Can a Vegan Diet Cure Diabetes?
Andrew Nicholson, M.D.
Physicians committee for responsible medicine
PCRM Clinical Research
Diabetes is not necessarily a one-way street. Early studies suggest that persons with diabetes can improve and, in some cases, even cure themselves of the disease by switching to an unrefined, vegan diet. Unfortunately, none of these studies included a comparison group. So the Diabetes Action and Research Education Foundation provided a grant to PCRM to perform a carefully controlled test.
Working with Georgetown University, we compared two different diets: a high-fiber, low-fat, vegan diet and the more commonly used American Diabetes Association (ADA) diet. We invited persons with non-insulin-dependent diabetes and their spouses or partners to follow one of the two diets for three months. Caterers prepared take-home lunches and dinners, so participants could simply heat up the food at home.
The vegan meals were made from unrefined vegetables, grains, beans, and fruits, with no refined ingredients, such as vegetable oil, white flour, or white pasta. These meals averaged just 10 percent fat (as a percentage of calories) and 80 percent complex carbohydrate. They also offered 60-70 grams of fiber per day and had no cholesterol at all.
The comparison (ADA) diet contained somewhat more plant-based ingredients than the average American diet, but still relied on the conventional chicken and fish recipes. This diet was 30 percent fat and 50 percent carbohydrate. It provided about 30 grams of fiber and 200 milligrams of cholesterol per day.
Participants in both groups came to the University two evenings per week for group sessions covering nutrition, cooking, and support.
There were several challenges in planning the study. Would persons with diabetes—and their partners—volunteer for the study? Would they change their eating habits and maintain the study program for the full three months? Could we find caterers who would dependably prepare and deliver attractive vegan and ADA meals?
The first of these worries was quickly dispelled. On the very first day that our advertisement appeared in the newspaper, more than 100 people responded. The participants who were accepted for the study threw themselves into it with enthusiasm. One said, “I was amazed at how powerful the vegan diet was right from the beginning. The blood sugars and weight just started falling off.”
Some subjects were pleasantly surprised at how well they adapted to the experimental diet. One said, “If anyone had told me 12 weeks ago that I would be satisfied with a totally vegetarian diet, I would not have believed it.” Another participant needed more time to adjust: “In the beginning, it’s not an easy diet. But I managed to lose, at last count, 17 pounds. I am no longer on medication for diabetes, and I am no longer on medication for blood pressure. So, actually, it’s been a very, very positive result for me.”
Some found unexpected benefits: “My asthma has really improved. I’m not taking as much asthma medicine because I can breathe better. The overall mental outlook on how I feel about myself as a diabetic is much more hopeful now, as I am self-sufficient with a diet that makes sense for me.”
Both groups did an overall great job in adhering to their prescribed diets. However, the vegan group clearly had the edge in many of the results. Fasting blood sugars decreased 59 percent more in the vegan group than in the ADA group. And, while the vegans needed less medication to control their blood sugars, the ADA group needed just as much medicine as before. The vegans were taking less medicine, but were in better control.
While the ADA group lost an impressive 8 pounds, on average, the vegans lost nearly 16 pounds. Cholesterol levels also dropped more substantially in the vegan group compared to the ADA group.
Diabetes can cause serious damage to the kidneys, resulting in protein loss in the urine. Several of our subjects already had significant protein loss at the beginning of the study, and the ADA group did not improve in this respect. In fact, their protein losses actually worsened somewhat over the 12 weeks of the study. The vegan group, on the other hand, had a large reduction in protein losses.
Encouraged by the strong results of this pilot study, we are planning a much larger study for next year. We all owe a great debt to these volunteers who generously gave their time to help us learn how to improve our treatments for diabetes.