Calcium carbonate

experimental_model

Randomized post-polypectomy surveillance; 832 participants completed both examinations.

exposure

Adjusted RR 0.81 (95% CI 0.67-0.99) between first and second surveillance examinations.

limitations

Adenoma recurrence is distinct from colorectal-cancer incidence or mortality.

nutrient_topic

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

organism

Homo sapiens

plain_language

One trial found fewer recurring colorectal polyps.

primary_references

[cal-clin-baron1999] Calcium supplements for the prevention of colorectal adenomas. Calcium Polyp Prevention Study Group (1999). https://pubmed.ncbi.nlm.nih.gov/9887161/ DOI: 10.1056/NEJM199901143400204

tissue_or_cell_type

Human clinical or absorption endpoint

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Randomized post-polypectomy surveillance; 832 participants completed both examinations. · source_derived_draft · unverified_draft

### cal-baron1999-adenomas Calcium carbonate reduced recurrent adenomas in the 1999 prevention trial. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: One trial found fewer recurring colorectal polyps. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: Randomized post-polypectomy surveillance; 832 participants completed both examinations. limitations: Adenoma recurrence is distinct from colorectal-cancer incidence or mortality. exposure: Adjusted RR 0.81 (95% CI 0.67-0.99) between first and second surveillance examinations. [cal-clin-baron1999] Calcium supplements for the prevention of colorectal adenomas. Calcium Polyp Prevention Study Group (1999). https://pubmed.ncbi.nlm.nih.gov/9887161/ DOI: 10.1056/NEJM199901143400204

experimental_model

2259 participants randomized in partial factorial design, 3-5-year follow-up.

exposure

1200 mg calcium/day; calcium versus no-calcium adjusted RR 0.95 (95% CI 0.85-1.06).

limitations

Trial contexts differ; mechanism of between-trial disagreement remains unproven.

nutrient_topic

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

organism

Homo sapiens

plain_language

A later trial did not confirm the earlier polyp benefit.

primary_references

[cal-clin-baron2015] A Trial of Calcium and Vitamin D for the Prevention of Colorectal Adenomas (2015). https://pubmed.ncbi.nlm.nih.gov/26465985/ DOI: 10.1056/NEJMoa1500409

tissue_or_cell_type

Human clinical or absorption endpoint

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 2259 participants randomized in partial factorial design, 3-5-year follow-up. · source_derived_draft · unverified_draft

### cal-baron2015-adenomas The 2015 trial found no significant reduction in recurrent adenomas with assigned calcium. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: A later trial did not confirm the earlier polyp benefit. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: 2259 participants randomized in partial factorial design, 3-5-year follow-up. limitations: Trial contexts differ; mechanism of between-trial disagreement remains unproven. exposure: 1200 mg calcium/day; calcium versus no-calcium adjusted RR 0.95 (95% CI 0.85-1.06). [cal-clin-baron2015] A Trial of Calcium and Vitamin D for the Prevention of Colorectal Adenomas (2015). https://pubmed.ncbi.nlm.nih.gov/26465985/ DOI: 10.1056/NEJMoa1500409

experimental_model

Same short crossover experiment.

limitations

A saturation-related proxy is not an observed kidney-stone event or a universal prediction.

nutrient_topic

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

organism

Homo sapiens

plain_language

The urinary crystallization proxy depended on timing.

primary_references

[cal-clin-domrong2004] Schedule of taking calcium supplement and the risk of nephrolithiasis (2004). https://pubmed.ncbi.nlm.nih.gov/15086924/ DOI: 10.1111/j.1523-1755.2004.00587.x

tissue_or_cell_type

Human clinical or absorption endpoint

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

### cal-bedtime-activity-product Urinary calcium-oxalate activity product increased after bedtime calcium carbonate but not after meal dosing. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: The urinary crystallization proxy depended on timing. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: Same short crossover experiment. limitations: A saturation-related proxy is not an observed kidney-stone event or a universal prediction. [cal-clin-domrong2004] Schedule of taking calcium supplement and the risk of nephrolithiasis (2004). https://pubmed.ncbi.nlm.nih.gov/15086924/ DOI: 10.1111/j.1523-1755.2004.00587.x

experimental_model

11 achlorhydric patients and nine controls; 250 mg calcium isotope tests.

exposure

Fasting achlorhydric mean fractions: carbonate 0.042, citrate 0.452; normal subjects showed no significant formulation difference.

limitations

Not evidence that carbonate always fails or citrate always outperforms it.

