The study was led by epidemiologist Katherine Tucker with the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts University in Boston, Mass. Tucker directs the HNRCA's Dietary Assessment and Epidemiology Research Program.
Osteoporosis -- a condition in which bones become porous and weak -- affects about 10 million people in the U.S. population, and low bone mass is a public health concern among another 44 million people aged 50 or older. The researchers wanted to examine whether fruit- and vegetable-specific antioxidants such as vitamin C might decrease oxidative stress that is linked to accelerated bone loss.
In the Framingham Osteoporosis Study, bone mineral density at the hip, spine and forearm was measured in 344 men and 540 women aged 75 on average.
Because people at risk for bone loss, such as smokers, may use vitamin C supplements more often, the potential effects of vitamin C intake obtained from diet, supplements, and both diet and supplements were examined. Interactions based on smoking, calcium and vitamin E intakes were tracked. The researchers observed significant positive associations for total vitamin C—both dietary and supplemental—among men who never smoked.
Among a subset of the participants -- whose bone mineral density was again measured after four years -- different interactions were observed. During those four years, total vitamin C appeared to be protective against losses in bone mineral density in two areas of the hip among men with low calcium or vitamin E intakes. That finding is consistent with previous reports by Tucker and other researchers that higher fruit and vegetable intake has positive effects on bone mineral status.
The researchers did not observe significant effects of vitamin C intake on bone in women.
From the October 27, 2008, Prepared Foods e-Flash