Does Vitamin D Protect Against High BP?

Early Research in Young Women Suggests It Does

By Salynn Boyles
WebMD Health News

Reviewed By Louise Chang, MD

Sept. 24, 2009 -- Women who do not have enough vitamin D before menopause may have an elevated risk of developing high blood pressure years later, new research suggests.

Vitamin D deficiency before age 45 was associated with a threefold increased risk for hypertension in midlife.

Researchers analyzed data from a Michigan Bone Health and Metabolism Study that followed 559 women in their late 20s, 30s, and early 40s for 15 years. Vitamin D levels were measured soon after the women entered the study and blood pressure readings were taken each year.

By the end of the trial, when the average age of the women was 53, about one in four had developed high blood pressure.

Vitamin D deficiency earlier in life appeared to be a predictor of hypertension more than a decade later, lead researcher Flojaune C. Griffin, MPH, tells WebMD.

The research was presented in Chicago at the American Heart Association's 63rd High Blood Pressure Research Conference.

"This is preliminary data so we can't say with certainty that low vitamin D levels are directly linked to high blood pressure," says Griffin, who is a doctoral candidate in epidemiology at the University of Michigan. "But this may be another example of how what you do early in life impacts your health years later."

Vitamin D: The Super Vitamin

The study is not the first to suggest that vitamin D may help protect against heart disease, and recent research has also implicated vitamin D deficiency as a possible risk factor for a host of other diseases, including multiple cancers, arthritis, diabetes, multiple sclerosis, and even tuberculosis.

With the exception of bone diseases such as rickets and osteoporosis, which are clearly linked to vitamin D deficiency, none of these associations has been proven, however.

Exposure to sunlight is the easiest way to get enough of the vitamin, because the body uses ultraviolet rays from the sun to make vitamin D.

Many foods -- including milk, yogurt, breads, and cereals -- are fortified with vitamin D, but experts say that it would be very difficult to get adequate levels of the vitamin from food sources alone.

And there is no consensus regarding the optimal supplement dosage of vitamin D. Most multivitamins contain 400 international units (IU) of the vitamin, but Griffin says much of the current research suggests that the optimal dosage may be closer to 10 times this amount.

"It may be time to consider the possibility that we need a more nuanced public health message about sun exposure so that we are not putting people at risk for skin cancer, but are also alerting them to the fact that a few minutes of exposure before they put on sunscreen may be a good thing," she says.

More Study Needed, Experts Say

Study co-author and University of Michigan professor of epidemiology Mary Fran Sowers, PhD, agrees that the public health message advocating head-to-toe, 24/7 protection from the sun may need to change.

"We have recognized for a long time that it takes very limited sun exposure to get adequate vitamin D," she says.

Hypertension expert Rhian M. Touyz, MD, PhD, of the University of Ottawa, says the idea that vitamin D levels decades earlier can influence blood pressure in middle age is intriguing but unproven.

"This definitely needs more study," she tells WebMD.

Cardiologist Nieca Goldberg, MD, who directs the Women's Heart Program at New York University, agrees.

"This research certainly raises some interesting questions," she tells WebMD. "Vitamin D is important for the absorption of calcium and its role in bone health is proven. If we find out that it also helps prevent high blood pressure, that's a real plus. But we aren't there yet."

SOURCES: American Heart Association 63rd High Blood Pressure Research Conference, Chicago, Sept. 24, 2009. Flojaune C. Griffin, MPH, doctoral candidate in epidemiology, University of Michigan School of Public Health at Ann Arbor. Mary Fran Sowers, PhD, professor of epidemiology, University of Michigan at Ann Arbor. Rhian M. Touyz, MD, PhD, senior scientist, professor of medicine, Kidney Research Centre, Ottawa Research Institute, University of Ottawa. Nieca Goldberg, MD, cardiologist, medical director, NYU Women's Heart Program, New York University; spokeswoman, American Heart Association. News release, American Heart Association.

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