Going Vegan May Lower Your Cholesterol, Insulin and Weight—Study

Going vegan may lower your cholesterol, insulin and weight, a new study involving identical twins has suggested.

Vegan diets—a vegetarian diet that also excludes eggs and dairy products—are becoming more popular every year, and there is increasing evidence that if done right, they could provide certain benefits.

To test this theory, scientists compared a vegan diet with an omnivorous diet in 22 pairs of identical twins over a period of eight weeks. One twin was given a healthy vegan diet, while the other was given a healthy omnivorous diet. The scientists' findings are published in a JAMA Network Open study.

They found that the healthy vegan diet led to "improved cardiometabolic outcomes" when compared to a healthy omnivorous diet. They found that overall, cholesterol and insulin levels were better in vegan twins. They also found that the vegan group lost more weight than the omnivorous group.

The scientists, from Stanford University and several other California institutions, conclude that a healthy vegan diet could be a healthy alternative.

Vegan diets have been controversial in terms of nutrition. This is because vegan diets often lack essential nutrients such as protein, calcium, iron and vitamin B12.

Dr. Duane Mellor, a registered dietitian and senior lecturer at Aston Medical School in the U.K., who was not involved with the research, expressed skepticism because the study did not include much detail about the diets and nutritional intake of the participants.

"This is in part because participants were allowed to select their own meals which were delivered and then could add additional snacks to this," Mellor said in a statement. "When delving into the supplementary information it was apparent that those being provided the vegan/plant-based diet consumed on average about 200 kcal a day less than those consuming the mixed/omnivorous diet. This could explain the non-significant reduction in weight and perhaps at least partly explain the reduction in LDL cholesterol."

Mellor said that it is also difficult to interpret the data on cholesterol as the "changes are not reported."

"This is important as LDL cholesterol levels were estimated in this study, in the same way it is done in a routine health test and uses the values of total cholesterol, HDL cholesterol and a type of fat in the blood called triglycerides to calculate the amount of LDL cholesterol. So it is possible that there could be confounding caused by the differences in total cholesterol levels in this study."

Another scientist, Tom Sanders, a professor emeritus of nutrition and dietetics at King's College, London, said in a statement in response to the study that it is important to understand what makes a good and bad vegan diet.

"Vegan diets are defined by what they exclude rather than what is consumed. There are good and bad vegan diets. For example, a bad vegan diet would be lacking vitamin B12, and high in fat, salt and sugar," Sanders said. "The increased popularity of vegan diets has led to a large increase "vegan junk food" high in fat, salt and sugar. A healthy vegan diet would consist of whole grain cereals, pulses, nuts and fresh fruit and vegetables with vegetable oils low in saturated fat (e.g. olive oil or rapeseed oil) and supplemented with vitamin B12. It is important to recognise that it usually takes several years to deplete body stores of vitamin B12 so it is not surprising that no differences in blood levels of serum vitamin B12 were observed in this study."