A new study at Emory University shows some slight diet changes can lead to significant improvements in an obese person's cardiovascular health and even aid in repairing damage from the past. The findings were presented Nov. 6 at the American Heart Association Scientific Sessions conference in Orlando.
A team of researchers, led by Emory cardiologist Arshed A. Quyyumi, MD, compared the effects of following a Mediterranean style diet versus continuing to follow an American type diet - and supplementing parts of the Mediterranean diet, including omega-3 fatty acids - on markers of heart disease risk. A third group, serving as a control, continued to follow their usual diet without supplements.
"Overall, we measured several indicators of cardiovascular health including blood vessel function and the stem cells, or progenitor cells, that actually repair damage to the lining of the blood vessels," says Dr. Quyyumi.
The findings indicate that because of the Mediterranean diet obese participants -- weighing 185 to 245 pounds or more - had improved function of the blood vessel lining, lower levels of inflammation and reduced stimulation of repairing stem cells.
The study showed in healthy obese subjects, circulating progenitor cell levels - the cells that contribute to vessel lining repair after damage - are higher compared to lean subjects.
However, after these obese persons underwent a lifestyle intervention with a Mediterranean style diet, a reversal of this increase resulted. This means that intake of a highly saturated fat American diet leads to stimulation of the progenitor cells and results in a repair phenomenon. Improvement in the diet leads to a switch off of this stimulus.
"Obesity often leads to diabetes and heart disease, partly because of injury to the endothelium or lining of the blood vessels," explains Dr. Quyyumi. "Injury to the endothelium elicits a repair response that can be seen as increased circulating levels of progenitor cells that prevent the damage that can potentially occur. This finding is important because it illustrates the heightened repair response that these obese persons have which can be lowered by modifying the diet."
A typical Mediterranean diet has a large amount of fruit, vegetables, whole grain breads, fish and poultry. Olive oil is the main source of fat and there is a daily use of dairy products (such as cheese and yogurt) in low to moderate amounts.
An American diet is typically high in fat, especially saturated fats, and cholesterol. Fried foods and red meat are common.
Dr. Quyyumi moderated the "Obesity and Human Atherosclerosis: Mechanisms and Epithelial Progenitor Cells" session at the AHA conference where these findings were presented by his colleague, Salman Sher, MD, Emory University School of Medicine.