Strong evidence informs dietary recommendations for heart health

Cardiovascular disease is the leading cause of death around the world, accounting for more than 20% of mortality. Many different types of research — from studies of new drugs to studies of people’s diets — have been conducted in an effort to improve cardiovascular health. Dietary clinical trials have been important for understanding which dietary patterns decrease cardiovascular disease risk, according to a recent position paper led by researchers from the Penn State Department of Nutritional Science. 

Penny Kris-Etherton, retired Evan Pugh University Professor of Nutritional Sciences at Penn State and Kristina Petersen, associate professor of nutritional sciences at Penn State, led a group of 10 nutrition researchers from across the United States and Canada. Their paper was recently published in the Journal of Clinical Lipidology, and they recently spoke to Lipid Insights Podcast about the role of nutrition-related clinical trials.  

Nutritional and dietary clinical trials face challenges that are not encountered in medication trials, the authors wrote. For example, it is very difficult to have a “blind” dietary study, since participants can tell what they are eating. Also, often there are no objective dietary adherence biomarkers that would allow the researchers to use blood or other biological samples to understand what research participants are eating; researchers must rely on what participants report.  

These and other challenges must be considered, but dietary clinical trials are still very valuable, the researchers said. For example, dietary trials helped scientists reach consensus around what constitutes a heart-healthy diet.  

“This paper describes landmark nutrition-related clinical trials that have informed dietary recommendations for prevention and management of heart disease as well as the challenges of conducting rigorous clinical trials, the highest quality evidence, in the area of nutrition,” Petersen said. “Our goal is to inform readers about the inherent complexities of nutrition research and promote greater awareness of what nutrition-related clinical trials can be feasibly and ethically designed to test and how this evidence contributes to dietary recommendations.” 

Moving forward, the researchers advocated for studies designed to increase adherence to evidence-based dietary recommendations. 

“It is not possible to conduct a clinical trial for all nutrition questions of importance,” Petersen said. “Therefore, we need to embrace using other research methods and designs to investigate causal relationships when clinical trials are impractical or unethical.” 

Originally published in February 2025.