Conference Coverage

Diet explains black Americans' high stroke risk



HONOLULU – Nearly two-thirds of the racial disparity in stroke risk is explainable by African Americans’ greater adherence to a dietary pattern high in fat, salt, and sugar, according to a major national study.

Investigators in the REGARDS (Reasons for Geographic and Racial Differences in Stroke) study named this dietary pattern the "Southern diet" because that’s where its following is greatest. It is one of five broad U.S. dietary patterns identified in the study, which involved detailed assessment of 30,239 black and white participants aged 45 years and older.

Dr. Suzanne Judd

The Southern diet was the one that stood out in terms of increased stroke risk. It features heavy consumption of fried foods, including fried vegetables, as well as organ meats, processed meats, full-fat milk, and sugar-sweetened drinks, while downplaying fruits, salads, and whole grains.

The Southern diet is a dietary pattern that’s far more popular among blacks than whites, including blacks living in the so-called "stroke belt" in the Southeast. Enthusiasm for the dietary pattern, however, is by no means limited to the South: Among the top-10 states with the greatest adherence to the Southern diet are Delaware, Illinois, and Michigan, Suzanne Judd, Ph.D., noted at the International Stroke Conference, which was sponsored by the American Heart Association.

It is well established that African Americans are at sharply higher risk of stroke than are their same-age white counterparts. Mathematical modeling of the REGARDS data showed that the Southern diet explains 63% of the excess stroke risk among black Americans under age 65 years.

"That’s something we’re very excited to know because it’s something we could intervene in and make changes to reduce this racial disparity in stroke," observed Dr. Judd, a nutritional epidemiologist at the University of Alabama, Birmingham.

People who ate Southern diet–type foods six times per week had a 41% higher stroke risk than did those who ate such foods once a month. In a multivariate analysis that adjusted for age, race, gender, location, socioeconomic and educational status, total energy intake, smoking, and sedentary behavior, adherence to the Southern diet was independently associated with stroke risk in a dose-response fashion. The stroke rate climbed by 30% as adherence to the dietary pattern increased from the lowest to the highest quartile.

"I think that it’s a very positive message to show that even small changes in adding some of these plant-based foods into the diet seem to be protective against stroke in this population." -Dr. Suzanne Judd

Although it’s customary in dietary studies not to include factors that could lie in the causal pathway between diet and stroke, even when major known stroke risk factors such as hypertension, diabetes, atrial fibrillation, and prior MI were included in the modeling, there was still an association between adherence to the Southern dietary pattern and stroke risk, albeit an attenuated one, she noted.

The other four major dietary patterns identified by Dr. Judd and her associates were the Convenience pattern, typified by take-out pizza, Mexican and Chinese foods, and pastas – a diet favored by busy young working people; the Plant-based diet; the Sweets diet; and the Alcohol and Salads diet, which emphasizes beer, wine, liquor, salads, nuts and seeds, butter, and coffee. Dr. Judd conceded that the Alcohol and Salads pattern is poorly understood and is a construct that requires further study.

The Plant-based diet emphasizes cruciferous, green leafy, and other vegetables, fruits, beans, whole grains, yogurt, fish, and poultry. In the multivariate analysis, subjects in the second through fourth quartiles in terms of adherence to this dietary pattern enjoyed roughly a 20% reduction in stroke risk.

"I really want to highlight this Plant-based pattern. I think that it’s a very positive message to show that even small changes in adding some of these plant-based foods into the diet seem to be protective against stroke in this population," Dr. Judd said.

The REGARDS study was funded by the National Institute of Neurological Disorders and Stroke. Dr. Judd reported having no financial conflicts.

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