(Andrew Vaughan/CP)

As evidence of the health benefits of Vitamin D continues to grow, running out and catching a few rays of sunshine has never felt healthier. However, here in the northern hemisphere the days of sunshine are fast diminishing and it’s time for Canadians to start looking elsewhere for their daily vitamin D fix.

In the past, vitamin D was known to reduce the risks of osteoporosis, heart disease and Type 2 diabetes. Now there’s strong data to suggest it’s a formidable weapon in the fight against cancer.

The big questions are how much vitamin D do we need and what’s the best way to obtain it.

A tanning bed with medium-pressure lamps that generate UVB rays is one way to help the body make vitamin D during months when the sunshine is weak. (Al Grillo/AP)

The first question is a bit trickier than the second. In its latest news release on the subject, Health Canada recommends adults 19 to 50 need 200 international units (IU) of vitamin D per day – that includes pregnant and lactating women. Everyone over the age of 50 is advised to take a daily supplement of 400 IU of vitamin D, and parents are told to give children over two years of age two cups of milk a day (one cup of milk has 100 IU of vitamin D).

However, the Canadian Cancer Society recommends 1,000 IU a day and the Canadian Association of Naturopathic Doctors goes as far as recommending 2,000 to 4,000 IU a day.

How to get your daily D-dose

The most efficient way to take and absorb Vitamin D is through a supplement, says Dr. Michael Holick, a professor with Boston University School of Medicine and author of The UV Advantage.

"We did a study several years ago that showed healthy adults in the winter can barely raise their blood levels to what’s considered healthy even when they eat fish once a week, take a multivitamin and drink a glass of milk every day," he said.

While some people favour taking cod liver oil, believing vitamin D is absorbed more easily that way, Dr. Holick says it’s a myth.

What’s most important is the type of vitamin D you’re taking.

Dr. David Lescheid, spokesperson for the Canadian Association of Naturopathic Doctors, explains, "There are two forms of supplemental vitamin D. One is called ergocalciferol and one is cholecalciferol. The second one is what you want to take; otherwise you don’t get the benefit of it. That’s important because we see an incredible number of people who are vitamin D deficient – about 80 per cent of Canadians in the winter."

The body's do-it-yourself approach

In addition to being able to pop vitamins into our systems via a tablet, our bodies create vitamin D when exposed to UVB rays from the sun. Generally, doctors recommend that 10 to 15 minutes outdoors at least twice a week in summer without sunscreen is adequate.

Catching some rays is simple in summer, but the sun becomes so weak in Canadian climes in fall and winter that our bodies don't get much UVB exposure (even when they aren't bundled up against cold weather).

Some health experts generally advise against going to tanning salons due to the risk of skin cancer from the tanning rays, but in winter time this is a potential option for people looking to boost their vitamin D level – as long as they do their homework.

Dr. Holick advises, "Make sure the tanning salon bed puts out UVB. That’s done with medium-pressure lamps. High-pressure lamps only put out UVA, which will not make any vitamin D. With UVB rays, you won’t get a burn, you won’t even get much of a tan, but you’ll get lots of vitamin D."

Tanya Horricks, manager of Edmonton’s European Tan and Spa, says, "I’m seeing more people realizing the benefits of vitamin D and wanting to get it naturally. If you want vitamin D you should ask for a bed with a stronger UVB bulb. Depending on the intensity of the beds, we tell people 10 minutes three times a week."

Dr. Holick also recommends using the beds for just 30 per cent to 50 per cent of the normal time recommended for tanning, and wearing sun screen on your face during each visit. "That’s because the rest of your body is very capable of making vitamin D, but your face makes very little."

One thing that won’t help you get your daily dose of vitamin D is standing outside in the winter time. Dr. Holick says, "Above Atlanta Georgia [in latitude], you can’t make vitamin D in your skin in the winter time. We did a study involving Edmonton residents. For six months of the year, they were unable to make vitamin D in their skin. Stand naked outside from the time the sun rises until it sets, freeze every appendage on your body and you will not make vitamin D."

Special lights used to combat Seasonal Affective Disorder also won’t help in the vitamin D department. That’s because they don’t emit UVB rays.

Useful Links

• Health Canada
• Dietary Supplement Fact Sheet from the National Institute of Health
• The UV Advantage
• New England Journal of Medicine on Vitamin D deficiency, Michael Holick
• Canadian Cancer Society
• Sperti Lamps

However, the U.S. Federal Drug Administration has sanctioned Sperti lamps as vitamin D-producers. "They work very well for patients who have malabsorption syndrome," Dr. Holick says. "You can raise your blood levels of vitamin D by being exposed to it."

People with cystic fibrosis, Crohn’s disease or those who have had intestinal bypass surgery often have trouble absorbing vitamin D from foods, so a tanning bed or Sperti lamp is best for them, Dr. Holick says.

Avoiding overload

How much vitamin D is too much is debatable.

You don't want to overdo it, because too much vitamin D in the body can cause vomiting, raise blood levels of calcium causing confusion, and cause heart rhythm abnormalities. Health Canada warns exceeding the recommended limit could lead to an overdose that can cause kidney stones as well as damage to the heart, lungs and blood vessels.

Health Canada advises against more than 2,000 IU a day, although Dr. Lescheid says he would put that number at 10,000 IU. For now, at least, the jury is out on a maximum recommended level until more research is done on vitamin D.

But remember, six months from now (we hope), getting vitamin D from sources such as foods and lamps won't be a worry. We’ll be able to reap the sun’s benefits by simply going for a walk in the sunshine.