. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28106620/ · DOI 10.1249/MSS.0000000000001213

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 108–114

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Thirty adults; 23 days; BA 6 g/day, histidine 3.5 g/day or both. · source_derived_draft · unverified_draft

## carnosine-histidine-loading More of one precursor helped; adding the other did not further raise carnosine. Beta-alanine alone or with histidine increased muscle carnosine; histidine alone did not, and the combined group did not exceed beta-alanine alone. Model: Thirty adults; 23 days; BA 6 g/day, histidine 3.5 g/day or both. Limitations: Study exposures, not personal dosing guidance. Evidence access: Primary abstract Effects of Histidine and β-alanine Supplementation on Human Muscle Carnosine Storage. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28106620/ · DOI 10.1249/MSS.0000000000001213

evidence_access

Primary abstract

experimental_model

Cell-free 10 mM amino-acid comparison.

limitations

Not evidence that dietary histidine damages human DNA.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The breakdown product did not behave like the intact peptide.

primary_references

Antioxidant properties of carnosine re-evaluated with oxidizing systems involving iron and copper ions. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15853927/ · DOI 10.1111/j.1742-7843.2005.pto_03.x

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 316–322

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Cell-free 10 mM amino-acid comparison. · source_derived_draft · unverified_draft

## carnosine-histidine-metal The breakdown product did not behave like the intact peptide. Histidine increased DNA damage in the tested iron/peroxide/ascorbate system and weakened carnosine protection when combined with it. Model: Cell-free 10 mM amino-acid comparison. Limitations: Not evidence that dietary histidine damages human DNA. Evidence access: Primary abstract Antioxidant properties of carnosine re-evaluated with oxidizing systems involving iron and copper ions. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15853927/ · DOI 10.1111/j.1742-7843.2005.pto_03.x

evidence_access

Primary abstract

experimental_model

Recombinant human enzyme substrate comparison.

limitations

Shared synthesis does not mean the two peptides have identical functions.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The same enzyme can assemble a related GABA-containing peptide.

primary_references

Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1). · 2010 · https://pubmed.ncbi.nlm.nih.gov/20097752/ · DOI 10.1074/jbc.M109.095505

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 36–42

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Recombinant human enzyme substrate comparison. · source_derived_draft · unverified_draft

## carnosine-homocarnosine The same enzyme can assemble a related GABA-containing peptide. Purified human CARNS1 also synthesized homocarnosine using GABA, with lower catalytic efficiency than the beta-alanine reaction. Model: Recombinant human enzyme substrate comparison. Limitations: Shared synthesis does not mean the two peptides have identical functions. Evidence access: Primary abstract Molecular identification of carnosine synthase as ATP-grasp domain-containing protein 1 (ATPGD1). · 2010 · https://pubmed.ncbi.nlm.nih.gov/20097752/ · DOI 10.1074/jbc.M109.095505

evidence_access

Primary abstract plus Reactome reaction R-HSA-8876789

experimental_model

Purified human enzyme; reaction identity also curated in Reactome R-HSA-8876789.

limitations

Does not establish methyl-donor depletion or benefit from folate/B12 supplements.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A methyl group turns carnosine into a distinct peptide.

primary_references

UPF0586 Protein C9orf41 Homolog Is Anserine-producing Methyltransferase. · 2015 · https://pubmed.ncbi.nlm.nih.gov/26001783/ · DOI 10.1074/jbc.M115.640037

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 148–154

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Purified human enzyme; reaction identity also curated in Reactome R-HSA-8876789. · source_derived_draft · unverified_draft

