In a groundbreaking study led by Stanford Medicine, researchers have discovered compelling evidence that adopting a vegan diet can significantly enhance cardiovascular health. Conducted with 22 pairs of identical twins, the study compared the effects of vegan and omnivore diets, showcasing the vegan diet’s positive impact in just eight weeks.
While the benefits of reducing meat consumption on cardiovascular health are well-known, previous diet studies often faced challenges due to genetic variations, upbringing differences, and diverse lifestyles among participants. The use of identical twins in this study allowed researchers to control for genetic factors and minimize other variables, as twins grew up in the same households and reported similar lifestyles.
Senior author Christopher Gardner, PhD, the Rehnborg Farquhar Professor and a professor of medicine, expressed enthusiasm for the study’s unique approach and the engaging participation of identical twins. “Not only did this study provide a groundbreaking way to assert that a vegan diet is healthier than the conventional omnivore diet, but the twins were also a riot to work with,” he noted.
The study, published in JAMA Network Open on November 30, involved 22 pairs of identical twins, totaling 44 participants. The researchers selected healthy individuals without cardiovascular disease from the Stanford Twin Registry, ensuring a diverse yet genetically matched group. One twin from each pair adhered to a vegan diet, while the other followed an omnivore diet. Both diets included healthy components such as vegetables, legumes, fruits, and whole grains, with the vegan diet excluding all animal products.
A meal service delivered 21 weekly meals for the first four weeks, and participants prepared their own meals for the subsequent four weeks. A registered dietitian provided guidance throughout the study, highlighting the feasibility of adopting a healthy diet within four weeks.
Results indicated the most significant improvements occurred during the initial four weeks of diet change. Participants following a vegan diet experienced substantial reductions in low-density lipoprotein cholesterol (LDL-C) levels, insulin, and body weight—key indicators of enhanced cardiovascular health—compared to their omnivore counterparts.
Gardner emphasized the practicality of adopting a vegan diet, stating, “Our study used a generalizable diet that is accessible to anyone, because 21 out of the 22 vegans followed through with the diet. This suggests that anyone who chooses a vegan diet can improve their long-term health in two months, with the most change seen in the first month.”
The vegan participants demonstrated a 20% drop in fasting insulin levels, a critical factor in diabetes risk, and an average weight loss of 4.2 pounds compared to omnivore participants. While the participants already had healthy LDL-C levels at the study’s onset, Gardner speculated that those with higher baseline levels might experience more significant improvements.
Despite acknowledging that not everyone may adopt a vegan lifestyle, Gardner encouraged incorporating more plant-based foods into daily diets. “What’s more important than going strictly vegan is including more plant-based foods into your diet,” Gardner said. He highlighted the additional benefits of a vegan diet, such as increased gut bacteria and reduced telomere loss, which slows aging in the body.
As researchers continue to explore the broader impacts of plant-based diets, the study underscores the potential of a vegan or predominantly plant-based diet in promoting cardiovascular health.
