Background: Dietary and lifestyle variations may be too small to detect possible associations with bone mineral density (BMD) within a community. Pooled data from communities with different diets and lifestyle but of the same ethnicity may help explore these associations.
Objective: To examine the effects of dietary and lifestyle factors on BMD in young Chinese women.
Methods: Baseline data were analyzed from 441 women aged 20 to 35 years in Hong Kong and Beijing who were participating in a longitudinal study evaluating the effect of milk supplementation on bone health. Data on demographic characteristics, lifestyle, use of oral contraceptives, diet, physical activity, and BMD of total hip, femoral neck, and total spine measured by dual-energy x-ray absorptiometry were pooled for analysis.
Results: Hong Kong subjects had significantly lower BMD and higher body-size-adjusted dietary intakes of protein, fat, fiber, vitamins, potassium, sodium, and selenium than Beijing subjects. Multivariate regression of pooled data showed that body mass index was the most important determinant of BMD at all sites. Age was negatively associated and use of oral contraceptives was positively associated with femoral neck BMD. Carbohydrate intake was positively associated with total hip BMD. Fiber intake was negatively associated with BMD at total hip and total spine. Increased vitamin E intake was associated with greater total spine BMD. None of the nutrients were associated with BMD at the femoral neck.
Conclusions: Diet, lifestyle, and BMD differed greatly between young women from Hong Kong and Beijing. Body mass index was the most important determinant of BMD in young Chinese women, whereas age, use of oral contraceptives, and diet had less pronounced effects.