A new study published in the Journal of Clinical Endocrinology and Metabolism has revealed that many young adults are lacking vitamin D, which is linked to increased body fat. Due to the inverse relationship between muscle fat and strength, the study is being approached as a plausible explanation for weakness symptoms.

“The levels of vitamin D are inversely related to the weight of the subjects, so fatter people have lower levels of vitamin D,” said Dr. Vicente Gilsanz, professor of radiology and pediatrics at USC and co-investigator in the study.

The study, led by McGill researcher Dr. Richard Kremer, was performed on otherwise healthy women in California. However, despite their relative health, a vitamin D deficiency was evident in the majority of the subjects.

“We found that 60 per cent of these young women lacked vitamin D in their system and this was associated with too much fat¬ – mainly in the abdomen and in skeletal muscle tissue,” said Kremer, the study’s principal investigator and co-director of the Musculoskeletal Axis of the Research Institute of the McGill University Health Centre.

Sources of vitamin D include exposure to sunlight and foods such as salmon, broccoli, and enriched foods, like milk. However, Kremer said the deficiency is in large part an unintended consequence of growing efforts to protect ourselves from health problems associated with exposure to too much sunlight.

“[The risk] is very widespread and the reason for this is because we tend to protect ourselves from the sun and the effect of sunshine is a lot less than what it used to be,” said Kremer.

“It is very, very common everywhere, unfortunately, even in sunny California,” added Gilsanz.

Although people lack vitamin D everywhere in the world, countries with reduced sunlight, like Canada, are particularly at risk.

“This is exemplified in Canada because basically from November to March there is no sunshine effect, which inhibits the production of vitamin D,” said Kremer.

Benefits of vitamin D include calcium absorption in the bones, regulation of the immune system, and the combat of infectious diseases.Kremer said that a lack of vitamin D is associated with increased incidences of breast cancer and other conditions such as diabetes and other endocrine disorders.

In addition, Gilsanz speculated that widespread viatmin D deficiencies may play a part in the continent’s growing obesity epidemic.

“It may be associated with the fact that we are becoming a population of fatter people and indeed some studies have shown that vitamin D is trapped by the fat cells,” he said.

John White, a professor in the McGill department of physiology who previously conducted a study on vitamin D, found that the active form of vitamin D directly stimulates the body’s capacity to fight microbial infection. He agreed that the insufficiency is far-reaching.

“It is very widespread in many populations, 50 per cent or more of a given population may be deficient in vitamin D,” he said.

According to Professor White, the consequences of the deficiency differ between children and adults.

“For children, or somebody with a growing skeleton, severe vitamin D deficiency over a relatively short period of time will lead to a condition called Rickets, which develops in children because they have a greater need for calcium during their growth,” he said. “Adult’s overtime can get a condition called osteomalazia, which basically means soft or weakened bones.”

In addition, while new studies on vitamin D are constantly being published, White emphasized that this is not a new issue.

“This is a problem that is widely spread, it probably has been for a number of years, and we are only really beginning to recognize the extent of the problem,” he said.