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evidence · mechanism · dose
Supplements/Mineral

Calcium Citrate

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

Bone DensityOsteoporosis PreventionBone Health

Overview

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

Natural sources
    Common forms

      Mechanism of action

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

      Pathways

        Effects on the body

        Organ system effects

        Evidence-based benefits

        Maintains BMD with vit D and K2

        Strong evidence

        Potential side effects

        Common
        • · Constipation
        Rare
          Serious
          • · Hypercalcemia at high dose

          Drug interactions

          No notable interactions reported.

          Supplement interactions

          Pairs well with
          • Vitamin D3 + K2
            Calcium trafficking to bone.
          Avoid combining with

          No specific avoidances listed.

          Dosing & bioavailability

          Typical dose
          500–600 mg elemental BID with meals
          Upper safe limit
          2500 mg/d UL
          With food?
          With meals

          Where to buy

          Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

          Mineral
          Calcium Citr…
          Amazon
          Wide selection · fast shipping
          Mineral
          Calcium Citr…
          iHerb
          Global delivery · curated brands
          Mineral
          Calcium Citr…
          Thorne
          Practitioner-grade · NSF tested

          Scientific evidence (8)

          RCTJ Clin Pharmacol · 2000

          Calcium citrate vs carbonate absorption

          Heller HJ, et al.

          Crossover trial of Ca forms.

          Key findings

          Citrate absorbed 22-27% better, especially on empty stomach.

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Calcium Citrate — Maintains BMD with vit D and K2

          Live PubMed search

          Live results for "Calcium Citrate Maintains BMD with vit D and K2" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

          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.

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Calcium Citrate — randomized controlled trial

          Live PubMed search

          Live results for "Calcium Citrate randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

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

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Calcium Citrate — meta-analysis

          Live PubMed search

          Live results for "Calcium Citrate meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

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

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Calcium Citrate — pharmacokinetics

          Live PubMed search

          Live results for "Calcium Citrate pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

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

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Calcium Citrate — safety adverse events

          Live PubMed search

          Live results for "Calcium Citrate safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

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

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: Calcium Citrate — dose response

          Live PubMed search

          Live results for "Calcium Citrate dose response" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

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

          Open study
          Systematic reviewGoogle Scholar · 1970

          Google Scholar: Calcium Citrate — clinical evidence

          Live Scholar search

          Cross-database citation index for Calcium Citrate as it relates to "clinical evidence".

          Key findings

          Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

          Open study
          Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.