July 31, 2001 A new study at The Rockefeller University Hospital will assess the potential of a fatty acid found in fish to reduce heart attack risk. The researchers are testing the hypothesis that a daily dose of the omega-3 fatty acid known as DHA will positively alter heart disease risk factors in at-risk individuals, specifically overweight and obese people. Participants who meet certain weight and health criteria are currently being enrolled in the clinical trial.
Although the American Heart Association now recommends eating fish twice a week to prevent heart disease, Americans continue to shy away from the food; indeed, the United States has one of the lowest rates of fish consumption, in addition to one of the highest levels of heart disease, in the world. Now, Rockefeller researchers are asking whether a daily supplement of DHA might provide people with heart benefits similar to those obtained from a diet high in fish.
"Efforts to encourage individuals at increased risk for heart attacks to adopt lifestyle changes, such as diet modification and exercise, have met with limited success," says lead investigator Jan L. Breslow, M.D., Frederick Henry Leonhardt Professor and head of the Laboratory of Biochemical Genetics and Metabolism at Rockefeller. "We propose that a dietary supplement might provide this population with additional protection against heart disease."
Previous studies have suggested that DHA, or docosahexanoic acid, may reduce the risk of coronary heart disease by reducing levels of triglycerides in the blood, raising the number of HDL molecules (the "good" cholesterol), preventing irregular heart beats called arrhythmias and possibly lowering blood pressure?all indicators of good heart health.
DHA is an essential component of our eyes, brains and heart muscles. It is predominatly produced by marine algae and is abundant in fish because they feed on algae. This essential fatty acid is necessary for the normal development of the visual and nervous systems in infants. Consequently, the World Health Organization recommends supplementing baby formulas with DHA, and the U.S. Food and Drug Administration recently approved its use in formulas.
Together with eicosapentaenoic acid (EPA) and alpha-linolenic acid (LNA), DHA constitues a group of fatty acids called omega-3 fatty acids. Scientists believe these polyunsaturated fats are important in preventing a number of diseases, including heart disease; inflammatory diseases, such as rheumatoid arthritis; mental disorders, such as bipolar disorder and attention deficit disorder, and certain types of cancer.
The main dietary source of DHA and EPA is fish, especially oily fish like salmon and anchovies. Major dietary sources of LNA?a building block of DHA and EPA?include flaxseed oil, canola oil, walnuts and dark greens. Americans, however, continue to shift their diet away from these foods. Instead, they are consuming more and more omega-6 fatty acids, which are found in vegetable oils. This increase in the ratio of omega-6 to omega-3 fatty acids in the diet, according to some studies, may play a major role in heart disease risk.
"This study will test the effect of bringing omega-3 levels in the diet back up on heart disease risk factors," says Barbara Levine, Ph.D., co-investigator of the study and co-director, with Breslow, of the Human Nutrition Program at Rockefeller.
The researchers currently are recruiting volunteers between the ages of 18 and 65 for the double-blind study, which lasts five-and-a-half months. Of the 40 patients the researchers plan to enlist, half will receive placebo, and the other half will receive 2 grams of DHA per day. Throughout the study, levels of cholesterol and triglycerides in the blood, along with blood pressure and other indicators of cardiovascular health, will be measured.
Study participants will be required to stay at The Rockefeller University Hospital for 21 days at the beginning of the study, followed by a four month outpatient period during which they will be seen once a month. The study is concluded by another 21 day inpatient period for a total of 42 days of inpatient testing. During the inpatient periods, patients will be placed on a strict diet designed to maintain body weight and eliminate fish intake. Throughout the study, patients will be able to attend work or school.
Eligible participants must have a body mass index (BMI) between 25 and 39.9. BMI is a measure of a person?s weight in relation to his or her height. Specific health criteria also must be met. Study participants will receive $2500.
"This is a very exciting time," says Eileen Buckley, M.S.N., adult nurse practitioner and clinical research coordinator at Rockefeller. "For years my patients have asked me when more studies could be done regarding natural substances that might prove beneficial to our bodies. This is exactly what is being done now with our DHA study."
For more information about enrolling in this study contact Eileen Buckley at (212) 327-7445. For more information about DHA, contact the DHA Information Center Hotline at (800) 353-3606.
The Rockefeller University Hospital was the first medical institution in the U.S. devoted solely to the purpose of patient-oriented clinical research. Established in 1910, the hospital links laboratory investigations with bedside observations to provide a scientific basis for disease detection, prevention and treatment. The hospital is a New York State licensed facility and is accredited by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO). The hospital is supported in part by a General Clinical Research Center grant from the National Center for Research Resources at the National Institutes of Health.
John D. Rockefeller founded Rockefeller University in 1901 as The Rockefeller Institute for Medical Research. Rockefeller scientists have made significant achievements, including the discovery that DNA is the carrier of genetic information. The University has ties to 21 Nobel laureates, six of which are on campus. Rockefeller University scientists have received this award for two consecutive years: neurobiologist Paul Greengard, Ph.D., in 2000 and cell biologist Gunter Blobel, M.D., Ph.D., in 1999, both in Physiology or Medicine. At present, 34 faculty are elected members of the U.S. National Academy of Sciences. Celebrating its Centennial anniversary in 2001, Rockefeller?the nation?s first biomedical research center?continues to lead the field in both scientific inquiry and the development of tomorrow?s scientists.
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