Study leader Dr. David D. Gutterman of the Medical College of Wisconsin in Milwaukee and lead author Dr. Shane Phillips of the University of Illinois-Chicago found, over a six-week period, there was reduced flow-mediated dilation in the arm artery in participants who were on the low-carbohydrate diet.

Reduced flow-mediated dilation, as measured in this study, is an early indicator of cardiovascular disease. Flow-mediated dilation improved significantly in participants on the low-fat diet suggesting a healthier artery which is less prone to developing atherosclerosis, the researchers said.

"The higher fat content of a low-carbohydrate diet may put dieters at an increased risk of atherosclerosis -- hardening of the arteries -- because low-carbohydrate diets often reduce protection of the endothelium, the thin layer of cells that line the blood vessels of the circulatory system," Gutterman said in a statement.

"The reduced production from the endothelium of nitric oxide, a specific chemical, puts the vessel at higher risk of abnormal thickening, greater clotting potential, and cholesterol deposition, all part of the atherosclerosis process."

The findings are published in the journal Hypertension.