The study, led by David D. Gutterman, M.D., Northwestern Mutual Professor of Cardiology, professor of medicine and physiology, and senior associate dean of research at the Medical College of Wisconsin, monitored 20 volunteers between the ages of 18 to 50 with a body mass index ranging from 29 to 39.
"Low-carbohydrate diets are significantly higher in total grams of fat, protein, dietary cholesterol and saturated fats than are low-fat diets. While a low-carbohydrate diet may result in weight loss and improvement in blood pressure, similar to a low-fat diet, the higher fat content is ultimately more detrimental to heart health than is the low-fat diet suggested by the American Heart Association," said Shane Phillips, M.D., an assistant professor in the department of physical therapy at the University of Illinois and the study's lead author.
Gutterman 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. 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."
In the study, the participants were randomly assigned the type of diet and their weight loss, flow-mediated dilation, blood pressure and insulin and glucose levels were measured every two weeks.
Over the six-week period, the researchers found 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. On the other hand, flow-mediated dilation improved significantly in participants on the low-fat diet suggesting a healthier artery which is less prone to developing atherosclerosis.
"We observed a reduction in brachial artery flow-mediated dilation after six weeks of weight loss on a low-carbohydrate, Atkins'-style diet," said Gutterman.
Low-carbohydrate diets were also found to have significantly less daily folic acid than low-fat diets. Folic acid is thought to be helpful in reducing the likeliness of heart disease.
The low-carbohydrate diet provided 20 grams of carbohydrates daily and was supplemented with protein and fat content according to the Atkins diet recommendations. The low-fat diet provided 30 percent of the calories as fat.
The study is published in the journal Hypertension.
From the March 3, 2008, Prepared Foods e-Flash