A Plant-Based Diet for Type 2 Diabetes
By Neal Barnard on August 25th, 2016
Neal Barnard, MD, FACC, is the author of Dr. Neal Barnard’s Program for Reversing Diabetes. .
The main goal of diabetes treatment is to protect the blood vessels. When the
delicate blood vessels of the heart, eyes, kidneys, and feet are attacked, the complications can be devastating, even fatal. Foods are our first line of defense, and a plant-based diet is your arteries’ best friend. It has no animal fat and no cholesterol at all. And as part of a healthful lifestyle, it has been shown to reopen narrowed arteries. In 2003, our research team was funded by the National Institutes of Health to put a plant-based diet to the test. The year-and-a-half study used a three-pronged regimen: it was vegan—that is free of animal products. It was low in fat, and was low-Glycemic-Index. It was already clear that a low-fat vegan diet is highly effective for improving body weight, cholesterol, and blood pressure. The new study showed that, compared with a more conventional regimen focused on limiting calories and carbohydrates, the plant-based diet was much more effective in improving blood sugar control. In participants whose medication regimens remained constant, the drop in A1C was 0.4 points for the conventional diet and 1.2 points for a plant-based diet.1Since then, many people have used this approach, finding that it is really quite easy—because there is no calorie-counting, no skimpy portions, and not even carb-counting, except when needed for calibrating insulin doses.
Low-carb diets are based on the simplistic idea that “carbs release glucose into the blood.” True enough, but our bodies run on glucose. It is our basic fuel. So the real issue is, what is preventing glucose from getting from the bloodstream into the cells where it belongs? The answer, of course, is insulin resistance.
At Yale University, researchers have investigated the causes of insulin resistance. With MR spectroscopy, they found the culprit: microscopic fat droplets building up inside the muscle and liver cells.2 This fat comes from the diet, for the most part. Although there is much more to this research, the take-home message is that, if we can tackle intracellular fat build-up, we are addressing the cause of the insulin resistance that is at the core of type 2 diabetes.
A vegan diet has no animal fat at all, needless to say. And if one also keeps oils to a minimum, insulin resistance improves. A low-carb diet, on the other hand, simply tries to compensate for the body’s inability to handle carbohydrate by asking you to limit bread, spaghetti, beans, rice, and every other carb-containing food for the rest of your life. And a low-carb diet does not come anywhere near the lipid-lowering effect of a vegan diet; for many people low-carb diets increase LDL cholesterol, sometimes dramatically.In large epidemiological studies, people following vegan diets are slimmer and have a lower risk of developing diabetes than all other diet groups.3 Our randomized clinical trials support the same observations. And at the National Institutes of Health, Kevin Hall and his team investigated weight loss in carefully controlled laboratory studies, finding that, for shedding body fat, reducing the fat content of the diet is significantly more effective than reducing carbohydrate. 4When it comes to carbohydrate-rich foods, the key is not to avoid them, but to make the most healthful choices. So, instead of white bread, rye and pumpernickel bread are better. And instead of sugar, we’re better off with fruit, beans, or other foods that are gentler on your blood sugar. Putting it all together, avoiding animal products and added oils and favoring low-GI foods is a powerful regimen. Sometimes when people start a low-fat vegan diet, their after-meal blood sugars spike a bit for a few days. That’s understandable, given that they are insulin-resistant. But as time goes on and the body’s ability to handle glucose is restored, those spikes typically vanish.
1. Barnard ND, Cohen J, Jenkins DJ, Turner-McGrievy G, Gloede L, Jaster B, Seidl K, Green AA, Talpers S. A low-fat, vegan diet improves glycemic control and cardiovascular risk factors in a randomized clinical trial in individuals with type 2 diabetes. Diabetes Care 2006;29:1777-1783.
2. Shulman GI. Mechanism of free fatty acid induced insulin resistance in humans. J Clin Invest. 1996;97:2859-2865.
3. Tonstad, S, Butler T, Yan R, Fraser GE.Type of vegetarian diet, body weight and prevalence of type 2 diabetes. Diabetes Care. 2009;32:791-6.
4. Hall KD, Bemis T, Brychta R, et al. Calorie for calorie, dietary fat restriction results in more body fat loss than carbohydrate restriction in people with obesity. Cell Metabolism. 2015;22:427-36.