New study shows low-fat diets more likely to reduce risk of heart disease than low-carb diets

http://www.eurekalert.org/pub_releases/2008-02/mcow-nss022908.php

Public release date: 29-Feb-2008
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Contact: Toranj Marphetia
Medical College of Wisconsin

Low-fat diets are more effective in preserving and promoting a healthy cardiovascular system than low-carbohydrate, Atkins’-like diets, according to a new study by researchers at the Medical College of Wisconsin in Milwaukee.

“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,” points out Dr. Phillips.

“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,” says Dr. Gutterman.

Over a 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,” Dr. Gutterman says.

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. This protective effect results from the antioxidant property of folic acid and its ability to lower levels of homocysteine, a naturally occurring amino acid that can be dangerous at elevated levels.

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, and was modeled after the American Heart Association’s recommendations.