Ingredient intelligence · non-production preview

Calcium carbonate

Not medically reviewed

mineral compoundentity:ingredient:calcium-carbonateCompare this ingredient View evidence

Identity structure

Parent and form relationships

Ingredients, supplement concepts, supplement-form projections, and commercial products remain separate records.

Parent supplement

Calciumentity:supplement:calcium

Related ingredient forms

Calcium citratemineral compound

Origin is not a quality score

Origin classification is not assigned for this pilot. MEDucated does not rank naturally occurring or manufactured ingredients as better or worse based on origin.

Evidence availability

Direct ingredient evidence boundaries

Supplement-level evidence is reused only when a frozen source block explicitly names this ingredient or form. Missing topics remain unavailable.

Identity and what it is

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Common uses

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Biological role

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

What evidence has studied

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Potential benefits studied

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Safety considerations

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Side effects

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Medication interactions

A frozen NIH ODS source explicitly identifies this ingredient or form. Source wording is preserved without creating a new conclusion.

Source-backed preview

Structural characterization

Evidence profile

No overall rating assigned

Evidence source: NIH ODS evidence synthesis
Linked references: 4 identified
Human evidence: Human evidence not identified in the frozen metadata
Randomized trials: Randomized trials not identified in the frozen metadata
Reviews and meta-analyses: Systematic reviews or meta-analyses not identified in the frozen metadata
Evidence recency: 1998–2019
Source-described consistency: Not characterized in these source blocks
MEDucated evidence rating: Not assigned

Reference counts describe frozen source associations; a larger count does not establish stronger evidence.

Inspect technical evidence details

Evidence types identified

Study type could not be determined3
Regulatory source1

Source-described limitations

No explicit limitation phrase was identified in these imported source blocks.

Classified references

Morini E, Catalano A, Lasco A, Morabito N, Benvenga S. L-thyroxine malabsorption due to calcium carbonate impairs blood pressure, total cholesterolemia, and fasting glycemia. Endocrine 2019;64:284-92. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Singh N, Singh PN, Hershman JM. Effect of calcium carbonate on the absorption of levothyroxine. Jama 2000;283:2822-5. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
Schneyer CR. Calcium carbonate and reduction of levothyroxine efficacy. Jama 1998;279:750. [PubMed abstract]
Study type could not be determined · Population basis: unknown · Directness: not assessed
U.S. Food and Drug Administration. LEVO-T Label. 2017.
Regulatory source · Population basis: unknown · Directness: not assessed

Calcium carbonate supplements can interfere with the absorption of levothyroxine (Synthroid, Levoxyl, and others), a thyroid hormone used to treat hypothyroidism and thyroid cancer [104-106]. The FDA-approved label for this medication instructs patients who are taking calcium carbonate supplements to avoid taking levothyroxine within 4 hours of taking the supplement [107].

Where did MEDucated get this?

Calcium

Publisher: NIH Office of Dietary Supplements
Revision: June 22, 2026
Source fingerprint: 5139a098b618d4d9810942614ee016aa45b5a58c35e89d7a588a9d7d93a4f2f7
Source blocks: ingredient-block:calcium-carbonate:ods-block:calcium-health-professional:interactions-with-medications:4

Inspect the official source

Source attribution does not imply NIH or ODS endorsement of MEDucated.

Supplement interactions

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Food interactions

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Forms and chemical variants

A frozen NIH ODS source explicitly identifies this ingredient or form. Source wording is preserved without creating a new conclusion.

Source-backed preview

Structural characterization

Evidence profile

No overall rating assigned

Evidence source: NIH ODS evidence synthesis
Linked references: 3 identified
Human evidence: Human evidence not identified in the frozen metadata
Randomized trials: Randomized trials not identified in the frozen metadata
Reviews and meta-analyses: Systematic reviews or meta-analyses not identified in the frozen metadata
Evidence recency: 2011–2021
Source-described consistency: Not characterized in these source blocks
MEDucated evidence rating: Not assigned

Reference counts describe frozen source associations; a larger count does not establish stronger evidence.

