The Sunshine Vitamin

We’ve heard a lot about vitamin D, but what is the recommended amount?

It’s been called the Sunshine Vitamin. Hundreds of studies link vitamin D—of which humans make 90 percent of their supply from natural sunlight exposure—to decreased rates of many diseases, including some forms of cancer, heart disease, osteoporosis and multiple sclerosis. No wonder Canada has proposed a national vitamin D day and the Florida Keys’ new advertising campaign is, “Think of it as your vitamin D supplement.”

But that’s not to suggest you start baking in the sun or ingesting mass quantities of cod liver oil (another natural source of the vitamin). Vitamin D is often scrutinized—usually when it’s proposed as a panacea to yet another ailment. Recently, in the Archives of Internal Medicine, a peer-reviewed journal published by the American Medical Association, the vitamin got another cold, hard look. A small study done by doctors from the University of Messina, in Italy, suggests that women plagued by menstrual cramps might find relief with vitamin D3, and that the supplement could one day be an alternative to painkillers.

The catch: The treatment involves a mega-dose of 300,000 IUs of vitamin D—a whopping 500 times the amount recommended by the U.S. Institute of Medicine. The Institute recommends that women ages 19 to 50 get 600 IUs of the vitamin a day (though many recommend 1,000). Doses higher than 4,000 per day may damage the heart, blood vessels and kidneys by raising calcium levels in the blood.

Without going overboard on the Sunshine Vitamin, here’s what you should know, according to the New England Journal of Medicine:

1. Humans spend less time in the sun today than at any point in human history, which is why more than 1 billion people worldwide are vitamin D deficient. (So get out of the office during lunch and take a walk around the block.)
    
2. Few foods naturally contain or are fortified with supplemental vitamin D. For example, an 8-ounce glass of whole milk is fortified with 100 IU (international units) of vitamin D.
    
3. While overexposure to sunlight carries risks, regular, non-burning exposure to UV light can help you get the vitamin D your body needs. And when you get your “D” from sunshine, your body takes what it needs, and de-metabolizes the extra.

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