by A study of 22 pairs of identical twins found that a vegan diet may be better than an omnivorous diet in boosting cardiovascular health.
The researchers ordered one of the twins to eat an omnivorous diet, and the other to eat a vegan diet, for eight weeks. The paper it was published in the Journal of the American Medical Association on November 30.
During the first four weeks, prepared meals were served to the twins. Over the final four, they planned their own meals with the help of a registered dietitian. They were asked to log all food consumed over the course of the study.
Both diets were healthy, with a variety of vegetables, legumes, fruit and whole grains. The only difference was the presence of meat products in the omnivorous diet – chicken, fish, eggs, dairy and cheese, for example.
By the end of the trial period, the two who ate the vegan diet had lower levels of low-density lipoprotein cholesterol (LDL-C) – known as “bad” cholesterol because it can clog the arteries.
In general, a healthy LDL-C level is below 100 milligrams per deciliter. At the start of the trial, the vegans had an average level of 110.7, and the omnivores 118.5. By the end of the trial, the vegans’ level had fallen to 95.5 and the omnivores’ to 116.1. When asked about the difference in initial cholesterol levels in the two groups, study author Christopher Gardner said they were due to chance.
Researchers also found that the vegan participants had lower fasting insulin levels by the end of the trial than their omnivore counterparts and lost an average of 4.2 pounds more.
Tools for a few to use
Studies tracking vegetarian benefits can be complicated by confounding factors related to a participant’s social environment or genetics. The study of identical twins was largely controlled for this.
In addition to keeping most variables the same except for the inclusion of animal products in the omnivorous diet, the trial also ruled that not all vegan diets are necessarily healthy.
“Vegan diets are defined by what is excluded rather than what is consumed. There are good and bad vegan diets,” said Tom Sanders, a professor of nutrition and dietetics at King’s College London who was not involved in the study. “For example, a bad vegan diet would lack vitamin B12, and be high in fat, salt and sugar.”
The study accounted for this by closely monitoring what the participants ate, adding a level of rigor that could not be accounted for if the diet was not controlled.
Lower nutritional satisfaction among vegans
However, the study had some difficulties. First, the sample size was small. Researchers also noted that the total food intake of the vegans was lacking in about 200 calories per day than that of the omnivores.
“This may explain the non-significant reduction in weight and may at least partially explain the reduction in LDL cholesterol,” said Duane Mellor, a registered dietitian and senior lecturer at Aston University who was not involved. with the research.
This could be because dietary satisfaction was lower among vegans, Mellor said. This was reflected in the additional materials of the study.
“Participants eating the vegan diet reported the greatest reduction in dietary satisfaction when eating out (at a restaurant) at weeks 4 and 8 compared to baseline,” the study said. “Among participants in the omnivorous diet arm, diet satisfaction at weeks 4 and 8 increased or was maintained from reported baseline levels.”
When asked about these criticisms, lead author Christopher Gardner, a professor of nutritional studies at Stanford University in the United States, told DW that the calorie deficit was not due to the design of the study, but because the vegan participants did not eat the whole . food served to them in the first four weeks. Each group was delivered the same number of calories, he said – the people in the vegan group ate just less.
“Vegan diets are very restrictive,” Gardner said in an explanation posted on the X platform. “I assume that those on the vegan diet may have been hungry for some fish or eggs or yogurt or meat. But those were restricted. They weren’t restricted. Hungry for more veggies & beans.”
External researcher Mellor said the reported levels of satisfaction show that if people are going to adopt a healthier diet, “it should be based on their preferences and not based on one particular dietary approach or another.” who prefers their health professional or their online collider,” he said.
When asked about the application of this study, given the dietary dissatisfaction reported by the vegans, Gardner agreed that “if the satisfaction of the diet is low, it suggests that it would be difficult to maintain that type of diet.”
“Over time, a person may switch back to the type of diet they are more used to and familiar with,” he told DW. “It would be great to do these studies for a year, 5 years, 10 years. Then we would be more confident about sustainability. Realistically, most people are not willing to enter a nutritional intervention study for a few months .”
That said, surprisingly, the researchers found that a large majority of the twins assigned a vegan diet (91%) said they planned to continue the habits learned in the trial in their everyday lives, compared to the twins who meat was assigned to them. – eating a diet (67%).
Edited by: Sushmitha Ramakrishnan
