Vegan diet provides most health benefits among plant-based eating patterns
Vegetarian and vegan diets provide greater reductions in body weight, fat mass and LDL cholesterol and improved insulin sensitivity compared with other plant-based eating patterns, such as a Mediterranean diet, according to two speakers.
Hana Kahleova, MD, PhD, MBA, director of clinical research for the Physicians Committee for Responsible Medicine, said adopting a vegan diet could result in several health benefits and significantly lower risks for cardiovascular disease and other conditions.
“Vegetarians have half of the risk of developing diabetes throughout their life compared with meat eaters,” Kahleova told Healio. “Vegetarians include lacto-vegetarians. A vegan diet is a bit stricter, so potentially the benefits may be even larger. The vegan diet has been shown to be one of the most efficient ways to treat diabetes.”
People in the United States have been consuming more animal products and refined carbohydrates over the past 70 years. Compared with eating habits from 1950, people in the United States today are eating 25% more calories overall, including 68% more meat, 317% more cheese, and 67% more added fats and oils. The typical American diet today consists of about 57% refined carbohydrates, 32% animal products and 11% plant-based foods.
Meghan Jardine, MS, MBA, RND, LD, CDCES, associate director of diabetes nutrition education for the Physicians Committee for Responsible Medicine, said plant-based foods have a low calorie density, meaning 500 calories of fruits and vegetables will more easily fill the stomach than 500 calories of meat, cheese or oil.
“Fiber is the key to the metabolic benefits of plant-based eating,” Jardine said during a virtual presentation at the Association of Diabetes Care & Education Specialists Annual Conference. “Fiber not only tells your brain that it is full ... but fiber also reduces postprandial glucose levels, fiber binds with cholesterol and bile, reducing lipid levels, and fiber also plays a role in the microbiome.”
In data from 8,300 adults with diabetes from multiple countries, people with the highest fiber intake had 45% lower all-cause mortality and 39% lower CVD mortality rates.
Greater weight loss, fat reduction with vegan diet
Several healthy plant-based eating patterns options are available, including the Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet, the Nordic diet and a vegetarian or vegan diet, Kahleova said. Although studies have shown all four eating patterns have clear health benefits, a strictly vegetarian or vegan diet may provide additional health benefits when compared with the Mediterranean, DASH and Nordic diets.
In a randomized crossover trial, participants ate a Mediterranean or low-fat vegan diet for 16 weeks. At the conclusion of the 16-week period, participants switched to the opposite diet.
After 16 weeks, participants on the vegan diet lost an average of 13 lb of body weight, 7.7 lb of fat mass and 315 cm3 of visceral fat, with no changes observed with the Mediterranean diet. Insulin sensitivity also improved, and LDL cholesterol was reduced by an average of 15 mg/dL on the vegan diet. Systolic and diastolic blood pressure were reduced on both diets.
Lower dietary acid load, greater energy expenditure
A vegan diet offers additional metabolic benefits. In a randomized clinical trial, 244 adults with overweight were randomly assigned to a low-fat vegan diet or control group. In a subset of 44 participants, those on a vegan diet had a 34% reduction in liver fat at 16 weeks.
In the same randomized clinical trial, researchers observed a significant drop in dietary acid load with a vegan diet. Those on a vegan diet had a potential renal acid load reduction of 24.3 mEq per day and a 14.1 lb reduction in body weight during the study.
Eating a vegan diet could also increase energy expenditure. Researchers randomly assigned trial participants to a vegan diet consisting of fruits, vegetables, whole grains and legumes, or a standard American diet consisting of half vegetables, one-quarter protein and one-quarter starch. Those on the vegan diet experienced a 14% increase in energy expenditure, with no change observed in the standard diet group.
Kahleova said any plant-based diet offers more health benefits than the typical American diet, but a vegan diet can help take those health benefits a step forward.
“You’re on the right track if you’re on the DASH diet, the Mediterranean diet or the Nordic diet, that’s definitely better than being on the standard American diet,” Kahleova told Healio. “But can you still improve your diet? Absolutely. If you’re on the Mediterranean diet and you need to lose some weight and you’re struggling with high blood lipids, you may consider going on a vegan diet to get the extra benefits and see what a vegan diet can do for you.”