Bone and teeth, muscle contraction, nerve transmission, blood clotting and cell signalling.
Switzerland age 18–65: 950 mg/day; age 18–24: 1,000 mg/day.
Milk/yoghurt/cheese, calcium-fortified plant drinks, calcium-set tofu, sardines with bones, kale and sesame/tahini.
Blood calcium is maintained from bone stores for a long time. Marked hypocalcaemia can cause tingling, muscle cramps/spasms, seizures and arrhythmias.
Long-term low intake contributes with vitamin D deficiency, inactivity and other factors to low bone mass and osteoporosis.
Hair and nails are not a reliable calcium-deficiency test. Brittle nails have many more common causes.
Dairy-free diet without fortified alternatives, malabsorption, older age, eating disorders and low vitamin D status.
Assess dietary intake, bone risk and vitamin D; serum calcium is a poor measure of long-term intake.
Food first. Supplement only to fill a defined gap or for a medical indication; consider total dose and kidney/stone risk.
Too much from supplements can promote constipation, kidney stones and hypercalcaemia.