August 7 , 2006
New Study Notes Benefits of Consuming Polyunsaturated Fat
Just one meal high in saturated fat is enough to inhibit the body’s ability to protect arteries from the accumulation of plaque, a prime contributor to heart disease and stroke, according to a new study.
The research led by Stephen Nicholls, M.D, B.S., Ph.D., a cardiologist at Cleveland Clinic, appears in the Aug. 15, 2006 issue of the Journal of the American College of Cardiology.
According to the study, a single meal high in saturated fat reduces the ability of high-density lipoproteins (HDL), or “good” cholesterol, to keep plaque and other harmful substances from accumulating and clogging arteries. Such a meal also can limit the ability of arteries to expand and transport blood when necessary, the study found.
In turn, a meal high in polyunsaturated fat, a healthier form of fat, boosts the ability of HDL to keep plaque from clogging the inner lining of arteries, called the endothelium, the researchers report.
“These findings further illustrate the importance of maintaining a diet that is low in saturated fat,” Dr. Nicholls said. “The results strongly suggest that a diet’s fat composition affects the ability of HDL to serve as an anti-inflammatory agent for the arteries. This is significant given that the accumulation of plaque in the arteries is the main risk factor leading to heart attacks and strokes.”
Saturated fat is most often found in animal products and is solid at room temperature. Such fats include butter, red meat and whole milk, in addition to coconut and other tropical oils.
In contrast, polyunsaturated fats usually are liquid at room temperature and include safflower, corn and sunflower oils.
In the study, researchers led by Dr. Nicholls fed 14 healthy volunteers two meals, containing either a polyunsaturated or saturated fat, one month apart. The participants, ages 18 to 40 years, had their blood drawn prior to eating each meal, three hours after the meal and again six hours after the meal.
The meals were the same, except that one was high in polyunsaturated fat and the other was high in saturated fat. They consisted of a slice of carrot cake and a milkshake containing the equivalent of 1 gram of fat per kilogram of body weight, or 1 kilogram of fat for every 2.2 pounds. The participants and the researchers did not know what meals were being eaten at each point in the study.
In studying their results, the researchers found that just three hours after the meal, the saturated fat had restricted the ability of the artery walls to expand and increase blood flow. The polyunsaturated meal also reduced this ability, but the results were not statistically significant.
After six hours, the researchers determined the saturated fat had limited the protective properties of HDL, which allowed more inflammatory substances to accumulate in the arteries. However, the polyunsaturated meal seemed to increase the HDL’s ability to function, reducing the amount of inflammatory agents found in the arteries.
“Although this was a small study, it reiterates the importance of diet in the prevention and management of heart disease,” Dr. Nicholls said.
Dr. Nicholls received a Young Investigator Award from Pfizer Inc. to support this research.
The saturated fat study is one of four Cleveland Clinic studies highlighted in the Aug. 15, 2006 issue of the Journal of the American College of Cardiology. The others pertain to blood pressure and the progression of coronary artery disease; the use of advanced CT scanning to monitor heart transplant patients for heart disease; and the effects of cocaine on Taser-induced ventricular fibrillation.
Cleveland Clinic, located in Cleveland, Ohio, is a not-for-profit multispecialty academic medical center that integrates clinical and hospital care with research and education. Cleveland Clinic was founded in 1921 by four renowned physicians with a vision of providing outstanding patient care based upon the principles of cooperation, compassion and innovation. U.S. News & World Report consistently names Cleveland Clinic as one of the nation’s best hospitals in its annual “America’s Best Hospitals” survey. Approximately 1,500 full-time salaried physicians at Cleveland Clinic and Cleveland Clinic Florida represent more than 100 medical specialties and subspecialties. In 2005, there were 2.9 million outpatient visits to Cleveland Clinic. Patients came for treatment from every state and from more than 80 countries. There were nearly 54,000 hospital admissions to Cleveland Clinic in 2005. Cleveland Clinic’s Web site address is http://author.my.clevelandclinic.org/default.aspx.
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