Zinc intakes and plasma concentrations in men with osteoporosis: the Rancho Bernardo Study.

BACKGROUND Low zinc intakes and reduced blood zinc concentrations have been reported to be associated with osteoporosis in women. OBJECTIVE The objective was to examine the independent association between dietary zinc and plasma zinc and the association of each with bone mineral density (BMD) and 4-y bone loss in community-dwelling older men. DESIGN Of the original Rancho Bernardo Study subjects, 396 men (age: 45-92 y) completed BMD measurements at baseline in 1988-1992 and 4 y later. Osteoporosis was defined as a BMD > or = 2.5 SDs below the mean for young women (a T-score < or = -2.5). At baseline, dietary intake data were collected by using a standard food-frequency questionnaire, and plasma zinc concentrations were measured by using inductively coupled plasma spectroscopy. RESULTS The mean dietary zinc intake was 11.2 mg, and the mean plasma zinc concentration was 12.7 micromol/L. Plasma zinc was correlated with total zinc intake (diet plus supplements). Dietary zinc intake and plasma zinc concentrations were lower in men with osteoporosis at the hip and spine than in men without osteoporosis at those locations. BMDs for the hip, spine, and distal wrist were significantly lower in men in the lowest plasma zinc quartile (<11.3 micromol/L) than in men with higher plasma zinc concentrations. The association between plasma zinc and BMD was cross-sectional, longitudinal, and independent of age or body mass index. However, plasma zinc did not predict bone loss during the 4-y interval. CONCLUSION Dietary zinc intake and plasma zinc each have a positive association with BMD in men.