Elements of fish oil may improve brain function in people with coronary artery disease

American Heart Association

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People with coronary artery disease are at risk for cognitive decline, but high doses of two omega-3 fatty acids found in fish oil could improve their brain function, according to a study.

Prescription-level doses of two omega-3 fatty acids found in fish oil may improve brain function in older adults with coronary artery disease, or CAD, known to put people at risk for cognitive decline. 

CAD is a common type of heart disease that occurs when plaque builds up in the arteries and hinders proper blood flow. Studies have shown people with CAD have a 45% increased risk for cognitive decline.

The most improvement was observed when higher levels of both DHA and EPA were present in the bloodstream, according to a recent study. The beneficial levels, however, are above what people could get from eating fish, thus the need for supplements. 

"The study showed EPA adds additional benefit when DHA levels are already high," said researcher Dr. Francine Welty, an associate professor of medicine at Harvard Medical School in Boston. "But EPA levels alone had no predictive ability for cognitive improvement."

The study included 291 adults with stable CAD. They averaged 63 years old, and 83% were men. None showed problems with cognition at the beginning of the study.

Half were given 3.36 grams of EPA and DHA combined, and half were not. All participants received cognitive function tests at baseline, one year after treatment began and at the end of 30 months. The tests measured verbal fluency, language and memory, visual motor coordination and processing speed. Blood tests at the end of the study measured DHA and EPA levels.

The team hoped to show long-term, high-dose omega-3 fatty acids could prevent cognitive decline in people with CAD but were surprised to find the supplements did much more than that, Welty said.

"Someone who wants to use fish oil supplements to improve cognitive function should get a prescription for a supplement that combines the two," Welty said. She cautioned against buying over-the-counter supplements, which are not regulated by the Food and Drug Administration.

The same level of omega-3 fatty acids used in the study could not be obtained just through diet, said Penny Kris-Etherton, an Evan Pugh University professor of nutritional sciences at Penn State College of Health and Human Development.

"Getting 3.36 grams per day is hard to do just eating fish," said Kris-Etherton, who was not involved in the study.

"You'd have to eat a lot of fatty fish every single day. One serving of fatty fish, which is 3.5 ounces of salmon, for example, has about 2.2 to 2.3 grams of omega-3 fatty acids. To get 3.36 grams per day means that you'd have to eat about 1 1/2 servings of fatty fish every day. The recommendation of two fish meals per week, including fatty fish and lean seafood like shrimp, would only get you about 0.25 gram per day, and most Americans don't even eat that much," she said.

Omega-3 fatty acids are highest in fatty fish such as salmon, sardines, mackerel, herring, lake trout and albacore tuna. The AHA recommends eating two servings of fish per week to help reduce heart disease and stroke risk. It issued a science advisory in 2019 saying prescription fish oil supplements were a safe and effective way to lower triglycerides. The same advisory warned consumers not to take unregulated supplements.