ARS | Publication request: High Vitamin C intake is associated with lower 4-year bone loss in elderly men

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 24, 2008
Publication Date: October 1, 2008
Citation: Sahni, S., Hannan, M.T., Gagnon, D., Blumberg, J., Cupples, L., Kiel, D.P., Tucker, K. 2008. High Vitamin C intake is associated with lower 4-year bone loss in elderly men. Journal of Nutrition. 138:1931-1938.

Interpretive Summary: It has been estimated that almost 10 million Americans have osteoporosis, and low bone mass is a major public health threat for almost 44 million people in the US population, aged 50 y and older. Studies have consistently shown that higher fruit and vegetable intake has positive effects on bone mineral status and that fruit and vegetable specific antioxidants, such as vitamin C, may decrease oxidative stress arising from reactive oxygen intermediates that may be involved in the bone-resorptive process. Therefore, vitamin C might help in preventing osteoporosis. In addition, bone matrix contains over 90% of protein as collagen, and it is well established that vitamin C is an essential cofactor for collagen formation. Furthermore, animal studies have demonstrated that experimental deficiency of vitamin C leads to impaired bone mass, cartilage and connective tissue. Several epidemiologic studies have examined the association of vitamin C in relation to bone mineral density (BMD). However, results from these studies have been mixed, indicating a complex association involving interaction of vitamin C with nutritional and non-nutritional factors. Therefore, we examined associations between vitamin C intake (total, supplemental and dietary intake) and changes in BMD at the hip, spine and radial shaft, in men and women in the Framingham Osteoporosis Study. Furthermore, we examined these associations for effect modification by smoking status, total calcium and vitamin E intake, and current estrogen use (in women alone). We did not observe any significant effects of vitamin C intake and BMD in women. In men, we observed effects only in interaction with smoking, suggesting that smokers with low BMD are using more vitamin C supplements. Consistent with previous findings of protective effects of fruit and vegetables, we observed protective associations between vitamin C intake and 4-y change in femoral neck BMD as well as trochanter BMD, among men with low calcium or vitamin E intakes. The dietary rather than the supplement component of vitamin C intakes appeared most strongly protective against bone loss. Further adjustment for dietary quality weakened these associations further, suggesting that possible effects of vitamin C may not be able to be separated from other protective factors in fruit and vegetables.

Technical Abstract: Vitamin C is essential for collagen formation and normal bone development. Therefore, we evaluated associations of total, supplemental and dietary vitamin C intake with bone mineral density (BMD) at the hip (femoral neck and trochanter), spine and radial shaft and 4 y change in BMD, in elderly men and women from the Framingham Osteoporosis Study. Energy adjusted vitamin C intakes were estimated from the Willett FFQ in 1988-89. Mean BMD and 4 y BMD change was estimated, for men and women, by tertile or category of vitamin C intake, adjusting for covariates. We tested for interaction with smoking, calcium and vitamin E intake. Among 334 men and 540 women (mean age 75 y), we observed negative associations between intakes of total and supplemental vitamin C and trochanter BMD among currently smoking men (P trend = 0.01). Among men who never smoked, total vitamin C intake was positively associated with femoral neck BMD (P trend = 0.04). Higher total vitamin C intake was associated with less BMD loss at the femoral neck and trochanter, in men with low calcium (all P trend < 0.1), after adjusting for potassium intake. Null associations were observed among women. These results suggest a possible protective role of vitamin C for bone health in older men, but not women.