One identical twin became vegan, the other did not. Look what happened

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Healthy twins who followed a vegan diet for eight weeks had lower “bad” low-density lipoprotein, or LDL, cholesterol, better blood sugar control and greater weight loss than siblings who ate a diet of meat and vegetables, a study shows. new study.

“There was a 10% to 15% drop in LDL cholesterol, a 25% drop in insulin and a 3% drop in body weight in just eight weeks, all from eating real food without animal products,” says lead study author Christopher Gardner. , a research professor of medicine at the Stanford Prevention Research Center in Palo Alto, California.

A vegan diet differs from a vegetarian diet in that it eliminates not only animal meat, but also dairy, eggs, or other ingredients derived from animals. A strict plant-based diet may provide more fiber, vitamins, minerals and phytonutrients compared to other diets, says Gardner, who is also director of the Nutrition Studies Research Group at Stanford.

“The results of this study confirm the benefit of current dietary guidelines in reducing the risk of cardiovascular disease,” Alice Lichtenstein, director and senior scientist at Tufts University’s Cardiovascular Nutrition Laboratory, told CNN in an email. She was not involved in the investigation.

“The diet with more unsaturated fats versus saturated fats, more whole grains versus refined grains, fewer calories, more fiber and vegetables, and less cholesterol resulted in a more favorable risk factor profile for cardiovascular disease than the comparison diet,” she said.

The study was unusual in that it used genetically identical twins, most of whom shared similar lifestyle behaviors, including hairstyles and clothing.

“The twin study design is elegant because it largely controls for genetic and environmental factors that could influence the study results,” said Dr. Frank Hu, professor of nutrition and epidemiology and chairman of the department of nutrition at Harvard TH Chan School of Public. Health in Boston. He was not involved in the investigation.

“However, recruitment of identical twins in nutritional intervention studies is challenging; Therefore, the design has rarely been used in nutritional studies,” Hu said. “Additionally, findings from identical twins may not be generalizable to the general population.”

The study, published Thursday in the journal JAMA Network Open, involved 22 identical twins. From each pair, one twin was assigned a vegan diet, while the other was assigned an omnivore diet. They each followed their respective diets for eight weeks. For the first four weeks, all meals were provided to each twin so they could see what type of food to eat.

“I feel like a lot of people who follow a vegan diet think, ‘Oh great, soda is vegan. Pancakes are vegan.’ No, they are refined, ultra-processed grains,” says Gardner. “So we tried to get a healthy vegan diet and quickly demonstrate what that was for four weeks.”

The meat and vegetable group also had meals delivered that were a step above their normal fare.

“I really like balance or equilibrium in my studies — I don’t have a miraculously healthy vegan diet and a crappy straw man diet that can be toppled,” Gardner said. “People who ate the omnivore diet ate more vegetables, more whole grains, less added sugars and fewer refined grains than they did in their usual diet. They didn’t get crappy meat either, it was all good quality. So they actually had some improvements in their diet.”

Once each pair of twins learned what types of foods to eat, they were asked to prepare their own diet-appropriate meals and snacks for the second half of the study, Gardner said.

Biological markers, including blood and stool, were collected from each twin at baseline and again at weeks four and eight. Surprisingly, twins on the vegan diet tested younger on measures of biological versus chronological age, data that will be presented in a future study, Gardner said.

However, the improvement in cardiovascular biomarkers such as lower LDL cholesterol, insulin resistance and weight loss was expected, Gardner said.

“The vegetarians got more fiber and less saturated fat. That explains the LDL cholesterol. More fiber explains less fasting insulin because they simply have a slower release of glucose into the bloodstream,” he said. “And all vegetables, fruits and grains are bulkier than meat, allowing people to feel more satisfied and eat fewer calories.”

But as with all diets that restrict people from the foods they are used to eating, it can be difficult to stay on this course.

“Honestly, twins who followed a vegan diet had less satisfaction because it was so restrictive. So there’s definitely a downside to it: ‘Oh, I could have eaten more, but I just wasn’t hungry for more grains and more vegetables.’

Despite the rapid improvements in health, people don’t have to become vegan to benefit from the study’s findings, Gardner said. Cutting back on eating meat and animal by-products can happen slowly, little by little.

Harvard’s Hu agreed: “While this study showed that a vegan diet can provide additional benefits compared to a healthy omnivorous diet, this does not mean that everyone should become vegan or vegetarian.

“Dietary choices are influenced by a variety of factors, such as individual health conditions, personal preferences, cultural traditions and ethical and environmental considerations,” he said.