Meta-study finds close alignment on benefits of plant food groups for treatment and prevention of chronic disease

The results of a study published in Advances in Nutrition that compared dietary and nutrition recommendations from dozens of clinical practice guidelines around the world for treating, managing and preventing major chronic diseases should increase clinician confidence on recommending consumption of fruits, vegetables, legumes and whole grains.

The meta-epidemiological study from the American College of Lifestyle Medicine (ACLM) reviewed 78 clinical practice guidelines published between 2010 and 2021 in North America, Europe and Asia and found close alignment in their recommendations for encouraging daily intake of plant food sources, while limiting consumption of alcohol, salt or sodium.

The paper states that the findings are important because patients have reported confusion caused by contradictory nutrition messaging, in part due to fad diets and pseudo-expert advice on the Internet. However, physicians, whose expertise is frequently sought by patients, often receive insufficient nutrition education in medical school to feel confident giving dietary guidance to patients for the treatment of chronic disease.

"Clinicians depend on clinical practice guidelines developed from the most current and rigorous medical research to help steer their diagnoses, treatment and management of common chronic diseases," said Beth Frates, MD, FACLM, DipABLM, ACLM President and Clinical Assistant Professor at Harvard Medical School.

"The results of this comprehensive review of evidence-based clinical practice guidelines are important because they can benefit both clinicians and their patients by reducing the variability in dietary and nutrition guidance that often prevents clinicians from providing optimal care."

Clinical practice guidelines reviewed for the study were developed by governments, major medical professional societies and large health stakeholder associations to improve the health of adults with chronic diseases, such as type 2 diabetes, cancer, cardiovascular disease, digestive diseases, weight-related conditions and chronic obstructive pulmonary disease. Dietary patterns, food groups and food components were of primary interest in the study, with macronutrient and micronutrient recommendations a secondary interest.

For food groups, nearly three quarters of clinical practice guidelines recommended including or increasing intake of vegetables, which was the highest percentage of any food group. No guidelines recommended excluding or reducing vegetables. After vegetables, fruit at 69%, whole grains at 58% and legumes at 47% were the most commonly recommended food groups. The food groups most often recommended to limit or reduce among guideline recommendations were red meat at 32%, followed by processed meat at 27% and refined grains at 19%.

Among food components, 62% of guidelines recommended excluding, decreasing or limiting alcohol and 56% recommended the same of salt or sodium. The most recommended food components were vegetable oils at 35% and soy protein at 18%.

"These findings demonstrate that global dietary and nutrition guidelines support and are aligned with ACLM's recommendation that, for the treatment, reversal and prevention of lifestyle-related chronic disease, the optimal eating plan is predominantly based on a variety of minimally processed vegetables, fruits, whole grains, legumes, nuts and seeds," said Micaela Karlsen, Ph.D., MSPH, ACLM Senior Director of Research and senior study author.

The Global Burden of Disease Report has confirmed that unhealthy diet is responsible for more deaths globally than any other risk factor, including tobacco smoking. To the authors' knowledge, this was the first study to compare dietary recommendations across current clinical practice guidelines for multiple major chronic diseases.

"The growing prevalence of overweight and obesity and the associated chronic conditions are a serious public health threat that must be urgently addressed," said Kelly C. Cara, MS, doctoral student at Tufts University Friedman School of Nutrition Science and Policy, the study's first author.

"Patients look to health care professionals for dietary guidance, so it is critical that physicians are fully informed and confident when offering recommendations to patients in order to provide the best outcomes. We hope the results of this study will assist physicians in developing the foundation of knowledge needed to achieve those outcomes."