Scientists presenting at the annual conference of the American Association of Diabetes Educators in August 2019 (AADE19), in Houston, noted that the benefits of plant-based diets such as a vegan diet may be due to better beta cell function. According to the American Diabetes Association, beta cells in the pancreas produce insulin, a hormone that enables the body to use blood sugar (glucose) it gets from food. As type 2 diabetes progresses, these cells lose mass and function, past research reveals. “While modern pharmacotherapy [treatment with drugs] is just able to slightly slow down the decline of beta-cell function in diabetes, we found that a plant-based diet is able to completely reverse the process and improve beta-cell function,” says the lead author, Hana Kahleova, MD, the director of clinical research with the Physicians Committee for Responsible Medicine in Washington, DC. “This finding gives hope to many people suffering from diabetes, but also to those who are at a high risk of developing diabetes in the future,” she says. RELATED: 8 Type 2 Diabetes Risk Factors You Probably Didn’t Know The vegan group ate meals composed of vegetables, grains, legumes, and fruits, and they limited their daily fat intake to about 1 ounce or less. (A vegan diet calls for completely omitting animal products, including not only meat, but also cheese, eggs, and milk.) Meanwhile, the control group maintained their current diets, which included meat and dairy. Neither group restricted their calories. Subjects had to complete a three-day dietary record at the start and finish of the study to demonstrate that they were sticking to their assigned eating plan. Although participants were diabetes free, they all had high body mass indexes (BMIs) of 28 to 40, which put them at high risk for developing type 2 diabetes. At the beginning of the study, about one-third had prediabetes, meaning their blood sugar levels were higher than normal but not high enough to signify type 2 diabetes. “Insulin resistance is high in overweight people without diabetes, exerting high demands on beta cells to produce insulin,” says Kahleova. “By the time type 2 diabetes is diagnosed, about 50 percent of the beta cells are already dead. Therefore, the greatest opportunity to preserve beta-cell function is before diabetes onset.” The average age of the participants was 53, and about 9 out of 10 subjects were women. All had no history of smoking or alcohol or drug abuse, and none were following a vegan diet before the study began. A sign of beta-cell failure is a loss of sensitivity to glucose. On the basis of an analysis of blood samples at the beginning and end of the study, scientists determined that beta-cell glucose sensitivity increased by 65.5 percent in the vegan group, resulting in a marked increase in insulin secretion compared with the control group. Researchers speculate that a diet high in plants and low in animal products may produce these positive results by reducing oxidative stress and inflammation. “I was struck by the power of a plant-based diet to improve beta-cell function,” says Kahleova. The study authors observed an average drop in BMI of 2 among the vegan group but no change in the control group. They also noted that, in most cases, those with prediabetes who followed the vegan eating plan were able to put the health condition in remission. RELATED: A Plant-Based Diet Is Linked to a 23 Percent Reduced Risk for Type 2 Diabetes
Unveiling the Power of a Plant-Based Diet in Type 2 Diabetes Prevention
“This study is great because it shows that nutritionally you may be able to prevent type 2 diabetes,” says Audrey Koltun, RD, a certified diabetes educator with Cohen Children’s Medical Center in New Hyde Park, New York. Kristin Kirkpatrick, RD, the manager of wellness nutritional services at the Cleveland Clinic, says this investigation supports previous research showing an association between plant-based eating plans and a reduction in diabetes risk. For example, a review of three studies published in June 2016 in PLoS Medicine suggests that cutting back on meat and dairy, and increasing fruit, veggie, nut, and seed intake, is linked to a “substantially” lower risk for type 2 diabetes. “Even starting small can help,” says Kirkpatrick, who was not involved in the research. “Choose one or two days a week that will just be plant-based. Make more effort to get natural color in your diet, and try to omit all processed red meat,” such as bacon, sausage, deli meat, and hot dogs, per the World Health Organization, which notes that these foods are also associated with a higher risk for cancer. Yet Koltun, who wasn’t involved in the study, warns that not all vegan foods are good for you. “French fries, chips, and white bread are all vegan foods,” she says. “You have to follow a healthy vegan diet with real fiber from whole grains, nuts, and legumes. These foods help slow down how fast a meal is digested, therefore requiring less abundance of insulin to be used.” While Koltun helps her patients who are obese or overweight eat healthier, she recognizes that changing eating habits can be challenging. “Sometimes, it’s like you’re asking them to bungee jump off the Empire State Building. They just don’t want to do it.” RELATED: The Best and Worst Foods to Eat in a Type 2 Diabetes Diet
Recognizing the Limitations of the Current Study on Plant-Based Diets
Both Koltun and Kirkpatrick flagged limitations in the investigation. Researchers relied on self-reported dietary data, which is not always accurate, and the subjects were predominantly women. Participants were already health-conscious and willing to make substantial changes to their diet, which may not be representative of the general population. Currently, Kahleova and her collaborators are continuing this research — 244 people have now completed the study, and the authors plan to publish updated results in the near future. “Plant-based diets have been shown to be sustainable in the long term,” says Kahleova. “They not only reduce the risk of diabetes but also cancer and heart disease, and they may prolong life by 10 to 12 years.” RELATED: An Ultimate Guide to the Mediterranean Diet
