Vegan better than omnivorous diet for heart and metabolism

Vegan diet confers cardiometabolic advantages compared with healthy omnivorous diet, as shown in a twins study.

In a cohort of 22 pairs of identical twins (mean age 39.6 years, 77.3 percent women, mean body mass index 25.9 kg/m²), the twins assigned a vegan diet had substantially lower low-density lipoprotein cholesterol (LDL-C) concentration, the primary study endpoint, at week 8 than the twins assigned an omnivorous diet (−13.9 mg/dL, 95 percent confidence interval [CI], −25.3 to −2.4) at week 8. [JAMA Netw Open  2023;6:e2344457]

Additionally, the twins in the vegan group had greater reductions in fasting insulin level (−2.9 μIU/mL, 95 percent CI, −5.3 to −0.4) and body weight (−1.9 kg, 95 percent CI, −3.3 to −0.6).

Valuable data

Already, multiple studies, including a recent randomized clinical trial, have demonstrated that vegan diets can effectively improve cardiovascular and metabolic health. [JAMA Netw Open 2023;6:e2250626; Nutr Rev 2022;80:1094-1104; J Hypertens 2021;39:23-37; Clin Nutr 2019;38:1133-1145; Diabetes Metab Syndr Obes 2020;13:2811-2822]

But unlike the previous ones, the present study involves identical twins, which the investigators highlighted as “a valuable resource in scientific research that 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. [Twin Res Hum Genet 2020;23:8-15; J Lipid Res 2009;50:1917-1926]

“Because identical twins have nearly identical DNA and many shared experiences (eg, 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,” they added.

Low dietary satisfaction

In terms of nutritional intake, the vegan group had total lower protein intake as a percentage of calories and lower intake of dietary cholesterol, but higher intake of vegetable servings and intake of dietary iron. However, this group also had lower dietary satisfaction compared with the omnivorous group.

Both diets embraced a healthy approach, centring around an abundance of vegetables, legumes, fruits, and whole grains while eliminating sugary beverages and refined starches. The vegan diet adhered to a strict plant-based philosophy, void of all meat or animal products, including eggs and dairy. On the other hand, the omnivore diet incorporated chicken, fish, eggs, cheese, dairy, and other animal-sourced foods.

“We believe lower dietary satisfaction in the vegan group may have been attributable to the strictness of the vegan diet, creating more barriers for people to follow the vegan diet guidelines,” according to the investigators. “Some people may find a less restrictive diet preferable for LDL-C–lowering effects.”

In a statement, senior study investigator Dr Christopher Gardner, professor of medicine at Stanford University, California, US, acknowledged that while adopting a fully vegan diet may not be achievable for everyone, introducing more plant-based foods into one’s diet can still yield substantial health benefits, such as increased gut bacteria and reduced telomere loss, which slows ageing in the body.

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