MONDAY, June 26, 2006 (HealthDay News) -- Eating dairy products, especially low-fat ones, could help lower your blood pressure, a new study suggests.
Scientists aren't clear where the beneficial effect comes from, but they said low-fat dairy might be a crucial component of a healthy diet.
"If you like to eat dairy products, you may be better off watching the fat content," said Dr. Luc Djousse, lead author of the study and associate epidemiologist at Brigham and Women's Hospital, in Boston. "Low-fat dairy products may be better than full dairy products, where the saturated fat especially is high," Djousse said.
For the new study, the investigators looked at a possible link between dairy consumption and blood pressure among 4,797 participants of the Family Heart Study, sponsored by the U.S. National Heart, Lung, and Blood Institute.
The researchers divided participants into four groups based on the amount of dairy consumed. Those consuming the most dairy said they ate more than three servings per day, while those consuming the least averaged less than half a serving per day. Dairy included, cheese, yogurt and milk.
Systolic blood pressure was 2.6 millimeters of mercury (mm Hg) lower, on average, for people eating the highest amount of dairy, compared with those eating the least amount of dairy. Systolic blood pressure is the first (higher) number in a blood-pressure reading, and it indicates the pressure in the arteries when the heart beats.
But when saturated fat content was taken into account, the beneficial effect on blood pressure was only seen among those who ate lower amounts of saturated fat. In this group, participants who ate the most dairy had a systolic blood pressure that was 3.5 mm Hg lower than those who ate the least dairy.
Among participants who ate lower amounts of saturated fat, those who also ate the most dairy had 54 percent lower odds of high blood pressure than those eating the least amount of dairy.
The study was not able to identify those people who ate low-fat dairy, but it had data on total fat, polyunsaturated fat, and saturated fat.
Samantha Heller, senior clinical nutritionist at New York University Medical Center in New York City, said: "The association [in the study] was mainly among people with less saturated fat. We know this is a bad fat, and eat as little as possible."
The findings appear in the August issue of the journal Hypertension.
About one in three Americans suffers from high blood pressure, which is a major risk factor for stroke, heart attack as well as kidney and heart failure.
Drugs can treat the condition, as can lifestyle changes such as diet. The Dietary Approaches to Stop Hypertension (DASH) diet, which is low in salt and rich in fruits, vegetables and low-fat dairy products, has been shown to significantly lower blood pressure.
But the secrets to the success of the DASH diet have remained elusive.
"There was such a combination of factors that we don't know whether the effect of DASH came from low sodium, low cholesterol or fruit and vegetables," explained Djousse, who's also an assistant professor of medicine at Harvard Medical School. "It has been hard to tell which part of that, or a combination of all, that were producing the effects," Djousse said.
It's not clear where the benefit is coming from or even if it's cause-and-effect. It's unlikely to be calcium, Djousse said, although potassium and magnesium, which are also plentiful in the DASH diet, might be responsible. "Our study showed that dietary potassium and magnesium were associated with a lower odds of high blood pressure," Djousse said.
The bottom line?
"It would help to eat dairy products as long as you keep the saturated fats in check," Djousse said.
Visit the American Heart Association for more on high blood pressure.