Calcium Requirements of Lactating Gambian Mothers: Effects of a Calcium Supplement on Breast-Milk Calcium Concentration, Maternal Bone Mineral Content, and Urinary Calcium Excretion

The calcium requirement for prolonged lactation was investigated in a randomized supplementation study of Gambian mothers consuming a low-calcium diet (7.1 mmol/day or 283 mg/day). 60 women were studied from 10 days to 78 weeks of lactation receiving calcium or placebo for the first 12 months. The supplement increased average calcium intake by 17.9 mmol/day (714 mg/day). Supplementation had no effect on breast-milk calcium concentration or on maternal bone mineral content. Urinary calcium output was higher in supplemented than in unsupplemented mothers by 1.18 mmol/day (47 mg/day) p urinary calcium output and bone mineral content made a substantial contribution to calcium requirements for lactation. This study suggests that in women with low calcium intakes there is no direct benefit from increasing calcium intake during lactation and that physiological mechanisms operate to furnish calcium for breast-milk production. (authors)