Antioxidant intake and risk of osteoporotic hip fracture in Utah: An effect modified by smoking status

The role of antioxidant intake in osteoporotic hip fracture risk is uncertain and may be modified by smoking. In the Utah Study of Nutrition and Bone Health, a statewide, population-based case-control study, the authors investigated whether antioxidant intake was associated with risk of osteoporotic hip fracture and whether this association was modified by smoking status. The analyses included data on 1,215 male and female cases aged >= 50 years who incurred a hip fracture during 1997-2001 and 1,349 age- and sex-matched controls. Diet was assessed by food frequency questionnaire. Among ever smokers, participants in the highest quintile of vitamin E intake (vs. the lowest) had a lower risk of hip fracture after adjustment for confounders (odds ratio = 0.29, 95% confidence interval (CI): 0.16, 0.52; p-trend < 0.0001). The corresponding odds ratio for beta-carotene intake was 0.39 (95% CI: 0.23, 0.68; p-trend = 0.0004), and for selenium intake it was 0.27 (95% CI: 0.12, 0.58; p-trend = 0.0003). Vitamin C intake did not have a significant graded association with hip fracture risk among ever smokers. Similar findings were obtained when an overall antioxidant intake score was used (odds ratio = 0.19, 95% CI: 0.10, 0.37; p-trend < 0.0001). No similar associations were found in never smokers. Antioxidant intake was associated with reduced risk of osteoporotic hip fracture in these elderly subjects, and the effect was strongly modified by smoking status.