October 02, 2018

Dietary pattern is the biggest contributor to higher rates of hypertension in African Americans

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george howard 2016George Howard, DrPHDiet is the predominant factor explaining why more African-Americans develop high blood pressure than their white counterparts, according to a national study led by researchers at the University of Alabama at Birmingham. After analyzing nearly 7,000 adults, researchers identified factors that help explain why African-Americans have a higher risk of hypertension than whites. The leading factor to explain the difference is eating a southern-style diet, which is high in fried and processed foods. The other key factors are salt intake and level of education.

The study, based on data from a national study based at the School of Public Health at UAB, was published Oct. 2 in the Journal of the American Medical Association.

Lead study author, George Howard, DrPH, professor of biostatistics in the UAB School of Public Health, says the most significant part of the study is that it identifies some lifestyle changes that can be made to reduce the higher risk of hypertension in African-Americans. This higher risk of hypertension in African-Americans is the main reason they are at higher risk of stroke and heart attacks, and also one of the main reasons they have a shorter life expectancy.

“Hypertension is the single biggest contributor to racial disparities in cardiovascular disease,” Howard said. “Preventing hypertension is a critical piece of reducing health disparities in cardiovascular disease. This work identifies factors contributing to the development of high blood pressure and how they differ between African-Americans and white Americans.”

Cardiovascular disease, including stroke, is the largest contributor to the mortality difference between the black and white populations of the United States, accounting for 34 percent of the difference in years of life lost, according to data from the National Health Interview Survey.

suzanne judd experts2017Suzanne Judd, Ph.D.“Life expectancy is about four years shorter in African-Americans compared to whites, and a driving force of life expectancy differences is cardiovascular diseases,” Howard said. “The higher risk of hypertension in African-Americans plays a central role in this problem. Not only does hypertension have a direct impact on racial disparities, it also drives the disparities in stroke and heart-related conditions.”

The researchers analyzed 6,897 participants from across the nation over a period of nearly 9.5 years; 1,807 were black and 5,090 were white. The participants are all part of the REGARDS (Reasons for Geographic and Racial Differences in Stroke) study, a federally funded study based at UAB. The participants in the study were interviewed by telephone, and then a health professional went to their homes and took measurements including blood pressure, weight, height and waist. The participants answered questions about their health and completed questionnaires measuring their diets.  

Twelve potential factors were studied for their relationship with the development of hypertension in blacks compared to whites. For both men and women, the biggest factor explaining the difference in the risk of developing high blood pressure between African Americans and whites was eating a Southern-style diet. This is a dietary pattern high in fried foods including fried fish, fried chicken and fried potatoes. It also contains sweetened beverages and processed foods. Suzanne Judd, Ph.D., a nutritional epidemiologist in UAB’s School of Public Health, is one of the investigators who first identified this eating pattern.

“This diet likely contributes to excess hypertension due to higher sodium intake, but it is impossible to guess at which component of this dietary pattern is the ‘silver bullet,’” Judd said. “Likely it could be all of the foods eaten together. The combination of a high-sodium diet with excess calories from fat and sugar and limited beneficial foods containing anti-oxidants, vitamins and minerals probably creates the perfect storm to make this diet less healthy.”

The study also found that there were both similar and varying factors for men and women.

“The other important factors for both men and women are salt intake and education,” Howard said. “For women, the other factors are obesity and larger waist size. We know obesity is related to the development of hypertension in both men and women, but we didn’t know that it contributed differently in men and women to the racial difference in hypertension. We now know that obesity helps to explain the racial disparities between black and white women.”

Howard hopes the findings will help guide efforts to reduce the “extra” risk of hypertension in African-Americans, and this may help to reduce the extra risk of stroke and heart attack, and to reduce the shorter life expectancy in African-Americans.   

“The best way to treat high blood pressure is to prevent it,” Howard said. “This study points to lifestyle changes that can be made to reduce the black-white difference in hypertension, which will in turn reduce the racial disparities in cardiovascular disease.”

The study was supported by the National Institute of Neurological Disorders and Stroke, which is part of the National Institutes of Health. The other study authors are Suzanne Oparil, M.D., Paul Muntner, Ph.D., Virginia G. Wadley, Ph.D., Leann Long, Ph.D., and Virginia Howard, Ph.D, all from UAB; as well as Mary Cushman, M.D., University of Vermont School of Medicine; Claudia S. Moy, Ph.D., National Institute of Neurological Disorders and Stroke, National Institutes of Health; Daniel T. Lackland, Medical University of South Carolina; Jennifer J. Manly, Ph.D., Columbia University; and Matthew L. Flaherty, M.D., University of Cincinnati Academic Health Center.