## carnosine-methylation A methyl group turns carnosine into a distinct peptide. Recombinant human CARNMT1 methylated carnosine to anserine; the reaction uses S-adenosylmethionine as methyl donor. Model: Purified human enzyme; reaction identity also curated in Reactome R-HSA-8876789. Limitations: Does not establish methyl-donor depletion or benefit from folate/B12 supplements. Evidence access: Primary abstract plus Reactome reaction R-HSA-8876789 UPF0586 Protein C9orf41 Homolog Is Anserine-producing Methyltransferase. · 2015 · https://pubmed.ncbi.nlm.nih.gov/26001783/ · DOI 10.1074/jbc.M115.640037

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Old and aged mice, 18 and 24 months.

limitations

Tissue/age specificity remains important; does not negate chemical scavenging.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

An antioxidant role was not necessary for these measured outcomes.

primary_references

Absence of endogenous carnosine synthesis does not increase protein carbonylation and advanced lipoxidation end products in brain, kidney or muscle. · 2022 · https://pubmed.ncbi.nlm.nih.gov/35294673/ · DOI 10.1007/s00726-022-03150-8

trigger_kind

machinery_impairment Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 420–426

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Old and aged mice, 18 and 24 months. · source_derived_draft · unverified_draft

## carnosine-mouse-carbonyl-null An antioxidant role was not necessary for these measured outcomes. Carns1 deletion did not increase brain or kidney protein carbonylation in the studied aging cohorts. Model: Old and aged mice, 18 and 24 months. Limitations: Tissue/age specificity remains important; does not negate chemical scavenging. Evidence access: Primary abstract Absence of endogenous carnosine synthesis does not increase protein carbonylation and advanced lipoxidation end products in brain, kidney or muscle. · 2022 · https://pubmed.ncbi.nlm.nih.gov/35294673/ · DOI 10.1007/s00726-022-03150-8

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Double-mutant mouse kidney analysis.

limitations

One marker and model do not establish absence of every effect.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The tested diabetic injury marker did not worsen further.

primary_references

Absence of endogenous carnosine synthesis does not increase protein carbonylation and advanced lipoxidation end products in brain, kidney or muscle. · 2022 · https://pubmed.ncbi.nlm.nih.gov/35294673/ · DOI 10.1007/s00726-022-03150-8

trigger_kind

machinery_impairment Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 428–434

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Double-mutant mouse kidney analysis. · source_derived_draft · unverified_draft

## carnosine-mouse-diabetes-null The tested diabetic injury marker did not worsen further. Adding Carns1 deficiency to Lepr-db/db mice did not further increase the already elevated renal malondialdehyde adducts. Model: Double-mutant mouse kidney analysis. Limitations: One marker and model do not establish absence of every effect. Evidence access: Primary abstract Absence of endogenous carnosine synthesis does not increase protein carbonylation and advanced lipoxidation end products in brain, kidney or muscle. · 2022 · https://pubmed.ncbi.nlm.nih.gov/35294673/ · DOI 10.1007/s00726-022-03150-8

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Genetic mouse knockout.

limitations

Machinery failure, not a human dietary-deficiency syndrome.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Removing synthesis emptied the measured peptide pools.

primary_references

Carnosine synthase deficiency is compatible with normal skeletal muscle and olfactory function but causes reduced olfactory sensitivity in aging mice. · 2020 · https://pubmed.ncbi.nlm.nih.gov/33040025/ · DOI 10.1074/jbc.RA120.014188

trigger_kind

machinery_impairment Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 396–402

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Genetic mouse knockout. · source_derived_draft · unverified_draft

## carnosine-mouse-loss Removing synthesis emptied the measured peptide pools. Carns1 deletion made histidine-containing dipeptides undetectable in the primary olfactory system and skeletal muscle. Model: Genetic mouse knockout. Limitations: Machinery failure, not a human dietary-deficiency syndrome. Evidence access: Primary abstract Carnosine synthase deficiency is compatible with normal skeletal muscle and olfactory function but causes reduced olfactory sensitivity in aging mice. · 2020 · https://pubmed.ncbi.nlm.nih.gov/33040025/ · DOI 10.1074/jbc.RA120.014188

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Mouse knockout.

