Do calcium supplements help reduce symptoms of PMS?

Several small and heterogeneous clinical studies suggest that daily supplementation with 500–1,200 milligrams of calcium for up to 3 menstrual cycles improves PMS symptoms such as bloating, food cravings, and pain when compared to placebo. Also, several observational studies have found that PMS symptoms are associated with lower total calcium levels. It is possible that calcium levels are reduced during menstruation, precipitating PMS symptoms. Estrogen may lower calcium in the blood by inhibiting bone resorption. During the menstrual cycle, estrogen has two peaks: right before the luteinizing hormone surge and during the luteal phase. Theoretically, the peaks in estrogen lower total calcium levels. In some, the lower blood calcium levels can increase parathyroid hormone levels and lower calcium levels in the smooth muscle, which in turn might precipitate PMS symptoms such as cramping and pain.^[1]