Fish rich with omega-3 fatty acids can lower levels of triglycerides, the chemical form in which most fat exists in food and in the body, according to a study by researchers at California's Loma Linda University.
The study, published in the 1 April issue of the American Journal of Clinical Nutrition, compared the effects of walnuts and fatty fish in the fight against heart disease. Walnuts lower cholesterol more than fish, but both can reduce the overall risk of coronary heart disease.
"The practical significance of the study is that eating an easy-to-incorporate amount of walnuts and fatty fish can cause meaningful decreases in blood cholesterol and triglycerides even in healthy individuals," said lead author Sujatha Rajaram, Ph.D., associate professor in the department of nutrition at Loma Linda University School of Public Health.
Following the qualified health claim issued by the U.S. Food and Drug Administration, researchers found that incorporating approximately 1.5 ounces of walnuts (42 grams, a handful of whole nuts or about three tablespoons of chopped nuts) into the daily diet lowered serum total cholesterol by 5.4 percent and LDL (bad) cholesterol by 9.3 percent, compared to a control diet based on U.S. Department of Agriculture recommendations.
Using American Heart Association guidelines, the researchers also found that a diet including two servings of fatty fish per week (roughly 4 ounces each as recommended by the AHA for individuals without heart disease) decreased triglyceride levels by 11.4 percent. Additionally, it increased HDL (good) cholesterol by 4 percent, but also slightly increased LDL (bad) cholesterol compared to the control diet.
The fish used in the study was salmon.
"Both plant- and marine-derived omega-3 fats are cardio-protective, and since they seem to be effective for lowering different risk factors, it would be prudent to include both in the diet," said Joan Sabate, M.D., DrPH, one of the authors of the study and chair of the department of nutrition.
"Individuals should strive to include a plant source of omega-3 fat in their diet, like walnuts, and also a marine source of omega-3 fat," added Dr. Rajaram. "If fatty fish is not a preferred option for marine-derived omega-3 fat, other options include microalgae oil or DHA-enriched eggs."
Subjects were randomly assigned to each of the three diets for eight weeks over a 24-week feeding schedule. This gave the researchers a chance to compare the effect of each diet on each participant.
April 12, 2009
