Vitamin D: Are you getting enough?

~ July 6, 2009

By MARILYN LINTON
The Toronto Sun
www.TorontoSun.com

Here comes the sun and you'd better NOT stay out of it!

The sun, by far, provides us with the biggest dose of vitamin D, says Dr. Reinhold Vieth, a vitamin D booster and researcher in the Department of Pathology and Laboratory Medicine at Mount Sinai Hospital in Toronto.

"My prescription for a white person is to lie on your tummy for 10 minutes and then flip over on your back for 10 minutes on a day when the sun is reasonably high in the sky. That'll do it -- you'll make about 10,000 units, your week's worth."

Despite the media attention directed at this new superstar of vitamins, many of us are unaware of what vitamin D's relation to the sun is all about.

When the sun's rays hit the skin, a pre-vitamin D compound is manufactured and transformed by the body into active vitamin D.

Vieth is not advocating over-exposure to the sun -- he wears sunscreen if he's out at the beach -- but he joins many experts in thinking that our fear of the sun may be contributing to vitamin D deficiency -- itself a definite health hazard.

The relationship between sun exposure and skin cancer is complicated: Some research suggests that vitamin D protects against skin cancers, but stronger research shows a connection between melanoma and too much sun.

The Vitamin D Council (www.vitamindcouncil.org) notes that the skin produces approximately 10,000 international unit (IU) vitamin D in response to 20 to 30 minutes of summer sun exposure. That's 50 times more than the daily recommendation of 200 IU a day. (If you're over 50, the RDA goes to 400 IU.)

Vieth is adamant that current RDAs on this vitamin need to be revised. He says that even 50 years ago, scientists knew that the body, when exposed to normal sun, makes 50 times what policy makers today say we need.

"Medical societies are relatively wishy-washy," he says, but the Canadian Cancer Society (www.cancer.ca) has now said that Canadians might "consider" taking 1,000 IUs a day in supplemental form.

Vitamin D advocates, including the Vitamin D Council in the U.S., infer that even 1,000 IU is not enough. In addition to suggesting sunbathing, the council's other controversial recommendations for ensuring that we get adequate levels of vitamin D include using a sun bed (avoiding sunburn) during winter months, and that we take 5,000 IU per day for three months and then obtaining a 25-hydroxy vitamin D test.

Depending on what the test shows, we should then adjust our dosage of vitamin D intake so that blood levels are between 50 to 80 ng/mL (nanograms per millilitre) or 125-200 nM/L (nanomoles per litre) year-round.

According to Vieth, about 40% of doctors are huge fans of the 25-hydroxy vitamin D blood test, which means that about 60% of Canadian physicians are not.

I asked Vieth how you would know if you're not getting enough of the vitamin. "Vitamin D deficiency is not unlike general pain syndrome or chronic fatigue syndrome," he says, adding his view that testing for vitamin D deficiency is a good idea.

In Vieth's line of work, D does not stand for diet. To get enough vitamin D from food, he says, you'd have to consume about one pound of fish a day. "Even if you drank an extra glass of milk a day, it would only raise your blood vitamin D levels by 2.5 nM/L. Considering you'd want a level higher than 75, it's just absurd how much more milk you'd have to drink."

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Are Canadians vitamin D deficient?

At latitudes above 40 degrees north, the skin cannot produce adequate vitamin D. Despite concerns about skin cancer, vitamin D is not only essential to health but may help to prevent a growing list of conditions and diseases. Canadians, especially those in the West, can be sorely deprived of the sunshine vitamin - especially during winter months. Research has shown that a lack of vitamin D raises the risk of the following:

- Fractures

- Several cancers

- Alzheimer's disease and vascular dementia

- Multiple sclerosis (MS)

- Rheumatoid arthritis

- Some cardiovascular disease

- Asthma

- Autoimmune diseases

- Osteoporosis

- Muscle weakness or wasting

Young and Old need D

One-third of urban Canadian toddlers don't get enough vitamin D, placing them at higher risk for problems including rickets, Type 1 diabetes, MS and certain types of cancers. Results of research released in May from Toronto's Hospital for Sick Children indicated that factors associated with lower levels of vitamin D in kids included lower milk intake, higher BMI and watching TV while snacking.

Meanwhile, researchers in Britain and China have shown an association between low vitamin D and metabolic syndrome (which increases the risk of developing cardiovascular diseases and diabetes) in people aged 50 to 70. Seniors' bodies are less efficient at forming vitamin D and their diets may be D-deficient, say the researchers. Spending more time outdoors may be one way they can increase their D levels.

http://www.torontosun.com/life/healthandfitness/2009/07/06/10034416-sun.html