SEATTLE Overweight or obese women with less-than-optimal levels of vitamin D who lose more than 15 percent of their body weight experience significant increases in circulating levels of this fat-soluble nutrient, according to a new study by researchers at Fred Hutchinson Cancer Research Center.
"Since vitamin D is generally lower in persons with obesity, it is possible that low vitamin D could account, in part, for the link between obesity and diseases such as cancer, heart disease and diabetes," said Caitlin Mason, Ph.D., lead author of the paper, published online May 25 in the American Journal of Clinical Nutrition. "Determining whether weight loss helps change vitamin D status is important for understanding potential avenues for disease prevention," said Mason, a postdoctoral research fellow in the Hutchinson Center's Public Health Sciences Division.
According to the National Institutes of Health, vitamin D plays many important roles in the body. It promotes calcium absorption and is needed for bone growth and bone healing. Along with calcium, vitamin D helps protect older adults from osteoporosis. The nutrient also influences cell growth, neuromuscular and immune function, and reduces inflammation. Many gene-encoding proteins that regulate cell proliferation, differentiation, and apoptosis (programmed cell death) are modulated in part by the vitamin.
The year-long study one of the largest ever conducted to assess the effect of weight loss on vitamin D involved 439 overweight-to-obese, sedentary, postmenopausal Seattle-area women, ages 50 to 75, who were randomly assigned to one of four groups: exercise only, diet only, exercise plus diet and no intervention.
Those who lost 5 percent to 10 percent of their body weight equivalent to approximately 10 to 20 pounds for most of the women in the study through diet and/or exercise saw a relatively small increase in blood levels of vitamin D (about 2.7 nanograms per milli
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Fred Hutchinson Cancer Research Center