nutrient_topic

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

organism

Homo sapiens

plain_language

Low stomach acid can change how a calcium preparation is absorbed.

primary_references

[cal-clin-recker1985] Calcium absorption and achlorhydria (1985). https://pubmed.ncbi.nlm.nih.gov/4000241/ DOI: 10.1056/NEJM198507113130202

tissue_or_cell_type

Human clinical or absorption endpoint

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 11 achlorhydric patients and nine controls; 250 mg calcium isotope tests. · source_derived_draft · unverified_draft

### cal-carbonate-fasting-achlorhydria Fasting achlorhydric participants absorbed substantially less calcium from carbonate than from citrate. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: Low stomach acid can change how a calcium preparation is absorbed. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: 11 achlorhydric patients and nine controls; 250 mg calcium isotope tests. limitations: Not evidence that carbonate always fails or citrate always outperforms it. exposure: Fasting achlorhydric mean fractions: carbonate 0.042, citrate 0.452; normal subjects showed no significant formulation difference. [cal-clin-recker1985] Calcium absorption and achlorhydria (1985). https://pubmed.ncbi.nlm.nih.gov/4000241/ DOI: 10.1056/NEJM198507113130202

experimental_model

Two visits separated by four weeks; serum-based pharmacokinetic estimation.

exposure

1000 micrograms levothyroxine with or without 2 g elemental calcium as carbonate; six-hour total absorption differed (P=0.02).

limitations

Small acute high-dose experiment, not individualized medicine instructions.

nutrient_topic

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

organism

Homo sapiens

plain_language

The tested calcium preparation reduced the medicine reaching circulation.

primary_references

[cal-clin-singh2001] The acute effect of calcium carbonate on the intestinal absorption of levothyroxine (2001). https://pubmed.ncbi.nlm.nih.gov/11716045/ DOI: 10.1089/105072501753211046

tissue_or_cell_type

Human clinical or absorption endpoint

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Two visits separated by four weeks; serum-based pharmacokinetic estimation. · source_derived_draft · unverified_draft

### cal-carbonate-levothyroxine-absorption Simultaneous calcium carbonate reduced measured levothyroxine absorption in a seven-volunteer experiment. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: The tested calcium preparation reduced the medicine reaching circulation. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: Two visits separated by four weeks; serum-based pharmacokinetic estimation. limitations: Small acute high-dose experiment, not individualized medicine instructions. exposure: 1000 micrograms levothyroxine with or without 2 g elemental calcium as carbonate; six-hour total absorption differed (P=0.02). [cal-clin-singh2001] The acute effect of calcium carbonate on the intestinal absorption of levothyroxine (2001). https://pubmed.ncbi.nlm.nih.gov/11716045/ DOI: 10.1089/105072501753211046

experimental_model

Meal comparison in the achlorhydria absorption study.

limitations

Small study; the meal experiment did not isolate a molecular rescue mechanism.

nutrient_topic

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

organism

Homo sapiens

plain_language

The meal changed the result seen during fasting.

primary_references

[cal-clin-recker1985] Calcium absorption and achlorhydria (1985). https://pubmed.ncbi.nlm.nih.gov/4000241/ DOI: 10.1056/NEJM198507113130202

tissue_or_cell_type

Human clinical or absorption endpoint

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Meal comparison in the achlorhydria absorption study. · source_derived_draft · unverified_draft

### cal-carbonate-meal-achlorhydria Calcium carbonate given with a normal breakfast showed normal absorption in the achlorhydric participants. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: The meal changed the result seen during fasting. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: Meal comparison in the achlorhydria absorption study. limitations: Small study; the meal experiment did not isolate a molecular rescue mechanism. [cal-clin-recker1985] Calcium absorption and achlorhydria (1985). https://pubmed.ncbi.nlm.nih.gov/4000241/ DOI: 10.1056/NEJM198507113130202

experimental_model

In-vitro adsorption arm accompanying a 20-patient study.

limitations

Supports an absorption-interference mechanism; does not show a systemic blockade of deiodinases.

nutrient_topic

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

organism

Homo sapiens

plain_language

A calcium preparation can bind a thyroid medicine before absorption.

primary_references

[cal-clin-singh2000] Effect of calcium carbonate on the absorption of levothyroxine (2000). https://pubmed.ncbi.nlm.nih.gov/10838651/ DOI: 10.1001/jama.283.21.2822

tissue_or_cell_type

Cell-free acidic solution

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · In-vitro adsorption arm accompanying a 20-patient study. · source_derived_draft · unverified_draft

