Vitamin-D nutrition and bone mass in adolescent black girls

To examine the relationship between bone mass and serum levels of 25-hydroxyvitamin D and parathyroid hormone in African-American adolescent girls.

A cross-sectional sample at a suburban research center.

Twenty-one adolescent black girls 12-14 years of age, were studied during winter with biochemical measurements of serum 25-hydroxyvitamin D (25-OHD) and parathyroid hormone (PTH). Bone mass assessment was done with dual energy x-ray absorbsiometry (DXA) and peripheral quantitative computed tomography of the radius (p-QCT). Anthropometric, physical activity and nutritional data were collected.

All participants were vitamin-D deficient (serum 25-OHD level <50 nmol/L), of whom nine (43%) were severely vitamin-D deficient (serum 25-OHD level <20 nmol/L). Mean daily intake of dietary calcium was 540 mg/d and vitamin D was 195 IU/d. There was a positive correlation, although statistically not significant, between serum 25-OHD and various bone mass measurements. Serum PTH was inversely correlated to total body BMD (r = -0.51, p = 0.02) and other bone mineral density at the lumbar spine, total femur and mid-radius.

Vitamin-D insufficiency is a widely prevalent problem among adolescent African-American girls. Our data implies that enhancing vitamin-D nutrition resulting in lower serum PTH levels could potentially influence their peak bone mass.