There are few studies assessing the effects of a vegetarian diet in diabetes (1). Most of the studies involving plant foods, plant food components, or diets have been assessed for their ability to reduce blood lipids or other risk factors related to cardiovascular disease (CVD). Nevertheless, these attributes of diet are also very relevant to the treatment of diabetes because diabetes greatly increases the chance that an individual will suffer from CVD, possibly by 3–5-fold (2). Diabetes is a key factor in the predictive equations for CVD (3). It is therefore appropriate that dietary advice determined to be of use in the prevention and treatment of CVD should be considered as part of the advice for the prevention and treatment of diabetes. Thus, although an attempt will be made to discuss the effects of plant foods on glycemia, a large part of this discussion of the diabetic diet will deal with the role of plant foods in prevention of the major complications of diabetes, especially CVD.
Growth of interest in dietary fiber and its possible metabolic benefits in the prevention and treatment of chronic diseases, including diabetes, has been put forward as one of the reasons to include more plant foods in the diet (4). Notable are the early studies of Anderson using high-carbohydrate, high-fiber diets with initial carbohydrate contents of 70% and maintenance intakes of 60% (5). These diets resulted in improved glycemic control in type 2 diabetes, lower serum cholesterol levels, and no rise in serum triacylglycerol. Shortly after these studies, supportive data appeared from the Pritikin Institute (6, 7), where high-carbohydrate plant-based diets were emphasized together with exercise as part of the program for treatment of type 2 diabetic subjects. These studies demonstrated reductions in oral hypoglycemic agent use, together with improved blood glucose, cholesterol, and triacylglycerol levels, the latter 2 by 25% and 27%, respectively (6). These improvements tended to be maintained over the 2–3 y of follow-up (6). However, these studies were also confounded by exercise and weight loss, which has a major effect on all aspects of diabetes control (8). Confounding by weight loss has also existed in the majority of studies targeted more specifically at the use of vegetarian diets.
The American Journal of Clinical Nutrition