All-trans-beta-carotene

dose

Pureed labeled Moringa leaves providing 1 mg beta-carotene plus a reference retinyl-acetate dose

duration

Thirty-five-day isotope sampling

evidence_access

Primary PubMed abstract and indexed metadata reviewed. Full-text method details not stated here remain unresolved.

evidence_scope

literature_reviewed; model-specific source-derived curation

experimental_model

Fifteen Mexican children aged 17-35 months

limitations

Children were well nourished with adequate vitamin A stores; the estimate may differ with deficiency, food matrix, genetics and infection.

nutrient_topic

Moringa oleifera chapter; interacting nutrients, drugs, peptides and proteins retain their experimental settings. · Moringa oleifera

organism

Fifteen Mexican children aged 17-35 months

plain_language

In fifteen well-nourished young children, intrinsically labeled beta-carotene from pureed Moringa leaves had 28% relative bioefficacy and an estimated vitamin A equivalence of 3.3:1 by weight.

primary_references

Use of a "Super-child" Approach to Assess the Vitamin A Equivalence of Moringa oleifera Leaves, Develop a Compartmental Model for Vitamin A Kinetics, and Estimate Vitamin A Total Body Stores in Young Mexican Children. (2017). https://pubmed.ncbi.nlm.nih.gov/28931584/ DOI: 10.3945/jn.117.256974

route

Oral

tissue

Stable-isotope plasma retinol kinetics

Moringa oleifera: mechanism of action and interactions (2026-09-20) · lines 233–242

Original AI-assisted source-specific curation with primary-study citations, model, exposure, route, duration, negative findings and limitations preserved. Not publisher full text. · supports · Fifteen Mexican children aged 17-35 months · source_derived_draft · unverified_draft

## moringa-child-vitamin-a-equivalence In fifteen well-nourished young children, intrinsically labeled beta-carotene from pureed Moringa leaves had 28% relative bioefficacy and an estimated vitamin A equivalence of 3.3:1 by weight. Model/species: Fifteen Mexican children aged 17-35 months Tissue/system: Stable-isotope plasma retinol kinetics Exposure: Pureed labeled Moringa leaves providing 1 mg beta-carotene plus a reference retinyl-acetate dose Route: Oral Duration: Thirty-five-day isotope sampling Limits: Children were well nourished with adequate vitamin A stores; the estimate may differ with deficiency, food matrix, genetics and infection. Primary reference: Use of a "Super-child" Approach to Assess the Vitamin A Equivalence of Moringa oleifera Leaves, Develop a Compartmental Model for Vitamin A Kinetics, and Estimate Vitamin A Total Body Stores in Young Mexican Children. (2017). https://pubmed.ncbi.nlm.nih.gov/28931584/ DOI: 10.3945/jn.117.256974 Access: Primary PubMed abstract and indexed metadata reviewed. Full-text method details not stated here remain unresolved.

evidence_span

{"source_cache": "artifacts/lycopene-research/9278568.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e318f6fef0bfed88403fa2adf46f9713ebddfe6ea586c29614e820442c57d056", "start_char": 0, "end_char": 1510, "text_sha256": "e318f6fef0bfed88403fa2adf46f9713ebddfe6ea586c29614e820442c57d056"}

experimental_model

Randomized-order double-blind crossover dosing experiment

exposure

60 mg beta-carotene, 60 mg lycopene, or 60 mg of each together

limitations

Acute high-dose study; does not justify routine co-supplementation or establish universal competition rules.

nutrient_topic

Lycopene research collection; topical membership is not evidence of a direct dietary effect. · Lycopene

organism

Human, ten healthy men

plain_language

Two carotenoids did not simply block one another in this experiment.

primary_references

[lycopene-p9278568] Ingestion by men of a combined dose of beta-carotene and lycopene does not affect the absorption of beta-carotene but improves that of lycopene. (1997). https://pubmed.ncbi.nlm.nih.gov/9278568/ DOI: 10.1093/jn/127.9.1833

tissue_or_cell_type

Serum carotenoid AUC over 24 hours

Lycopene: absorption, metabolism, nutrient connections and human outcomes (2026-09-17) · lines 780–791

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Randomized-order double-blind crossover dosing experiment · source_derived_draft · unverified_draft

### lycopene-beta-carotene-co-dose Co-dosing beta-carotene increased the 24-hour lycopene AUC relative to lycopene alone. Condition category: normal nutrient_topic: Lycopene research collection; topical membership is not evidence of a direct dietary effect. plain_language: Two carotenoids did not simply block one another in this experiment. organism: Human, ten healthy men tissue_or_cell_type: Serum carotenoid AUC over 24 hours experimental_model: Randomized-order double-blind crossover dosing experiment limitations: Acute high-dose study; does not justify routine co-supplementation or establish universal competition rules. exposure: 60 mg beta-carotene, 60 mg lycopene, or 60 mg of each together evidence_span: {"source_cache": "artifacts/lycopene-research/9278568.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e318f6fef0bfed88403fa2adf46f9713ebddfe6ea586c29614e820442c57d056", "start_char": 0, "end_char": 1510, "text_sha256": "e318f6fef0bfed88403fa2adf46f9713ebddfe6ea586c29614e820442c57d056"} [lycopene-p9278568] Ingestion by men of a combined dose of beta-carotene and lycopene does not affect the absorption of beta-carotene but improves that of lycopene. (1997). https://pubmed.ncbi.nlm.nih.gov/9278568/ DOI: 10.1093/jn/127.9.1833

evidence_span

{"source_cache": "artifacts/lutein-research/15554873.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "3dfbef37e3c73db4732f66083063e548a1654cb759ff46392c981c50f338d8a0", "start_char": 0, "end_char": 2014, "text_sha256": "3dfbef37e3c73db4732f66083063e548a1654cb759ff46392c981c50f338d8a0"}

experimental_model

Mixed-micelle transport across Caco-2 TC-7 monolayers

exposure

Micellar lutein 1.5–15 micromolar; antibodies and BLT1

limitations

Partial inhibition supports a contribution, not an exclusive route; cell experiments do not set clinical supplement spacing.

nutrient_topic

Lutein research collection; topical membership is not evidence of a direct dietary effect. · Lutein

organism

Human intestinal cell model

plain_language

Another carotenoid competed under these conditions.

primary_references

[lutein-p15554873] Lutein transport by Caco-2 TC-7 cells occurs partly by a facilitated process involving the scavenger receptor class B type I (SR-BI). (2005). https://pubmed.ncbi.nlm.nih.gov/15554873/ DOI: 10.1042/bj20040554

tissue_or_cell_type

Apical intestinal epithelial transport

Lutein: metabolism, signaling and nutrient connections (2026-09-17) · lines 489–500

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Mixed-micelle transport across Caco-2 TC-7 monolayers · source_derived_draft · unverified_draft

### lutein-beta-competition Co-incubated beta-carotene reduced lutein absorption by approximately 20% in this cell model. Condition category: normal nutrient_topic: Lutein research collection; topical membership is not evidence of a direct dietary effect. plain_language: Another carotenoid competed under these conditions. organism: Human intestinal cell model tissue_or_cell_type: Apical intestinal epithelial transport experimental_model: Mixed-micelle transport across Caco-2 TC-7 monolayers limitations: Partial inhibition supports a contribution, not an exclusive route; cell experiments do not set clinical supplement spacing. exposure: Micellar lutein 1.5–15 micromolar; antibodies and BLT1 evidence_span: {"source_cache": "artifacts/lutein-research/15554873.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "3dfbef37e3c73db4732f66083063e548a1654cb759ff46392c981c50f338d8a0", "start_char": 0, "end_char": 2014, "text_sha256": "3dfbef37e3c73db4732f66083063e548a1654cb759ff46392c981c50f338d8a0"} [lutein-p15554873] Lutein transport by Caco-2 TC-7 cells occurs partly by a facilitated process involving the scavenger receptor class B type I (SR-BI). (2005). https://pubmed.ncbi.nlm.nih.gov/15554873/ DOI: 10.1042/bj20040554

cross_nutrient

Carotene/vitamin E/tobacco context.

