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Calcium

Essential mineral with EFSA claims for bone, teeth, muscle and blood-clotting, best paired with vitamin D and ideally food-source.

Why

Calcium is essential for bone matrix, muscle contraction, neurotransmission and blood coagulation. EFSA has authorised health claims for normal bone, normal teeth, normal muscle function, normal neurotransmission and normal blood clotting. Supplementation at 500–1,200 mg/day is widely used in postmenopausal osteoporosis prevention. The Bolland 2010 BMJ meta-analysis raised a cardiovascular event signal with calcium supplements (without vitamin D), clinical practice has moved towards food-first calcium with vitamin D co-supplementation when supplements are needed.

How it works

Hydroxyapatite formation in bone (with phosphate). Excitation-contraction coupling in muscle (binding troponin C). Synaptic vesicle release at neurotransmitter terminals. Coagulation factor IV (the central divalent cation of clotting).

Expected onset · Bone-marker changes over weeks; clinical osteoporosis outcomes over years

How to take

Dosage

RDI: 800–1,200 mg/day total intake (food + supplement). Supplement: 500–600 mg per dose (absorption limited above this). Avoid total intakes above 2,000 mg/day.

Timing

With meals; split for higher doses; separate from iron and thyroid medication by 4 hours

On the label

Calcium citrate (better absorbed independent of food/acid; safer in hypochlorhydria) or calcium carbonate (cheaper, take with food). Stated elemental calcium per dose, not salt weight.

Ideal for

Postmenopausal women and adults with low dietary calcium intake (<700 mg/day from food); osteoporosis prevention contexts under clinical guidance; pregnancy and lactation.

Safety

Bolland 2010 BMJ meta-analysis raised concern about cardiovascular events with calcium supplements (without vitamin D), debate ongoing, but practice is food-first calcium with vit D co-supplementation when needed. Constipation, bloating, increased kidney-stone risk in stone-formers. Reduces absorption of iron, thyroxine, tetracyclines, quinolones. Separate by 4 hours. Pregnancy and breastfeeding: increased dietary need; supplement when food intake is inadequate.

Evidence

At a glance

EFSA-authorised claims cover six separate functions of calcium. Tang 2007 Lancet meta-analysis: calcium 1,200 mg + vitamin D 800 IU reduced fracture risk by 12% over 3.5 years in older adults. Bolland 2010 BMJ raised concern over calcium alone for cardiovascular events, practical takeaway is to favour dietary calcium and pair supplements with vitamin D.

Where to get it

Shop Calcium on Amazon

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