Calcium
Critical for bone, but get it from food rather than pills. Calcium supplements carry cardiovascular risk that food calcium doesn't.
Strong evidence calcium is required for bone — but the case for supplementation specifically (beyond diet) is weaker than once thought. Bolland et al. meta-analyses raised concerns about MI risk from supplemental calcium. Bone density benefits are real but modest; fracture reduction more so when combined with vitamin D + K2 + weight-bearing exercise.
Calcium is the most abundant mineral in the body — 99% sits in bones and teeth, the remaining 1% drives muscle contraction, nerve signalling, blood clotting, and hormonal release. Bone calcium acts as a reservoir the body draws on to keep blood levels stable. Adequate intake is essential, especially for women in perimenopause and beyond when bone loss accelerates. The catch: high-dose supplemental calcium has been linked to increased cardiovascular events in some studies, while calcium from food shows no such risk. The mechanism appears to be the abrupt blood-level spike from a 500–1000 mg pill that food can't produce.
- Form
- Food first, always. If you must supplement: calcium citrate (well-absorbed, doesn't require stomach acid, fine on empty stomach). Hydroxyapatite (bone-form calcium with co-factors). Avoid calcium carbonate (cheap, needs stomach acid, constipating). Avoid combined calcium-D supplements that deliver >500 mg calcium per dose.
- Dose
- Total intake 1,000–1,200 mg/day (food + supplement). If supplementing, keep doses under 500 mg at a time and not more than 500 mg/day from supplements — the rest should be food.
- Timing
- With food. Split doses across the day if supplementing more than 250 mg.
- Schedule
- Daily.
- Side effects
- Constipation (especially carbonate). Bloating. Kidney stones at high doses combined with low water intake. Hypercalcemia at very high doses.
- Interactions
- Reduces absorption of thyroid medication (levothyroxine — separate by 4 hours), tetracyclines, fluoroquinolones, bisphosphonates, iron, zinc — separate dose timing. Thiazide diuretics elevate calcium retention.
- Contraindications
- Hyperparathyroidism. History of kidney stones (esp. calcium oxalate). Hypercalcemia. Active cardiovascular disease (relative — discuss with cardiologist before supplementing).
- Lab markers
- Serum calcium (corrected for albumin) — narrow normal range; deviations matter. Ionized calcium (more accurate). DEXA scan for bone density (every 2 years for at-risk adults). Parathyroid hormone (PTH) if abnormal calcium.
- Food sources
- Dairy — yogurt, kefir, cheese (especially aged hard cheeses), milk. Plant sources — sardines and canned salmon with bones, leafy greens (kale, collards, bok choy — NOT spinach, which binds it), tahini, almonds, broccoli, fortified plant milks. Two servings of dairy + a serving of greens easily delivers 1,000+ mg without supplements.
Pairs with
Vitamin D3 (essential for absorption). Vitamin K2 (routes calcium to bone, not arteries). Magnesium (often deficient together; needed for bone matrix). Weight-bearing exercise (the actual signal for bone deposition).
within Minerals