limitations

Different from adding carnosine to isolated human fibers; not a direct contradiction.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Loss of the peptide did not disable every proposed function.

primary_references

Carnosine synthase deficiency is compatible with normal skeletal muscle and olfactory function but causes reduced olfactory sensitivity in aging mice. · 2020 · https://pubmed.ncbi.nlm.nih.gov/33040025/ · DOI 10.1074/jbc.RA120.014188

trigger_kind

machinery_impairment Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 412–418

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Mouse knockout. · source_derived_draft · unverified_draft

## carnosine-mouse-muscle-null Loss of the peptide did not disable every proposed function. Deleting Carns1 did not measurably impair skeletal-muscle contraction or buffering capacity in the tested mice. Model: Mouse knockout. Limitations: Different from adding carnosine to isolated human fibers; not a direct contradiction. Evidence access: Primary abstract Carnosine synthase deficiency is compatible with normal skeletal muscle and olfactory function but causes reduced olfactory sensitivity in aging mice. · 2020 · https://pubmed.ncbi.nlm.nih.gov/33040025/ · DOI 10.1074/jbc.RA120.014188

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Mouse aging study, 18–24 months versus eight months.

limitations

Cannot convert genetic aging effects into human intake thresholds.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The functional effect depended on age and tissue.

primary_references

Carnosine synthase deficiency is compatible with normal skeletal muscle and olfactory function but causes reduced olfactory sensitivity in aging mice. · 2020 · https://pubmed.ncbi.nlm.nih.gov/33040025/ · DOI 10.1074/jbc.RA120.014188

trigger_kind

machinery_impairment Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 404–410

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Mouse aging study, 18–24 months versus eight months. · source_derived_draft · unverified_draft

## carnosine-mouse-olfaction The functional effect depended on age and tissue. Aged Carns1-null mice showed reduced olfactory sensitivity and fewer olfactory receptor neurons; younger tested mice did not show this deficit. Model: Mouse aging study, 18–24 months versus eight months. Limitations: Cannot convert genetic aging effects into human intake thresholds. Evidence access: Primary abstract Carnosine synthase deficiency is compatible with normal skeletal muscle and olfactory function but causes reduced olfactory sensitivity in aging mice. · 2020 · https://pubmed.ncbi.nlm.nih.gov/33040025/ · DOI 10.1074/jbc.RA120.014188

evidence_access

Primary abstract

experimental_model

Twenty men; 6.4 g/day; proton and phosphorus MRS.

limitations

Without demonstrated loading, the result cannot isolate whether added tissue carnosine would buffer exercise pH.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Loading and buffering benefits were not demonstrated in every trial.

primary_references

The Effects of β-Alanine Supplementation on Muscle pH and the Power-Duration Relationship during High-Intensity Exercise. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29515455/ · DOI 10.3389/fphys.2018.00111

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 228–234

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Twenty men; 6.4 g/day; proton and phosphorus MRS. · source_derived_draft · unverified_draft

## carnosine-negative-loading-ph Loading and buffering benefits were not demonstrated in every trial. In a 28-day randomized trial, beta-alanine did not significantly change measured muscle carnosine or exercise muscle pH versus placebo. Model: Twenty men; 6.4 g/day; proton and phosphorus MRS. Limitations: Without demonstrated loading, the result cannot isolate whether added tissue carnosine would buffer exercise pH. Evidence access: Primary abstract The Effects of β-Alanine Supplementation on Muscle pH and the Power-Duration Relationship during High-Intensity Exercise. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29515455/ · DOI 10.3389/fphys.2018.00111

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Mouse tracer disposition.

limitations

Endogenous plasma and CSF concentrations did not differ; tracer and steady-state results are distinct.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The transporter also changes distribution around the brain.

primary_references

Influence of genetic knockout of Pept2 on the in vivo disposition of endogenous and exogenous carnosine in wild-type and Pept2 null mice. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19225147/ · DOI 10.1152/ajpregu.90744.2008

trigger_kind

machinery_impairment Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 100–106

