Women who regularly consume low-fat milk or yogurt may have a lower risk of developing high blood pressure, new research suggests.

In a study of nearly 29,000 U.S. women age 45 or older, researchers found that those who had the most low-fat dairy in their diets were slightly less likely to develop high blood pressure over 10 years.

They found a similar blood pressure benefit when they looked at the women’s intake of calcium and vitamin D - which most Americans get mainly through dairy products.

Calcium and vitamin D from supplements, however, were unrelated to blood pressure, the researchers report in the medical journal Hypertension.

It’s not clear from this study why supplements showed no positive effects on blood pressure. However, other research has found greater blood pressure reductions from whole foods compared with supplements, explained lead researcher Dr. Lu Wang, of Brigham and Women’s Hospital in Boston.

Altogether, the evidence suggests that the “complete nutrition profile” of foods is important in their blood pressure effects, Wang told Reuters Health.

Still, calcium itself may play a “major role” in the association between low-fat dairy foods and lower blood pressure, according to Wang.

When the researchers factored in calcium, the beneficial effect attributed to low-fat dairy was largely diminished - indicating that calcium may explain a good share of the relationship.

The study included 28,886 middle-aged and older U.S. women who completed detailed dietary questionnaires at the outset. Over the next 10 years, 8,710 women developed high blood pressure, but the risk was 11 percent lower among those who consumed the most low-fat dairy compared with those who consumed the least.

Higher-fat milk and dairy products, on the other hand, conferred no such benefit. It’s possible, according to Wang’s team, that the saturated fat in whole milk counteracts any blood-pressure benefits of calcium or other dairy nutrients.

U.S. dietary guidelines call for Americans to strive for three servings of milk products per day. “Our study findings support this recommendation and emphasize the importance of low-fat dairy products,” Wang said.

The study received funding from the National Institutes of Health. The researchers report no conflicts of interest.

SOURCE: Hypertension, April 2008.