The idea that eating less meat can improve cardiovascular health certainly isn’t new. Studies have found that people who eat less meat—especially less red meat—have a lower incidence of cardiovascular diseases and a lower risk of fatal ischemic stroke. While there is some debate as to the exact relationship of meat consumption to heart disease risk, it’s generally accepted that eating less meat improves cardiovascular health.
Part of the problem in determining the exact role of diet on health is that studies are hampered by confounding factors such as genetic differences, upbringing, and lifestyle choices. Researchers at Stanford University came up with a unique way to deal with these differences. By studying pairs of identical twins, they were able to control for genetics and limit the other factors, as the twins grew up in the same households and reported similar lifestyles. The results of their research were published on November 30 in the journal JAMA Network Open.
The eight-week trial followed 22 pairs of identical twins without cardiovascular disease. One twin from each pair was placed on a vegan diet, and the other on an omnivore diet. Both diets were healthy, featuring plenty of vegetables, legumes, fruits, and whole grains with little or no sugars and refined starches. The difference was that the vegan diet was entirely plant-based, with no meat or animal products, while the omnivore diet included chicken, fish, eggs, cheese, dairy, and other animal-sourced foods.
During the first four weeks of the study, participants received 21 meals per week delivered by a meal service—seven breakfasts, lunches, and dinners. For the second four weeks, participants prepared their own meals. A registered dietitian was on call to offer suggestions and answer questions during the duration of the study.
The participants were interviewed about their dietary intake and kept a log of the food they ate. Additionally, researchers weighed the participants and drew their blood at baseline and again at the end of the four- and eight-week periods.
The average baseline LDL (“bad” cholesterol) level for the vegans was 110.7 mg/dL and 118.5 mg/dL for the omnivore participants; it dropped to 95.5 for vegans and 116.1 for omnivores at the end of the study. The optimal healthy LDL-C level is less than 100. The vegan participants also showed about a 20 percent drop in fasting insulin—a higher insulin level is a risk factor for developing diabetes. The vegans also lost an average of 4.2 more pounds than the omnivores.
“This suggests that anyone who chooses a vegan diet can improve their long-term health in two months,” said Christopher Gardner, PhD, the study’s senior author.
While Gardner admits that trying to get most people to go vegan is a stretch, he notes that both the vegan and omnivorous participants in the study did the three most important things to improve cardiovascular health: They cut back on saturated fats, increased dietary fiber, and lost weight.
“A vegan diet can confer additional benefits such as increased gut bacteria and the reduction of telomere loss, which slows aging in the body…[But] what’s more important than going strictly vegan is including more plant-based foods into your diet,” said Gardner, who has been “mostly vegan” for the last 40 years.