Though it’s often dubbed the "sunshine vitamin," you’ve probably heard that vitamin D comes from several sources, such as foods, supplements and even tanning beds. But what’s the best way to get enough of this vitamin? The truth is, your body can’t create vitamin D on its own’your skin produces it in response to exposure to ultraviolet B (UVB) light. Our bodies need vitamin D, which we can ingest in supplement form, for cell growth and to ensure strong, healthy bones. Recent research suggests there may be links between vitamin D deficiency, especially in northern climates where there is limited sun in winter months, and various diseases, including heart disease, multiple sclerosis and a few types of cancers. So what is the best way for you to get vitamin D?
From the sun
Experts point out that relying on unprotected exposure to the sun or tanning beds to obtain adequate levels of vitamin D can lead to increased risk of skin cancer and premature aging. However, some safe exposure to sunlight is recommended. “I myself believe that a little dose of sunlight every day provides a very efficient conversion to vitamin D, that is probably not harmful, especially outside of childhood,” says Dr. Stephanie Atkinson, professor and associate chair of pediatrics at McMaster University in Hamilton, Ont. According to the United States National Institutes of Healh, spending just 10 to 15 minutes in sunlight, three times a week, is enough for the body to produce the vitamin D it needs.
The challenge, according to the experts, is that we Canadians aren’t guaranteed to get enough consistent, and safe exposure to sunlight to produce enough vitamin D to through the winter months. "Many years ago, when the governments in North American realized that lack of sun exposure was causing rickets in children, they made it mandatory to fortify milk with vitamin D," Atkinson points out.
Experts predict that in the near future, we’ll see more foods fortified with vitamin D. Currently most milk is fortified, but this isn’t a viable source for people who are allergic to milk or lactose intolerant. Some soymilks, yogurts and orange juices are also now fortified with vitamin D. However, foods in general, even fortified foods, are not adequate sources of vitamin D, says Atkinson.
The average Canadian has about 60 to 65 nanomoles per litre (nmol/L) of vitamin D in their blood, according to Reinhold Vieth, professor, Department of Nutritional Sciences, and Department of Laboratory Medicine and Pathobiology at the University of Toronto. Taking 1,000 IU of vitamin D in a supplement over the long-term will raise your vitamin D blood levels by 25 per cent, bringing you close the 75 nmol/L you need to maintain strong bones.
Most vitamin D supplements are created equal, adds Atkinson. "The only thing that differs is the amount provided in a tablet," she says. You can get vitamin D in a multivitamin (usually about 100 IU) or in a single tablet in different doses, usually 400 IU to 1,000 IU. You don’t need to take the vitamin with food, or with a calcium supplement.
The bottom line
The best way to get vitamin D is to combine all three of the above methods by spending a safe amount of time in sunlight, eating foods fortified with vitamin D and taking a daily supplement. Before taking supplement however, Atkinson suggests that it’s a good idea to measure how much vitamin D you are getting from fortified foods and a multivitamin, if you take one. Then take the appropriate amount if vitamin D in a supplement so that your total intake for the day is 1,000 IU and not more than the upper limit of 2,000 IU daily.
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