experimental_model

29,133 male smokers; factorial randomized trial.

exposure

20 mg/day beta-carotene, 5-8 years; study exposure only.

limitations

Supplement exposure is not equivalent to eating carotenoid-rich foods; the molecular cause was not isolated.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens

plain_language

The proposed antioxidant benefit did not predict the actual outcome.

primary_references

[va-atbc1994] The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers (1994). https://pubmed.ncbi.nlm.nih.gov/8127329/ DOI: 10.1056/nejm199404143301501

tissue_or_cell_type

Clinical lung-cancer incidence

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 1718–1729

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 29,133 male smokers; factorial randomized trial. · source_derived_draft · unverified_draft

### va-atbc-carotene-lung-cancer Beta-carotene increased lung-cancer incidence in the male-smoker trial; alpha-tocopherol did not show a significant interaction with this effect. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: The proposed antioxidant benefit did not predict the actual outcome. organism: Homo sapiens tissue_or_cell_type: Clinical lung-cancer incidence experimental_model: 29,133 male smokers; factorial randomized trial. limitations: Supplement exposure is not equivalent to eating carotenoid-rich foods; the molecular cause was not isolated. cross_nutrient: Carotene/vitamin E/tobacco context. exposure: 20 mg/day beta-carotene, 5-8 years; study exposure only. [va-atbc1994] The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers (1994). https://pubmed.ncbi.nlm.nih.gov/8127329/ DOI: 10.1056/nejm199404143301501

cross_nutrient

Retinoid/iron chemistry; hypothesis boundary retained.

experimental_model

Cell-free pH-shift experiment.

limitations

Solubility alone neither proves a defined retinoid-iron complex nor absorption in vivo.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens

plain_language

A laboratory solubility result supported a proposed explanation for the meal findings.

primary_references

[va-garciacasal1998] Vitamin A and beta-carotene can improve nonheme iron absorption from rice, wheat and corn by humans (1998). https://pubmed.ncbi.nlm.nih.gov/9482776/ DOI: 10.1093/jn/128.3.646

tissue_or_cell_type

Cell-free chemistry

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 1554–1564

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Cell-free pH-shift experiment. · source_derived_draft · unverified_draft

### va-retinoid-iron-solubility-assay Adding beta-carotene or vitamin A retained more iron in solution when the assay pH rose from acidic toward near-neutral. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: A laboratory solubility result supported a proposed explanation for the meal findings. organism: Homo sapiens tissue_or_cell_type: Cell-free chemistry experimental_model: Cell-free pH-shift experiment. limitations: Solubility alone neither proves a defined retinoid-iron complex nor absorption in vivo. cross_nutrient: Retinoid/iron chemistry; hypothesis boundary retained. [va-garciacasal1998] Vitamin A and beta-carotene can improve nonheme iron absorption from rice, wheat and corn by humans (1998). https://pubmed.ncbi.nlm.nih.gov/9482776/ DOI: 10.1093/jn/128.3.646

dose

Fresh or lyophilized leaves with 5% peanut oil

duration

Digestion and uptake time course

evidence_access

Primary PubMed abstract and indexed metadata reviewed. Full-text method details not stated here remain unresolved.

evidence_scope

literature_reviewed; model-specific source-derived curation

experimental_model

Simulated digestion coupled to human Caco-2 cells

limitations

This food-matrix result supports a fat effect on bioaccessibility but does not quantify human vitamin A status.

nutrient_topic

Moringa oleifera chapter; interacting nutrients, drugs, peptides and proteins retain their experimental settings. · Moringa oleifera

organism

Simulated digestion coupled to human Caco-2 cells

plain_language

Adding 5% peanut oil to Moringa leaves during simulated digestion increased beta-carotene and lutein micellarization, particularly beta-carotene, before uptake by Caco-2 cells.

primary_references

Micellarization and intestinal cell uptake of beta-carotene and lutein from drumstick (Moringa oleifera) leaves. (2007). https://pubmed.ncbi.nlm.nih.gov/17651060/ DOI: 10.1089/jmf.2006.250

route

In vitro digestion

tissue

Carotenoid micellarization and cell accumulation

Moringa oleifera: mechanism of action and interactions (2026-09-20) · lines 222–231

Original AI-assisted source-specific curation with primary-study citations, model, exposure, route, duration, negative findings and limitations preserved. Not publisher full text. · supports · Simulated digestion coupled to human Caco-2 cells · source_derived_draft · unverified_draft

## moringa-peanut-oil-carotenoid-bioaccessibility Adding 5% peanut oil to Moringa leaves during simulated digestion increased beta-carotene and lutein micellarization, particularly beta-carotene, before uptake by Caco-2 cells. Model/species: Simulated digestion coupled to human Caco-2 cells Tissue/system: Carotenoid micellarization and cell accumulation Exposure: Fresh or lyophilized leaves with 5% peanut oil Route: In vitro digestion Duration: Digestion and uptake time course Limits: This food-matrix result supports a fat effect on bioaccessibility but does not quantify human vitamin A status. Primary reference: Micellarization and intestinal cell uptake of beta-carotene and lutein from drumstick (Moringa oleifera) leaves. (2007). https://pubmed.ncbi.nlm.nih.gov/17651060/ DOI: 10.1089/jmf.2006.250 Access: Primary PubMed abstract and indexed metadata reviewed. Full-text method details not stated here remain unresolved.

evidence_access

Primary abstract

experimental_model

Cell-free phospholipid liposomes.

limitations

Regional chemistry was inferred from oxidation products, not direct proof of a permanently membrane-spanning orientation.

nutrient_topic

Astaxanthin collection; molecular form, preparation, species, exposure and manipulation remain explicit. · Astaxanthin

plain_language

Different regions of the molecule may participate in radical trapping.

primary_references

Efficient radical trapping at the surface and inside the phospholipid membrane is responsible for highly potent antiperoxidative activity of the carotenoid astaxanthin. · 2001 · https://pubmed.ncbi.nlm.nih.gov/11406102/ · DOI 10.1016/s0005-2736(01)00326-1

Astaxanthin: transport, membrane chemistry, signaling and nutrient interactions (2026-09-19) · lines 158–164

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

## astaxanthin-iron-liposome Different regions of the molecule may participate in radical trapping. Astaxanthin inhibited ADP/Fe2+-initiated liposome peroxidation more strongly than beta-carotene in this assay; chemical degradation patterns suggested contributions from both its polyene and terminal rings. Model: Cell-free phospholipid liposomes. Limitations: Regional chemistry was inferred from oxidation products, not direct proof of a permanently membrane-spanning orientation. Evidence access: Primary abstract Efficient radical trapping at the surface and inside the phospholipid membrane is responsible for highly potent antiperoxidative activity of the carotenoid astaxanthin. · 2001 · https://pubmed.ncbi.nlm.nih.gov/11406102/ · DOI 10.1016/s0005-2736(01)00326-1

evidence_access

Primary abstract

experimental_model

Photosensitized model lipid bilayers.

limitations

Oxidant source and position differ from other assays; this is context dependence, not an error requiring a universal ranking.

nutrient_topic

Astaxanthin collection; molecular form, preparation, species, exposure and manipulation remain explicit. · Astaxanthin

plain_language

Greater chemical stability did not guarantee greater protection.

primary_references

Inhibitory effect of beta-carotene and astaxanthin on photosensitized oxidation of phospholipid bilayers. · 1993 · https://pubmed.ncbi.nlm.nih.gov/8006717/ · DOI 10.3177/jnsv.39.607

Astaxanthin: transport, membrane chemistry, signaling and nutrient interactions (2026-09-19) · lines 166–172

