What’s So Great About…Vitamin D?

I was all set to write my post on Vitamin D for the first day of winter (and the shortest day of the year in 372 years due to a lunar eclipse) and then, like a Hollywood starlet on a bender, Vitamin D found itself splashed across the headlines again. Up until just recently, Vitamin D was making news as a cure all. It was being touted as the answer to why us folks up here in northern climates have higher instances of certain types of cancers and other ailments including influenza. Everyone and their doctors were pumping us full of Vitamin D supplements. Easy right? Wrong.

On November 30th, 2010 the Institute of Medicine published a report on Vitamin D and Calcium intake. The report puts forward that while both Vitamin D and Calcium  are essential to bone health, there is not enough evidence to suggest that increasing Vitamin D is of any benefit against other ailments.  Indeed, the IOM warns that there may even be potential risk associated with long term high Vitamin D intake, although they also admit that this too, needs further study.

While the IOM is saying take it easy on Vitamin D, The Canadian Cancer Society, The Canadian Pediatrics Society and Osteoperosis Canada remain loyal to the supplement.  And there are some scientists who continue to trumpet the vitamin as a miracle worker:

“The new recommendations of only 600 to 800 IU are a ‘health catastrophe,’” according to Cedric Garland, a professor of preventive medicine at the Moores Cancer Center at the University of California, San Diego.

Dr. Garland is one of the leading U.S. vitamin D researchers, and published the first studies showing that colon cancer is more prevalent in northerly areas, a strong hint that seasonal lack of vitamin D due to less wintertime sunshine is a trigger. He later duplicated the work with breast cancer.

“Vitamin D has the capability of preventing most cases of breast cancer, virtually all cases of bowel cancer,” he said. “The idea that we’re sitting back and allowing time to go forward without acting on these discoveries is extremely frustrating.”

— The Globe and Mail, “Vitamin D panel triples recommended dose,” November 30, 2010

That’s the thing about nutrition and studies and the media (an unholy trinity, or so they can seem at times). We no sooner declare something good for us than someone turns around, does another study, or writes a report and tells us that we’ve got it backwards. And here I am faced with the task of telling you what’s so great about Vitamin D.  As the IOM’s report shows, we can not definitively say that taking Vitamin D supplements will help prevent certain types of cancer (colon and breast) or help prevent heart disease or reduce flu symptoms. What we can say is that Vitamin D is of particular importance for bone health, as it is required for proper calcium absorption.

I spoke with Du La, a Naturopathic Doctor in Toronto (www.torontonaturopathicmedicine.ca) about Vitamin D, and where we can get it.

Where can we get our Vitamin D?

Vitamin D is not found in many foods.  Good food sources of vitamin D are cod liver oil, and certain fish (e.g., sardines, mackerel, tuna) which can provide 300-700 IU per serving, and of coarse the sun.

How much sunshine do we need?

There is no specific guideline for amount of sunshine one should be exposed to, but recent research suggests that daily dietary intake for children and adolescents should be 400 IU daily, and for adults should be 1000 IU daily.  Sufficient sun exposure to produce these amounts of vitamin D in the body may be considered a guideline of sorts.

Vitamin D is produced by the skin with exposure to ultraviolet light B (UVB), the type that shines when your shadow is shorter than you are (generally, between noon and 3:00 pm).  In the winter, when only our faces are exposed to sunlight, to produce 1000 IU of vitamin D, a pale-skinned person would have to spend between 9 and 23 minutes in direct sunlight between noon and 3:00 pm.  Dark-skinned persons would have to spend between two and three hours to achieve the same benefit.  On a cloudy day, one would have to spend about twice as long outside for the same amount of vitamin D to be produced by their body.

What are your thoughts on sunscreen?

In general, I prefer shade to sunscreen.  Sunscreen can contribute to a false sense of security, and contains many chemicals you may not want to be exposed to.  When your skin begins to feel warm it’s time to  seek out shade (the only guaranteed form of sunscreen).  Hats and long-sleeves are good for children who may not be able to communicate effectively how warm they feel.

Do you recommend any particular brands?

Neal’s Yard Remedies and Jason’s Natural Cosmetics produce, between them, several low-in-toxic-chemicals; SPF greater than 30 products, but otherwise shade or covering up is the best sunscreen.