### cal-carbonate-thyroxine-adsorption Thyroxine adsorbed to calcium carbonate under acidic in-vitro conditions. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: A calcium preparation can bind a thyroid medicine before absorption. organism: Homo sapiens tissue_or_cell_type: Cell-free acidic solution experimental_model: In-vitro adsorption arm accompanying a 20-patient study. limitations: Supports an absorption-interference mechanism; does not show a systemic blockade of deiodinases. [cal-clin-singh2000] Effect of calcium carbonate on the absorption of levothyroxine (2000). https://pubmed.ncbi.nlm.nih.gov/10838651/ DOI: 10.1001/jama.283.21.2822

experimental_model

32 healthy men, one-week crossover regimens.

exposure

1 g calcium carbonate with each of three meals versus 3 g carbonate at bedtime: compound mass, not 3 g elemental calcium.

limitations

This experiment measured urine, not long-term stone incidence.

nutrient_topic

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

organism

Homo sapiens

plain_language

Taking the tested preparation with food changed oxalate handling.

primary_references

[cal-clin-domrong2004] Schedule of taking calcium supplement and the risk of nephrolithiasis (2004). https://pubmed.ncbi.nlm.nih.gov/15086924/ DOI: 10.1111/j.1523-1755.2004.00587.x

tissue_or_cell_type

Human clinical or absorption endpoint

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 32 healthy men, one-week crossover regimens. · source_derived_draft · unverified_draft

### cal-meal-urinary-oxalate Calcium carbonate with meals lowered urinary oxalate from baseline; bedtime dosing did not. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: Taking the tested preparation with food changed oxalate handling. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: 32 healthy men, one-week crossover regimens. limitations: This experiment measured urine, not long-term stone incidence. exposure: 1 g calcium carbonate with each of three meals versus 3 g carbonate at bedtime: compound mass, not 3 g elemental calcium. [cal-clin-domrong2004] Schedule of taking calcium supplement and the risk of nephrolithiasis (2004). https://pubmed.ncbi.nlm.nih.gov/15086924/ DOI: 10.1111/j.1523-1755.2004.00587.x

availability_state

nutrient_deficiency Imported condition classification; unverified.

experimental_model

123 children, 24-week randomized trial; low calcium intake also present in matched controls.

exposure

1000 mg elemental calcium/day, vitamin D injections, or both. Combined healing endpoint: calcium 61%, combined 58%, vitamin D 19%. Historical regimens only.

limitations

Does not make every case of rickets calcium-deficiency disease. The combined endpoint included alkaline phosphatase and radiographs. The injected vitamin D molecular form is not assigned here.

nutrient_topic

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

organism

Homo sapiens

plain_language

In these children, replacing calcium helped heal rickets.

primary_references

[cal-clin-thacher1999] A Comparison of Calcium, Vitamin D, or Both for Nutritional Rickets in Nigerian Children (1999). https://www.nejm.org/doi/full/10.1056/NEJM199908193410803 DOI: 10.1056/NEJM199908193410803

tissue_or_cell_type

Human clinical or absorption endpoint

trigger_kind

nutrient_deficiency Imported condition classification; unverified.

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 123 children, 24-week randomized trial; low calcium intake also present in matched controls. · source_derived_draft · unverified_draft

### cal-rickets-repletion Calcium-containing treatment produced more biochemical and radiographic healing than vitamin D alone in the Nigerian rickets trial. Condition category: nutrient_deficiency nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: In these children, replacing calcium helped heal rickets. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: 123 children, 24-week randomized trial; low calcium intake also present in matched controls. limitations: Does not make every case of rickets calcium-deficiency disease. The combined endpoint included alkaline phosphatase and radiographs. The injected vitamin D molecular form is not assigned here. exposure: 1000 mg elemental calcium/day, vitamin D injections, or both. Combined healing endpoint: calcium 61%, combined 58%, vitamin D 19%. Historical regimens only. [cal-clin-thacher1999] A Comparison of Calcium, Vitamin D, or Both for Nutritional Rickets in Nigerian Children (1999). https://www.nejm.org/doi/full/10.1056/NEJM199908193410803 DOI: 10.1056/NEJM199908193410803

experimental_model

Prespecified secondary WHI outcome; seven years.

exposure

MI/coronary-death HR 1.04, 95% CI 0.92-1.18.

