Abstract

A higher calcium intake is still the primary recommendation for the prevention of osteoporosis, while vitamin D deficiency is often not addressed. To study the relative importance of dietary calcium intake and serum 25-hydroxyvitamin D (25(OH)D) status in regard to hip bone mineral density (BMD) in 4958 community-dwelling women and 5003 men age 20 years + from the US NHANES III population-based survey. Calcium supplement users and individuals with a prior radius or hip fracture were excluded. We calculated standardized means for BMD by quartiles of gender-specific calcium intake for three 25(OH)D categories (< 50, 50-74, 75+ nmol/l) among men and women separately controlling for other important predictors of BMD . Only for women with 25(OH)D status below 50 nmol/l , a higher calcium intake was significantly associated with higher BMD (p-value for trend: p = 0.005), whereas calcium intake beyond the upper end of the lowest quartile ( > 566 mg/d) was not significantly associated with BMD at 25(OH)D concentrations above 50 nmol/l. Among men, there was no significant association between a higher calcium intake beyond the upper end of the lowest quartile (626 mg/d) and BMD within all 25(OH)D categories. Among both genders, BMD increased stepwise and significantly with higher 25(OH)D concentrations(< 50, 50-74, 75+ nmol/l; p-value for trend: women < 0.0001; men = 0.0001). Among men and women, 25(OH)D status appears to be the dominant predictor of BMD relative to calcium intake. Only women with 25(OH)D concentrations below 50 nmol/l appear to benefit from a higher calcium intake.