DASH (hypertension) diet improved by reducing carbohydrates

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Scientists Fine-Tune Diet by Adding Beans

By Sally Squires

Washington Post Staff Writer

Wednesday, November 16, 2005; A04

Trading about 10 percent of carbohydrates in the diet for beans and

healthful fats such as olive oil can help control high blood pressure

and raise the level of " good cholesterol, " according to a new study.

Experts said that the findings will help alter the standard dietary

advice for people at high risk of heart disease. They also underscore

the health benefits of popular foods including nuts, avocados and

olive oil.

" We've got evidence to say that people should be more selective about

what they eat, " said J. Roccella, coordinator of the National

High Blood Pressure Education Program at the National Heart, Lung and

Blood Institute. " If they follow a diet similar to that in the study,

it may give them a chance to lower their risk of heart disease. And

for some this might mean taking fewer drugs. "

The results, presented yesterday at the American Heart Association's

annual meeting in Dallas, caught even some of the study's researchers

by surprise.

" I thought that we were going to see a protein effect " on cholesterol

and high blood pressure, said Lawrence Appel, professor at s

Hopkins School of Medicine and lead author of the trial. " But the

addition of unsaturated fat in lowering blood pressure was a surprise. "

Diet has long been an important tool in reducing the risk of heart

disease. That is why experts urge limiting salt intake, unhealthful

saturated fats, trans fats and cholesterol. But there has been great

debate about what role other nutrients might play, including lean

protein, whole-grain carbohydrates and healthful fat.

The 2001 Dietary Approaches to Stop Hypertension (DASH) trial

conducted by the National Heart, Lung and Blood Institute proved that

diet could be as effective in controlling blood pressure as some

medications. The low-sodium DASH diet is " a hallmark to prevent and

treat hypertension, " said M. Sacks, a co-investigator of the new

study, in a statement released by Brigham and Women's Hospital, where

he is on staff.

The trouble is that the DASH diet -- which includes plenty of fruits

and vegetables, moderate amounts of foods with healthful fat such as

nuts, and low-fat dairy products, along with high amounts of

carbohydrates and lean meat, fish and poultry -- produces mixed

results when it comes to cholesterol. The DASH regimen lowers

low-density lipoprotein (LDL), one of the most damaging types of

cholesterol, but has little effect on triglycerides -- another

unhealthful type of blood fat. But the regimen also reduces levels of

the protective high-density lipoprotein (HDL), the so-called " good

cholesterol. "

That is why " there are additional growing cardiovascular health risks

that we need to address, " Sacks said.

To do that, Sacks and Appel launched the Optimal Macronutrient Intake

Trial to Prevent Heart Disease (OmniHeart) to compare the effects of

three diets on blood pressure, blood cholesterol and heart disease

risk in a group of 164 people, age 30 and older. The results are being

published in this week's Journal of the American Medical Association.

Like more than half of Americans, all were considered

" pre-hypertensive " or having stage one high blood pressure. Their

systolic pressure -- measured when the heart contracts -- was in the

range of 120 to 159 millimeters of mercury. Their diastolic readings

-- the pressure when the heart rests between beats -- were 80 to 99.

About 75 percent of the participants were overweight or obese, and

slightly more than half were African American, a group at high risk

for hypertension.

The participants, from Baltimore and Boston, were randomly assigned to

three healthful diets, all low in saturated fat, cholesterol, trans

fatty acids and sodium -- much like the DASH diet. All diets were also

rich in fruit, vegetables, fiber, potassium and other minerals. The

researchers varied protein, carbohydrate and fat content, however, so

that one diet was richer in carbohydrates, one richer in protein and

one richer in healthful fat.

The volunteers followed the assigned diet for six weeks. All the food

was provided by the researchers, who also monitored participants' body

weight and adjusted calorie amounts to make sure weight stayed steady

throughout the study.

All three diets produced large enough drops in blood pressure and LDL

cholesterol to cut the 10-year risk of coronary heart disease by at

least 16 percent. But the diets rich in protein and healthful fats

outperformed the standard high-carbohydrate diet on both measures,

cutting risk by 20 percent.

" We have a two-part take-home message here, " Appel said. " All three

diets were healthy and had favorable effects. But the current

recommended DASH diet that is rich in carbohydrates can be further

improved by partially replacing some of those carbohydrates with lean

protein from plants and low-fat dairy products, or with

monounsaturated fats " such as olive oil or nuts.