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

## astaxanthin-photosensitizer-context Greater chemical stability did not guarantee greater protection. With a lipid-soluble photosensitizer in bilayers, astaxanthin was more stable yet less inhibitory than beta-carotene. Model: Photosensitized model lipid bilayers. Limitations: Oxidant source and position differ from other assays; this is context dependence, not an error requiring a universal ranking. Evidence access: Primary abstract Inhibitory effect of beta-carotene and astaxanthin on photosensitized oxidation of phospholipid bilayers. · 1993 · https://pubmed.ncbi.nlm.nih.gov/8006717/ · DOI 10.3177/jnsv.39.607

evidence_span

{"source_cache": "artifacts/lycopene-research/15735074.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "31bfa6900bd41221e84a0713fc5ccf97341dfb80d997eecc37a1f2a121b9d814", "start_char": 0, "end_char": 1730, "text_sha256": "31bfa6900bd41221e84a0713fc5ccf97341dfb80d997eecc37a1f2a121b9d814"}

experimental_model

Acute crossover meal experiment

exposure

Salsa with or without 150 g avocado; 9.5-hour sampling

limitations

Food comparison, not a requirement for this quantity of fat or evidence of a specific fatty-acid cofactor.

nutrient_topic

Lycopene research collection; topical membership is not evidence of a direct dietary effect. · Lycopene

organism

Human, 11 participants in the salsa study

plain_language

Eating the carotenoid within a meal containing fat changed absorption.

primary_references

[lycopene-p15735074] Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil. (2005). https://pubmed.ncbi.nlm.nih.gov/15735074/ DOI: 10.1093/jn/135.3.431

tissue_or_cell_type

Postprandial triglyceride-rich lipoproteins

Lycopene: absorption, metabolism, nutrient connections and human outcomes (2026-09-17) · lines 767–778

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Acute crossover meal experiment · source_derived_draft · unverified_draft

### lycopene-avocado-absorption Adding avocado to salsa increased mean lycopene TRL AUC 4.4-fold compared with avocado-free salsa. Condition category: normal nutrient_topic: Lycopene research collection; topical membership is not evidence of a direct dietary effect. plain_language: Eating the carotenoid within a meal containing fat changed absorption. organism: Human, 11 participants in the salsa study tissue_or_cell_type: Postprandial triglyceride-rich lipoproteins experimental_model: Acute crossover meal experiment limitations: Food comparison, not a requirement for this quantity of fat or evidence of a specific fatty-acid cofactor. exposure: Salsa with or without 150 g avocado; 9.5-hour sampling evidence_span: {"source_cache": "artifacts/lycopene-research/15735074.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "31bfa6900bd41221e84a0713fc5ccf97341dfb80d997eecc37a1f2a121b9d814", "start_char": 0, "end_char": 1730, "text_sha256": "31bfa6900bd41221e84a0713fc5ccf97341dfb80d997eecc37a1f2a121b9d814"} [lycopene-p15735074] Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil. (2005). https://pubmed.ncbi.nlm.nih.gov/15735074/ DOI: 10.1093/jn/135.3.431

evidence_span

{"source_cache": "artifacts/lycopene-research/9278568.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e318f6fef0bfed88403fa2adf46f9713ebddfe6ea586c29614e820442c57d056", "start_char": 0, "end_char": 1510, "text_sha256": "e318f6fef0bfed88403fa2adf46f9713ebddfe6ea586c29614e820442c57d056"}

experimental_model

Randomized-order double-blind crossover dosing experiment

exposure

60 mg beta-carotene, 60 mg lycopene, or 60 mg of each together

limitations

Acute high-dose study; does not justify routine co-supplementation or establish universal competition rules.

nutrient_topic

Lycopene research collection; topical membership is not evidence of a direct dietary effect. · Lycopene

organism

Human, ten healthy men

plain_language

The measured interaction was not symmetrical.

primary_references

[lycopene-p9278568] Ingestion by men of a combined dose of beta-carotene and lycopene does not affect the absorption of beta-carotene but improves that of lycopene. (1997). https://pubmed.ncbi.nlm.nih.gov/9278568/ DOI: 10.1093/jn/127.9.1833

tissue_or_cell_type

Serum carotenoid AUC over 24 hours

Lycopene: absorption, metabolism, nutrient connections and human outcomes (2026-09-17) · lines 793–804

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Randomized-order double-blind crossover dosing experiment · source_derived_draft · unverified_draft

### lycopene-beta-carotene-response-null The beta-carotene serum AUC did not differ when beta-carotene was taken alone or with lycopene. Condition category: normal nutrient_topic: Lycopene research collection; topical membership is not evidence of a direct dietary effect. plain_language: The measured interaction was not symmetrical. organism: Human, ten healthy men tissue_or_cell_type: Serum carotenoid AUC over 24 hours experimental_model: Randomized-order double-blind crossover dosing experiment limitations: Acute high-dose study; does not justify routine co-supplementation or establish universal competition rules. exposure: 60 mg beta-carotene, 60 mg lycopene, or 60 mg of each together evidence_span: {"source_cache": "artifacts/lycopene-research/9278568.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e318f6fef0bfed88403fa2adf46f9713ebddfe6ea586c29614e820442c57d056", "start_char": 0, "end_char": 1510, "text_sha256": "e318f6fef0bfed88403fa2adf46f9713ebddfe6ea586c29614e820442c57d056"} [lycopene-p9278568] Ingestion by men of a combined dose of beta-carotene and lycopene does not affect the absorption of beta-carotene but improves that of lycopene. (1997). https://pubmed.ncbi.nlm.nih.gov/9278568/ DOI: 10.1093/jn/127.9.1833

evidence_span

{"source_cache": "artifacts/lycopene-research/2802626.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "91ad9c300da17ee4e4c78a9ba980a7a4f05eef2328a64b5a9f75d4023abdc521", "start_char": 0, "end_char": 1046, "text_sha256": "91ad9c300da17ee4e4c78a9ba980a7a4f05eef2328a64b5a9f75d4023abdc521"}

experimental_model

Cell-free singlet-oxygen quenching comparison

exposure

Lycopene, beta-carotene, alpha-tocopherol and albumin-bound bilirubin

limitations

Rate constants are solvent/assay-dependent, not a clinical ranking of antioxidant supplements.

nutrient_topic

Lycopene research collection; topical membership is not evidence of a direct dietary effect. · Lycopene

organism

Chemical assay and plasma-concentration comparison

plain_language

A faster molecule is not automatically the more important antioxidant in blood.

primary_references

[lycopene-p2802626] Lycopene as the most efficient biological carotenoid singlet oxygen quencher. (1989). https://pubmed.ncbi.nlm.nih.gov/2802626/ DOI: 10.1016/0003-9861(89)90467-0

tissue_or_cell_type

Solution kinetics

Lycopene: absorption, metabolism, nutrient connections and human outcomes (2026-09-17) · lines 429–440

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Cell-free singlet-oxygen quenching comparison · source_derived_draft · unverified_draft

### lycopene-quenching-comparison Lycopene quenched singlet oxygen faster per molecule than alpha-tocopherol, but concentration-adjusted plasma capacities were comparable. Condition category: normal nutrient_topic: Lycopene research collection; topical membership is not evidence of a direct dietary effect. plain_language: A faster molecule is not automatically the more important antioxidant in blood. organism: Chemical assay and plasma-concentration comparison tissue_or_cell_type: Solution kinetics experimental_model: Cell-free singlet-oxygen quenching comparison limitations: Rate constants are solvent/assay-dependent, not a clinical ranking of antioxidant supplements. exposure: Lycopene, beta-carotene, alpha-tocopherol and albumin-bound bilirubin evidence_span: {"source_cache": "artifacts/lycopene-research/2802626.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "91ad9c300da17ee4e4c78a9ba980a7a4f05eef2328a64b5a9f75d4023abdc521", "start_char": 0, "end_char": 1046, "text_sha256": "91ad9c300da17ee4e4c78a9ba980a7a4f05eef2328a64b5a9f75d4023abdc521"} [lycopene-p2802626] Lycopene as the most efficient biological carotenoid singlet oxygen quencher. (1989). https://pubmed.ncbi.nlm.nih.gov/2802626/ DOI: 10.1016/0003-9861(89)90467-0

evidence_span

{"source_cache": "artifacts/lycopene-research/2802626.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "91ad9c300da17ee4e4c78a9ba980a7a4f05eef2328a64b5a9f75d4023abdc521", "start_char": 0, "end_char": 1046, "text_sha256": "91ad9c300da17ee4e4c78a9ba980a7a4f05eef2328a64b5a9f75d4023abdc521"}

experimental_model

Cell-free singlet-oxygen quenching comparison

exposure

Lycopene, beta-carotene, alpha-tocopherol and albumin-bound bilirubin

limitations

Rate constants are solvent/assay-dependent, not a clinical ranking of antioxidant supplements.

