Cornflakes, White Bread Could be Bad for the Heart

Carbohydrates that boost blood sugar levels, like those found in foods such as cornflakes or white bread, may reduce the function of blood vessels and raise the risk of cardiovascular disease, according to researchers from Israel's Chaim Sheba Medical Center.

In the study, researchers evaluated 56 healthy, but overweight or obese men and women, aged 35 to 60. None had diabetes or a history of hospitalizations for cardiovascular disease. Each subject ate either glucose, cornflakes, high-fiber cereal or water, in descending order of glycemic index, for breakfast following an overnight fast. The higher the glycemic index, the more that food raises blood sugar levels.

Before and after the meals or the water, the team of researchers measured the functioning of the endothelium, the layer of cells that line the inside of blood vessels. If the endothelial function is poor, it is thought to increase the risk of cardiovascular disease. Researchers also measured the participants' blood sugar levels.

The blood sugar levels were higher at 30 to 90 minutes after the high-glycemic meals, but returned to the pre-meal numbers two hours after the meals.

The endothelium function was reduced two hours after eating for all groups, but the reduction was more marked after the high-glycemic meals, which suggests the high-glycemic meals impair the endothelial function.

The study is published in the June 16 issue of the Journal of the American College of Cardiology.