By Amy Norton
Vegan diets are free of all animal products, including eggs and dairy. Instead, people get their protein, fat and all other nutrients from foods such as beans, nuts, whole grains, vegetables, fruit and plant-based oils.
In the new study, researchers tested whether a vegan diet could help people with type 2 diabetes and painful nerve damage in their feet or hands.
The investigators found that over 20 weeks, the 17 people they assigned to the diet lost an average of 15 pounds. At the same time, blood flow to their feet improved and their pain eased up.
But it's not clear that you have to go vegan to do that.
"It's hard to say that it's this particular diet, itself," said Dr. Maria Pena, an endocrinologist and weight-management specialist at Lenox Hill Hospital in New York City.
"The weight loss, by itself, can help with pain," said Pena, who was not involved in the study. Losing extra fat can decrease inflammation in the body, and improve a person's mobility -- both of which could help ease diabetic nerve pain, she explained.
That shows the all-plant diet had benefits, according to Pena. But, she said, any diet that encourages weight loss and replaces processed foods with healthy "whole" foods might do the same.
About half of all people with diabetes eventually develop nerve damage because of chronically high blood sugar levels, according to the U.S. National Institutes of Health.
The nerve damage -- known as neuropathy -- can occur anywhere, but most often affects the feet and legs. It can trigger sharp pain, burning sensations, tingling or sensitivity to even a light touch; it also makes people susceptible to serious foot problems, including ulcers and infections.
Cameron Wells, one of the researchers on the study, agreed that the finding doesn't prove that the vegan diet, per se, improved people's neuropathy.
But the "hypothesis," she said, is that the diet worked by boosting people's sensitivity to the hormone insulin, which then brought down their blood sugar levels.
Wells is acting director of nutrition education for the Physicians Committee for Responsible Medicine, a Washington, D.C.-based nonprofit that promotes vegetarian and vegan diets.
For the study, Wells and her colleagues recruited 34 adults with type 2 diabetes and painful neuropathy. They randomly assigned half to follow a vegan diet and take a vitamin B12 supplement; the rest took the supplement but stuck with their normal diets.
The dieters were told to limit themselves to 20 to 30 grams of fat per day, and to load up on "low GI" foods, which are foods that do not cause a large surge in blood sugar.
Breakfast might include oatmeal with raisins, Wells said, while dinner could be lentil stew, or a vegetable stir-fry with rice.
After about five months, the vegan group had lost 15 pounds, on average, versus about 1 pound in the comparison group. They also reported bigger improvements on a standard pain-rating survey.
"In just 20 weeks, we had people lose weight, see their blood sugar levels drop and their pain improve," Wells said. "Sometimes doctors are quick to rely on medications, but diet can make a big difference."
But while Pena said that plant-based diets can benefit people's health, this study does not prove vegan eating is the best or only way to manage diabetes and neuropathy.
And if people with diabetes do want to try going vegan, they need to make sure they're doing it right, Pena said.
"I'd recommend taking a B12 supplement, like they did in this study," Pena said.
That's key for a few reasons: Vitamin B12 is found naturally only in animal products, so it's lacking in vegan diets. Plus, Pena said, many people with diabetes take a medication called metformin, which lowers the body's B12 levels. Finally, deficiency in vitamin B12 can actually cause nerve damage.
Many lifelong meat-eaters may also need help in figuring out good vegetarian sources of protein and certain other nutrients, Pena said.
Wells said the people in her study went to weekly nutrition classes. "But," she added, "I also think that people can do this on their own, once you get over the initial mental block to becoming vegan. There are good books and online resources."