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| |  Lower Fat Diet Rich in Dairy Foods May Lower Blood Pressure NEW ORLEANS-- Nov. 13, 1996 -- A balanced diet rich in low-fat dairy products, including skim milk, and fruits and vegetables, helped lower blood pressure in patients with mild hypertension, according to a new study funded by the National Heart, Lung and Blood Institute (NHLBI). Researchers presented the results of the new study today at the American Heart Association's 69th Scientific Sessions. These findings are important for the millions of Americans who are at risk for developing hypertension, a major risk factor for heart disease and stroke. The Dietary Approaches to Stop Hypertension (DASH) Study compared three diets -- a higher fat "control diet," a "fruit and vegetable diet" and a lower fat "combination diet" that included higher amounts of low-fat dairy products -- to determine their effects on blood pressure among mildly hypertensive patients. "The findings identify an apparent link between a diet rich in dietary calcium, that also incorporates the benefits of magnesium, potassium, fiber and lower fat content, and improved blood pressure for those with high normal blood pressure or mild hypertension," said David A. McCarron, M.D., professor of medicine at Oregon Health Sciences University, and study investigator, whose laboratory first identified a possible link between calcium and hypertension. "The patients consuming the diet with the most low-fat dairy foods showed the greatest improvement in blood pressure, significantly more than patients in the lower-calcium diet groups." Ninety percent of adult women and 60 percent of adult men in America, however, do not meet the National Institutes of Health (NIH) recommendations for calcium intake, according to Dr. McCarron. "Too often, patients think of dairy products as being off-limits. However, skim and 1% milk, which are excellent sources of dietary calcium and also have potassium and magnesium, have little or no fat. The DASH study findings provide Americans with another compelling reason to make sure they get at least the daily 1,000 mg. of calcium recommended by the NIH," he added. Funded by the NHLBI and the National Center for Research Resources, with supplemental support from the NIH Office of Research on Minority Health, the DASH Study was a multicenter, randomized feeding trial designed to assess the effects of three specific diets on blood pressure. Three dietary patterns were evaluated in the study: the first was the "control diet," modeled after the typical American diet, in which 37% of calories were derived from fat and 15% from protein. The second diet, termed the "fruit and vegetable diet," was similar to the control diet in fat and protein content, but included more fruits and vegetables, providing two to three times more potassium, magnesium and fiber than the control diet. The third pattern assessed was the "combination diet," which was similar to the fruit and vegetable diet but was reduced in fat and cholesterol content, and included low-fat dairy products, providing significantly more dietary calcium than the other two diets -- the amount in about three to five 8-ounce glasses of milk daily. Both the control diet and the fruit and vegetable diet were deficient in calcium, with less than the equivalent of two 8-ounce glasses of milk consumed each day. Sodium and calorie content were similar in all diets. Overall, the combination diet reduced systolic blood pressure by an average of 5.5 mm Hg and diastolic by an average of 3.0 mm Hg. The fruit and vegetable diet also reduced blood pressure but less -- by an average of 2.8/1.1 mm Hg. For those with hypertension, the combination diet reduced systolic blood pressure by an average of 11.4 mm Hg and diastolic by an average of 5.5 mm Hg. The fruit and vegetable diet reduced blood pressure by 7.2/2.8 mm Hg for hypertensives. Calcium Deficiencies Widespread While the study findings indicate that a lower fat diet rich in dairy products and high in calcium and other minerals could be helpful in lowering blood pressure, calcium deficiency continues to be a widespread problem in the typical American diet. At least 50% of all Americans fail to consume adequate amounts of calcium on a daily basis, according to the USDA. A 1994 NIH Consensus Statement on Optimal Calcium Intake recommends at least 1,000 mg. of dietary calcium per day for most adults and 1,200 to 1,500 mg. for pregnant women, preferably from food sources like low-fat dairy products. This is equivalent to three to five 8-ounce servings of skim or low-fat milk each day. DASH Supports JAMA Findings The DASH Study comes on the heels of a recent Journal of the American Medical Association (JAMA) study (April 3, 1996), which showed a small but statistically significant reduction in systolic blood pressure in the patients who increased their daily calcium intake. Consistent with the DASH results, the study also found that there was a larger reduction in both systolic and diastolic blood pressure in hypertensive patients. The authors of the JAMA study suggested that calcium deficiency may raise blood pressure and that increasing calcium to about 1,000 mg. a day, meeting the daily requirements for most adults, may reduce hypertension risk. In an accompanying editorial in JAMA (April 10, 1996), Dr. McCarron noted that there may be a "threshold" for calcium intake that must be exceeded by adults in order to gain the benefits of calcium in blood pressure control. Dr. McCarron postulates that the amount of calcium included in the DASH "combination diet" may have achieved this level. A total of 459 adults (ages 21 years and older) with high normal diastolic blood pressure or with stage 1 (mild) hypertension were enrolled in the DASH study. The average DBP was 80-95 mm Hg and average SBP was less than 160 mm Hg. Participants were randomly enrolled in either the control diet, the fruit and vegetable diet, or the combination diet. The DASH Study was conducted at Brigham and Women's Hospital and Harvard Medical School in Boston, MA; The Johns Hopkins University, Baltimore, MD; Duke University, Durham, N.C. and the Pennington Biomedical Research Center, Baton Rouge, La. The Kaiser Permanente Center for Health Research, in Portland, Ore. served as the coordinating center for the study and was supported, in part, by staff from the Oregon Health Sciences University in Portland.
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