The relation of dietary vitamin C intake to bone mineral density: results from the PEPI study

Ascorbic acid is a required cofactor in the hydroxylations of lysine and proline necessary for collagen formation; its role in bone cell differentiation and formation is less well characterized. This study examines the cross-sectional relation between dietary vitamin C intake and bone mineral density (BMD) in women from the Postmenopausal Estrogen/Progestin Interventions Trial. BMD (spine and hip) was measured using dual energy X-ray absorptiometry (DXA). The PEPI participants (n = 775) included in this analysis were Caucasian and ranged in age from 45 to 64 years. At the femoral neck and total hip after adjustment for age, BMI, estrogen use, smoking, leisure physical activity, calcium and total energy intake, each 100 mg increment in dietary vitamin C intake, was associated with a 0. 017 g/cm2 increment in BMD (P = 0.002 femoral neck; P = 0.005 total hip). After adjustment, the association of vitamin C with lumbar spine BMD was similar to that at the hip, but was not statistically significant (P = 0.08). To assess for effect modification by dietary calcium, the analyses were repeated, stratified by calcium intake (>500 mg/day and