Dec. 4, 2023 — People who ate a vegan diet improved their health after just eight weeks compared to a control group that ate meat during that period, a study published in JAMA Network Open shows.

Researchers from Stanford Medicine divided 22 sets of identical twins into two groups from May to June 2022. Both groups got healthy diets with vegetables and whole grains, but one group ate a healthy amount of meat while the other group consumed a strict plant-based diet.

Both groups had meals delivered for four weeks and were instructed what snacks to eat and not eat, the study said. For the final four weeks, the participants cooked for themselves following instructions from the research team.  A registered dietitian was on call to answer questions during the study, Stanford University said in a news release.

After eight weeks, the group consuming the vegan diet showed lower insulin, decreased weight, and reduced levels of lipoprotein cholesterol, a protein associated with heart disease and stroke.

“The findings from this trial suggest that a healthy plant-based diet offers a significant protective cardiometabolic advantage compared with a healthy omnivorous diet,” the researchers from concluded.

Using identical twins allowed researchers to reduce variables such as genetic differences, upbringing, and lifestyle choices, the news release said. The twins were chosen from the Stanford Twin Registry, a database of fraternal and identical twins who agreed to take part in research.

The senior author of the study, professor of medicine Christopher Gardner, PhD., acknowledged that most people won’t go vegan but that eating more fruits and vegetables will improve people’s health.

“What’s more important than going strictly vegan is including more plant-based foods into your diet,” he said in the release. “Luckily, having fun with vegan multicultural foods like Indian masala, Asian stir-fry and African lentil-based dishes can be a great first step.”