Diet high in poor quality carbohydrates increases risk of heart attacks, strokes, and death A global study of people living on five continents has found a diet high in poor quality carbohydrates leads to a higher risk of heart attacks, strokes, and death. The higher risks of a diet high in poor quality carbohydrates, called a high glycemic diet, were similar whether people had previous cardiovascular disease or not. The study, published in the New England Journal of Medicine today, is the largest of a geographically and dietary diverse population on this issue, as previous studies have chiefly focused on high income Western countries.