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Mouse tracer disposition. · source_derived_draft · unverified_draft

## carnosine-pept2-brain The transporter also changes distribution around the brain. After injected carnosine, Pept2-null mice had an approximately eightfold greater CSF-to-plasma concentration ratio. Model: Mouse tracer disposition. Limitations: Endogenous plasma and CSF concentrations did not differ; tracer and steady-state results are distinct. Evidence access: Primary abstract Influence of genetic knockout of Pept2 on the in vivo disposition of endogenous and exogenous carnosine in wild-type and Pept2 null mice. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19225147/ · DOI 10.1152/ajpregu.90744.2008

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Wild-type and Pept2-null mice; radiolabeled IV carnosine.

limitations

Mouse disposition does not give a human oral dose.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Kidney peptide transport helps retain the molecule.

primary_references

Influence of genetic knockout of Pept2 on the in vivo disposition of endogenous and exogenous carnosine in wild-type and Pept2 null mice. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19225147/ · DOI 10.1152/ajpregu.90744.2008

trigger_kind

machinery_impairment Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 92–98

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Wild-type and Pept2-null mice; radiolabeled IV carnosine. · source_derived_draft · unverified_draft

## carnosine-pept2-kidney Kidney peptide transport helps retain the molecule. Deleting Pept2 increased renal clearance of injected carnosine about 18-fold and reduced fractional reabsorption. Model: Wild-type and Pept2-null mice; radiolabeled IV carnosine. Limitations: Mouse disposition does not give a human oral dose. Evidence access: Primary abstract Influence of genetic knockout of Pept2 on the in vivo disposition of endogenous and exogenous carnosine in wild-type and Pept2 null mice. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19225147/ · DOI 10.1152/ajpregu.90744.2008

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Four-month-old male knockout rats.

limitations

Loss affects carnosine and anserine; cannot assign all effects to one peptide.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Heart calcium handling changed when synthesis was absent.

primary_references

Histidine dipeptides are key regulators of excitation-contraction coupling in cardiac muscle: Evidence from a novel CARNS1 knockout rat model. · 2021 · https://pubmed.ncbi.nlm.nih.gov/34038814/ · DOI 10.1016/j.redox.2021.102016

trigger_kind

machinery_impairment Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 436–442

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Four-month-old male knockout rats. · source_derived_draft · unverified_draft

## carnosine-rat-calcium Heart calcium handling changed when synthesis was absent. Carns1 deletion eliminated histidine dipeptides and produced lower cardiomyocyte calcium peaks with slower calcium removal. Model: Four-month-old male knockout rats. Limitations: Loss affects carnosine and anserine; cannot assign all effects to one peptide. Evidence access: Primary abstract Histidine dipeptides are key regulators of excitation-contraction coupling in cardiac muscle: Evidence from a novel CARNS1 knockout rat model. · 2021 · https://pubmed.ncbi.nlm.nih.gov/34038814/ · DOI 10.1016/j.redox.2021.102016

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Echocardiography and ex vivo rat cardiomyocytes.

limitations

Oxidative-stress markers and mitochondrial respiration were not impaired in parallel.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A machinery defect affected heart function in this model.

primary_references

Histidine dipeptides are key regulators of excitation-contraction coupling in cardiac muscle: Evidence from a novel CARNS1 knockout rat model. · 2021 · https://pubmed.ncbi.nlm.nih.gov/34038814/ · DOI 10.1016/j.redox.2021.102016

trigger_kind

machinery_impairment Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 444–450

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Echocardiography and ex vivo rat cardiomyocytes. · source_derived_draft · unverified_draft

