December 6, 2013
Study Casts Doubt On Benefits Of Vitamin D Supplements
Brett Smith for redOrbit.com - Your Universe Online
A new research review from a team of French and Belgian researchers has cast some doubt on the health benefits of vitamin D supplements.
Sometimes referred to as the ‘sunshine vitamin,’ vitamin D is generated by the skin when it is exposed to ultraviolet radiation. It can also be found in fish liver oil, eggs and fatty fish such as salmon or mackerel. Americans spend approximately $600 million a year on vitamin D supplements, which are supposed to boost bone health and lower disease risk, according to previous studies.
In the recent research review, published in The Lancet Diabetes & Endocrinology, researchers examined 290 prospective observational studies and over 170 randomized trials to determine the impacts of vitamin D levels on health outcomes, excluding bone health, up to December 2012.
Some of the observational studies in the review found that there were some benefits from high vitamin D, such as a lower risk of cardiovascular disease and cancer. However, the same benefits were not seen in clinical trials, where patients were given vitamin D supplements to determine if they protected against illness.
According to report co-author Philippe Autier, from the International Prevention Research Institute in Lyon, France, serious illnesses may reduce vitamin D in the body, but raising vitamin D levels does not necessarily prevent the illness from occurring.
"What this discrepancy suggests is that decreases in vitamin D levels are a marker of deteriorating health,” he said. "Aging and inflammatory processes involved in disease occurrence reduce vitamin D concentrations, which would explain why vitamin D deficiency is reported in a wide range of disorders."
Many experts cautioned against reading too much into the results of the review.
“These findings shouldn’t be misinterpreted, that vitamin D has no value,” Duffy MacKay, vice president of scientific and regulatory affairs at the trade group Council for Responsible Nutrition told Bloomberg News. “This doesn’t change the fact that we have recommended intake levels backed by the science around bone health, which is rock solid.”
“This paper is a valuable contribution in the field of nutrition, but it has little to contribute to our problem in the U.K., where low levels of vitamin D result in hypocalcaemic seizures in infants and bone disorders such as rickets,” said Colin Michie, chairman of the Nutrition Committee at the Royal College of Pediatrics and Child Health in London. “It has been known for almost a century that vitamin D supplements given to those with deficient vitamin D levels results in improved bone health.”
The review researchers said they were limited by the variable quality of the randomized trials and other factors. They also noted that there are currently five randomized controlled trials trying to determine if vitamin D supplements can reduce the risk of cancer, heart disease, infections, declining brain functions, and other illnesses.
“The first results are not expected before 2017, but these studies have the potential to test our hypothesis,” the review authors wrote.
The National Institutes of Health (NIH) currently recommends 15 micrograms of daily vitamin D for people between the ages of 1 through 70. Those over 70 should have a daily intake of 20 micrograms, according to the NIH.