Vitamin D: Vital Role in Your Health

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Researchers conclude the 'sunshine vitamin' is good medicine.

By Richard Trubo
WebMD Weight Loss Clinic - Feature

Reviewed By Brunilda Nazario, MD

Vitamins like C and E continue to be the darlings of many supplement lovers. But those vitamin superstars are being forced to share their throne with the long neglected vitamin D, which is finally getting the attention it may have always deserved.

No doubt, you're probably familiar with the role of vitamin D in promoting healthy bones, largely by promoting the absorption of calcium. "If you have a vitamin D deficiency, particularly in your older years, it can lead to osteoporosis or osteomalacia [bone softening]," says Lona Sandon, RD, assistant professor of clinical nutrition at the University of Texas Southwestern in Dallas.

But there is recent and mounting evidence that links low levels of the vitamin to an increased risk of type 1 diabetes, muscle and bone pain, and, perhaps more serious, cancers of the breast, colon, prostate, ovaries, esophagus, and lymphatic system.

If you want to lower your blood pressure, vitamin D may be just what the doctor ordered. If you're trying to reduce your risk of diabetes, or lower your chances of heart attacks, rheumatoid arthritis, or multiple sclerosis, then vitamin D should be at the front of the line in your daily supplement regimen.

D-fense for Your Health

As the research into vitamin D is accumulating, it's hard to know where the accolades should start. "Activated vitamin D is one of the most potent inhibitors of cancer cell growth," says Michael F. Holick, PhD, MD, who heads the Vitamin D, Skin, and Bone Research Laboratory at Boston University School of Medicine. "It also stimulates your pancreas to make insulin. It regulates your immune system."

Just consider these recent studies:

• At Boston University, after people with high blood pressure were exposed to UVA and UVB rays for three months, their vitamin D levels increased by more than 100% -- and more impressively, their high blood pressure normalized. "We've followed them now for nine months, and their hypertension continues to be in remission," says Holick, professor of medicine, physiology and biophysics at Boston University. One theory about how vitamin D reduces blood pressure: It decreases the production of a hormone called renin, which is believed to play a role in hypertension.
  
  
• In a study published in the Journal of the American Medical Association in December 2003, of more than 3,000 veterans (ages 50 to 75) at 13 Veterans Affairs medical centers, those who consumed more than 645 IU of vitamin D a day along with more than 4 grams per day of cereal fiber had a 40% reduction in their risk of developing precancerous colon polyps.
  
  
• In a report in the Journal of the American Geriatrics Society in February 2004, researchers at the University of Basel in Switzerland showed that elderly women who took a vitamin D supplement plus calcium for three months reduced their risk of falling by 49% compared with consuming calcium alone. Those women who had fallen repeatedly in the past seemed to gain the most benefit from vitamin D.
  
  
• A study in the Jan. 13, 2004 issue of Neurology indicated that women who get doses of vitamin D that are typically found in daily multivitamin supplements -- of at least 400 international units -- are 40% less likely to develop multiple sclerosis compared with those not taking over-the-counter supplements.

Your D-Day Plan of Attack

Many vitamin D researchers are convinced the government's recommendations for adequate vitamin D intake are far below what your body really needs. Those guidelines call for 200 IU a day up to the age of 50, 400 IU from 51 to 70, and 600 IU over age 70.

But, says Holick, studies show that to achieve blood levels of vitamin D that can protect you against chronic diseases, you need an optimal dose of 1,000 IU of vitamin D a day. The vitamin is well absorbed from foods like fortified milk and from vitamin pills, whether taken alone or in combination with other foods.

So how can you get enough of this overlooked vitamin? Most foods aren't filled to the brim with vitamin D -- far from it. You can get 425 IU in a 3-ounce serving of salmon, and 270 IU in 3.5 ounces of canned sardines. But most foods provide much more modest amounts of vitamin D, from egg yolks (25 IU per egg) to cheddar cheese (2.8 IU per ounce).

"You'll get 200 IUs of vitamin D by drinking two glasses of fortified milk," says Sandon, spokeswoman for the American Dietetic Association. But at age 70, even reaching the government's recommended level of 600 IU from diet alone can be a challenge. "These people are probably not drinking six glasses of milk a day for various reasons, including a higher incidence of lactose intolerance in the elderly," she tells WebMD.