A “groundbreaking” new study of 22 pairs of identical twins has found that it only takes eight weeks for a plant-based diet to improve cardiovascular health.
The research, led by Stanford University Department of Medicine, put one twin from each pair on a vegan diet and the other on an omnivore diet for two months. At the start of the study, all participants were healthy and free of cardiovascular disease.
After eight weeks, the researchers found that participants on vegan diets had significantly lower cholesterol (LDL) levels (sometimes known as “bad” cholesterol), insulin, and body weight than the omnivore participants. All three health outcomes are associated with improved cardiovascular health.
“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,” Christopher Gardner, a professor of medicine at Stanford and an author on the study, said in a statement.
Studying identical twins means the researchers could control for genetic differences and limit environmental factors that could make it harder to compare different diets. The twins had the same upbringings and reported that they lived similar lifestyles.
The diets of both vegan and omnivore participants were described as healthy. They contained an abundance of vegetables, legumes, fruits, and whole grains, and no sugars or refined starches. The omnivore diet included animal-based foods including chicken, fish, eggs, and dairy.
A meal service provided the meal for the twins for the first four weeks of the study. The participants made their own meals for the remaining four weeks, with access to a dietician. They were interviewed about, and kept a log of, what they ate.
The diets were said to be healthier than the diets the twins had before the study.
After eight weeks, the plant-based eaters had significantly lower bad cholesterol (produced by foods higher in saturated fats) than the omnivores. Both omnivores and those on a vegan diet had lost weight, but the latter lost an average of 4.2 more pounds (1.9 kilos) than the omnivores.
Compared with the omnivores, those on a plant-based diet had a significant reduction in fasting insulin of 20 percent. Higher insulin level means a higher risk of developing diabetes.
“A vegan diet can confer additional benefits such as increased gut bacteria and the reduction of telomere [sections of DNA at the ends of chromosomes] loss, which slows aging in the body,” Gardner said.
Myths about vegan diets
The plant-based participants had lower protein intake as a percentage of calories – something which may worry people wanting to go vegan. But the idea that vegans can’t get enough protein is a myth. Eating a variety of plant-based protein sources including nuts, beans, and wholegrains will cover all your protein needs.
Iron is another nutrient that is sometimes thought to be lacking in a vegan diet. But the vegan participants in the study actually had a higher intake of dietary iron compared with the omnivores.
“Based on these results and thinking about longevity, most of us would benefit from going to a more plant-based diet,” Gardner said.