Atkins (not low fat) Diets Decrease Brachial Artery Flow

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" 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 Fat Diets More Likely To Reduce Risk Of Heart Disease Than Low

Carb Diets

01 Mar 2008

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.

The study, published in the February edition of the scientific journal

Hypertension, was led by D. Gutterman, M.D., Northwestern Mutual

Professor of Cardiology, professor of medicine and physiology, and

senior associate dean of research at the Medical College. Shane

, M.D., a former Cardiology faculty member at the Medical

College, and now assistant professor in the department of physical

therapy at the University of Illinois Chicago, was the lead author.

Public awareness of the " obesity epidemic " has resulted in various

dietary weight loss strategies. In America, it is estimated that 45

percent of women and 30 percent of men diet to lose weight.

" The nutrient-specific effects of these diets on cardiovascular health

are largely unknown, " says Dr. Gutterman.

" 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. ..

" 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.

" The composition of diet may be as important as the degree of weight

loss in determining the effect of dietary interventions on vascular

health, " Dr. Gutterman notes.

Twenty participants between the ages of 18 to 50 with a body mass

index ranging from 29 to 39 were monitored for the study, and the type

of diet was randomly assigned to participants. Weight loss, flow-

mediated dilation, blood pressure and insulin and glucose levels in

the participants were measured every two weeks for the six-week study.

The study was funded by the support of the National Institutes of

Health General Clinical Research Center and the Medical College of

Wisconsin Cardiovascular Center. It was conducted at Froedtert

Hospital, the College's major teaching affiliate.

Co-authors of the study included Jurva, M.D., assistant

professor of medicine; Amjad Syed, resident in surgery (University of

Illinois Chicago); Amina Syed, resident in family practice with the

Medical College of Wisconsin Affiliated Hospitals; Jacquelyn Kulinski,

senior medical student; Joan Pleuss, M.D., senior research dietician;

and Hoffmann, Ph.D., professor of population health in the

division of biostatistics.

Medical College of Wisconsin

8701 Watertown Plank Rd.

Milwaukee, WI 53226

United States

http://www.mcw.edu

Article URL: http://www.medicalnewstoday.com/articles/99141.php