nutrient_topic

Lycopene research collection; topical membership is not evidence of a direct dietary effect. · Lycopene

organism

Chemical assay and plasma-concentration comparison

plain_language

It can remove excitation energy from this reactive oxygen species.

primary_references

[lycopene-p2802626] Lycopene as the most efficient biological carotenoid singlet oxygen quencher. (1989). https://pubmed.ncbi.nlm.nih.gov/2802626/ DOI: 10.1016/0003-9861(89)90467-0

tissue_or_cell_type

Solution kinetics

Lycopene: absorption, metabolism, nutrient connections and human outcomes (2026-09-17) · lines 416–427

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Cell-free singlet-oxygen quenching comparison · source_derived_draft · unverified_draft

### lycopene-singlet-quenching Lycopene had a reported singlet-oxygen quenching constant of 31 billion per molar per second in the assay. Condition category: normal nutrient_topic: Lycopene research collection; topical membership is not evidence of a direct dietary effect. plain_language: It can remove excitation energy from this reactive oxygen species. organism: Chemical assay and plasma-concentration comparison tissue_or_cell_type: Solution kinetics experimental_model: Cell-free singlet-oxygen quenching comparison limitations: Rate constants are solvent/assay-dependent, not a clinical ranking of antioxidant supplements. exposure: Lycopene, beta-carotene, alpha-tocopherol and albumin-bound bilirubin evidence_span: {"source_cache": "artifacts/lycopene-research/2802626.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "91ad9c300da17ee4e4c78a9ba980a7a4f05eef2328a64b5a9f75d4023abdc521", "start_char": 0, "end_char": 1046, "text_sha256": "91ad9c300da17ee4e4c78a9ba980a7a4f05eef2328a64b5a9f75d4023abdc521"} [lycopene-p2802626] Lycopene as the most efficient biological carotenoid singlet oxygen quencher. (1989). https://pubmed.ncbi.nlm.nih.gov/2802626/ DOI: 10.1016/0003-9861(89)90467-0

dose

Single 500 g cactus pear pulp meal: 28 mg indicaxanthin and 16 mg betanin

duration

Plasma/urine followed for 12 h

evidence_access

Primary PubMed abstract; detailed exposure for PMID 23931157 additionally checked in publisher results. No uninspected full text is claimed.

evidence_scope

literature_reviewed; source-derived curation, not universally established human effects

experimental_model

Eight healthy human volunteers

limitations

Whole-food exposure cannot attribute the LDL response exclusively to either pigment; urinary recovery is not absolute absorption.

nutrient_topic

Betalains collection; each molecular form, species, exposure and preparation remains explicit. · Betalains

organism

Eight healthy human volunteers

plain_language

LDL isolated 3 and 5 h after cactus pear ingestion resisted ex vivo oxidation more strongly; LDL vitamin E and beta-carotene levels were unchanged.

primary_references

Absorption, excretion, and distribution of dietary antioxidant betalains in LDLs: potential health effects of betalains in humans. (2004). https://pubmed.ncbi.nlm.nih.gov/15447903/ DOI: 10.1093/ajcn/80.4.941

route

Oral whole food

tissue

Plasma, urine and isolated LDL

Betalains: mechanisms, molecular forms and cross-actor connections (2026-09-20) · lines 517–525

Original AI-assisted curation of twelve primary research papers; study-specific PubMed/DOI links and limitations retained. Not publisher full text. · supports · Eight healthy human volunteers · source_derived_draft · unverified_draft

## betalains-human-food-ldl LDL isolated 3 and 5 h after cactus pear ingestion resisted ex vivo oxidation more strongly; LDL vitamin E and beta-carotene levels were unchanged. Model/species: Eight healthy human volunteers Tissue: Plasma, urine and isolated LDL Exposure: Single 500 g cactus pear pulp meal: 28 mg indicaxanthin and 16 mg betanin Route: Oral whole food Duration: Plasma/urine followed for 12 h Limits: Whole-food exposure cannot attribute the LDL response exclusively to either pigment; urinary recovery is not absolute absorption. Primary reference: Absorption, excretion, and distribution of dietary antioxidant betalains in LDLs: potential health effects of betalains in humans. (2004). https://pubmed.ncbi.nlm.nih.gov/15447903/ DOI: 10.1093/ajcn/80.4.941

evidence_span

{"source_cache": "artifacts/lutein-research/23644932.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1bd379926e56d7243222c2ef69d6367b74aede2b02faabfb77fadcbadf95008f", "start_char": 0, "end_char": 3037, "text_sha256": "1bd379926e56d7243222c2ef69d6367b74aede2b02faabfb77fadcbadf95008f"}

experimental_model

AREDS2 phase 3 factorial randomized trial

exposure

Lutein 10 mg + zeaxanthin 2 mg daily; background AREDS formula; median five years

limitations

Combination and background treatment prevent attribution to lutein alone; primary contrast differs from replacement and main-effects analyses. Published correction 10.1001/jama.2013.6403 changes the Table 3 lung-neoplasm row label and Table 4 lung-neoplasm entries. These records use the indexed abstract and do not reproduce the uncorrected Table 4. Correction: https://jamanetwork.com/journals/jama/fullarticle/1710434 .

nutrient_topic

Lutein research collection; topical membership is not evidence of a direct dietary effect. · Lutein

organism

4203 adults aged 50–85 at elevated AMD progression risk

plain_language

The comparator carotenoid had a separate safety signal.

primary_references

[lutein-p23644932] Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. (2013). https://pubmed.ncbi.nlm.nih.gov/23644932/ DOI: 10.1001/jama.2013.4997

tissue_or_cell_type

Eyes with large drusen and/or fellow-eye advanced AMD

Lutein: metabolism, signaling and nutrient connections (2026-09-17) · lines 736–747

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · AREDS2 phase 3 factorial randomized trial · source_derived_draft · unverified_draft

### lutein-areds-beta-lung Lung cancers occurred in 2.0% with beta-carotene versus 0.9% without, predominantly among former smokers. Condition category: normal nutrient_topic: Lutein research collection; topical membership is not evidence of a direct dietary effect. plain_language: The comparator carotenoid had a separate safety signal. organism: 4203 adults aged 50–85 at elevated AMD progression risk tissue_or_cell_type: Eyes with large drusen and/or fellow-eye advanced AMD experimental_model: AREDS2 phase 3 factorial randomized trial limitations: Combination and background treatment prevent attribution to lutein alone; primary contrast differs from replacement and main-effects analyses. Published correction 10.1001/jama.2013.6403 changes the Table 3 lung-neoplasm row label and Table 4 lung-neoplasm entries. These records use the indexed abstract and do not reproduce the uncorrected Table 4. Correction: https://jamanetwork.com/journals/jama/fullarticle/1710434 . exposure: Lutein 10 mg + zeaxanthin 2 mg daily; background AREDS formula; median five years evidence_span: {"source_cache": "artifacts/lutein-research/23644932.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1bd379926e56d7243222c2ef69d6367b74aede2b02faabfb77fadcbadf95008f", "start_char": 0, "end_char": 3037, "text_sha256": "1bd379926e56d7243222c2ef69d6367b74aede2b02faabfb77fadcbadf95008f"} [lutein-p23644932] Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. (2013). https://pubmed.ncbi.nlm.nih.gov/23644932/ DOI: 10.1001/jama.2013.4997

evidence_span

{"source_cache": "artifacts/lutein-research/24310343.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72", "start_char": 0, "end_char": 2419, "text_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72"}

experimental_model

Exploratory secondary analyses of AREDS2

exposure

L+Z 10/2 mg; direct comparison with beta-carotene on AREDS background

limitations

Exploratory contrasts and different confidence thresholds do not contradict the prespecified primary analysis.

