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Vegan meals increase satiety in type 2 diabetes, obesity

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February 5, 2019

Satiety hormone secretion in men may be increased after eating a plant-based meal compared with a meal consisting of processed meat and cheese, according to findings published in Nutrients.

“Gastrointestinal hormones are involved in regulation of glucose metabolism, energy homeostasis, satiety and weight management,” Hana Kahleova, MD, PhD, director of clinical research at the Physicians Committee for Responsible Medicine in Washington, D.C., and colleagues wrote. “Furthermore, the satiety hormones GLP-1, peptide YY (PYY), pancreatic polypeptide and amylin regulate appetite and energy homeostasis. The release of these satiety hormones can depend on meal composition and differs between impaired and normoglycemia.”

As part of a randomized crossover study, Kahleova and colleagues recruited 60 adult men from the hospital database of the Thomayer Hospital and Institute for Clinical and Experimental Medicine in Prague. Recruitment took place between June 2015 and June 2017.

Among the cohort, 20 men had type 2 diabetes (mean age, 47.8 years; mean BMI, 34.5 kg/m2), 20 had obesity (mean age, 43 years; mean BMI, 32.7 kg/m2) and 20 were healthy men with neither condition (mean age, 42.7 years; mean BMI, 23.8 kg/m2). Men in the diabetes and obesity groups were BMI-matched, and all groups were age-matched.

Participants underwent two study visits and were randomly assigned to a meal made up of a processed meat and cheese burger or a plant-based tofu burger during their first visit. Each participant was then assigned to the second meal option on their second visit. Both meals were matched for energy and macronutrient content. Before meals, each participant fasted between 10 and 12 hours overnight. Measurements for plasma concentrations of gastrointestinal hormones were taken at baseline, and then at 30, 60, 120 and 180 minutes after the meal. Satiety was self-reported at each time point as well.

Men with type 2 diabetes exhibited increased postprandial secretion of GLP-1 after the plant-based meal (30.5%; 95% CI, 21.2-40.7), as did men without diabetes or obesity (15.8%; 95% CI, 8.6-23.5), the researchers wrote.

All three groups experienced an increase in amylin concentrations after the plant-based meal, with men with type 2 diabetes increasing by 15.7% (95% CI, 11.8-19.6), men with obesity increasing by 11.5% (95% CI, 7.8-15.3) and men without either condition increasing by 13.8% (95% CI, 8.4-19.5).

Men without diabetes or obesity had increased levels of PYY (18.9%; 95% CI, 7.5-31.3), but no significant difference was reported in the other two groups, according to the study.

All three groups reported greater satiety after the plant-based meal compared with the meat-based meal, including men with type 2 diabetes (9%; 95% CI, 4.4-13.6), men with obesity (18.7%; 95% CI, 12.8-24.6) and men with neither condition (25%; 95% CI, 18.2-31.7).

“The main components responsible for the beneficial effects of a plant-based meal on satiety and the secretion of gastrointestinal hormones are fiber and bioactive compounds, such as polyphenols,” the researchers wrote. “Dietary fiber may increase PYY secretion and satiety in healthy people. Additionally, resistant starch was shown to increase PYY concentrations in overweight individuals. ... The effect of additional bioactive compounds of plant foods on satiety and secretion of gastrointestinal hormones is an emerging area of research.” – by Phil Neuffer

Disclosures: The authors report no relevant financial disclosures.

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Plant-based nutrition has been established as an effective eating pattern for the prevention and management of type 2 diabetes. Vegetarians and vegans have a lower prevalence of diabetes as well as fewer risk factors for diabetes and cardiovascular disease, including obesity, high blood pressure and dyslipidemia. Vegan and vegetarian diets are also higher in diet quality, which is associated with a reduction in diabetes, CV and all-cause mortality. 

This study provides a fascinating perspective on the potential effects a plant-based meal has on gut hormones, significantly improving post-meal incretin secretion and promoting satiety. I found it interesting that these meals were comparable in calories as well as macronutrient breakdown. The vegan meal was higher in fiber (7.8 grams vs. 2.2 grams). Dietary fiber may be a key advantage plant-based diets have over other eating patterns, as vegetarians and vegans consume significantly more dietary fiber than non-vegetarians.

Diets high in animal protein, especially from red and processed meat, are associated with an increased risk for type 2 diabetes. A diet high in whole grains, vegetables, fruits and legumes and low in animal products may benefit people with or at risk for diabetes by reducing risk and providing therapeutic benefits. Clinicians treating people with diabetes should become more familiar with this eating pattern so they can provide adequate nutrition education and counseling.

In their 2016 consensus statement on the comprehensive management of type 2 diabetes, the American Association of Clinical Endocrinologists and the American College of Endocrinology (AACE/ACE) recommend a plant-based eating pattern. The Dietary Guidelines for Americans includes a healthy vegetarian eating pattern with recommendations on vegan diet to improve the health of Americans. Dean Ornish, MD, demonstrated reversal of atherosclerosis with a plant-based eating pattern in the Lifestyle Heart Trial.

Type 2 diabetes is a growing problem, and medications to treat diabetes are becoming more expensive. This study adds to the growing evidence that consuming plant-based meals is a simple and beneficial way to prevent and treat diabetes, and clinicians should consider using this in their practice. 

Meghan Jardine MS, MBA, RDN, LD, CDE

Associate Director of Diabetes Nutrition Education,
The Physicians Committee for Responsible Medicine

Disclosure: Jardine reports no relevant financial disclosures.