Should You Worry About Your Vitamin D Levels?

The Editors of WOMEN'S HEALTH

Staying up to date on the latest vitamin D research is practically a full-time job--new studies come out so often. The latest findings? Consuming higher-than-recommended amounts of D may give your immune system a boost--potentially lowering their risk of some cancers, heart disease, and other conditions, according to research published online last week in the journal PLOS ONE. While previous studies have linked adequate vitamin D intake to increases in bone strength and decreases in cancer, depression, and autoimmune disorders such as Type I diabetes and multiple sclerosis, this is the first study to show that exceeding the minimum RDA could be key to better health, explains New York City nutritionist Stephanie Middleberg, RD. So does that mean you should start popping vitamin D like candy--or that a deficiency could be to blame for any health issues you might currently have?

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Not so fast. First, the PLOS ONE study was small; it included just eight subjects, and even its authors concede that more research needs to be done to back up their findings. What's more, vitamin D's link to cancer and heart disease is unclear: A 2010 Institutes of Medicine report that investigated the connection uncovered mostly inconsistent or inconclusive results. That same report also stated that most people in the U.S. are already meeting their D needs--in part because our bodies are like vitamin D factories, absorbing UV light from the sun and synthesizing it into the nutrient. Odds are you're getting enough, but if you suffer from unexplained symptoms such as fatigue and bone or joint pain, you should consider seeing your MD for a blood test.

As for consuming more vitamin D than the 600 IU the average adult woman needs, be careful. Like many vitamins, D can become toxic if taken in large amounts, says Kassandra Munger, PhD, a research associate in the department of nutrition at Harvard University School of Public Health. And unfortunately, it's not exactly clear exactly how much qualifies as toxic.

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Bottom line: Though taking excess amounts might one day prove to be beneficial, for now, just make sure you meet the current daily D requirement of 600 IU. "Many foods pack decent amounts of it--for example, fatty fish like salmon, nuts, and fortified milk and orange juice--but this nutrient can be hard to get via your diet alone," says Munger. "Play it safe by taking a daily supplement, and you'll be covered."

And though our bodies ares designed to make vitamin D from sunlight, you don't want to rely on that. Depending on the time of year and your skin tone, it can take 10 to 20 minutes a day in the summer for UV rays to be turned into vitamin D. Problem is, for the UV rays to be absorbed, you likely have to forgo sunscreen, which increases your risk of skin cancer--not to mention fried, damaged skin.

The Verdict: Vitamin D holds promise as a key to improving immunity and preventing conditions such as cancer, heart disease, and diabetes. But until more research confirms vitamin D's health-boosting rep, don't OD on it--just make sure you get the recommended amount (600 IU), ideally through your diet and a daily supplement.

--By Esther Crain, Women's Health

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