nutrient_topic

Lutein research collection; topical membership is not evidence of a direct dietary effect. · Lutein

organism

Same AREDS2 cohort, not an independent replication

plain_language

The same comparison did not show benefit for every subtype.

primary_references

[lutein-p24310343] Secondary analyses of the effects of lutein/zeaxanthin on age-related macular degeneration progression: AREDS2 report No. 3. (2014). https://pubmed.ncbi.nlm.nih.gov/24310343/ DOI: 10.1001/jamaophthalmol.2013.7376

tissue_or_cell_type

Late AMD subtypes

Lutein: metabolism, signaling and nutrient connections (2026-09-17) · lines 775–786

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Exploratory secondary analyses of AREDS2 · source_derived_draft · unverified_draft

### lutein-areds-replacement-atrophy-null Central geographic atrophy HR was 0.94 (95% CI 0.70–1.26), without a significant difference. Condition category: normal nutrient_topic: Lutein research collection; topical membership is not evidence of a direct dietary effect. plain_language: The same comparison did not show benefit for every subtype. organism: Same AREDS2 cohort, not an independent replication tissue_or_cell_type: Late AMD subtypes experimental_model: Exploratory secondary analyses of AREDS2 limitations: Exploratory contrasts and different confidence thresholds do not contradict the prespecified primary analysis. exposure: L+Z 10/2 mg; direct comparison with beta-carotene on AREDS background evidence_span: {"source_cache": "artifacts/lutein-research/24310343.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72", "start_char": 0, "end_char": 2419, "text_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72"} [lutein-p24310343] Secondary analyses of the effects of lutein/zeaxanthin on age-related macular degeneration progression: AREDS2 report No. 3. (2014). https://pubmed.ncbi.nlm.nih.gov/24310343/ DOI: 10.1001/jamaophthalmol.2013.7376

evidence_span

{"source_cache": "artifacts/lutein-research/24310343.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72", "start_char": 0, "end_char": 2419, "text_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72"}

experimental_model

Exploratory secondary analyses of AREDS2

exposure

L+Z 10/2 mg; direct comparison with beta-carotene on AREDS background

limitations

Exploratory contrasts and different confidence thresholds do not contradict the prespecified primary analysis.

nutrient_topic

Lutein research collection; topical membership is not evidence of a direct dietary effect. · Lutein

organism

Same AREDS2 cohort, not an independent replication

plain_language

Replacement comparison favored the xanthophyll pair.

primary_references

[lutein-p24310343] Secondary analyses of the effects of lutein/zeaxanthin on age-related macular degeneration progression: AREDS2 report No. 3. (2014). https://pubmed.ncbi.nlm.nih.gov/24310343/ DOI: 10.1001/jamaophthalmol.2013.7376

tissue_or_cell_type

Late AMD subtypes

Lutein: metabolism, signaling and nutrient connections (2026-09-17) · lines 749–760

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Exploratory secondary analyses of AREDS2 · source_derived_draft · unverified_draft

### lutein-areds-replacement-late Exploratory L+Z versus beta-carotene comparison gave late-AMD HR 0.82 (95% CI 0.69–0.96). Condition category: normal nutrient_topic: Lutein research collection; topical membership is not evidence of a direct dietary effect. plain_language: Replacement comparison favored the xanthophyll pair. organism: Same AREDS2 cohort, not an independent replication tissue_or_cell_type: Late AMD subtypes experimental_model: Exploratory secondary analyses of AREDS2 limitations: Exploratory contrasts and different confidence thresholds do not contradict the prespecified primary analysis. exposure: L+Z 10/2 mg; direct comparison with beta-carotene on AREDS background evidence_span: {"source_cache": "artifacts/lutein-research/24310343.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72", "start_char": 0, "end_char": 2419, "text_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72"} [lutein-p24310343] Secondary analyses of the effects of lutein/zeaxanthin on age-related macular degeneration progression: AREDS2 report No. 3. (2014). https://pubmed.ncbi.nlm.nih.gov/24310343/ DOI: 10.1001/jamaophthalmol.2013.7376

evidence_span

{"source_cache": "artifacts/lutein-research/24310343.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72", "start_char": 0, "end_char": 2419, "text_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72"}

experimental_model

Exploratory secondary analyses of AREDS2

exposure

L+Z 10/2 mg; direct comparison with beta-carotene on AREDS background

limitations

Exploratory contrasts and different confidence thresholds do not contradict the prespecified primary analysis.

nutrient_topic

Lutein research collection; topical membership is not evidence of a direct dietary effect. · Lutein

organism

Same AREDS2 cohort, not an independent replication

plain_language

The subtype result favored the pair for neovascular AMD.

primary_references

[lutein-p24310343] Secondary analyses of the effects of lutein/zeaxanthin on age-related macular degeneration progression: AREDS2 report No. 3. (2014). https://pubmed.ncbi.nlm.nih.gov/24310343/ DOI: 10.1001/jamaophthalmol.2013.7376

tissue_or_cell_type

Late AMD subtypes

Lutein: metabolism, signaling and nutrient connections (2026-09-17) · lines 762–773

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Exploratory secondary analyses of AREDS2 · source_derived_draft · unverified_draft

### lutein-areds-replacement-neovascular The corresponding neovascular-AMD HR was 0.78 (95% CI 0.64–0.94). Condition category: normal nutrient_topic: Lutein research collection; topical membership is not evidence of a direct dietary effect. plain_language: The subtype result favored the pair for neovascular AMD. organism: Same AREDS2 cohort, not an independent replication tissue_or_cell_type: Late AMD subtypes experimental_model: Exploratory secondary analyses of AREDS2 limitations: Exploratory contrasts and different confidence thresholds do not contradict the prespecified primary analysis. exposure: L+Z 10/2 mg; direct comparison with beta-carotene on AREDS background evidence_span: {"source_cache": "artifacts/lutein-research/24310343.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72", "start_char": 0, "end_char": 2419, "text_sha256": "617cbda47a00c8fc552395a255003b013afa72aca6640c5c2e49d2b4caf09a72"} [lutein-p24310343] Secondary analyses of the effects of lutein/zeaxanthin on age-related macular degeneration progression: AREDS2 report No. 3. (2014). https://pubmed.ncbi.nlm.nih.gov/24310343/ DOI: 10.1001/jamaophthalmol.2013.7376

evidence_span

{"source_cache": "artifacts/pectin-research/1309477.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "fd0dad35ab4b3d100f22763fd9f5493d4ee5cc4e36f6f959436157484bd3f2f7", "start_char": 0, "end_char": 1044, "text_sha256": "fd0dad35ab4b3d100f22763fd9f5493d4ee5cc4e36f6f959436157484bd3f2f7"}

experimental_model

Crossover meal study in seven participants

exposure

12 g citrus pectin with 25 mg beta-carotene and a 500-kcal meal

limitations

Plasma response is an absorption-related endpoint, not a direct vitamin A deficiency measurement.

nutrient_topic

Pectin research collection; topical membership is not evidence of a direct dietary effect. · Pectin, structurally heterogeneous plant polysaccharides

organism

Homo sapiens

plain_language

The meal experiment found less beta-carotene appearing in blood.

primary_references

[pectin-p1309477] Plasma beta-carotene response in humans after meals supplemented with dietary pectin. (1992). https://pubmed.ncbi.nlm.nih.gov/1309477/ DOI: 10.1093/ajcn/55.1.96

tissue_or_cell_type

Post-meal plasma

Pectin: metabolism, signaling and nutrient connections (2026-09-17) · lines 659–670

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Crossover meal study in seven participants · source_derived_draft · unverified_draft

