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Although identical twins share a significant amount of their DNA, their dietary habits can lead to very different health outcomes for them.
In March 2022, 22 pairs of identical adult twins participated in a randomized clinical trial in which one twin followed a vegan (completely plant-based) diet – and the other twin followed an omnivorous (carnivorous) diet.
The results, published Nov. 30, 2023, in JAMA Network Open, showed that the twins who ate a healthy vegan diet had “significantly improved low-density lipoprotein cholesterol concentrations, fasting insulin levels, and weight loss” compared to the twins , who ate meat-containing diets.
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The reduced fasting insulin levels, which fell by 20%, suggest the twins had less insulin resistance, meaning they were less likely to develop diabetes and metabolic syndrome.
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Although identical twins share a significant amount of their DNA, their dietary habits can lead to very different health outcomes. (iStock)
“Even compared to a healthy omnivore diet that includes plant-based foods, including more plants in the diet and eating less meat may have additional health benefits,” said lead researcher Christopher Gardner, PhD, professor of medicine at the Stanford Medicine Fox News Digital.
All participants were healthy and had no history of cardiovascular disease.
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The twins stuck to their assigned diets for eight weeks between May and July 2022.
Both the vegan and omnivore diets were considered healthy – “rich in vegetables, legumes, fruits and whole grains and free of sugar and refined starches,” according to the study article.
The vegan diet contained only plant-based foods, without meat or animal products.
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The omnivore diet included chicken, fish, eggs, cheese, dairy products and other animal foods, the researchers noted.
Both the vegan and omnivore diets were considered healthy – “rich in vegetables, legumes, fruits and whole grains and free of sugar and refined starches,” according to the study article. (iStock)
For the first four weeks of the study, meals were provided to participants by a delivery service.
In the second half of the study, the twins cooked all of their own meals.
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Researchers collected weight data and blood samples from participants at the start of the study and then after four and eight weeks.
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In evaluating the result at the end of the eight weeks, the Stanford researchers worked with a Kentucky-based company called TruDiagnostic, which measures biological age based on epigenetics, the study of how a person's environment and lifestyle affect their Genes affect.
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“A vegan diet was associated with better cardiovascular health in this study, but a completely vegan diet may not be the right answer for everyone.”
“The TruDiagnostic group initially reported to us that there had been a statistically significant shift in one of the groups, which meant a reduction in biological age. Both the vegan and omnivore diets were considered healthy – “rich in vegetables, legumes, fruits and whole grains, free of sugar and refined starches,” the study article said, as Gardner told Fox News Digital.
“At the time, they were blind to the study groups and didn’t know whether it was the omnivore group or the vegan group.”
Based on the study results, researchers recommend that people experiment and add more vegetables, beans, fruits, nuts, seeds and whole grains to their diet. (iStock)
It turned out that the vegan group was the one that showed the age decline.
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“That was the most surprising realization for me,” said Gardner. “I assumed that the eight-week intervention in this study would be too short to produce significant change.”
Looking forward, he noted that further research is needed to reproduce these results.
Nutritionists weigh in
Michelle Routhenstein, a New York-based cardiology nutritionist who was not involved in the study, said there are many different factors that could explain the result.
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“People who want to change their diet should consult a registered dietitian to ensure they are meeting their nutritional needs and health goals.”
“The cardiometabolic benefits observed in healthy adult monozygotic twins consuming a healthy plant-based vegan diet, as opposed to those consuming a healthy omnivorous diet, may be due to factors such as reduced saturated fat intake, increased dietary fiber and a “Incorporation of beneficial fats, increased insulin sensitivity and potentially positive effects on the gut microbiome,” she told Fox News Digital.
“These elements collectively contribute to favorable changes in lipid profiles, insulin levels and body weight, highlighting the potential benefit of a well-structured plant-based diet in combating cardiometabolic risk factors in healthy individuals.”
Although the vegans in the study (not pictured) also lost an average of 4.2 pounds more than the omnivores, weight loss isn't always the most important factor in diet success, a nutritionist noted. (iStock)
The key components of a healthy dietary change are education and personalization, Routhenstein said.
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“A completely vegan diet can lead to deficiencies in iron, calcium and vitamin B12,” she told Fox News Digital.
“People who want to change their diet should consult a registered dietitian to ensure they are meeting their nutritional needs and health goals – this is very different for a male teenager who wants to build muscle than for a woman in the Thirty-something who wants to get pregnant,” she added.
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Someone could become vegan and still eat cookies, sodas, French fries and other processed foods all day, she noted — but that wouldn't lead to healthier results.
Although the vegans also lost an average of 4.2 pounds more than the omnivores, weight loss isn't always the most important factor in dieting success, noted Tanya Freirich, a registered dietitian in Charlotte, North Carolina, who practices nutrition as The Lupus Dietitian .
Eating more beans, lentils, chickpeas, mushrooms, nuts and seeds, and less processed meat for protein is a good way for everyone to start improving their cardiovascular health, a nutritionist said. (iStock)
“Bodybuilders, for example, appear to be overweight if you only examine their weight based on their height because their muscles weigh so much,” Freirich, who was not involved in the study, told Fox News Digital.
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“In addition, people of different shapes, sizes and weights can be healthy.”
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“Ideally, we should look more closely at the type of weight loss involved in any diet,” Freirich said. “This depends on many other factors, such as exercise and the actual foods chosen in the vegan or omnivore diet, including portions and meal combinations.”
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Fox News Digital has reached out to the North American Meat Institute for comment on the study results.
The study had “many” limitations
Because all study participants were generally healthy to begin with, Gardner acknowledged that the results cannot be generalized to younger or older people or to people with health problems.
The eight-week time frame was another limitation.
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“Ideally, we would conduct studies over many months or years to better understand how sustainable such dietary changes are,” he said. “The reality is that very few people are willing to voluntarily switch to one diet or another if the study period extends over months or years.”
Gardner also emphasized that there are many different ways to eat an omnivorous or vegan diet.
Although the vegans also lost an average of 4.2 pounds more than the omnivores, weight loss is not always the most important factor in diet success, a nutritionist said. (iStock)
“It's pretty easy for a nutritionist to design both a healthy and an unhealthy version of these two eating patterns,” he told Fox News Digital.
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“If others reading about the study are interested and want to try this, they may choose to eat an unhealthy vegan diet – for example, soda is vegan, many candies are vegan, and white refined flour is vegan.”
Based on the study's results, researchers recommend people experiment and add more vegetables, beans, fruits, nuts, seeds and whole grains to their diet.
Across all popular diet plans, there is a “broad consensus” that focusing on more whole foods, more vegetables, less added sugars and fewer refined grains would lead to “amazing improvements in health,” said Gardner, vice chairman of the American's Nutrition Committee Heart Association.
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“My best recommendation for [those] When trying to change your diet for the better, you should focus less on the “complete vegan” or “omnivore” label and instead focus on how many unprocessed foods, especially plants, you can include in your diet. said Frierich.
“Your diet needs to suit you and your lifestyle throughout your life, not just eight weeks.”
Eating more beans, lentils, chickpeas, mushrooms, nuts and seeds, and less processed meat for protein is a good way for everyone to improve their cardiovascular health, Frierich emphasized.
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“These foods are generally lower in saturated fat and sodium and higher in fiber,” she said.
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“Your diet needs to fit you and your lifestyle throughout your life, not just eight weeks,” Frierich noted.
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“A vegan diet was associated with better cardiovascular health in this study, but a completely vegan diet may not be the right answer for everyone.”
For more health articles, see www.foxnews.com/health.