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evidence · mechanism · dose
Supplements/Mineral

Calcium Citrate

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

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Overview

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

Natural sources
  • Whole foods (leafy greens, legumes, nuts, seeds, seafood, animal proteins)
  • Fortified foods such as cereals, breads, plant milks, and table salt
  • Mineral supplements as chelates, citrates, glycinates, or inorganic salts
Common forms
  • Chelated form (glycinate, bisglycinate, citrate, malate)
  • Inorganic salt (oxide, sulfate, chloride)
  • Liquid ionic solution
  • Topical or transdermal preparation

Mechanism of action

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

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

Effects on the body

Supports
Maintains BMD with vit D and K2

Organ system effects

Bones

Calcium Citrate contributes to bone mineralization, osteoblast activity, or calcium-phosphate homeostasis.

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

    Prescription medications (general)
    Always disclose Calcium Citrate use to your prescriber — additive, antagonistic, or pharmacokinetic interactions are possible.
    minor

    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
    Best form
    Most evidence is based on the chelated form (glycinate, bisglycinate, citrate, malate) form.
    Timing
    Consistent daily timing recommended; split larger doses if GI tolerance is a concern.
    With food?
    With meals

    Where to buy

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    Scientific evidence8Show studies
    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.

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