### pectin-beta-carotene-meal The beta-carotene plasma rise was smaller at 30 and 192 hours after the pectin meal; the 30-hour rise was reduced by more than half. Condition category: normal nutrient_topic: Pectin research collection; topical membership is not evidence of a direct dietary effect. plain_language: The meal experiment found less beta-carotene appearing in blood. organism: Homo sapiens tissue_or_cell_type: Post-meal plasma experimental_model: Crossover meal study in seven participants limitations: Plasma response is an absorption-related endpoint, not a direct vitamin A deficiency measurement. exposure: 12 g citrus pectin with 25 mg beta-carotene and a 500-kcal meal evidence_span: {"source_cache": "artifacts/pectin-research/1309477.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "fd0dad35ab4b3d100f22763fd9f5493d4ee5cc4e36f6f959436157484bd3f2f7", "start_char": 0, "end_char": 1044, "text_sha256": "fd0dad35ab4b3d100f22763fd9f5493d4ee5cc4e36f6f959436157484bd3f2f7"} [pectin-p1309477] Plasma beta-carotene response in humans after meals supplemented with dietary pectin. (1992). https://pubmed.ncbi.nlm.nih.gov/1309477/ DOI: 10.1093/ajcn/55.1.96

evidence_span

{"source_cache": "artifacts/pectin-research/10573545.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f0828162b0e41d10d79784cea5cc96e55409b4ee80be3afc399132a7ad087332", "start_char": 0, "end_char": 1340, "text_sha256": "f0828162b0e41d10d79784cea5cc96e55409b4ee80be3afc399132a7ad087332"}

experimental_model

Crossover mixed-carotenoid meal study in six healthy women

exposure

Pectin or other fibers at 0.15 g/kg with a carotenoid and alpha-tocopherol mixture

limitations

Reported effect-size ranges cover multiple fibers, not one pectin-specific estimate. Plasma exposure does not establish long-term deficiency.

nutrient_topic

Pectin research collection; topical membership is not evidence of a direct dietary effect. · Pectin, structurally heterogeneous plant polysaccharides

organism

Homo sapiens

plain_language

Fiber type affected beta-carotene exposure.

primary_references

[pectin-p10573545] Some dietary fibers reduce the absorption of carotenoids in women. (1999). https://pubmed.ncbi.nlm.nih.gov/10573545/ DOI: 10.1093/jn/129.12.2170

tissue_or_cell_type

Plasma 24-hour area under the curve

Pectin: metabolism, signaling and nutrient connections (2026-09-17) · lines 672–683

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Crossover mixed-carotenoid meal study in six healthy women · source_derived_draft · unverified_draft

### pectin-carotene-auc Pectin was among soluble fibers that lowered beta-carotene AUC; the 33-43% range covered the soluble fibers tested. Condition category: normal nutrient_topic: Pectin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Fiber type affected beta-carotene exposure. organism: Homo sapiens tissue_or_cell_type: Plasma 24-hour area under the curve experimental_model: Crossover mixed-carotenoid meal study in six healthy women limitations: Reported effect-size ranges cover multiple fibers, not one pectin-specific estimate. Plasma exposure does not establish long-term deficiency. exposure: Pectin or other fibers at 0.15 g/kg with a carotenoid and alpha-tocopherol mixture evidence_span: {"source_cache": "artifacts/pectin-research/10573545.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f0828162b0e41d10d79784cea5cc96e55409b4ee80be3afc399132a7ad087332", "start_char": 0, "end_char": 1340, "text_sha256": "f0828162b0e41d10d79784cea5cc96e55409b4ee80be3afc399132a7ad087332"} [pectin-p10573545] Some dietary fibers reduce the absorption of carotenoids in women. (1999). https://pubmed.ncbi.nlm.nih.gov/10573545/ DOI: 10.1093/jn/129.12.2170

evidence_location

Figure 3

experimental_model

Purified human BCO1 expressed in E. coli; substrate incubations and HPLC.

exposure

20 micromolar beta-carotene, 500 ng enzyme/200 microliters, 37 C, 15 minutes.

limitations

Purified-enzyme rates do not determine dietary conversion efficiency.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens protein expressed in Escherichia coli

outcome

Purified human BCO1 cleaved all-trans-beta-carotene centrally to all-trans-retinal.

plain_language

BCO1 turns a carotenoid precursor into retinal.

primary_references

[va-delasena-2013] Substrate specificity of purified recombinant human beta-carotene 15,15'-oxygenase (BCO1) (2013). https://pubmed.ncbi.nlm.nih.gov/24187135/ DOI: 10.1074/jbc.M113.507160

tissue_or_cell_type

Cell-free enzyme

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 131–143

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human BCO1 expressed in E. coli; substrate incubations and HPLC. · source_derived_draft · unverified_draft

### va-bco1-central-cleavage Purified human BCO1 cleaved all-trans-beta-carotene centrally to all-trans-retinal. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: BCO1 turns a carotenoid precursor into retinal. organism: Homo sapiens protein expressed in Escherichia coli tissue_or_cell_type: Cell-free enzyme experimental_model: Purified human BCO1 expressed in E. coli; substrate incubations and HPLC. limitations: Purified-enzyme rates do not determine dietary conversion efficiency. exposure: 20 micromolar beta-carotene, 500 ng enzyme/200 microliters, 37 C, 15 minutes. outcome: Purified human BCO1 cleaved all-trans-beta-carotene centrally to all-trans-retinal. evidence_location: Figure 3 [va-delasena-2013] Substrate specificity of purified recombinant human beta-carotene 15,15'-oxygenase (BCO1) (2013). https://pubmed.ncbi.nlm.nih.gov/24187135/ DOI: 10.1074/jbc.M113.507160

evidence_location

Abstract

experimental_model

Recombinant human BCO1 with isotopically labeled oxygen and water.

exposure

18O2 versus H2-18O incubations with beta-carotene.

limitations

Reaction chemistry; no claim about clinical hypoxia or oxygen supplementation.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens recombinant protein

outcome

Isotope tracing showed that oxygen incorporated into both BCO1-generated retinal products originated from molecular oxygen.

plain_language

BCO1 cleavage uses oxygen gas to make the two retinal aldehydes.

primary_references

[va-delasena-2014] The human enzyme that converts dietary provitamin A carotenoids to vitamin A is a dioxygenase (2014). https://pubmed.ncbi.nlm.nih.gov/24668807/ DOI: 10.1074/jbc.M114.557710

tissue_or_cell_type

Cell-free enzyme

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 173–185

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human BCO1 with isotopically labeled oxygen and water. · source_derived_draft · unverified_draft

### va-bco1-dioxygen-incorporation Isotope tracing showed that oxygen incorporated into both BCO1-generated retinal products originated from molecular oxygen. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: BCO1 cleavage uses oxygen gas to make the two retinal aldehydes. organism: Homo sapiens recombinant protein tissue_or_cell_type: Cell-free enzyme experimental_model: Recombinant human BCO1 with isotopically labeled oxygen and water. limitations: Reaction chemistry; no claim about clinical hypoxia or oxygen supplementation. exposure: 18O2 versus H2-18O incubations with beta-carotene. outcome: Isotope tracing showed that oxygen incorporated into both BCO1-generated retinal products originated from molecular oxygen. evidence_location: Abstract [va-delasena-2014] The human enzyme that converts dietary provitamin A carotenoids to vitamin A is a dioxygenase (2014). https://pubmed.ncbi.nlm.nih.gov/24668807/ DOI: 10.1074/jbc.M114.557710

availability_state

machinery_impairment Imported condition classification; unverified.

cross_nutrient

Links enzyme-bound iron to vitamin A precursor processing.

evidence_location

Abstract

experimental_model

Site-directed mutant mouse BCO1; cleavage assays and protein-bound iron spectroscopy.

exposure

Individual alanine substitutions at conserved catalytic-site residues.

limitations

Coordination inferred from mutagenesis and iron measurements, not a dietary iron trial.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Mus musculus recombinant protein

outcome

Substitution of conserved histidines or Glu405 in mouse BCO1 abolished cleavage and reduced protein-bound iron.

plain_language

An intact iron-binding environment is necessary for this enzyme to work.

primary_references

[va-poliakov-2005] Key role of conserved histidines in recombinant mouse beta-carotene 15,15'-monooxygenase-1 activity (2005). https://pubmed.ncbi.nlm.nih.gov/15951442/ DOI: 10.1074/jbc.M500409200

tissue_or_cell_type

Cell-free protein

trigger_kind

machinery_impairment Imported condition classification; unverified.