Inspect technical evidence details

Evidence types identified

Government reference1
Study type could not be determined2

Source-described limitations

No explicit limitation phrase was identified in these imported source blocks.

Classified references

Institute of Medicine. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: The National Academies Press; 2011.
Government reference · Population basis: unknown · Directness: not assessed
Weaver CM, Heaney RP. Calcium. In: Ross AC, Caballero B, Cousins RJ, Tucker KL, Ziegler TR, eds. Modern Nutrition in Health and Disease. 11th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014:133-49.
Study type could not be determined · Population basis: unknown · Directness: not assessed
Office of Dietary Supplements, National Institutes of Health. Dietary Supplement Label Database. 2021.
Study type could not be determined · Population basis: unknown · Directness: not assessed

Read imported source wording

Many dietary supplements contain calcium, usually in the form of calcium carbonate or calcium citrate. The percentage of calcium that is absorbed from supplements depends on a number of factors, including the form of the calcium and the total amount of elemental calcium consumed at one time.

The two most common forms of calcium in supplements are calcium carbonate and calcium citrate [1]. In people with low levels of stomach acid, the solubility rate of calcium carbonate is lower, which could reduce the absorption of calcium from calcium carbonate supplements unless they are taken with a meal [3]. Calcium citrate is less dependent on stomach acid for absorption than calcium carbonate, so it can be taken without food [1]. In general, however, absorption of calcium supplements is greater when they are taken with food, regardless of whether the user’s gastric acid is low [3]. Other calcium forms in supplements include calcium sulfate, ascorbate, microcrystalline hydroxyapatite, gluconate, lactate, and phosphate [14].

The forms of calcium in supplements contain varying amounts of elemental calcium. For example, calcium carbonate is 40% calcium by weight, whereas calcium citrate is 21% calcium [1]. Elemental calcium is listed in the Supplement Facts panel, so consumers do not need to calculate the amount of calcium supplied by various forms of calcium in supplements.

Some individuals who take calcium supplements might experience gastrointestinal side effects, including gas, bloating, constipation, or a combination of these symptoms. Calcium carbonate appears to cause more of these side effects than calcium citrate, especially in older adults who have lower levels of stomach acid [1]. Symptoms can be alleviated by switching to a supplement containing a different form of calcium, taking smaller calcium doses more often during the day, or taking the supplement with meals.

Where did MEDucated get this?

Calcium

Publisher: NIH Office of Dietary Supplements
Revision: June 22, 2026
Source fingerprint: 5139a098b618d4d9810942614ee016aa45b5a58c35e89d7a588a9d7d93a4f2f7
Source blocks: ingredient-block:calcium-carbonate:ods-block:calcium-health-professional:dietary-supplements:1, ingredient-block:calcium-carbonate:ods-block:calcium-health-professional:dietary-supplements:3, ingredient-block:calcium-carbonate:ods-block:calcium-health-professional:dietary-supplements:4, ingredient-block:calcium-carbonate:ods-block:calcium-health-professional:dietary-supplements:6

Inspect the official source

Source attribution does not imply NIH or ODS endorsement of MEDucated.

Intake and dose reference information

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Populations needing caution

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Pregnancy and lactation

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Laboratory and test considerations

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Regulatory status

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Evidence limitations

Direct source evidence for this ingredient topic is not yet available in MEDucated.

Evidence unavailable

Architecture readiness

Connected without overreaching

This identity can participate in future interaction and product-label models without creating an interaction conclusion or product score.

Interaction target ready

Canonical resolution

Exact names and registered aliases can resolve to entity:ingredient:calcium-carbonate. Uncertain terms remain unresolved.

Product-label ready

Identity mapping only

Future labels can preserve literal wording, quantity, unit, serving basis, order, and source provenance separately from this identity.