Blood pressure is a measure of the force of blood as it travels through the circulatory system. It's expressed in two numbers. The systolic pressure is the reading taken when the heart beats, or is working hardest. The diastolic pressure is taken between beats, or while the heart is at rest. The measurements are expressed in millimeters of mercury (mm Hg) with the systolic number first (on the top) and the diastolic number second (on the bottom).

Normal blood pressure is a systolic reading of less than 120 mm Hg and/or a diastolic reading of 80 mm Hg. High blood pressure (also called hypertension) is defined as a systolic pressure of 140 mm Hg or high or a diastolic pressure of 90 mm Hg or higher.

The American Heart Association estimates about 73 million Americans 20 and older (one in three adults) have high blood pressure. When blood pressure is continually elevated, the heart must work harder to get blood through the circulatory system. This can eventually weaken the heart muscle and lead to heart failure. The extra force can also damage the blood vessels and increase the risk of heart attacks, kidney failure, stroke and eye damage.

High Blood Pressure in African-Americans

Compared to other racial/ethnic groups, African-Americans have the highest rates of high blood pressure. The American Heart Association estimates hypertension affects 40 percent of black adults. In addition, the disease usually strikes blacks at an earlier age and tends to be more severe. Researchers say high blood pressure contributes to increased rates of death from stroke (1.8 times that of whites), heart disease (1.5 times higher) and end-stage kidney disease (4.2 times higher).

One of the goals of Healthy People 2010 is to reduce the proportion of African-Americans with high blood pressure from 40 percent to 16 percent. In addition, health experts hope to increase the number of African-Americans who have their blood pressure under control from 19 percent to 50 percent.

Diet for Blood Pressure Control

One of the treatments for lowering blood pressure is called Dietary Approaches to Stop Hypertension, or DASH. The DASH diet is recommended by the National Institutes of Health and the American Heart Association. It emphasizes plenty of fruits and vegetables, whole grains, fat-free or low-fat dairy products, fish, poultry, beans, seeds and nuts. It also reduces the consumption of salt, sodium, sugars, fats and red meats. Studies show using the DASH diet can significantly decrease systolic and diastolic blood pressure, especially in African-Americans.

If blood pressure can be controlled through diet, patients may be able to avoid the need to take medications. However, many African-Americans have a hard time changing their traditional foods or giving up family-honored recipes.

Researchers at the University of Alabama at Birmingham have put together a modification of the DASH diet for African-Americans with high blood pressure. The new diet is called Altering Diet in African American Populations to Treat Hypertension, or ADAPT. The diet still emphasizes fruits and vegetables. However, modifications are suggested to make healthier use of traditional foods, like herbs and spices in place of high-fat meat seasonings or low-fat yams instead of candied yams with butter.

Participants meet in group sessions with a dietitian, who leads discussions about healthy food choices and ways to adapt family menus. Participants can also offer suggestions and provide support for each other. Jamy Ard, M.D., an Internist with the University of Alabama Birmingham, teaches the importance of portion control. Participants are taken to a grocery store to learn how to read nutrition labels. Family members are invited to take part in the program to understand the importance of the dietary adaptations and provide support for the person in charge of shopping and cooking.

Currently, the ADAPT study is in a clinical trial to look at participants' willingness to accept and follow the plan and its effect on blood pressure control. Researchers will also examine the effects of the diet on weight, food intake, insulin/glucose levels and cholesterol.

For general information on high blood pressure:

American Heart Association

National Heart, Lung and Blood Institute