A study in the Journal of Clinical Endocrinology and Metabolism reports that Vitamin D deficiency may be more common among young people today than most researchers thought.

In the study, 59 per cent of participants had too little Vitamin D in their blood. Nearly a quarter of the group had serious deficiencies (less than 20 ng/ml) of this important vitamin. Since Vitamin D insufficiency is linked to increased body fat, decreased muscle strength and a range of disorders, this is a serious health issue

"Vitamin D insufficiency is a risk factor for other diseases," explains principal investigator, Dr. Richard Kremer, co-director of the Musculoskeletal Axis of the Research Institute of the MUHC. "Because it is linked to increased body fat, it may affect many different parts of the body. Abnormal levels of Vitamin D are associated with a whole spectrum of diseases, including cancer, osteoporosis and diabetes, as well as cardiovascular and autoimmune disorders."

The study, researchers say, is the first to show a clear link between Vitamin D levels and the accumulation of fat in muscle tissue – a factor in muscle strength and overall health. Scientists have known for years that Vitamin D is essential for muscle strength. Studies in the elderly have showed bedridden patients quickly gain strength when given Vitamin D.

Most surprising was that the study subjects – all healthy young women living in California – could logically be expected to benefit from good diet, outdoor activities and ample exposure to sunshine – the trigger that causes the body to produce Vitamin D.

"We are not yet sure what is causing Vitamin D insufficiency in this group," says Dr. Kremer. 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 results extend those of an earlier study which linked low levels of Vitamin D to increased visceral fat in a young population. "In the present study, we found an inverse relationship between Vitamin D and muscle fat," Dr. Kremer says. "The lower the levels of Vitamin D the more fat in subjects' muscles."

While study results may inspire some people to start taking Vitamin D supplements, Dr. Kremer recommends caution. "Obviously this subject requires more study," he says. "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."