## carnosine-rat-heart A machinery defect affected heart function in this model. Carns1-null rats had impaired cardiac contraction/relaxation in vivo and in isolated cardiomyocytes. Model: Echocardiography and ex vivo rat cardiomyocytes. Limitations: Oxidative-stress markers and mitochondrial respiration were not impaired in parallel. Evidence access: Primary abstract Histidine dipeptides are key regulators of excitation-contraction coupling in cardiac muscle: Evidence from a novel CARNS1 knockout rat model. · 2021 · https://pubmed.ncbi.nlm.nih.gov/34038814/ · DOI 10.1016/j.redox.2021.102016

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Same rat model.

limitations

Tissue difference rather than opposing statements about the same condition.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The cardiac phenotype did not apply equally to skeletal muscle.

primary_references

Histidine dipeptides are key regulators of excitation-contraction coupling in cardiac muscle: Evidence from a novel CARNS1 knockout rat model. · 2021 · https://pubmed.ncbi.nlm.nih.gov/34038814/ · DOI 10.1016/j.redox.2021.102016

trigger_kind

machinery_impairment Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 452–458

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Same rat model. · source_derived_draft · unverified_draft

## carnosine-rat-muscle-null The cardiac phenotype did not apply equally to skeletal muscle. Carns1 deletion did not impair measured skeletal-muscle force, fatigability, exercise capacity or buffering in the rats. Model: Same rat model. Limitations: Tissue difference rather than opposing statements about the same condition. Evidence access: Primary abstract Histidine dipeptides are key regulators of excitation-contraction coupling in cardiac muscle: Evidence from a novel CARNS1 knockout rat model. · 2021 · https://pubmed.ncbi.nlm.nih.gov/34038814/ · DOI 10.1016/j.redox.2021.102016

availability_state

biomarker_context Imported condition classification; unverified.

evidence_access

Primary abstract

experimental_model

Human blood-sample handling experiment.

limitations

A negative untreated plasma assay cannot prove no absorption occurred.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Breakdown after blood collection can hide the signal.

primary_references

Intestinal absorption of the intact peptide carnosine in man, and comparison with intestinal permeability to lactulose. · 1991 · https://pubmed.ncbi.nlm.nih.gov/1910085/ · DOI 10.1113/jphysiol.1991.sp018673

trigger_kind

biomarker_context Imported condition classification; unverified.

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 84–90

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human blood-sample handling experiment. · source_derived_draft · unverified_draft

## carnosine-sample-hydrolysis Breakdown after blood collection can hide the signal. Intact carnosine became detectable in sampled plasma when ex vivo blood carnosinase activity was inhibited. Model: Human blood-sample handling experiment. Limitations: A negative untreated plasma assay cannot prove no absorption occurred. Evidence access: Primary abstract Intestinal absorption of the intact peptide carnosine in man, and comparison with intestinal permeability to lactulose. · 1991 · https://pubmed.ncbi.nlm.nih.gov/1910085/ · DOI 10.1113/jphysiol.1991.sp018673

evidence_access

Primary abstract

experimental_model

Mice; beta-alanine 0.1% in drinking water for two weeks.

limitations

Broad inhibitor experiment; not an intervention recommendation.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Blocking multiple precursor-disposal routes changed tissue peptide stores.

primary_references

Carnosine and anserine homeostasis in skeletal muscle and heart is controlled by β-alanine transamination. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27062388/ · DOI 10.1113/JP272050

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 140–146

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Mice; beta-alanine 0.1% in drinking water for two weeks. · source_derived_draft · unverified_draft

## carnosine-transamination-block Blocking multiple precursor-disposal routes changed tissue peptide stores. AOA treatment during beta-alanine feeding raised circulating beta-alanine and muscle/heart carnosine and anserine; selective GABA-T inhibition with vigabatrin did not. Model: Mice; beta-alanine 0.1% in drinking water for two weeks. Limitations: Broad inhibitor experiment; not an intervention recommendation. Evidence access: Primary abstract Carnosine and anserine homeostasis in skeletal muscle and heart is controlled by β-alanine transamination. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27062388/ · DOI 10.1113/JP272050

evidence_access

Primary abstract

experimental_model

Human enzyme expressed in HEK293T cells.

