Effects of a low sodium diet on bone metabolism.

Osteoporosis is a serious public health problem, and dietary interventions may potentially be helpful in preventing this disorder. The purpose of this study was to determine the effects of a low sodium diet on bone metabolism in postmenopausal women. This was a longitudinal study to determine the effects of a low sodium (2-g/day) diet on bone. Forty postmenopausal African-American and Caucasian women were enrolled in a 2-g/day sodium diet for 6 months. Sodium and calcium excretion, bone turnover, and calcitropic hormones (intact parathyroid hormone (PTH) and 1,25 dihydroxyvitamin D) were measured before and 6 months after the intervention. In women who had baseline sodium excretions equal to or greater than the average sodium intake in the United States (> or =3.4 g/day), the low sodium diet resulted in significant decreases in sodium excretion (P = 0.01), in calcium excretion (P = 0.01), and in a biomarker of bone turnover, aminoterminal propeptide of type I collagen (P = 0.04). However, there were no significant changes in calcitropic hormones, including intact PTH (P = 0.97) or 1,25 dihydroxyvitamin D (P = 0.49) with the low sodium diet. These findings suggest that in postmenopausal women with sodium intakes > or =3.4 g/day, a low sodium diet may have benefits for skeletal health.