Can 8 Weeks of a Plant Diet Lower Weight, Cholesterol, and Insulin? A Twin Study Says Yes

Are you considering a health upgrade for 2024? Adopting a plant-based diet of whole foods may be your best choice. Need some convincing? Are you wondering what are the benefits of a healthy plant-based (vegan) vs a healthy omnivorous diet, even for just 8 weeks?  A new study provides the answer and suggests Veganuary is your best choice!

STUDY OBJECTIVE AND DESIGN

To compare the effects of a healthy vegan vs healthy omnivorous diet on cardiometabolic measures during an 8-week intervention.

The study was a single center randomized clinical trial of 22 pairs of twins (N = 44) randomized participants to a vegan or omnivorous diet (1 twin per diet). Participant enrollment began on March 28, 2022, and continued through May 5, 2022.

This 8-week, open-label, parallel, dietary randomized clinical trial compared the health impact of a vegan diet vs an omnivorous diet in identical twins. The primary analysis included all available data.

Twin pairs were randomized to follow a healthy vegan diet or a healthy omnivorous diet for 8 weeks. Diet-specific meals were provided via a meal delivery service from baseline through week 4, and from weeks 5 to 8 participants prepared their own diet-appropriate meals and snacks.

STUDY RESULTS

A total of 22 pairs (N = 44) of twins (mean age of 40 years, mean body mass index BMI of 26) were enrolled in the study.

After 8 weeks, compared with twins randomized to an omnivorous diet, the twins randomized to the vegan diet experienced significant mean decreases in low-density lipoprotein cholesterol concentration (−13.9 mg/dL), fasting insulin level (−2.9 μIU/mL), and body weight (−1.9 kg).

STUDY CONCLUSIONS

In this randomized clinical trial of the cardiometabolic effects of omnivorous vs vegan diets in identical twins, the healthy vegan diet led to improved cardiometabolic outcomes compared with a healthy omnivorous diet. 

The research team at Stanford University was led by Christopher Garnder, Ph.D. They commented that:

Although it’s well-known that eating less meat improves cardiovascular health, diet studies are often hampered by factors such as genetic differences, upbringing, and lifestyle choices. By studying identical twins, however, the researchers were able to control for genetics and limit the other factors, as the twins grew up in the same households and reported similar lifestyles.

“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,” said Christopher Gardner, Ph.D., the Rehnborg Farquhar Professor and a professor of medicine. “They dressed the same, they talked the same and they had a banter between them that you could have only if you spent an inordinate amount of time together.”

Gardner emphasizes that although most people will probably not go vegan, a nudge in the plant-based direction could improve health. “A vegan diet can confer additional benefits such as increased gut bacteria and the reduction of telomere loss, which slows aging in the body,” Gardner said.

“What’s more important than going strictly vegan is including more plant-based foods into your diet,” said Gardner, who has been “mostly vegan” for the last 40 years. “Luckily, having fun with vegan multicultural foods like Indian masala, Asian stir-fry, and African lentil-based dishes can be a great first step.”