An eating plan known to lower blood pressure also significantly lowers blood cholesterol levels, according to results of a study supported by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health. Scientists have found that the DASH (Dietary Approaches to Stop Hypertension) diet significantly reduces the levels of total cholesterol and of low-density lipoprotein (LDL), or "bad" cholesterol.
Compared to those on a control diet, which reflected a typical American's eating habits, individuals on the DASH eating plan reduced on average their levels of total cholesterol by 13.7 mg/dL or 7.3 percent, and their levels of LDL cholesterol by 10.7 mg/dL or 9 percent. The findings are published in the July 2001 issue of the American Journal of Clinical Nutrition.
"Studies have proven the DASH diet to be beneficial for individuals with high blood pressure or those wishing to prevent high blood pressure. These latest findings provide strong evidence that individuals with high blood cholesterol can also benefit significantly from this eating plan," commented NHLBI director Dr. Claude Lenfant. "Physicians and their patients with heart disease can add the DASH diet to the armament of tools known to help lower a person's risk of coronary heart disease."
In the DASH study, 459 participants were randomly assigned to either the control diet, a diet enriched with fruits and vegetables, or the DASH eating plan. The DASH diet was also rich in vegetables and fruit, but was low in saturated and total fat, and cholesterol and used low-fat dairy products. Both the fruits and vegetables diet and the DASH eating plan were higher in fiber and lower in sucrose than the control diet.
Levels of triglycerides, which may increase heart disease risk, were not significantly changed in participants on the DASH diet. DASH was associated, however, with an average decrease of 3.7 mg/dL, or 7.5 percent, of levels of high-density lipoprotein (HDL), the "good" cholesterol. HDL at low levels (less than 40 mg/dL) is a CHD risk factor; at high levels (60 mg/dL or above), HDL is considered protective of heart disease. The drop was directly related to the individual's starting level of HDL; thus, HDL concentrations decreased more in people with higher HDL levels compared to individuals with lower levels. The researchers report that although this undesirable response to the DASH diet needs further study, overall, "the DASH diet affects coronary heart disease (CHD) risk favorably."
The DASH research group observed that the DASH diet reduced blood cholesterol and LDL levels by the same amount in African Americans as in whites. They also found that changes in HDL and triglyceride levels between men and women were similar. Total and LDL cholesterol levels, however, fell significantly more in men than in women: on average, total cholesterol levels were reduced by 10.3 mg/dL more in men than in women, and LDL levels were reduced by 11.2 mg/dL more in men than in women. Other, smaller studies comparing men and women's lipid response to diet have yielded mixed results - some have indicated no differences between men and women and others have indicated a more favorable response by men.
"The size of the DASH study provided an unprecedented opportunity to look at how the different sexes and races respond to dietary changes with regard to their blood cholesterol, or lipid levels," said Dr. Eva Obarzanek, NHLBI Project Officer of the DASH study. "In addition, we found that the DASH eating plan, which is low in saturated fat and cholesterol and high in fiber, is one kind of approach that individuals can use in making the therapeutic lifestyle changes, or TLC, that are recommended in the new National Cholesterol Education Program guidelines for lowering cholesterol levels."
Findings that the DASH diet significantly lowers blood pressure were published in the April 17, 1997, issue of the New England Journal of Medicine. A subsequent analysis found that DASH also lowers the level of the amino acid homocysteine, a substance that has been related to heart disease risk. In addition, the DASH-Sodium study recently showed that low-sodium versions of the DASH diet were more effective at further reducing blood pressure than a regular, low sodium diet - in some cases yielding results similar to those achieved through a single hypertension medication.
The DASH study was conducted at four sites and a coordinating center: Brigham and Women's Hospital and Harvard Medical School in Boston, MA; The Johns Hopkins University in Baltimore, MD; Pennington Biomedical Research Center in Baton Rouge, LA; and Duke University Medical Center in Durham, NC. The DASH Coordinating Center is at the Kaiser Permanente Center for Health Research in Portland, OR.
For more information or to arrange an interview with Dr. Obarzanek, please call the NHLBI Communications Office at 301-496-4236.
- Healthy Eating and the DASH Diet: http://www.nhlbi.nih.gov/health/health-topics/topics/dash/
- National Cholesterol Education Program guidelines for lowering cholesterol levels: http://www.nhlbi.nih.gov/health-pro/guidelines/current/cholesterol-guidelines/
- Dietary Approach Significantly Lowers Blood Pressure (news release): http://www.nih.gov/news/pr/apr97/nhlbi-16.htm
- Blood Pressure-Lowering DASH Diet Also Reduces Homocysteine (news release): http://www.nhlbi.nih.gov/news/press-releases/2000/blood-pressure-lowering-dash-diet-also-reduces-homocysteine