The Role of Vegan Diets in Lipotoxicity-induced Beta-cell Dysfunction in Type-2-Diabetes: A Narrative Review

Type-2-diabetes is considered the new plague of the current century and its incidence and prevalence are rapidly increasing. Chronic insulin resistance and a progressive decline in beta-cell function are discussed as the root causes of type-2-diabetes. Both are associated with obesity and prolonged exposure to pathologically elevated concentrations of circulating free fatty acid (FFA) levels in the blood. Fatty acid derivatives may interfere with beta-cell function and ultimately lead to their death through lipoapoptosis. The harmful effects of chronically elevated FFA levels on glucose homeostasis and non-adipose tissues are generally referred to as lipotoxicity. Pancreatic beta-cells appear to be particularly vulnerable, and both dietary fat quantity and quality may impact their function. Diets high in saturated fat are especially harmful to beta-cells while (poly-)unsaturated fatty acids (PUFA) are associated with beta-cell protective effects. Therefore, this narrative review suggests that a dietary modification toward a low-fat vegan diet might help to prevent or reduce lipotoxicity-induced beta-cell dysfunction. By cutting the oversupply of saturated fat and reducing total calorie intake, and by improving both body weight and glycemic control, low-fat vegan diets may reduce the likelihood of lipotoxic events to occur. In light of the accumulating evidence that lipotoxic events are tightly coupled to excess glucose levels, improved glycemic parameters appear to be of utmost importance. These mechanisms are likely to contribute complementarily to improved beta-cell function in individuals with type-2-diabetes who choose a low-fat vegan diet. Physicians must consider these findings when counseling patients on lifestyle modifications and healthy nutrition.