Groundbreaking study reveals heart-protective benefits of vegan diet

A new study tapped nearly two dozen sets of identical twins to get a better grasp on how a vegan diet impacts the heart compared to a conventional meat-based diet. Key findings of the JAMA Network Open study showed a healthy vegan diet produced a number of heart-protective benefits, including decreased low-density lipoprotein (LDL or “bad”) cholesterol and insulin level, and weight loss.

Plant-based diets have seen a surge in popularity in recent years, underlined by steep growth of the plant-based food and beverage market. Many consumers opt for vegan options for their appeal to sustainability, but research shows most consumers follow plant-based diets for personal, health-motivated reasons.

The present study gives health-motivated consumers another reason to reach for plant-based foods and beverages.

For the study, researchers recruited 22 sets of identical twins. The twin pairs were randomly assigned to follow a vegan diet or an omnivorous diet for eight weeks. For the first four weeks, a meal delivery service provided diet-specific meals to the participants. For the remaining four weeks, participants prepared their own meals and snacks according to the diet protocol.

All participants, vegan and omnivore, were directed to follow a “healthy” diet that included minimally processed foods; a balanced plate with vegetables, starches, proteins and healthy fats; and a variety within each food group. Participants were not calorie restricted and were told to eat until they were satiated.

The sets of twins had grown up together and reported they followed similar lifestyle patterns in the present day.

The primary outcome of the study was to evaluate the change in LDL cholesterol after eight weeks of following the prescribed diet, compared to baseline. Then, researchers checked for changes in other cardiometabolic factors, including plasma lipids, glucose and insulin levels, as well as plasma vitamin B12 level, and body weight.

The results showed the twins who followed a vegan diet experienced significant decreases in LDL cholesterol concentration, fasting insulin level and body weight compared to those who ate diets containing meat.

The researchers underlined a critical component of the study: It was conducted in identical twins.

“Our population of identical twins … provided a unique opportunity to investigate the effects of a dietary intervention while controlling for genetic and environmental factors, influences that can significantly impact health outcomes, including body weight, cardiovascular health and metabolic function,” they wrote. “Because identical twins have nearly identical DNA and many shared experiences (e.g., upbringing, geographic region growing up and similar exposure to other variables), observed differences in health outcomes after adoption of different dietary patterns can largely be attributed to the diet itself.”

In addition to the primary and secondary outcomes of the study, researchers also explored diet satisfaction, including whether it was considered easy or difficult to follow the diet, energy levels and sense of well-being. They found participants partaking in the omnivorous diet had nominally higher diet satisfaction throughout the study compared to vegan participants.