Startling science: Taking an omega-3 supplement doesn’t boost memory or cognition

By Sandee LaMotte, CNN

(CNN) — If you’re taking an omega-3 fish oil or algae supplement to stave off Alzheimer’s disease and dementia, take note: A new clinical trial finds these supplements did nothing to improve memory, cognition or brain cell loss.

“Omega-3 supplements as a blunt instrument do not work,” said lead study author Dr. Hussein Yassine, the Volke Endowed Professor of Neurology at the University of Southern California’s Keck School of Medicine in Los Angeles.

“Even when we saw high levels of omega-3 in the brains of the treatment group, it did not improve cognition,” said Yassine, who directs Keck’s Center for Personalized Brain Health.

What does work? Optimizing your health with exercise, stress reduction, quality sleep and a plant-based diet while adding omega-3s from fatty fish, nuts and seeds, he said.

“In the Mediterranean, high omega-3 levels are very strong predictors of good cognition,” Yassine said. “But people in the Mediterranean are not popping supplements. They’re eating fatty fish, exercising, meeting with friends and living slowly with less stress.

“In that context, omega-3s are shining, helping the brain,” he added. “But if you eat a typical Western diet with fast food, don’t exercise, are stressed out all day from work, our study showed having more omega-3 in your brain doesn’t move the needle.”

After years of public messaging about how fish oil or algae supplements might protect against dementia, it’s time to refine our thinking, said Alzheimer’s prevention researcher Dr. Richard Isaacson, director of research at the Institute for Neurodegenerative Diseases of Florida.

“Omega-3s are absolutely critical to having optimal brain health, especially for people with the APOE4 gene, which increases the risk of developing Alzheimer’s,” said Isaacson, who was not involved in the new research. “However, this study shows they don’t work well in people who have not already optimized their health.”

CNN reached out to the Global Organization for EPA and DHA Omega-3s, which represents the omega-3 industry, but did not hear back before publication.

Why are omega-3 fatty acids essential?

Omega-3 polyunsaturated fatty acids are essential to any animal’s survival. In humans, they lower blood pressure, boost good cholesterol, maintain cell health and reduce the risk for cancer, dementia and Alzheimer’s disease.

Omega-3s are crucial for brain health. Up to 60% of the human brain is made up of lipids, or fats. Some 35% of those fats are omega-3s, experts say. Yet the body doesn’t produce omega-3s on its own. Instead, the fatty acids must be obtained from foods such as salmon, herring, mackerel, sardines, walnuts, chia seeds and flaxseeds.

Many people don’t eat enough fatty fish, seeds and nuts, so supplementation has become widespread. Fish oil supplements provide eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA. The two have different functions — EPA fights inflammation and supports heart health, while DHA is a core structural building block for the brain, eyes and central nervous system. Vegan supplements contain algal oil made from marine algae, which is also a source of EPA and DHA.

Chia, hemp and flaxseed oil capsules provide a third type of omega-3 called alpha-linolenic acid, or ALA, an antioxidant with the important job of turning food into energy. It’s also good for the heart — the risk of dying from heart disease falls by 10% for each gram of ALA eaten per day, according to the Cleveland Clinic.

Raw walnuts are an excellent source. One ounce, or about 14 walnut halves, provides 2.5 grams of ALA, nearly twice the recommended daily amount.

Walnuts also provide magnesium, manganese, copper, vitamin B6 and a host of other nutrients — a key feature of whole foods that experts say supplements can’t match.

Wild salmon, for example, contains proteins, vitamins A, D and B-12, and critical minerals such as selenium and potassium — as well as high-quality omega-3s.

“When you get omega-3s from eating fish, you’re not just getting the single nutrient; you’re getting the whole fish,” Yassine said.

“But it has to be part of a healthy lifestyle. If we take that salmon and fry it, it’s not going to count anymore. You can break the omega-3s down by frying the fish, or you can neutralize them by having french fries next to it.”

‘A drop in the ocean’

The results of the randomized, double-blind, placebo-controlled clinical trial — considered the gold standard of science — were published Thursday in The Lancet journal ebioMedicine.

The study divided 365 people without dementia between the ages of 55 and 80 into treatment and placebo groups. All had extremely low omega-3 levels and at least one risk factor for dementia, such as obesity, sedentary lifestyle, high blood pressure or cholesterol.

Nearly 50% had at least one copy of the APOE4 gene — a group that will be the mostly likely to benefit from supplementation because their brains struggle to process fats efficiently, Isaacson said.

The treatment group received a high dose omega-3 algae supplement (2,000 milligrams of DHA) each day for 24 months. The control group took a placebo for the same period. Both groups also took a vitamin B complex.

All participants underwent MRI brain scans, blood draws and cognitive testing at various points throughout the study.

Testing showed levels of omega-3s in red blood cells climbed from 4.9% to 11% in those taking the supplement. Measures of DHA levels in cerebrospinal fluid, which surrounds the brain, rose by an average of 17% after six months, confirming the omega-3 reached its intended target. The same increases were seen in people with an APOE4 gene, thought to benefit most from supplementation.

Despite evidence that levels of omega-3 had risen in the brains of people who took the supplement, there were no improvements in cognition or the size of the hippocampus, the brain’s memory center.

“In fact, there was no real difference between people taking an omega-3 supplement and those taking a placebo,” Yassine said.

The results show that omega-3 supplementation is like a “drop in the ocean” for people who don’t exercise, eat an ultraprocessed food diet and are overweight with signs of chronic disease, Isaacson said.

“What I’m telling my patients is that if a person with one or more copies of the APOE4 genetic variant has low blood levels of omega-3s and is overall healthy, they can still protect against Alzheimer’s and dementia risk by eating fatty fish twice a week and taking a high-quality omega-3 supplement,” he said. “But if they have an unhealthy lifestyle like the population in this study, an omega-3 supplement just isn’t going to work.”

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