limitations

Different cointervention, participants and ascertainment from the calcium-only trial; absence of significance does not prove universal safety.

nutrient_topic

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

organism

Homo sapiens

plain_language

This trial did not reproduce a clear increase in coronary events.

primary_references

[cal-clin-hsia2007] Calcium/vitamin D supplementation and cardiovascular events (2007). https://pubmed.ncbi.nlm.nih.gov/17309935/ DOI: 10.1161/CIRCULATIONAHA.106.673491

tissue_or_cell_type

Human clinical or absorption endpoint

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Prespecified secondary WHI outcome; seven years. · source_derived_draft · unverified_draft

### cal-whi-coronary-events WHI found no significant effect of calcium plus vitamin D on myocardial infarction or coronary death. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: This trial did not reproduce a clear increase in coronary events. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: Prespecified secondary WHI outcome; seven years. limitations: Different cointervention, participants and ascertainment from the calcium-only trial; absence of significance does not prove universal safety. exposure: MI/coronary-death HR 1.04, 95% CI 0.92-1.18. [cal-clin-hsia2007] Calcium/vitamin D supplementation and cardiovascular events (2007). https://pubmed.ncbi.nlm.nih.gov/17309935/ DOI: 10.1161/CIRCULATIONAHA.106.673491

experimental_model

36,282 postmenopausal women; seven-year mean follow-up.

exposure

1000 mg elemental calcium as carbonate plus 400 IU vitamin D3/day; hip-fracture HR 0.88, 95% CI 0.72-1.08.

limitations

Adherence and background supplement use complicate comparison; a nonsignificant result is not proof of zero effect.

nutrient_topic

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

organism

Homo sapiens

plain_language

A larger trial did not establish a hip-fracture benefit for its overall assigned-treatment groups.

primary_references

[cal-clin-jackson2006] Calcium plus vitamin D supplementation and the risk of fractures (2006). https://pubmed.ncbi.nlm.nih.gov/16481635/ DOI: 10.1056/NEJMoa055218

tissue_or_cell_type

Human clinical or absorption endpoint

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 36,282 postmenopausal women; seven-year mean follow-up. · source_derived_draft · unverified_draft

### cal-whi-hip-fractures WHI calcium plus vitamin D did not significantly reduce hip fractures in the intention-to-treat analysis. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: A larger trial did not establish a hip-fracture benefit for its overall assigned-treatment groups. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: 36,282 postmenopausal women; seven-year mean follow-up. limitations: Adherence and background supplement use complicate comparison; a nonsignificant result is not proof of zero effect. exposure: 1000 mg elemental calcium as carbonate plus 400 IU vitamin D3/day; hip-fracture HR 0.88, 95% CI 0.72-1.08. [cal-clin-jackson2006] Calcium plus vitamin D supplementation and the risk of fractures (2006). https://pubmed.ncbi.nlm.nih.gov/16481635/ DOI: 10.1056/NEJMoa055218

experimental_model

Randomized WHI safety outcome.

exposure

Renal-calculus HR 1.17, 95% CI 1.02-1.34; same assigned regimen as the fracture analysis.

limitations

Combined intervention; cannot attribute the whole effect to calcium or identify every stone composition.

nutrient_topic

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

organism

Homo sapiens

plain_language

The same trial recorded more kidney-stone events with the combined supplements.

primary_references

[cal-clin-jackson2006] Calcium plus vitamin D supplementation and the risk of fractures (2006). https://pubmed.ncbi.nlm.nih.gov/16481635/ DOI: 10.1056/NEJMoa055218

tissue_or_cell_type

Human clinical or absorption endpoint

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AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Randomized WHI safety outcome. · source_derived_draft · unverified_draft

### cal-whi-urinary-stones WHI assigned calcium plus vitamin D increased reported renal-calculus events relative to placebo. Condition category: normal nutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect. plain_language: The same trial recorded more kidney-stone events with the combined supplements. organism: Homo sapiens tissue_or_cell_type: Human clinical or absorption endpoint experimental_model: Randomized WHI safety outcome. limitations: Combined intervention; cannot attribute the whole effect to calcium or identify every stone composition. exposure: Renal-calculus HR 1.17, 95% CI 1.02-1.34; same assigned regimen as the fracture analysis. [cal-clin-jackson2006] Calcium plus vitamin D supplementation and the risk of fractures (2006). https://pubmed.ncbi.nlm.nih.gov/16481635/ DOI: 10.1056/NEJMoa055218