Vitamin D receptor variability and physical activity are jointly associated with low handgrip strength and osteoporosis in community-dwelling elderly people in Taiwan: the Taichung Community Health Study for Elders (TCHS-E)

Abstract

We studied 472 elders to assess joint association of vitamin D receptor (VDR) variability and physical activity on low handgrip strength (LHS) and osteoporosis (OST). Our findings showed that higher risks of OST were associated with physically inactive elders with some specific VDR variations, highlighting the importance of promotion program for physical activity. The aim of this study was to determine the joint association between VDR variability and physical activity on LHS and OST in community-dwelling elders. Bone mineral density of the lumbar spine (LS), the femoral neck (FN), and the total hip were measured by dual-energy X-ray absorptiometry. Four single-nucleotide polymorphisms (SNPs) (rs7975232, rs1544410, rs2239185, and rs3782905) of the VDR gene were examined in 472 participants. Physical inactivity and each of the four SNPs were jointly associated with a significantly greater risk of LHS in people than that associated with each of the VDR SNPs or low physical activity alone. Physically inactive men with the AG or AA genotype of rs2239185 had a significantly greater risk of overall, LS, and FN OST than those of physically active men with the GG genotype [odds ratio (OR) 3.57, 95% confidence interval (CI) 1.10-11.65; OR 4.74, 95% CI 1.43-15.70; and OR 5.06, 95% CI 1.08-23.71, respectively]. Similarly, physically inactive women with the CG or CC genotype of rs3782905 and the AG or AA genotype of rs1544410 had a significantly greater risk of FN OST than physically active women with the GG genotype (OR 5.33, 95% CI 1.23-23.06 and OR 5.36, 95% CI 1.11-25.94, respectively). VDR polymorphisms and physical activity are jointly associated with LHS and OST in elders. Health care programs should promote physical activity among elders as a cost-effective way to prevent LHS and OST, especially in those who may be genetically predisposed.