Vitamin D Deficiency Linked to Muscle Fat Accumulation and Decreased Strength
Vitamin D deficiency is a growing epidemic and a risk factor for many diseases and illnesses. A new study has found that insufficient levels of vitamin D likely occur in over half of the population and is linked to increased body fat and decreased muscle strength, contributing to the obesity epidemic.
Researchers from the Musculoskeletal Axis of the Research Institute of the MUHC and the Children’s Hospital Los Angeles of the University of Southern California have published their results in the March 2010 Journal of Clinical Endocrinology and Metabolism.
The researchers found that, in a study group of otherwise healthy young women, that 59% had an insufficient level of vitamin D in their blood. Nearly a quarter of the group had a serious deficiency.
The new study is the first to show a link between vitamin D levels and the accumulation of fat in muscle tissue, which is important for muscle strength. While scientists have known the link between vitamin D and muscle strength for years in the elderly population, this is the first to find the association in young people.
Vitamin D is a fat-soluble vitamin that helps the body control calcium levels. When the body is deficient in either vitamin D or calcium, there is an increase in the enzyme fatty acid synthase, which converts calories into fat. Having a lack of vitamin D causes more calories to be stored as body fat, particularly in the abdominal region.
Unfortunately, the increase in body fat can further exacerbate vitamin D deficiency. Vitamin D is taken into fat cells and stored, so it is less available for the body to use in metabolism. There is also a study that has shown that obese patients, when exposed to the same amount of sunlight as normal weight patients, produce only about 55% vitamin D.
The new study, conducted in California, is surprising because all the women could be assumed to have ample exposure to sunshine. "We are not yet sure what is causing Vitamin D insufficiency in this group," says Dr. Kremer, one of the lead investigators in the study. “High levels of Vitamin D could help reduce body fat. Or, fat tissues might absorb or retain Vitamin D, so that people with more fat are likely to also be Vitamin D deficient."
The researchers do caution against supplementing with vitamin D without discussion with a physician and being tested for a deficiency. Dr. Kremer adds, "Obviously this subject requires more study. We don't yet know whether Vitamin D supplementation would actually result in less accumulation of fat in the muscles or increase muscle strength. We need more research before we can recommend interventions. We need to take things one step at a time."