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 217–230

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Site-directed mutant mouse BCO1; cleavage assays and protein-bound iron spectroscopy. · source_derived_draft · unverified_draft

### va-bco1-iron-binding-machinery Substitution of conserved histidines or Glu405 in mouse BCO1 abolished cleavage and reduced protein-bound iron. Condition category: machinery_impairment nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: An intact iron-binding environment is necessary for this enzyme to work. organism: Mus musculus recombinant protein tissue_or_cell_type: Cell-free protein experimental_model: Site-directed mutant mouse BCO1; cleavage assays and protein-bound iron spectroscopy. limitations: Coordination inferred from mutagenesis and iron measurements, not a dietary iron trial. exposure: Individual alanine substitutions at conserved catalytic-site residues. outcome: Substitution of conserved histidines or Glu405 in mouse BCO1 abolished cleavage and reduced protein-bound iron. evidence_location: Abstract cross_nutrient: Links enzyme-bound iron to vitamin A precursor processing. [va-poliakov-2005] Key role of conserved histidines in recombinant mouse beta-carotene 15,15'-monooxygenase-1 activity (2005). https://pubmed.ncbi.nlm.nih.gov/15951442/ DOI: 10.1074/jbc.M500409200

experimental_model

18,314 high-risk participants; mean four years.

exposure

30 mg/day beta-carotene plus 25,000 IU/day preformed vitamin A; trial stopped early.

limitations

Combined intervention cannot separate the contribution of each ingredient or establish their biochemical interaction.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens

plain_language

Combining the two forms did not produce the hoped-for protection.

primary_references

[va-omenn1996] Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease (1996). https://pubmed.ncbi.nlm.nih.gov/8602180/ DOI: 10.1056/nejm199605023341802

tissue_or_cell_type

Clinical lung-cancer incidence

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 1731–1741

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 18,314 high-risk participants; mean four years. · source_derived_draft · unverified_draft

### va-caret-combination-lung-cancer CARET found increased lung-cancer incidence with beta-carotene plus retinyl palmitate versus placebo (relative risk 1.28). Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: Combining the two forms did not produce the hoped-for protection. organism: Homo sapiens tissue_or_cell_type: Clinical lung-cancer incidence experimental_model: 18,314 high-risk participants; mean four years. limitations: Combined intervention cannot separate the contribution of each ingredient or establish their biochemical interaction. exposure: 30 mg/day beta-carotene plus 25,000 IU/day preformed vitamin A; trial stopped early. [va-omenn1996] Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease (1996). https://pubmed.ncbi.nlm.nih.gov/8602180/ DOI: 10.1056/nejm199605023341802

cross_nutrient

Vitamin A/carotene -> iron absorption; contested.

experimental_model

Six human cereal-meal studies.

limitations

Not consistently replicated; the claimed iron-complex mechanism was proposed rather than structurally demonstrated.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens

plain_language

This study found that the meal additives made more iron available.

primary_references

[va-garciacasal1998] Vitamin A and beta-carotene can improve nonheme iron absorption from rice, wheat and corn by humans (1998). https://pubmed.ncbi.nlm.nih.gov/9482776/ DOI: 10.1093/jn/128.3.646

tissue_or_cell_type

Intestinal absorption

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 1542–1552

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Six human cereal-meal studies. · source_derived_draft · unverified_draft

### va-iron-absorption-positive1998 Vitamin A and beta-carotene increased labelled nonheme iron absorption from tested cereal meals. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: This study found that the meal additives made more iron available. organism: Homo sapiens tissue_or_cell_type: Intestinal absorption experimental_model: Six human cereal-meal studies. limitations: Not consistently replicated; the claimed iron-complex mechanism was proposed rather than structurally demonstrated. cross_nutrient: Vitamin A/carotene -> iron absorption; contested. [va-garciacasal1998] Vitamin A and beta-carotene can improve nonheme iron absorption from rice, wheat and corn by humans (1998). https://pubmed.ncbi.nlm.nih.gov/9482776/ DOI: 10.1093/jn/128.3.646

availability_state

machinery_impairment Imported condition classification; unverified.

cross_nutrient

Iron availability supports provitamin A cleavage in this in vitro model.

evidence_location

Abstract

experimental_model

Human small-intestinal mucosa and Caco-2 TC7 cells; desferrioxamine and iron addition.

exposure

Increasing desferrioxamine concentrations.

limitations

Drug-induced chelation; BCO1 protein abundance and human dietary deficiency were not directly established.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens

outcome

Desferrioxamine reduced beta-carotene-cleaving activity in human intestinal mucosa and TC7 cells.

plain_language

Sequestering iron limited conversion of provitamin A to retinal.

primary_references

[va-during-2001] beta-Carotene 15,15'-Dioxygenase activity in human tissues and cells: evidence of an iron dependency (2001). https://pubmed.ncbi.nlm.nih.gov/12031257/ DOI: 10.1016/S0955-2863(01)00184-X

tissue_or_cell_type

Small-intestinal mucosa and Caco-2 TC7 cells

trigger_kind

machinery_impairment Imported condition classification; unverified.

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 187–200

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human small-intestinal mucosa and Caco-2 TC7 cells; desferrioxamine and iron addition. · source_derived_draft · unverified_draft

### va-iron-chelation-cleavage Desferrioxamine reduced beta-carotene-cleaving activity in human intestinal mucosa and TC7 cells. Condition category: machinery_impairment nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: Sequestering iron limited conversion of provitamin A to retinal. organism: Homo sapiens tissue_or_cell_type: Small-intestinal mucosa and Caco-2 TC7 cells experimental_model: Human small-intestinal mucosa and Caco-2 TC7 cells; desferrioxamine and iron addition. limitations: Drug-induced chelation; BCO1 protein abundance and human dietary deficiency were not directly established. exposure: Increasing desferrioxamine concentrations. outcome: Desferrioxamine reduced beta-carotene-cleaving activity in human intestinal mucosa and TC7 cells. evidence_location: Abstract cross_nutrient: Iron availability supports provitamin A cleavage in this in vitro model. [va-during-2001] beta-Carotene 15,15'-Dioxygenase activity in human tissues and cells: evidence of an iron dependency (2001). https://pubmed.ncbi.nlm.nih.gov/12031257/ DOI: 10.1016/S0955-2863(01)00184-X

availability_state

machinery_impairment Imported condition classification; unverified.

cross_nutrient

Direct cellular iron-to-vitamin-A precursor interaction.

evidence_location

Abstract

experimental_model

Human small-intestinal mucosa and Caco-2 TC7 cells; desferrioxamine and iron addition.

exposure

Iron added during the chelation experiment.

limitations

Accessible source does not resolve the added salt/speciation; not a clinical repletion result.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens

outcome

Adding iron reversed desferrioxamine inhibition of carotenoid cleavage in TC7 cells.

plain_language

Iron restored the inhibited retinal-producing reaction.

primary_references

[va-during-2001] beta-Carotene 15,15'-Dioxygenase activity in human tissues and cells: evidence of an iron dependency (2001). https://pubmed.ncbi.nlm.nih.gov/12031257/ DOI: 10.1016/S0955-2863(01)00184-X

tissue_or_cell_type

Caco-2 TC7 cells

trigger_kind

machinery_impairment Imported condition classification; unverified.

