Calcium Carbonate
Also known as: Calcium carbonate (CaCO3), Elemental calcium (from carbonate)
Randomised controlled trials in adolescents report increases in whole-body and spine bone mineral content or density and modest increases in height and lean mass with daily calcium carbonate ranging from a few hundred mg of elemental calcium up to 1000 mg/day. Short-term trials in adults with chronic kidney disease show positive calcium balance with 1500 mg/day and caution about soft‑tissue calcium deposition. Small trials in subjects with sporadic colorectal adenoma report suppression of rectal epithelial proliferation at higher doses (around 2000 mg/day). Effects vary by age, sex and baseline vitamin D/calcium status.
Last reviewed: 2026-10-14 · 5 indexed studies
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Overview
Calcium carbonate is a common, inexpensive source of oral elemental calcium used to support bone mineralisation and to replace dietary calcium. Randomised trials in adolescents and selected clinical populations show increases in bone mineral content or density and effects on lean mass at typical supplemental doses; effects depend on baseline status, dose and population.
Mechanism & Function
Mechanism of Action
Provides bioavailable elemental calcium required for bone mineralisation and cellular processes; in the gut it can bind dietary phosphate and reduce phosphate absorption. Altered systemic calcium balance can affect bone formation/resorption and epithelial cell proliferation signalling.
Physiological Role
Structural mineral for bone and teeth, second‑messenger roles in cellular signalling, and regulator of neuromuscular function.
Primary Pathways
Performance / Health Relevance
Indirect: supports bone mineral accrual during growth which may contribute to long‑term skeletal health; small increases in lean mass reported in some adolescent trials.
Evidence Review
No meta-analyses or systematic reviews indexed for this ingredient yet.
Dimensions marked N/A have no indexed evidence of that class. They are shown as unavailable rather than scored.
Compare Calcium Forms
Full comparison7 calcium forms are indexed. Bioavailability, clinical evidence, and best-use cases differ meaningfully between them.
| Form | Evidence |
|---|---|
Calcium CarbonateThis page Calcium carbonate provides elemental calcium but requires gastric acid for absorption; absorption may be reduced on a completely achlorhydric stomach. | 67/100 |
| Calcium Caseinate DIAAS ≈ 1.18; complete EAA profile. | 78/100 |
| Calcium Citrate ~22–27% absorption regardless of stomach acidity. | 75/100 |
| HMB Ca-HMB ~80%; HMB-FA produces 2× higher peak plasma at same dose. | 68/100 |
| Vitamin B5 (Pantothenic Acid) Well-absorbed from the gastrointestinal tract. Bioavailability is generally high. | 65/100 |
| Calcium AKG Moderate. | 48/100 |
| Calcium Lactate One trial measured absorption from a calcium lactate drink; small differences in fractional absorption were observed when additional caseinophosphopeptide preparations were included, but these differences were judged unlikely to be biologically meaningful. | 45/100 |
Practical Use & Dosage
- Minimum Effective Dose
- Evidence of benefit in adolescents from ~230 mg elemental calcium/day (supplement) over two years; other trials used 500–1000 mg/day.
- Optimal Range
- Population dependent; adolescent bone accrual effects reported with supplemental elemental calcium in the range ~230–1000 mg/day. Short‑term studies in adults used 1500–2000 mg/day for specific endpoints.
- Upper / Caution Level
- Studies show effects and possible soft‑tissue calcium deposition at 1500 mg/day in CKD; epithelial effects studied at ~2000 mg/day. Tolerable upper intake levels should be consulted from authoritative bodies (Not established in these abstracts).
- Timing
- Not specified in the trials; typically given daily.
- Best Format
- Oral tablets/chewables containing calcium carbonate providing specified elemental calcium dose.
- Bioavailability
- Calcium carbonate provides elemental calcium but requires gastric acid for absorption; absorption may be reduced on a completely achlorhydric stomach.
- Absorption Considerations
- Concurrent vitamin D status influences calcium utilisation; some trials combined calcium with vitamin D. Dividing large doses may improve absorption.
Safety & Interactions
Side Effects
- •Gastrointestinal upset (not detailed in provided abstracts)
- •Potential for positive calcium balance and soft‑tissue deposition in CKD (observed in short trial)
Contraindications
- Established hypercalcaemia
- Caution in patients with advanced chronic kidney disease
Drug Interactions
- •May bind dietary phosphate (used as phosphate binder)
- •Can interfere with absorption of some oral medications (general known interaction; not detailed in provided abstracts)
Who Should Avoid
- •Patients with stage 3–4 chronic kidney disease should use with caution and under clinical guidance
- •Individuals with hypercalcaemia
Monitoring
In CKD or when using high doses, monitoring of serum calcium, phosphate and renal function is prudent (based on trial showing positive calcium balance in CKD).
Frequently Asked Questions
Auto-generated from indexed evidence — dosage, safety, interactions, and more.
When is Calcium Carbonate typically used or indicated?
Calcium Carbonate is most commonly used for: Bone health and development, Calcium supplementation to meet dietary requirements, Phosphate binding in CKD (clinical use). Structural mineral for bone and teeth, second‑messenger roles in cellular signalling, and regulator of neuromuscular function.
How does Calcium Carbonate work?
Provides bioavailable elemental calcium required for bone mineralisation and cellular processes; in the gut it can bind dietary phosphate and reduce phosphate absorption. Altered systemic calcium balance can affect bone formation/resorption and epithelial cell proliferation signalling.
