Mineral supplements. Calcium
ATC code: A12AA-CALCIUM (Calcium (oral salts, generic group))
Brand names – drugs
Caltrate
Brand names – supplements
Citracal, NOW Foods Calcium Citrate
Supplements are not tested in clinical trials and are not registered as medications.
Calcium is the main structural component of bone tissue (99% of total body calcium). A cofactor for blood coagulation cascades, neuromuscular transmission, and secretory processes. Maintains cell membrane resting potential. Absorbed in the small intestine via calcium-binding protein whose synthesis is regulated by calcitriol. Bioavailability depends on the salt form and gastric pH: citrate is absorbed independent of pH; carbonate requires an acidic environment and is taken with food.
First line
Oral calcium is first-line for mild-to-moderate hypocalcaemia. Treatment dose: 1,000–2,000 mg elemental calcium daily in 2–3 portions with concurrent vitamin D correction and elimination of the cause. In severe symptomatic hypocalcaemia (tetany, laryngospasm, QT prolongation), intravenous calcium gluconate is used.
Adjunct
A required component of combined postmenopausal osteoporosis therapy with vitamin D 800–1,000 IU and antiresorptive or anabolic agents. Endocrine Society 2019 and 2018 recommend 1,000–1,200 mg elemental calcium daily (including dietary intake) in postmenopausal women with osteoporosis or high fracture risk. Calcium monotherapy without vitamin D and without primary antiosteoporotic therapy does not reduce fracture incidence.
Consider total calcium intake (diet + supplementation). Doses above 2,000 mg daily as supplements increase vascular calcification risk without sound clinical justification.
Individual decision
In pregnant women with low dietary calcium intake (less than 600 mg daily), supplementation of 1.5–2 g elemental calcium daily reduces pre-eclampsia risk by about 50% per the 2015 Cochrane meta-analysis. 2020 recommends this intervention in populations with low baseline intake. In women with adequate dietary calcium, the effect is minimal.
The Russian population generally has adequate calcium intake on a varied diet. Supplementation decisions are individualised after dietary review.
Not recommended
Isolated supplemental calcium (above 1,000 mg daily) in adults without osteoporosis for cardiovascular risk reduction is not indicated. The 2010 BMJ meta-analysis (Bolland et al.) found a 24 % increase in myocardial infarction risk with isolated high-dose calcium. Subsequent data are mixed, but cardiology societies do not recommend isolated calcium as cardiovascular prevention. Standard prevention: blood pressure control, statins when clinically indicated, smoking cessation.
Calcium above 300 mg reduces iron absorption by 40–60%. Separate iron and calcium intake by at least 2 hours.
Vitamin D enhances intestinal calcium absorption by stimulating calcium-binding protein synthesis. In osteoporosis treatment, calcium is prescribed only with vitamin D – monotherapy is ineffective.
Safe at physiological doses. Supplementation at 1,000–1,200 mg daily during pregnancy and lactation is encouraged by international obstetric societies. In pregnant women with low dietary intake: 1,500–2,000 mg daily.
calcium (oral salts: carbonate, citrate, lactate, gluconate) is evaluated for the following indications with varying evidence strength: Postmenopausal osteoporosis (evidence tier A), Hypocalcaemia (evidence tier A), Pre-eclampsia prevention in low dietary calcium intake (evidence tier B). See the full indication matrix with dosing and citations above on this page.
Common side effects of calcium (oral salts: carbonate, citrate, lactate, gluconate) (≥ 1 in 100): Constipation, Flatulence, eructation, Nausea at larger doses. See the Safety section for uncommon and serious reactions.
FDA category C. Safe at physiological doses. Supplementation at 1,000–1,200 mg daily during pregnancy and lactation is encouraged by international obstetric societies. In pregnant women with low dietary intake: 1,500–2,000 mg daily.
Calcium is actively secreted into breast milk. Lactating women are advised to take 1,000–1,200 mg elemental calcium daily including dietary intake.
Calcium is actively secreted into breast milk. Lactating women are advised to take 1,000–1,200 mg elemental calcium daily including dietary intake.
calcium (oral salts: carbonate, citrate, lactate, gluconate) is contraindicated in: Hypercalcaemia of any aetiology; Severe hypercalciuria; Calcium-containing kidney stones; Severe renal impairment; Sarcoidosis and other granulomatous diseases (relative). Full list in the Safety section.
with adequate dietary intake, supplemental calcium does not reduce fracture risk in people without osteoporosis. Isolated supplementation without vitamin D and physical activity has minimal effect on bone density.
there are data on increased cardiovascular risk with high-dose calcium (above 1,000 mg daily isolated, without vitamin D), but with standard combined osteoporosis therapy with vitamin D the effect is minimised. The best approach is dietary calcium, not supplements.
gluconate contains little elemental calcium (9%) – 12–15 tablets are needed for a treatment dose. Carbonate contains 40% elemental calcium, citrate 21%. Carbonate is the most cost-effective form with preserved gastric acidity; citrate is for hypoacidity.