Vegan diet may be right choice for managing type 2 diabetes
In this issue, Susan Weiner, MS, RDN, CDE, CDN, talks to Meghan Jardine, MS, MBA, RD, LD, CDE, about the role of plant-based nutrition in the management of type 2 diabetes.
What first interested you in plant-based nutrition?
Jardine: I first became interested in plant-based nutrition during my undergraduate studies when I read about a population living in the mountains of Ecuador in which coronary artery disease, cancer and diabetes were unheard of. Their diets consisted of mostly unrefined carbohydrates, like sweet potatoes, grains, vegetables and fruit. More recently, there are reports on “blue zones,” places in the world where there are a higher percentage of centenarians living healthy lives, disability free. One thing they all have in common is a plant-based eating pattern. Now this eating pattern is growing in popularity and acceptability. Many clinicians are enjoying amazing results recommending plant-based diets in their practice.
It is well-established that individuals eating a vegetarian or vegan diet have a reduced risk for diabetes, weigh less, have lower blood pressure, and reduced risks for cardiovascular disease and certain types of cancer. The vegetarian and vegan groups in the Adventist Health Study-2, which consisted of more than 60,000 participants, had a 46% and 49% reduced risk for type 2 diabetes, respectively, when compared with nonvegetarian participants.
Is a plant-based diet, with its high carbohydrate content, safe for someone with diabetes?
Jardine: This is a typical concern of clinicians and people who have diabetes. A plant-based eating pattern consists of whole grains, legumes, fruits, vegetables, nuts and seeds, and is higher in carbohydrate than other eating patterns. The key is focusing on unrefined carbohydrates and high-fiber foods. Most Americans consume only about 15 g of fiber a day. In plant-based studies, the participants often get 40 g or more of fiber per day. Legumes should be the major source of protein, also providing a high amount of fiber with a very low glycemic index. There is good evidence that beans help to regulate postprandial glucose levels following a meal, but also at the subsequent meal 5 hours later. This is called the “second-meal effect.”
A 2006 randomized controlled trial conducted by Barnard and colleagues compared a low-fat vegan eating pattern with a more conventional diet of that time that controlled carbohydrates and restricted calories. The participants in the vegan group had greater improvements in glycemic control, lipid levels and weight loss compared with the conventional diet group. Forty-three percent of participants in the vegan group were able to reduce their diabetes medications compared with 26% of the conventional group. It’s worth noting that the participants in the vegan group had no calorie or portion restrictions. In addition, they ate some refined carbohydrates, including bread, pasta and white rice.
Because this approach is so effective, the American Association of Clinical Endocrinologists and the American College of Endocrinology recommend a plant-based diet to achieve and maintain an ideal body weight for people with type 2 diabetes. The American Diabetes Association also lists a plant-based diet as an example of a healthy eating pattern.
Can a vegan diet provide complete nutrition?
Jardine: Typically, we see a significant improvement in quality in a vegan diet compared with a more conventional diet, since there is a reduction in processed carbohydrates and an increase in fruits and vegetables. The study described above compared each group using the Alternative Healthy Eating Index (AHEI), which scores an eating pattern based on nutrition quality for disease risk reduction; the vegan group’s score significantly improved with the intervention compared with baseline and compared with the score of the conventional diet group. In fact, the AHEI score of the conventional group did not improve from baseline with the dietary intervention. Vegan and vegetarian diets are approved by the Academy of Nutrition and Dietetics, which has stated that “appropriately planned vegetarian, including vegan, diets are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases,” including diabetes. It is very important that individuals following a vegan diet get a reliable source of vitamin B12 from fortified foods or supplements. All people with type 2 diabetes, especially those on metformin, should have their vitamin B12 status evaluated.
How does a plant-based diet work for managing diabetes?
Jardine: There are multiple factors at work. First, a well-planned low-fat vegan diet is high in fiber and low in calories, which helps with weight loss. In our studies at the Physicians Committee, we do not restrict serving sizes. This is a plus for individuals who have a hard time with portion control. They get to eat larger portions, feel more satisfied and still lose weight.
Second, plant-based eating patterns enhance insulin sensitivity. Some of this comes from weight loss. There is evidence that a vegan eating pattern improves insulin resistance by reducing intramyocellular lipids. Eliminating meat reduces the intake of saturated fat, trans fats and heme iron, substances associated with insulin resistance. Population studies are reporting an increased risk for diabetes with meat consumption, particularly with processed meats.
Third, the improvement in diet quality from plant-based foods reduces inflammation and may protect the body from damage caused by high blood glucose levels. A plant-based diet significantly reduces intake of advanced glycation end products, further reducing risks for complications.
How would someone implement this in their practice?
I always recommend clinicians start with themselves. We can all help our patients by being better role models.
Assess your patient for readiness. Some patients are ready to jump in and do this 100%. Others need more support and education. For those who are ready, have handouts and educational materials available. Advise them on how to find appropriate recipes that are culturally relevant, easy to prepare, delicious and affordable. They should have a good idea of breakfast, lunch, snack and dinner options before they start. I often recommend that people take at least 2 weeks to plan how to modify the meals they usually eat or try a few new recipes before getting started.
Those who are not ready can start with smaller steps. Everyone can benefit from eating more plants. Sometimes it’s best to focus on what to eat rather than what not to eat. Write a prescription for eating at least two to four fruits, three to five vegetables, three whole grains, at least one serving of legumes, and 1 oz of nuts or seeds every day. This will fill them up with fiber-rich foods, helping to control glucose levels and improve satiety. The second step is to work on eliminating animal products. I usually encourage eliminating processed meats first, but this should be individualized based on an individual’s motivation and personal goals.
Always discuss glucose monitoring and signs and symptoms of high and low glucose levels. Everyone is different. Some may have temporary elevations in glucose. This often levels out as their insulin sensitivity improves. Some may respond very quickly, experiencing hypoglycemia. A significant dietary change may reduce the need for medications for diabetes and for hypertension. Patients should be counseled on what to watch for and when to contact their health care provider to evaluate medication adjustment.
Plant-based eating is growing in popularity. The motivations to eat this way range from compassion for animals to personal health and to using less land and water to produce food. There are more delicious options than ever before.
- Barnard ND, et al. Diabetes Care. 2006;doi:10.2337/dc06-0606.
- Gonzalez-Campoy JM, et al. Endocr Pract. 2013;doi:10.4158/EP13155.GL.
- Melina V, et al. J Acad Nutr Diet. 2016;doi:10.1016/ j.jand.2016.09.025.
- Tonstad S, et al. Diabetes Care. 2009;doi:10.2337/dc08-1886.
- For more information:
- Meghan Jardine, MS, MBA, RD, LD, CDE, is associate director of diabetes nutrition education at Physicians Committee for Responsible Medicine in Washington, D.C. She can be reached at firstname.lastname@example.org.
- Susan Weiner, MS, RDN, CDE, CDN, is the 2015 AADE Diabetes Educator of the Year and author of The Complete Diabetes Organizer and Diabetes: 365 Tips for Living Well. She is the owner of Susan Weiner Nutrition, PLLC and is the Endocrine Today Diabetes in Real Life column editor and Editorial Board member. She can be reached at email@example.com.
Disclosures: Jardine reports no relevant financial disclosures. Weiner reports serving as a clinical adviser to Livongo Health.