Maintains normal heartbeat, nerve and muscle function and blood clotting. Milk products, green leafy vegetables canned salmon with bones and sardines with bones, calcium-fortified orange juice, corn tortillas processed with lime. Calcium decreases the absorption of iron supplements unless vitamin C is taken at same time. Increases blood level of both calcium and magnesium-containing medications or supplements. Oral contraceptives and estrogens may increase calcium absorption.
Potassium supplements increases chance of heartbeat irregularities.
Decreases absorption of tetracycline. Mega-doses of vitamin A stimulates bone loss. Mega-doses of vitamin D excessively increases absorption of calcium supplements. Extremely low blood pressure. Extreme muscle weakness.