limitations

No clinical effect of changing vitamin B6 intake was established.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A competing enzyme can divert the precursor away from peptide synthesis.

primary_references

Carnosine and anserine homeostasis in skeletal muscle and heart is controlled by β-alanine transamination. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27062388/ · DOI 10.1113/JP272050

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 124–130

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human enzyme expressed in HEK293T cells. · source_derived_draft · unverified_draft

## carnosine-transamination-human-abat A competing enzyme can divert the precursor away from peptide synthesis. Recombinant human ABAT efficiently transaminated beta-alanine. Model: Human enzyme expressed in HEK293T cells. Limitations: No clinical effect of changing vitamin B6 intake was established. Evidence access: Primary abstract Carnosine and anserine homeostasis in skeletal muscle and heart is controlled by β-alanine transamination. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27062388/ · DOI 10.1113/JP272050

evidence_access

Primary abstract

experimental_model

Human enzyme expressed in HEK293T cells.

limitations

No clinical effect of changing vitamin B6 intake was established.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A competing enzyme can divert the precursor away from peptide synthesis.

primary_references

Carnosine and anserine homeostasis in skeletal muscle and heart is controlled by β-alanine transamination. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27062388/ · DOI 10.1113/JP272050

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 132–138

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human enzyme expressed in HEK293T cells. · source_derived_draft · unverified_draft

## carnosine-transamination-human-agxt2 A competing enzyme can divert the precursor away from peptide synthesis. Recombinant human AGXT2 efficiently transaminated beta-alanine. Model: Human enzyme expressed in HEK293T cells. Limitations: No clinical effect of changing vitamin B6 intake was established. Evidence access: Primary abstract Carnosine and anserine homeostasis in skeletal muscle and heart is controlled by β-alanine transamination. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27062388/ · DOI 10.1113/JP272050

evidence_access

Primary abstract

experimental_model

Eight-person four-arm crossover trial.

limitations

Small study; does not establish prevention of heat stroke.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

A separate challenge model showed a barrier-marker effect.

primary_references

Zinc carnosine works with bovine colostrum in truncating heavy exercise-induced increase in gut permeability in healthy volunteers. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27357095/ · DOI 10.3945/ajcn.116.134403

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 380–386

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Eight-person four-arm crossover trial. · source_derived_draft · unverified_draft

## carnosine-zinc-exercise A separate challenge model showed a barrier-marker effect. Zinc-carnosine reduced the exercise-associated permeability rise after fourteen days; combined colostrum treatment also showed an earlier response. Model: Eight-person four-arm crossover trial. Limitations: Small study; does not establish prevention of heat stroke. Evidence access: Primary abstract Zinc carnosine works with bovine colostrum in truncating heavy exercise-induced increase in gut permeability in healthy volunteers. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27357095/ · DOI 10.3945/ajcn.116.134403

evidence_access

Primary abstract

experimental_model

Ten healthy volunteers; five-day crossover; lactulose:rhamnose measurement.

limitations

Small trial and surrogate endpoint; not free-carnosine efficacy.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The complex changed a human intestinal-barrier marker.

primary_references

Zinc carnosine, a health food supplement that stabilises small bowel integrity and stimulates gut repair processes. · 2007 · https://pubmed.ncbi.nlm.nih.gov/16777920/ · DOI 10.1136/gut.2006.099929

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 372–378

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Ten healthy volunteers; five-day crossover; lactulose:rhamnose measurement. · source_derived_draft · unverified_draft

