Association between bone mineral density and lifestyle factors or vitamin D receptor gene polymorphism in adult male workers: a cross-sectional study.

OBJECTIVES: The aim of this cross-sectional study was to investigate the association between bone mineral density (BMD) and lifestyle factors, as well as the influence of vitamin D receptor (VDR) gene polymorphism, in adult male workers. METHODS: The subjects were 524 male employees aged 23-49 years (37.3 +/- 5.4 years, mean +/- standard deviation) working at a large-scale integrated manufacturing facility in Japan. BMD was measured at the nondominant radius by dual-energy X-ray absorptiometry. Lifestyle information was obtained by a questionnaire at the same time, and genomic DNA was isolated from peripheral leukocytes. RESULTS: The genotype frequencies of VDR gene polymorphism detected by Taq I digestion were 81.3%, 17.9%, and 0.8% for TT, Tt, and tt, respectively. BMD was 0.56 +/- 0.06 g/cm(2). Analysis of covariance with adjustment for age and body mass index (BMI) revealed that subjects who had a past history of exercise, current exercise from 3 to 7 days a week or daily alcohol intake showed significantly higher BMD than subjects without these features (0.56 +/- 0.06 versus 0.54 +/- 0.06, 0.58 +/- 0.06 versus 0.55 +/- 0.06, and 0.57 +/- 0.06 versus 0.55 +/- 0.06, respectively) (P < 0.05). Subjects who ate only 2 meals a day or smoked >/=21 cigarettes a day showed significantly lower BMD if they had the Tt or tt genotype than if they had the TT genotype (0.51 +/- 0.04 versus 0.56 +/- 0.06 and 0.51 +/- 0.05 versus 0.57 +/- 0.06, respectively) (P < 0.05). CONCLUSIONS: These findings suggest that the influence of lifestyle on BMD differs according to VDR gene polymorphism in adult male workers.