Modified DASH diet shows blood pressure benefits for adults with diabetes

An estimated 38.1 million adults in the United States had diagnosed diabetes in 2021, according to the Centers for Disease Control and Prevention. Of these, about 90% to 95% had type 2 diabetes. A new Johns Hopkins Medicine study finds that in adults with type 2 diabetes - most of whom were taking multiple antihypertensive medications - a lower-sodium DASH-style diet (Dietary Approaches to Stop Hypertension) achieved a clinically meaningful reduction in blood pressure, primarily from sodium reduction.

The DASH diet is rich in fruits, vegetables and low-fat dairy products, and is lower in saturated fat and cholesterol. For the DASH for Diabetes study, Johns Hopkins researches modified the original DASH diet for people with type 2 diabetes by lowering carbohydrates and increasing unsaturated fat. The researchers also reduced the potassium content to ensure the diet was safe for chronic kidney disease, which affects many people with diabetes.

The DASH diet has been around for a long time, and is part of the standard treatment for hypertension. We know that it lowers blood pressure, but there has been little study of this diet and sodium reduction in people with diabetes. The goal of the study was to develop a new version of the DASH diet and see how effective it was in lowering blood pressure for people with diabetes. We called it DASH4D."

Scott Pilla, M.D., M.H.S., lead author, assistant professor of medicine, Johns Hopkins University School of Medicine

The study was published June 9 in JAMA Internal Medicine.

Pilla says that people with diabetes tend to focus on their blood sugar levels, even though high blood pressure commonly affects those with diabetes and is an important cause of stroke and heart disease. The blood pressure goal for people with diabetes is less than 130 mmHg over less than 80 mmHg. When people take blood pressure medication, it typically lowers systolic blood pressure (the top number) by about 10 points. In this study, eating the low-sodium DASH4D diet lowered systolic blood pressure by about 5 additional points. In people with diabetes, a 5-point reduction in blood pressure reduced the risk of stroke by 14%, cardiovascular events by 6% and heart failure by 8%.

"A lot of people are interested in controlling diabetes and their blood pressure through diet and other lifestyle changes," says corresponding author Lawrence Appel, M.D., M.P.H., a professor of medicine at the Johns Hopkins University School of Medicine who helped develop the original DASH diet. "Most people in this study were taking more than one blood pressure medication, but we found that you can lower it further with dietary change. Blood pressure is one of the most important numbers to control because the higher the number, the higher the risk of stroke and heart disease."

Pilla says the study was a crossover feeding study in which every patient who joined the study received four diets in a randomly assigned sequence: 1) DASH4D diet with lower sodium, 2) DASH4D diet with higher sodium, 3) a typical American diet with lower sodium, and 4) a typical American diet with higher sodium. Participants ate each diet for five weeks. They were provided all of their food and ate no food other than what was provided by the study. Their calories were adjusted so that their weight remained stable throughout the study.

Of 102 participants, 85 completed all diet periods. The mean age was 66 years, 66% were women and 87% were self-reported Black race. The mean baseline blood pressure was 135/75 mmHg, and 66% used two or more antihypertensive medications. In contrast to the typical American diet with higher sodium, the DASH4D diet with lower sodium reduced end-of-period systolic blood pressure by 4.6 mmHg and diastolic blood pressure by 2.3 mmHg. The majority of blood pressure reduction occurred in the first three weeks of each diet.

"The next steps are to get the knowledge that we gained out to people with diabetes and help them use the diet to make healthy changes," Pilla says. "We need to make it easier for people to follow this diet in ways that are affordable and accessible to people of different cultures and with different dietary habits so they can integrate them into their daily life and make them part of their daily routine."

Other researchers who contributed to this research are Hsin-Chieh Yeh, Christine M. Mitchell, Edgar R. Miller, Susan Oh, Karen White, Nowella Durkin, Ariella A. Stein, Jeanne B. Charleston, Mengyang Lu, Xiao Hu, Beiwen Wu, Elizabeth Selvin, Michael Fang, Nisa M. Maruthur, Stephen P. Juraschek, Noel T. Mueller, and Nae-Yuh Wang.

Appel receives payments from Wolters Kluwer for chapters in UpToDate on the relationships of blood pressure with weight, exercise, smoking and sodium intake. The other authors report no conflict of interest.

Funding for this research was principally provided by the Sheikh Khalifa Stroke Institute at the Johns Hopkins University School of Medicine, with support from a National Institute of Diabetes and Digestive and Kidney Diseases grant (R01DK128900), a National Heart, Lung, and Blood Institute grant (R01HL166473), NIDDK career development awards and the Johns Hopkins Institute for Clinical and Translational Research, funded by the National Center for Advancing Translational Sciences through the Clinical and Translational Science Awards Program.