Adding Healthy Foods Can Lower Blood Pressure Without Weight Loss, Salt Restriction
DURHAM, N.C.-- A major study on high blood pressure has shown for the first time that simply eating more fruits, vegetables and low-fat dairy foods can significantly lower a person's blood pressure without weight loss or salt restriction. And the higher the person's blood pressure, the better the dietary regimen worked.
The study results are published in the April 17 issue of the New England Journal of Medicine.
Although they aren't sure how, researchers found the diet lowered blood pressure by an overall average of 5 points. Among people with mildly elevated blood pressure (mild hypertension), the diet lowered pressure even more dramatically: by 11 points.
The findings suggest that the diet could replace medication in people with mild hypertension, and for people on the verge of developing high blood pressure, the diet could prevent them from crossing the line, according to Dr. Laura Svetkey, who led the Duke University portion of the multi-center study.
The study was funded by the National Heart, Lung and Blood Institute (NHLBI) and was jointly conducted by Duke, Johns Hopkins University, Brigham and Women's Hospital, Pennington Biomedical Research Center, and Kaiser Permanente Center for Health Research. Dr. Lawrence J. Appel of Johns Hopkins was the lead author of the study report.
Svetkey said the public health implications of this study are dramatic because high blood pressure affects one in four adults and is a leading cause of heart disease, stroke, and kidney failure in the United States. Currently, there are three treatments for reducing high blood pressure. They include medication, weight loss and salt restriction.
Medications have unwanted side effects, and weight loss is difficult to achieve and even harder to maintain, Svetkey said. Fewer than 5 percent of adults who lose weight are able to keep it off for five years, no matter what weight-loss method they use, and 62 percent of them regain all of their lost weight within five years.
"The dietary regimen is quite novel because it doesn't require the same degree of deprivation as do current dietary treatments," Svetkey said. "Instead, they'll be adding healthier foods, which may be easier for people to maintain on a long-term basis."
Svetkey said the diet is the first new treatment to be proven effective in at least 10 years. It worked quickly, within two weeks, and it worked in everyone who tried it regardless of their initial blood pressure: men and women, blacks and whites, young and old, thin and overweight. That finding is especially important for blacks because they suffer from hypertension earlier in life, more frequently, and with far more dire consequences.
Moreover, the diet is consistent with all other national recommendations for preventing cancer, heart disease and other chronic diseases. "Healthy eating is healthy eating," Svetkey said. "You don't have to eat one way to prevent one disease and another way to prevent another disease."
The diet -- called DASH for dietary approaches to stop hypertension -- included four to five daily servings of fruits and four to five daily servings of vegetables, about twice the average American consumption of fruits and vegetables. It also included three daily servings of low-fat dairy foods. Despite the fact that the DASH diet is a reduced fat diet, participants also ate peanuts, cookies, meats and other high-calorie foods in moderation. All foods were bought off the grocery store shelf and required no special preparation. The participants were not allowed to lose weight or restrict salt so that researchers could study the effects of the diet independent of all other factors.
The 459 participants in the multi-center study ate one of three diets for approximately 11 weeks: either the DASH diet; a typical American diet high in fat but low in fruits and vegetables; or a typical American diet with added fruits and vegetables.
Duke study participants received all their meals free. Take-out meals were provided at breakfast, lunch and on weekends, and dinner was eaten at the Sarah W. Stedman Center for Nutritional Studies, located on the campus of the Duke Center for Living. Blood tests and urinalyses were given periodically to ensure that participants were adhering to the DASH diet.
The Duke study site enrolled 129 participants out of the total 459. All participants had either mild hypertension or high-normal blood pressure but none were on medication to treat high blood pressure. Half the participants were men and half were women, and 60 percent were African-American.
The next phase of research will test the DASH diet together with salt restriction to determine if both steps combined can lower blood pressure even more dramatically.