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Vitamin D has become a veritable medical sensation

The world loves a panacea.   Things that give hope for chronic diseases come along rarely, and when they do, they become popular among scientists and civilians alike.  But are they always effective?

Vitamin D is a good example of this phenomenon. Vital for human functioning, the vitamin aids in the creation of the hormone calcitriol when skin is exposed to sunlight.  It has long been known that the vitamin’s primary purpose is to aid in calcium absorption in the body, helping prevent osteoporosis in seniors and the strengthening of bones in adolescents. New research, however, has broadened its possible mechanisms of action, and led to its most recent label as a potential “nutrient of the decade” by the New York Times. Research gives hope that vitamin D could help in either the treatment or prevention of Alzheimer’s Disease, Crohn’s Disease, Multiple Sclerosis, depression, autism, obesity, and numerous cancers.

The Canadian Nutrition Society released a document last November advising Canadians to drastically increase their intake of vitamin D, from 200 International Units (IU) to 600IU per day.  According to research cited by the Society, vitamin D deficiency is the cause of 37,000 premature deaths and $14 billion in health care costs annually in Canada. The current amount recommended falls in line with the 600IUs recommended by the CNS, but critics argue that this still falls far short of what is necessary.

David Hanley, a professor at the University of Calgary’s Faculty of Medicine and the author of numerous studies on Vitamin D, advocates for doses based on age and risk factors. The Osteoporosis Canada Guidelines, a report coauthored by Hanley, “suggest a range of doses, which include the IOM (Institute of Medicine) dose recommendations, but also go higher.  For people under age fifty, we recommended an intake from supplements of 400-1,000 International Units (IU) perday, and over age fifty, 800-2,000 IU per day.”

Vitamin D, unlike most other vitamins, is not found abundantly in common food sources. Fatty fish, including salmon, tuna, and catfish, as well as beef liver and eggs, contain small amounts of the vitamin. Dairy products, although not a natural source, have been supplemented with vitamin D Canada-wide. One cup of milk contains, on average, 100 IU.

But by far the strongest natural source of the vitamin, and likely the reason so many Canadians are deficient, is UVB rays from the sun. In order to get enough vitamin D per day, an individual must spend 15 to 20 minutes in direct sunlight. Because most Canadians spend much of their time in the winter indoors, it’s easy to understand why this deficiency can be considered an epidemic.

There is agreement that vitamin D is good for people, but the recommended dosage varies depending on who you talk to, and, among other things, how much funding that person has received from either the tanning industry (for vitamin D) or the sunscreen and cosmetic industry (against vitamin D). Michael Holick, or “Dr.   Sunshine,” a member of the former group, advocates massive doses of both sun exposure and supplements, sometimes up to 6,000IU for pregnant women.  In 2004, he was fired from the dermatology department at Boston University (BU) because the chair of the department “couldn’t have someone promoting [sun] exposure.” This promotion could perhaps be explained by those who fund his research: the American UV Foundation (a branch of the Indoor Tanning Association) gave $150,000 to BU during his tenure.

Recently, promising research seemingly free of bias has been done on the positive effects of vitamin D. A study published in the Journal of Geriatric Psychology and Neurology examined 1,766 men and women in Britain, measuring the levels of vitamin D in their blood. The study showed that those in the lowest quarter of vitamin D levels were 2.3 times more likely to be cognitively impaired than those in the top quarter.

In response to these studies, Canadians are demanding more blood work to determine their levels of vitamin D, much to the chagrin of the federal government and overburdened family doctors.  In Calgary, testing for deficiency has increased 700 per cent in the past three years, accounting for $2 million locally.  Ontario recently stopped covering blood work for vitamin D, citing the financial burden of unnecessary testing.  Hanley suggests that testing be reserved only for those at high risk, while everyone else should simply take a supplement.

People are excited that such a simple and inexpensive vitamin could increase both quality and duration of life by preventing a host of diseases.  Now it’s just a matter of how much one needs, and how much one pays.


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