## carnosine-zinc-indomethacin The complex changed a human intestinal-barrier marker. Zinc-carnosine coadministration prevented the significant permeability rise seen during the placebo/indomethacin arm. Model: Ten healthy volunteers; five-day crossover; lactulose:rhamnose measurement. Limitations: Small trial and surrogate endpoint; not free-carnosine efficacy. Evidence access: Primary abstract Zinc carnosine, a health food supplement that stabilises small bowel integrity and stimulates gut repair processes. · 2007 · https://pubmed.ncbi.nlm.nih.gov/16777920/ · DOI 10.1136/gut.2006.099929

evidence_access

Primary abstract

experimental_model

Human Caco-2/HT29 cell models with a 2-degree temperature increase.

limitations

Cell experiments do not prove this mediated the volunteer outcome.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Tight-junction proteins offered a possible explanation.

primary_references

Zinc carnosine works with bovine colostrum in truncating heavy exercise-induced increase in gut permeability in healthy volunteers. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27357095/ · DOI 10.3945/ajcn.116.134403

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 388–394

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human Caco-2/HT29 cell models with a 2-degree temperature increase. · source_derived_draft · unverified_draft

## carnosine-zinc-occludin Tight-junction proteins offered a possible explanation. In heated intestinal-cell models, zinc-carnosine increased total occludin and reduced measured occludin phosphorylation changes. Model: Human Caco-2/HT29 cell models with a 2-degree temperature increase. Limitations: Cell experiments do not prove this mediated the volunteer outcome. Evidence access: Primary abstract Zinc carnosine works with bovine colostrum in truncating heavy exercise-induced increase in gut permeability in healthy volunteers. · 2016 · https://pubmed.ncbi.nlm.nih.gov/27357095/ · DOI 10.3945/ajcn.116.134403

evidence_access

Primary abstract

experimental_model

Human HT29 culture.

limitations

Cell proliferation is not universally beneficial and is not proof of whole-gut healing.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

Cell growth was measured separately from migration.

primary_references

Zinc carnosine, a health food supplement that stabilises small bowel integrity and stimulates gut repair processes. · 2007 · https://pubmed.ncbi.nlm.nih.gov/16777920/ · DOI 10.1136/gut.2006.099929

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 364–370

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human HT29 culture. · source_derived_draft · unverified_draft

## carnosine-zinc-proliferation Cell growth was measured separately from migration. Zinc-carnosine increased HT29 proliferation in thymidine-incorporation assays. Model: Human HT29 culture. Limitations: Cell proliferation is not universally beneficial and is not proof of whole-gut healing. Evidence access: Primary abstract Zinc carnosine, a health food supplement that stabilises small bowel integrity and stimulates gut repair processes. · 2007 · https://pubmed.ncbi.nlm.nih.gov/16777920/ · DOI 10.1136/gut.2006.099929

evidence_access

Primary abstract

experimental_model

Human colon-derived HT29 cells; maximal reported response near 100 micromolar.

limitations

Complex-specific experiment; not automatically attributable to free carnosine.

nutrient_topic

Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit. · L-Carnosine / beta-alanyl-L-histidine

plain_language

The zinc complex supported repair behavior in culture.

primary_references

Zinc carnosine, a health food supplement that stabilises small bowel integrity and stimulates gut repair processes. · 2007 · https://pubmed.ncbi.nlm.nih.gov/16777920/ · DOI 10.1136/gut.2006.099929

Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19) · lines 356–362

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human colon-derived HT29 cells; maximal reported response near 100 micromolar. · source_derived_draft · unverified_draft

## carnosine-zinc-repair The zinc complex supported repair behavior in culture. Zinc-carnosine treatment stimulated epithelial migration in wounded HT29 monolayers. Model: Human colon-derived HT29 cells; maximal reported response near 100 micromolar. Limitations: Complex-specific experiment; not automatically attributable to free carnosine. Evidence access: Primary abstract Zinc carnosine, a health food supplement that stabilises small bowel integrity and stimulates gut repair processes. · 2007 · https://pubmed.ncbi.nlm.nih.gov/16777920/ · DOI 10.1136/gut.2006.099929