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Calcium (Citrate)

Mineraloral · inferred

Essential for bone health, muscle function, and nerve signaling. Citrate form does not require stomach acid for absorption.

Projected serum levels — 500 mg, once daily

Calcium (Citrate)
Calcium (Citrate) modeled serum levels, 500 mg once daily over 95 days Population-based pharmacokinetic estimate. Steady state reached after approximately 35 days. 0 1.3k 2.5k 3.8k 5k Day 0 Day 24 Day 48 Day 71 Day 95 Time on a regular schedule ≈ steady state · day 35
Calcium (Citrate) modeled serum levels with a loading dose of 1.5k mg, then 500 mg once daily The first dose is larger so levels approach steady state faster. 0 1.3k 2.5k 3.8k 5k Day 0 Day 24 Day 48 Day 71 Day 95 Time on a regular schedule

Maintenance schedule: 500 mg once daily (oral).

Loading schedule: 1.5k mg on day 1, then 500 mg once daily — reaching therapeutic levels sooner.

Modeled steady state after ~35 days: peak ≈ 2.7k mg, trough ≈ 2.6k mg body load. Population-based estimate over 95 days for a 500 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.

Key facts

Category
Mineral
Route modeled
Oral
Model confidence
inferred
Half-life
13 days
Common dose
500 mg
Suggested maximum
2.5k mg/day
Reference dose range
250–2.5k mg (single dose)
Suggested cadence
once daily

Documented interactions

  • warning
    Iron (Bisglycinate) + Calcium (Citrate) Absorption

    Calcium inhibits both heme and non-heme iron absorption by up to 60% when taken together.

  • warning
    Levothyroxine (Synthroid) + Calcium (Citrate) Absorption

    Calcium binds levothyroxine in the gut, reducing absorption by up to 40%.

  • caution
    Alendronate (Fosamax) + Calcium (Citrate) Chelation

    Alendronate (Fosamax) (bisphosphonate) forms insoluble complexes with Calcium (Citrate) in the GI tract, reducing absorption of both.

  • caution
    Armour Thyroid (Desiccated Thyroid Extract) + Calcium (Citrate) Chelation

    Armour Thyroid (Desiccated Thyroid Extract) (thyroid hormone) forms insoluble complexes with Calcium (Citrate) in the GI tract, reducing absorption of both.

  • caution
    Caffeine + Calcium (Citrate) Depletion

    Caffeine modestly increases urinary calcium excretion (about 5 mg per cup of coffee).

  • caution
    Magnesium Citrate + Calcium (Citrate) Absorption

    Calcium and magnesium compete for the same absorption pathways. High-dose calcium reduces magnesium uptake.

Serum checks 12 modeled interaction pairings for calcium (citrate) across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. Calcium plus vitamin D supplementation and the risk of fractures Jackson RD et al. · New England Journal of Medicine, 2006 DOI

    Large WHI trial of 36,282 women found calcium plus vitamin D supplementation improved hip bone density, though fracture reduction was significant only in adherent participants.

  2. Calcium absorption from calcium citrate and calcium carbonate Heaney RP et al. · Calcified Tissue International, 1999 DOI

    Study showed calcium citrate is absorbed 22-27% better than calcium carbonate, especially on an empty stomach or in individuals with reduced stomach acid.

  3. Absorption of calcium as the carbonate and citrate salts, with some observations on method. Heaney RP, Dowell MS, Barger-Lux MJ · Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 1999 DOI

    This citation reports a human clinical study involving Calcium (Citrate). It does not by itself establish a qualified dose, safety profile, efficacy claim, or pharmacokinetic route for this record.

3 published studies referenced in the app, each with a plain-language summary.