Protective effect of total and supplemental vitamin C intake on the risk of hip fracture--a 17-year follow-up from the Framingham Osteoporosis Study.
Vitamin C may play a role in bone health. In the Framingham Study, subjects with higher total or supplemental vitamin C intake had fewer hip fractures and non-vertebral fractures as compared to subjects with lower intakes. Therefore, vitamin C may have a protective effect on bone health in older adults.


BACKGROUND
Dietary antioxidants such as vitamin C may play a role in bone health. We evaluated associations of vitamin C intake (total, dietary, and supplemental) with incident hip fracture and non-vertebral osteoporotic fracture, over a 15- to 17-year follow-up, in the Framingham Osteoporosis Study.


METHODS
Three hundred and sixty-six men and 592 women (mean age 75 +/- 5 years) completed a food frequency questionnaire (FFQ) in 1988-1989 and were followed for non-vertebral fracture until 2003 and hip fracture until 2005. Tertiles of vitamin C intake were created from estimates obtained using the Willett FFQ, after adjusting for total energy (residual method). Hazard ratios were estimated using Cox-proportional hazards regression, adjusting for covariates.


RESULTS
Over follow-up 100 hip fractures occurred. Subjects in the highest tertile of total vitamin C intake had significantly fewer hip fractures (P trend = 0.04) and non-vertebral fractures (P trend = 0.05) compared to subjects in the lowest tertile of intake. Subjects in the highest category of supplemental vitamin C intake had significantly fewer hip fractures (P trend = 0.02) and non-vertebral fractures (P trend = 0.07) compared to non-supplement users. Dietary vitamin C intake was not associated with fracture risk (all P > 0.22).


CONCLUSIONS
These results suggest a possible protective effect of vitamin C on bone health in older adults.
Dietary Assessment and Epidemiology Research Program, Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) and Friedman School of Nutrition Science and Policy (FSNSP), Tufts University, Boston, MA, USA.
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D000368:Aged; D000369:Aged, 80 and over; D001205:Ascorbic Acid / Q000008:administration & dosage*; D015519:Bone Density / Q000187:drug effects; D015986:Confounding Factors, Epidemiologic; D004032:Diet / Q000706:statistics & numerical data; D019587:Dietary Supplements; D004812:Epidemiologic Methods; D005260:Female; D006620:Hip Fractures / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D008875:Middle Aged; D010024:Osteoporosis / Q000150:complications / Q000453:epidemiology / Q000517:prevention & control; D058866:Osteoporotic Fractures / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D017419:Potassium, Dietary / Q000008:administration & dosage
D017419:Potassium, Dietary; D001205:Ascorbic Acid