WEST LAFAYETTE, Ind. — A new study by Purdue University researchers has found lean pork is an effective primary protein source in a DASH (Dietary Approaches to Stop Hypertension) diet to help improve blood pressure.

"While the traditional DASH diet includes chicken and fish, our research suggests that lean pork may also be a part of this healthy eating pattern," said Wayne Campbell, professor of nutrition science and the study’s lead author. "Many Americans enjoy red meat, so the recommendation to limit red meat in the typical DASH diet could be a potential barrier to adapting this eating plan. Swapping in lean pork could help more people follow this healthful eating plan."

Published in The American Journal of Clinical Nutrition June 10, researchers found when adults ate lean pork instead of the typical chicken and fish as their main protein source in the diet, "they had the same blood pressure benefits regardless of protein source – with systolic blood pressure decreasing around 7 to 8 points and diastolic around 4 to 5 points after six weeks, based on a 24-hour blood pressure monitoring system."

According to researchers, the DASH diet, which they cited as "one of the best-studied eating approaches," has been recognized by federal government and health organizations as "an eating pattern that can improve health and help lower the risk of chronic diseases."

Moreover, the 2015 Dietary Guidelines Advisory Committee recently included research showing the diet may have favorable effects on cholesterol and may help reduce the risk of heart disease, in addition to helping lower blood pressure, which impacts nearly 30 percent of Americans.

Funded by the National Pork Board, the National Institutes of Health’s Indiana Clinical and Translational Sciences Institute and Clinical Research Center and the USDA, the study included 19 "overweight or obese" older adults – 13 women and 6 men – with elevated blood pressure who were randomly assigned to follow the DASH diet with either chicken and fish or lean pork as the major protein source (about 55 percent of protein intake).

But Campbell said the study applied only to cuts of unprocessed lean pork, such as tenderloin and fresh, uncured ham trimmed of visible fat, with each serving size being just 3 ounces. He added these findings "should not be extrapolated to other pork products with higher fat and salt content."

According to the study, the effectiveness of the DASH diet limits red meat to reduce total and saturated fat and sodium, and is often recommended to reduce blood pressure. It is focused on the increased consumption of fruits and vegetables, whole grains, low-fat dairy, nuts, poultry and fish, while reducing fats, red meats – including pork – and added sugars.

Drew Sayer, a Purdue doctoral student in nutrition science and a co-author on the study, said any cuts of red meat, including beef or pork tenderloin and fresh ham, meet the USDA guidelines for lean, which is less than 10 grams total fat and less than 4.5 grams of saturated fat per 100 grams.

He said "extra lean" is less than 5 grams total fat and less than 2 grams saturated fat per 100 grams. "If people have to rely only on fish and chicken, their diet choices can be limited, and our findings support that lean pork may be a viable option for people who are consuming a DASH diet without compromising the effectiveness of the diet plan," he explained.

Sayer said the 19 participants in the study had elevated high blood pressure and their average age was 61. "The people in the study were at risk for hypertension, and they represent the 60 percent of Americans with prehypertension who are on the road to clinically high blood pressure," he said.

As part of the study, the participants consumed a DASH diet for two six-week periods, and they either ate lean pork or chicken and fish as the main protein source. They had a four-week break, then consumed the alternate meat, with blood pressures taken throughout the study.

He said pre- and post-intervention manual and 24-hour blood pressures were not different between either DASH option of pork or chicken and fish. Consumption of these diets for six weeks reduced all measures of blood pressure with no differences in responses between DASH with chicken and fish and DASH with pork.

The study also included Amy Wright, a research dietitian in the Department of Nutrition Science, and Ningning Chen, a doctoral student in statistics in the College of Science.