What is the recommended dose of Calcium Carbonate?
The optimal range is Population dependent; adolescent bone accrual effects reported with supplemental elemental calcium in the range ~230–1000 mg/day. Short‑term studies in adults used 1500–2000 mg/day for specific endpoints.. with a minimum effective dose of Evidence of benefit in adolescents from ~230 mg elemental calcium/day (supplement) over two years; other trials used 500–1000 mg/day.. Best taken: Not specified in the trials; typically given daily.. Upper / caution level: Studies show effects and possible soft‑tissue calcium deposition at 1500 mg/day in CKD; epithelial effects studied at ~2000 mg/day. Tolerable upper intake levels should be consulted from authoritative bodies (Not established in these abstracts)..
What are the side effects of Calcium Carbonate?
Reported side effects include: Gastrointestinal upset (not detailed in provided abstracts); and Potential for positive calcium balance and soft‑tissue deposition in CKD (observed in short trial). Monitoring: In CKD or when using high doses, monitoring of serum calcium, phosphate and renal function is prudent (based on trial showing positive calcium balance in CKD).
Does Calcium Carbonate interact with medications?
Known or theoretical interactions: May bind dietary phosphate (used as phosphate binder); and Can interfere with absorption of some oral medications (general known interaction; not detailed in provided abstracts). Always check with a clinician before combining with prescription medication.
Who should avoid Calcium Carbonate?
Calcium Carbonate is generally not recommended for: Patients with stage 3–4 chronic kidney disease should use with caution and under clinical guidance; Individuals with hypercalcaemia; Established hypercalcaemia; and Caution in patients with advanced chronic kidney disease.
How strong is the evidence for Calcium Carbonate?
Evidence level: Moderate (overall score 67/100), based on 5 indexed studies on SuppIndex.
Research & References (5)
Impact of high-dose vitamin D and calcium carbonate supplementation on bone density in adolescents living with HIV: a randomised, placebo-controlled trial.
Randomised, placebo‑controlled trial in 842 peripubertal adolescents with HIV given weekly high‑dose vitamin D3 plus daily calcium carbonate 500 mg for 48 weeks. Primary bone density outcomes (TBLH‑BMD, LS‑BMAD) did not differ overall, but among those with vitamin D insufficiency at baseline a small improvement in lumbar spine BMAD Z score was observed.
Calcium supplementation increases stature and bone mineral mass of 16- to 18-year-old boys.
Randomised trial in 143 boys aged 16–18 years given 1000 mg elemental calcium/day as calcium carbonate or placebo for 13 months. Supplementation increased whole‑body, lumbar spine and hip bone mineral content and was associated with greater height and lean mass.
Oral calcium carbonate affects calcium but not phosphorus balance in stage 3-4 chronic kidney disease.
Randomised, placebo‑controlled cross‑over balance study in eight adults with stage 3–4 chronic kidney disease receiving controlled diet with or without calcium carbonate 1500 mg/day for 3 weeks. Calcium carbonate produced positive calcium balance and modestly reduced urinary phosphate excretion, without changes in fasting biochemical measures.
Calcium supplementation for 2 years improves bone mineral accretion and lean body mass in Chinese adolescents.
Double‑blind RCT in 257 healthy Chinese adolescents (aged 12–15) given chewable calcium carbonate producing a range of elemental calcium doses; reclassified analyses (n=197) compared low (~85 mg/day), medium (~230 mg/day) and high (~500 mg/day) actual doses over 24 months. Total body and lumbar spine BMC and BMD increased in both sexes, with boys showing dose‑related increases in BMC and lean mass.
Calcium supplementation decreases rectal epithelial cell proliferation in subjects with sporadic adenoma.
Small crossover and sequential trials in subjects with sporadic colorectal adenoma showing that calcium carbonate at 2000 mg/day for short periods produced suppression of rectal epithelial cell proliferation compared with placebo; lower doses (1500 mg/day) did not show significant suppression in a small group.
Related Ingredients
Other top-rated ingredients in Minerals.
Magnesium Glycinate
84/100An amino acid chelate of magnesium providing elemental Mg²⁺ bound to two glycine molecules, offering superior bioavailability and minimal gastrointestinal side effects.
Calcium Citrate
75/100Calcium bound to citric acid; ~24% elemental Ca by mass; absorbed across the small intestine via active transport and paracellular diffusion regardless of gastric pH.
Zinc
74/100Systematic reviews and meta-analyses of human trials show that oral zinc supplementation reduces duration and increases recovery rates in acute and persistent watery diarrhoea in children; lowers inflammatory lesion counts in acne; reduces pain severity in primary dysmenorrhea; and in small trials (20–30 mg/day) improved fasting glucose and 2‑hr OGTT in people with prediabetes. Adverse effects reported include increased vomiting in children receiving zinc for diarrhoea.
Research Overview
Moderate EvidenceCite this ingredient
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Stable URL
https://thesuppindex.com/ingredients/calcium-carbonate
SuppIndex. (2026). Calcium Carbonate: Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/calcium-carbonate
Based on 5 indexed studies · Evidence level: Moderate.
Goal Ratings
Stack Compatibility
Often combined with vitamin D in trials to support absorption and bone effects; interactions with phosphate binders are clinically relevant.