Dietary carbohydrate: relationship to cardiovascular disease and disorders of carbohydrate metabolism

The nature of carbohydrate is of considerable importance when recommending diets intended to reduce the risk of type II diabetes and cardiovascular disease and in the treatment of patients who already have established diseases. Intact fruits, vegetables, legumes and wholegrains are the most appropriate sources of carbohydrate. Most are rich in nonstarch polysaccharides (NSPs) (dietary fibre) and other potentially cardioprotective components. Many of these foods, especially those that are high in dietary fibre, will reduce total and low-density lipoprotein cholesterol and help to improve glycaemic control in those with diabetes. There is no good long-term evidence of benefit when NSPs or other components of wholegrains, fruits, vegetables and legumes are added to functional and manufactured foods. Frequent consumption of low glycaemic index foods has been reported to confer similar benefits, but it is not clear whether such benefits are independent of the dietary fibre content of these foods or the fact that low glycaemic index foods tend to have intact plant cell walls. Furthermore, it is uncertain whether functional and manufactured foods with a low glycaemic index confer the same long-term benefits as low glycaemic index plant-based foods. A wide range of carbohydrate intake is acceptable, provided the nature of carbohydrate is appropriate. Failure to emphasize the need for carbohydrate to be derived principally from wholegrain cereals, fruits, vegetables and legumes may result in increased lipoprotein-mediated risk of cardiovascular disease, especially in overweight and obese individuals who are insulin resistant.