Vegan diet improves cardiovascular health in study of identical twins

Key takeaways:

• Twins assigned to a vegan diet had significant decreases in LDL that were seen as early as 4 weeks.
• According to researchers, the vegan diet was generalizable and accessible to anyone.

Among 22 pairs of twins, those who were randomly assigned to a vegan diet had improvements in several cardiovascular measures vs. their twin who was assigned to a healthy omnivore diet, according to findings published in JAMA Network Open.

“Based on these results and thinking about longevity, most of us would benefit from going to a more plant-based diet,” Christopher Gardner, PhD, the Rehnborg Farquhar Professor and a professor of medicine at Stanford University, said in a press release.

Gardner and colleagues noted that most prior studies on vegan diets are epidemiologic examinations, which are subject to “bias of self-decided vegans who may differ from non-vegans in factors that may influence diet and health.”

“In addition, a poorly formulated vegan diet can include low-quality plant foods, such as refined carbohydrates and added sugars,” they wrote.

The researchers aimed to overcome these barriers by conducting a study with 22 pairs of identical twins (mean age, 39 years; 77.3% women) where one twin from each pair was randomly assigned to a healthy vegan diet and the other assigned to a healthy omnivore diet for 8 weeks, with both groups exposed to legumes, vegetables, fruits, nuts, whole grains and seeds. The participants were weighed and had their blood checked at baseline, 4 weeks and 8 weeks.

Twins who were assigned to a vegan diet — compared with their counterparts — experienced significant mean decreases (SD) at 8 weeks in:

• LDL cholesterol (LDL-C) concentration (SD = 13.9 mg/dL; 95% CI, 25.3 to 2.4);
• fasting insulin level (SD = 2.9 IU/mL; 95% CI, 5.3 to 0.4); and
• body weight (SD = 1.9 kg; 95% CI, 3.3 to 0.6).

Notably, “as early as 4 weeks, we observed a significant decrease in mean LDL-C level among vegans compared with omnivores,” the researchers wrote.

However, vegan diet consumers had lower dietary satisfaction, protein intake and dietary cholesterol intake but higher intakes of vegetable servings and dietary iron.

Gardner added that the 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 2 months, with the most change seen in the first month,” he said.

The researchers acknowledged multiple study limitations. For example, the cohort was generally healthy and thus potentially not generalizable to other populations, while the duration of the trial was considered short.

Still, Gardner noted that “a vegan diet can confer additional benefits such as increased gut bacteria and the reduction of telomere loss, which slows aging in the body.”

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

References:

• Landry M, et al. JAMA Netw Open. 2023;doi:10.1001/jamanetworkopen.2023.44457.
• Twin research indicates that that a vegan diet improves cardiovascular health. https://www.eurekalert.org/news-releases/1009401. Published Nov. 30, 2023. Accessed Dec. 4, 2023.