Cardiovascular Benefits of Fish Oil Canceled by High-Fat Diet

Study highlights:

• In an animal study of heart failure, fish oil supplementation was helpful to animals on a low-fat diet, but not to those on a high-fat diet.

• Researchers think that a high-fat diet may block the heart cells’ ability to absorb the omega-3 fatty acids in fish oil.

Fish oil (EPA & DHA [eicosapentaenoic acid and docosahexaenoic acid]) supplementation helped the heart when paired with a low-fat diet, but not when added to a high saturated-fat diet fed to rats with heart failure, according to a [July 2009] study in Hypertension: Journal of the American Heart Association

 

Dietary Supplements and Cardiovascular Health

A group of six researchers from different institutions, led by William C. Stanley, PhD, from the University of Maryland-Baltimore, hypothesized that when the heart is stressed, such as in heart failure, a high-fat diet may block the heart cells’ ability to absorb the heart- healthy omega-3 polyunsaturated fatty acids (PUFAs) found in fish oil.

The investigators found that heart size—measured by left ventricular mass (LV mass)—increased in rats fed low- and high saturated-fat diets without fish oil by 40 percent and 42 percent respectively. On a low-fat plus fish oil diet, LV mass increased just 4 percent, while the group fed high saturated-fat diet with fish oil saw a 36 percent LV mass increase.

The scientists also found that certain genes associated with heart failure did not get “switched on” in the group fed a low-fat diet supplemented with fish oil.

The researchers conclude, “This suggests that in order to maximize the benefit from fish oil supplementation, patients at risk for heart failure should not consume a high saturated fat diet.”

As part of an overall healthy diet, the American Heart Association recommends limiting saturated fat in the diet to 7 percent or less of calories and consuming fish, especially oily fish, two times per week. Author disclosures are on the manuscript. The National Institutes of Health funded the study.
“Benefits of fish oil cancelled by high-fat diet in lab study of heart failure,” reprinted with permission. © 2009 American Heart Association,  Inc. (www.americanheart.org).