Supplement Scholar
Mineral

Calcium Citrate

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Calcium Citrate. Best-absorbed calcium salt — does not require stomach acid.

How it works. Citrate complex absorbed independent of gastric acid; better in PPI users.

What the research supports. 1 graded claims. Strongest: Maintains BMD with vit D and K2 (strong).

How much to take. Typical dose: 500–600 mg elemental BID with meals.

Side effects and interactions. 1 medication interaction listed. Serious: Hypercalcemia at high dose.

Stacking. Pairs well with Vitamin D3 + K2.

Common forms. Available as Chelated form (glycinate, bisglycinate, citrate, malate), Inorganic salt (oxide, sulfate, chloride), Liquid ionic solution, Topical or transdermal preparation.

Key studies. 8 studies cited. The strongest are listed with links to PubMed.

Community. Experiences from people who have tried Calcium Citrate. Anecdotes are not medical advice.

Calcium Citrate. Best-absorbed calcium salt — does not require stomach acid.

Molecular structureC12H10Ca3O14 · 498.4 g/mol

What it is

Best-absorbed calcium salt — does not require stomach acid.

Food sources

Whole foods (leafy greens, legumes, nuts, seeds, seafood, animal proteins)Fortified foods such as cereals, breads, plant milks, and table saltMineral supplements as chelates, citrates, glycinates, or inorganic salts

Goals

Bone DensityOsteoporosis PreventionBone Health

How it works

Citrate complex absorbed independent of gastric acid; better in PPI users.

Pathways

  • Citrate complex absorbed independent of gastric acid
  • better in PPI users

Effects

  • +Maintains BMD with vit D and K2 supports

What the research supports

Maintains BMD with vit D and K2strong

Strong: consistent results across large trials or meta-analyses. Moderate: several trials, mostly positive. Limited: small or mixed studies. Preclinical: animal or cell research only.

Typical dose
500–600 mg elemental BID with meals
TimingConsistent daily timing recommended; split larger doses if GI tolerance is a concern.
With foodWith meals
Best formMost evidence is based on the chelated form (glycinate, bisglycinate, citrate, malate) form.
Upper limit2500 mg/d UL
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Side effects & interactions

Common side effects

  • Constipation

Serious

  • Hypercalcemia at high dose

Medication interactions

Prescription medications (general)minor

Always disclose Calcium Citrate use to your prescriber — additive, antagonistic, or pharmacokinetic interactions are possible.

Check any supplement–medication combination with your pharmacist before starting.

Combines with

Pairs well

Common forms

  • Chelated form (glycinate, bisglycinate, citrate, malate)
  • Inorganic salt (oxide, sulfate, chloride)
  • Liquid ionic solution
  • Topical or transdermal preparation

Key studies

8 studies cited in total.

PubMed: Calcium Citrate — Maintains BMD with vit D and K2 ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching Calcium Citrate and "Maintains BMD with vit D and K2". Filter by RCT, meta-analysis, or year on the results page.

PubMed: Calcium Citrate — randomized controlled trial ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching Calcium Citrate and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

PubMed: Calcium Citrate — meta-analysis ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching Calcium Citrate and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

Discussion

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