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Take split doses max 500mg — absorption limited per dose. High doses may increase risk of kidney stones and cardiovascular events in susceptible individuals.
Calcium is the most abundant mineral in the body, essential for bone and teeth formation, muscle contraction, and nerve signalling. EU approved claims include: needed for maintenance of normal bones and teeth.
Structural component of hydroxyapatite in bone. Required for muscle contraction (troponin-tropomyosin regulation), nerve impulse transmission, and blood clotting.
| Population | Safety rating | Max safe dose |
|---|---|---|
| General | Likely safe | 2500mg/day |
| UL 2500mg/day. Excess may increase cardiovascular risk. | ||
| Pregnancy | Likely safe | 1000mg/day |
| Required for fetal bone development. Excess may cause kidney stones. | ||
| Children | Likely safe | 800-1300mg/day (age-dependent) |
| Essential for bone development. Generally safe at RDA levels. | ||
| Elderly | Possibly safe | Max 1200mg/day from all sources |
| Evidence of slight cardiovascular risk with high-dose calcium supplements (without co-supplemented K2). Split doses. | ||
| Kidney Disease | Possibly unsafe | Reduce dose |
| May worsen hypercalcaemia in CKD. | ||
No peer-reviewed clinical trial data found for this ingredient.
Bone resorption inhibitors
Calcium significantly reduces bisphosphonate absorption when taken simultaneously.
Cardiac glycosides
Hypercalcaemia from excessive calcium supplementation potentiates digoxin toxicity and cardiac arrhythmias.
Beta-blockers
Calcium reduces atenolol bioavailability by 20-30%
Minerals
Calcium competes with iron for intestinal absorption via shared divalent cation transporters.
Minerals
Calcium inhibits non-haem iron absorption when taken together, reducing iron bioavailability.
Thyroid hormones
Calcium carbonate significantly reduces levothyroxine absorption when taken simultaneously.
Antidiabetics
Absorption interference reduces metformin bioavailability
Calcium channel blockers
High-dose calcium may partially antagonize calcium channel blockade
Data by supplement.ge — Public Health Institute of Georgia (PHIG)