03 Oct Black-White Hypertension Divide: Is The Southern Diet a Culprit?
MedicalResearch.com Interview with:
Dr. George Howard DPH, for the research team
Professor and Chair of Biostatistics
University of Alabama at Birmingham
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Perhaps the most important distinction to draw for the readers is that this is not a paper about risk factors for hypertension, but rather a paper that looks for contributors to the black-white difference in the presence of hypertension. This racial difference in hypertension is the single biggest contributor to the immense disparities in cardiovascular diseases (stroke, MI, etc.) that underpin the approximate 4-year difference in black-white life expectancy. As such, this work is “going back upstream” to understand the causes that lead to blacks having a higher prevalence of hypertension than whites with hopes that changing this difference will lead to reductions in the black-white disparities in cardiovascular diseases and life expectancy. This difference in the prevalence of hypertension is immense … in our national study of people over age 45, about 50% of whites have hypertension compared to about 70% of blacks … that is HUGE. We think that changing this difference is (at least one of) the “holy grail” of disparities research.
This study demonstrates that there are several “targets” where changes could be made to reduce the black-white difference in hypertension, and thereby the black-white difference in cardiovascular diseases and life expectancy; however, the most “potent” of these appears to be diet changes. Even though we know what foods promote a heart healthy lifestyle, we still have major differences in terms of how that message is being adopted by various groups of Americans. We can’t know from our data what about the Southern diet is driving these racial differences in hypertension but we can begin to design community based interventions that could possibly help to reduce these racial disparities through diet. It is interested that diet more than being overweight was the biggest contributor to the racial disparities in hypertension. This would suggest we might want to consider interventions to increase health foods in the diet while minimizing fried foods and processed meats.
While this is not a clinical trial that “proves” that changes in diet will reduce the disparity in blood pressure, we consider the “message” of the paper to be good news, as the things that we found that contribute to this black-white difference are things that can be changed. While it is always hard for individual people to change their diet, it can be done. More importantly, over time we as a society have been changing what we eat … but we need to “double down” and try to change this faster. Also, policy changes of play a role to gently make changes in these diet, where for example Great Britain has been making policy changes to slowly remove salt from the diet. These changes are possible … and as such, we may see a day when the black-white differences in hypertension (and thereby CVD and death) may be reduced.
MedicalResearch.com: What should readers take away from your report?
Response: Because of the nature of our study as an observational design, we cannot say that the foods in the Southern diet caused the black-white difference in hypertension (and thereby the black-white difference in stroke and heart disease). However, specifically for black readers, changes can be made that will reduce your risk of developing hypertension, perhaps reducing it to the level of hypertension present in whites. There are several changes (particularly for women) that appear promising, but the largest of these appears changes in a very specific dietary eating pattern. Simultaneously at the level of society, to meet the noble goal of reducing black-white disparities in health, we need to incentivize changes to avoid this eating pattern that is high in fried food (potatoes, fish and chicken), high in sugar, and high in sodium from processed foods.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: Importantly, as this is the first report describing these differences, it will be important for these findings to be confirmed in other studies and in other population. Ideally, it would be great if these findings could be tested in a clinical trial; however, the design of a randomized study to reduce black-white differences could be a challenge, as it would need to include white participants where the intervention is targeted to have a larger impact in blacks.
We do know from clinical studies previous to our work that diets low in sodium and high in fruits, vegetables and whole grains lead to decreased blood pressure. We actually named the diet a Southern style diet because it was more commonly consumed by participants residing in the Southwestern United States; however, this diet is eaten by people across the nation (particularly blacks). The Southern style diet we observed was high in fried food (potatoes, fish and chicken), high in sugar, and high in sodium from processed foods. All three of these types of foods have been link to heart disease and hypertension. Another key point is that when we examine people who report being more adherent to this Southern Style diet, they are consuming these foods nearly every day. For those who report being less adherent, they eat them once a week or once a month. So it’s not that there are certain foods that should always be avoided. They should just be limited.
MedicalResearch.com: Is there anything else you would like to add?
1 We would like to credit the study participants from across the nation for the magnificent participation in the study. They have let us into their homes and given us their time (and blood). To the extent that there is “credit” here, they deserve it!
2.We are grateful for the support of the National Institute of Neurological Disorders and Stroke (NINDS/NIH) that supported the study. Without their support this would not have happened.
3. This is really “team science.” For example, Dr. Judd (copied on this) first “discovered” or “defined” (not sure what the right word is!) the Southern Diet eating pattern in a different paper. Dr. Cushman lead the laboratory efforts. Virginia Howard (in full disclosure … wife and research partner) has been a co-leader of REGARDS since its conception. Other authors made similar important contributions. This is a “we” effort.
Howard G, Cushman M, Moy CS, et al. Association of Clinical and Social Factors With Excess Hypertension Risk in Black Compared With White US Adults. JAMA. 2018;320(13):1338–1348. doi:10.1001/jama.2018.13467
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