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 202–215

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human small-intestinal mucosa and Caco-2 TC7 cells; desferrioxamine and iron addition. · source_derived_draft · unverified_draft

### va-iron-rescue-cleavage Adding iron reversed desferrioxamine inhibition of carotenoid cleavage in TC7 cells. Condition category: machinery_impairment nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: Iron restored the inhibited retinal-producing reaction. organism: Homo sapiens tissue_or_cell_type: Caco-2 TC7 cells experimental_model: Human small-intestinal mucosa and Caco-2 TC7 cells; desferrioxamine and iron addition. limitations: Accessible source does not resolve the added salt/speciation; not a clinical repletion result. exposure: Iron added during the chelation experiment. outcome: Adding iron reversed desferrioxamine inhibition of carotenoid cleavage in TC7 cells. evidence_location: Abstract cross_nutrient: Direct cellular iron-to-vitamin-A precursor interaction. [va-during-2001] beta-Carotene 15,15'-Dioxygenase activity in human tissues and cells: evidence of an iron dependency (2001). https://pubmed.ncbi.nlm.nih.gov/12031257/ DOI: 10.1016/S0955-2863(01)00184-X

evidence_location

Abstract

experimental_model

Scarb1-knockout mice, intestinal brush-border vesicles and transfected COS-7 cells.

exposure

Wild-type versus Scarb1-knockout mice; high-fat feeding.

limitations

Dependence was diet/model specific; this does not establish exclusive human transport.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Mus musculus

outcome

SCARB1 supported intestinal beta-carotene absorption in mice on a high-fat diet.

plain_language

The intestinal receptor helps beta-carotene enter the body.

primary_references

[va-vanbennekum-2005] Class B scavenger receptor-mediated intestinal absorption of dietary beta-carotene and cholesterol (2005). https://pubmed.ncbi.nlm.nih.gov/15766282/ DOI: 10.1021/bi0484320

tissue_or_cell_type

Small-intestinal brush border

transport_direction

intestinal lumen to enterocyte

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 116–129

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Scarb1-knockout mice, intestinal brush-border vesicles and transfected COS-7 cells. · source_derived_draft · unverified_draft

### va-scarb1-beta-carotene-uptake SCARB1 supported intestinal beta-carotene absorption in mice on a high-fat diet. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: The intestinal receptor helps beta-carotene enter the body. organism: Mus musculus tissue_or_cell_type: Small-intestinal brush border experimental_model: Scarb1-knockout mice, intestinal brush-border vesicles and transfected COS-7 cells. limitations: Dependence was diet/model specific; this does not establish exclusive human transport. exposure: Wild-type versus Scarb1-knockout mice; high-fat feeding. outcome: SCARB1 supported intestinal beta-carotene absorption in mice on a high-fat diet. evidence_location: Abstract transport_direction: intestinal lumen to enterocyte [va-vanbennekum-2005] Class B scavenger receptor-mediated intestinal absorption of dietary beta-carotene and cholesterol (2005). https://pubmed.ncbi.nlm.nih.gov/15766282/ DOI: 10.1021/bi0484320

cross_nutrient

true

experimental_model

ATBC randomized factorial trial secondary prostate-cancer endpoint; 29133 Finnish male smokers aged 50–69

exposure

Alpha-tocopherol 50 mg/day with or without beta-carotene 20 mg/day; median 6.1 years.

limitations

Secondary cancer endpoint in male smokers; differs from SELECT in dose, population and ascertainment. An opposite trial result is not automatically a same-condition biological contradiction. This result and SELECT must retain their different populations and regimens; neither supplies the molecular explanation for their difference.

nutrient_topic

Vitamin E research collection; topical membership is not evidence of a direct dietary effect. · Vitamin E

organism

Homo sapiens

plain_language

A lower-dose trial in male smokers found fewer prostate-cancer diagnoses.

primary_references

[e-clin-atbc1998] Prostate cancer and supplementation with alpha-tocopherol and beta-carotene: incidence and mortality in a controlled trial. (1998). https://pubmed.ncbi.nlm.nih.gov/9521168/ DOI: 10.1093/jnci/90.6.440

tissue_or_cell_type

Prostate and whole-person outcomes

Vitamin E: transport, membrane protection and nutrient interactions (2026-09-17) · lines 1323–1334

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · ATBC randomized factorial trial secondary prostate-cancer endpoint; 29133 Finnish male smokers aged 50–69 · source_derived_draft · unverified_draft

### e-clin-atbc-prostate-incidence The ATBC secondary analysis found 32% lower prostate-cancer incidence among men assigned alpha-tocopherol versus those not assigned it. Condition category: normal nutrient_topic: Vitamin E research collection; topical membership is not evidence of a direct dietary effect. plain_language: A lower-dose trial in male smokers found fewer prostate-cancer diagnoses. organism: Homo sapiens tissue_or_cell_type: Prostate and whole-person outcomes experimental_model: ATBC randomized factorial trial secondary prostate-cancer endpoint; 29133 Finnish male smokers aged 50–69 limitations: Secondary cancer endpoint in male smokers; differs from SELECT in dose, population and ascertainment. An opposite trial result is not automatically a same-condition biological contradiction. This result and SELECT must retain their different populations and regimens; neither supplies the molecular explanation for their difference. exposure: Alpha-tocopherol 50 mg/day with or without beta-carotene 20 mg/day; median 6.1 years. cross_nutrient: true [e-clin-atbc1998] Prostate cancer and supplementation with alpha-tocopherol and beta-carotene: incidence and mortality in a controlled trial. (1998). https://pubmed.ncbi.nlm.nih.gov/9521168/ DOI: 10.1093/jnci/90.6.440

cross_nutrient

false

experimental_model

ATBC randomized factorial trial secondary prostate-cancer endpoint; 29133 Finnish male smokers aged 50–69

exposure

Alpha-tocopherol 50 mg/day with or without beta-carotene 20 mg/day; median 6.1 years.

limitations

Secondary cancer endpoint in male smokers; differs from SELECT in dose, population and ascertainment. An opposite trial result is not automatically a same-condition biological contradiction.

nutrient_topic

Vitamin E research collection; topical membership is not evidence of a direct dietary effect. · Vitamin E

organism

Homo sapiens

plain_language

The smoker trial also reported fewer prostate-cancer deaths, with substantial uncertainty around the estimate.

primary_references

[e-clin-atbc1998] Prostate cancer and supplementation with alpha-tocopherol and beta-carotene: incidence and mortality in a controlled trial. (1998). https://pubmed.ncbi.nlm.nih.gov/9521168/ DOI: 10.1093/jnci/90.6.440

tissue_or_cell_type

Prostate and whole-person outcomes

Vitamin E: transport, membrane protection and nutrient interactions (2026-09-17) · lines 1336–1347

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · ATBC randomized factorial trial secondary prostate-cancer endpoint; 29133 Finnish male smokers aged 50–69 · source_derived_draft · unverified_draft

### e-clin-atbc-prostate-mortality Prostate-cancer mortality was 41% lower in ATBC participants assigned alpha-tocopherol, with a reported confidence interval extending from a 65% to a 1% reduction. Condition category: normal nutrient_topic: Vitamin E research collection; topical membership is not evidence of a direct dietary effect. plain_language: The smoker trial also reported fewer prostate-cancer deaths, with substantial uncertainty around the estimate. organism: Homo sapiens tissue_or_cell_type: Prostate and whole-person outcomes experimental_model: ATBC randomized factorial trial secondary prostate-cancer endpoint; 29133 Finnish male smokers aged 50–69 limitations: Secondary cancer endpoint in male smokers; differs from SELECT in dose, population and ascertainment. An opposite trial result is not automatically a same-condition biological contradiction. exposure: Alpha-tocopherol 50 mg/day with or without beta-carotene 20 mg/day; median 6.1 years. cross_nutrient: false [e-clin-atbc1998] Prostate cancer and supplementation with alpha-tocopherol and beta-carotene: incidence and mortality in a controlled trial. (1998). https://pubmed.ncbi.nlm.nih.gov/9521168/ DOI: 10.1093/jnci/90.6.440