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-ca lcium diet (7.1 mmol/d, or 283 mg/d). Sixty women were studied from 10 d to 78 wk of lactation, receiving calcium or placebo for the first 1 2 mo. The supplement increased average calcium intake by 17.9 mmol/d ( 714 mg/d). Supplementation had no effect on breast-milk calcium concen tration or on maternal. bone mineral content. Urinary calcium output w as higher in supplemented than in unsupplemented mothers by 1.18 mmol/ d (47 mg/d), P less than or equal to 0.005. Longitudinal changes in ur inary calcium output and bone mineral content made a substantial contr ibution to calcium requirements for lactation. This study suggests tha t, in women with low calcium intakes, there is no direct benefit from increasing calcium intake during lactation, and that physiological mec hanisms operate to furnish calcium for breast-milk production.