Carbohydrate rich diet boosts heart risk

Eating a carbohydrate-rich diet that boosts blood sugar levels hampers the functioning of blood vessels and raises the risk of developing cardiovascular disease.

Researchers evaluated 56 healthy but overweight or obese Israeli men and women, aged 35 to 60 years. None had diabetes or a history of hospitalisation for cardiovascular disease. The men and women were examined on four different mornings, following overnight fasts. They were randomly served either glucose, cornflakes, high-fibre cereal or water such that each subject received all 4 meals once throughout the study period. Low-glycaemic index foods include oatmeal, most fruits and vegetables, legumes and nuts. White bread, cornflakes and instant potatoes have high-glycaemic indexes. The higher the glycaemic index, the more that food raises blood sugar levels.

Before and after the meals or the water, the 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. Brachial artery flow-mediated dilation (FMD) was measured to see how well the endothelium is functioning. Researchers also measured the participants' blood sugar levels.

It was found that the blood sugar levels before and two hours after the meals were similar, but they were higher at 30 to 90 minutes after the high-glycaemic meals. The FMD was reduced two hours after eating for all groups, but the reduction was more marked after the high-glycaemic meals. The high-glycaemic meals, the researchers concluded, appeared to impair the endothelial function.

Based on the study, the researchers encourage low-glycaemic index carbohydrates instead of high-glyacaemic foods for better health and functioning of blood vessels. High-glycaemic index carbohydrates reduce or inhibit blood vessel function, leading to atherosclerosis and potential heart disease.

Previous research has also found that high blood sugar levels after meals are a risk factor for cardiovascular disease, not only in patients with diabetes but in the general population. Declining blood vessel function is considered a key variable in the development of hardening of the arteries and heart disease.