Vitamin K intake and bone mineral density in women and men

Abstract

Background: Low dietary vitamin K intake has been associated with an increased risk of hip fracture in men and women. Few data exist on the association between dietary vitamin K intake and bone mineral density (BMD). Objective: We studied cross-sectional associations between self-reported dietary vitamin K intake and BMD of the hip and spine in men and women aged 29-86 y. Design: BMD was measured at the hip and spine in 1112 men and 1479 women (x̄ ± SD age: 59 ± 9 y) who participated in the Framingham Heart Study (1996-2000). Dietary and supplemental intakes of vitamin K were assessed with the use of a food-frequency questionnaire. Additional covariates included age, body mass index, smoking status, alcohol use, physical activity score, and menopause status and current estrogen use among the women. Results: Women in the lowest quartile of vitamin K intake (x̄: 70.2 μg/d) had significantly (P ≤ 0.005) lower mean (±SEM) BMD at the femoral neck (0.854 ± 0.006 g/cm2) and spine (1.140 ± 0.010 g/cm2) than did those in the highest quartile of vitamin K intake (x̄: 309 μg/d): 0.888 ± 0.006 and 1.190 ± 0.010 g/cm2, respectively. These associations remained after potential confounders were controlled for and after stratification by age or supplement use. No significant association was found between dietary vitamin K intake and BMD in men. Conclusions: Low dietary vitamin K intake was associated with low BMD in women, consistent with previous reports that low dietary vitamin K intake is associated with an increased risk of hip fracture. In contrast, there was no association between dietary vitamin K intake and BMD in men.