Omega-3 Fatty Acid, Antioxidant Supplements Useless for Improving Cognitive Function

Countless companies heavily promote dietary supplements containing omega-3 fatty acids, antioxidants and other nutrients as the solution to many health problems. Among the many benefits attributed to these supplements are maintenance of brain health and cognitive function.

For example, one online company peddles a product called “Natural Omega-3 Brain Formula” with an advertisement claiming that the product supplies high levels of two omega-3 fatty acids "in a ratio scientifically relevant for maintaining brain health."[1] Another company hawks "Extreme Omega," with the claim that it supports "cognitive health … with the super-powered benefits of fish oil."[2]

Dietary supplement companies are not required to conduct the type of large, well-designed clinical trials needed to prove such health claims and rarely, if ever, do so. Fortunately, the National Institutes of Health sometimes funds such studies. The most recent, published in the Journal of the American Medical Association (JAMA), provides strong evidence debunking the cognitive health claims for dietary supplements containing omega-3 fatty acids. The study similarly found that dietary supplements containing a combination of the antioxidants lutein and zeaxanthin, often promoted for eye health, also are ineffective for maintaining cognitive function.

What are omega-3 fatty acids?

Omega-3 fatty acids, a type of polyunsaturated fat, are essential for life. One such fatty acid, alpha-linolenic acid (ALA), is not made in the body and must come from the diet.[3] Good sources of this critical nutrient are nuts, leafy green vegetables and certain vegetable oils, such as canola, soy and flaxseed oil.[4]

Once consumed, ALA is converted by the body into two other important omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).[5] Fish, fish oils and organ meats also are rich dietary sources of EPA and DHA.[6]

Omega-3 fatty acids play a key role in many functions in the body. Of note, DHA is the major type of omega-3 fatty acid found in the brain and is an essential part of brain cells.[7],[8] It is thought to be important for brain development and function, including transmission of signals between nerve cells and reduction of inflammation following injury.[9]

Previous observational studies suggested that eating high amounts of omega-3 fatty acids helps maintain cognitive function. Other studies have found that patients with Alzheimer’s disease have low levels of DHA. However, randomized, controlled clinical trials — the gold standard for medical research — all have failed to show any benefit of treatment with omega-3 fatty acids in patients with dementia.[10]

What are lutein and zeaxanthin?

Lutein and zeaxanthin are chemically similar pigments that impart yellow or orange color to foods such as cantaloupe, corn, carrots, orange and yellow peppers, salmon, and egg yolks.[11],[12] They also are found in large amounts in a variety of dark green leafy vegetables, such as parsley, spinach and kale.[13]

These pigments are antioxidants, which are thought to prevent or slow damage to cells and tissues following injury. They are found throughout the body, with particularly high amounts in the eye lens and retina.[14] Some observational studies have suggested that people who eat more lutein and zeaxanthin have a lower risk of certain eye disorders, such as cataracts and age-related macular degeneration.[15]

Also, similar to what was found with omega-3 fatty acids, observational studies seem to show that people who eat large amounts of antioxidants have better cognitive function. However, all the randomized, controlled trials conducted to date have failed to show that people can improve their scores on cognitive tests simply by taking supplements containing these nutrients.[16]

The JAMA study[17]

The study, published in August 2015, was the latest and best attempt to assess the benefits of omega-3 fatty acids and antioxidants for brain health. It was a large, randomized, placebo-controlled clinical trial led by researchers at the National Eye Institute. The initial primary goal of the trial — named the Age-Related Eye Disease Study II (AREDS2) — was to assess whether taking omega-3 fatty acids or a lutein-zeaxanthin combination was useful for treating age-related macular degeneration and cataracts.

As they were designing this trial, the researchers realized that it also provided an opportunity to test whether the same dietary supplements could prevent declines in brain function. Therefore, in addition to measuring the effect on macular degeneration and cataracts, researchers gave subjects enrolling in AREDS2 the option of undergoing a panel of cognitive function tests within three months of enrollment and approximately two and four years after enrollment.

The subjects were randomly assigned to take one of the following daily: an omega-3 fatty acids supplement, a lutein-zeaxanthin supplement, both supplements or a placebo. Subjects also were given varying combinations of vitamin C, vitamin E, beta carotene and zinc.

From October 2006 to September 2008, eye specialists at 82 clinics across the U.S. enrolled 4,203 adults with early age-related macular degeneration into AREDS2. Of these subjects, over 3,700 agreed to participate in the cognitive function testing.

A panel of eight well-established tests was used to assess multiple cognitive functions, including memory, attention, speech fluency and number processing. To minimize the chances of bias, neither the subject nor the person administering the cognitive tests knew what supplements the subject was taking.

The researchers combined the scores from all eight tests to generate an overall cognitive function score, called a composite score, for each subject. The researchers then calculated the average yearly change in the composite scores, as well as the changes in scores for each of the eight individual tests, between the initial testing and the follow-up testing over four years. The researchers obtained enough data to calculate changes in cognitive function in 3,073 subjects.

In general, scores on the cognitive function tests went down in subjects, including those getting a placebo, over the course of the trial. However, none of the dietary supplements had an impact on how fast scores declined, either for any of the individual tests or for the combined score. The same study also showed that these dietary supplements failed to slow the progression of age-related macular degeneration.[18] For patients with very low dietary intake of lutein-zeaxanthin, supplements with these antioxidants — but not omega-3 fatty acid supplements — decreased the need for cataract surgery.[19]

The results of AREDS2 reinforce findings of prior randomized trials which consistently failed to demonstrate any benefit from dietary supplements for improving cognitive function or preventing dementia.[20]

What You Can Do

Don't waste money on dietary supplements that promise to improve your cognitive function and brain health. Instead, eat a balanced diet that includes natural sources of omega-3 fatty acids and a wide variety of other nutrients.

If you are worried that you may have problems with memory or thinking, see your doctor for further evaluation. Some serious memory problems are due to treatable medical conditions, such as deficiencies in certain vitamins, hypothyroidism and depression.

For mild forgetfulness, the National Institute on Aging suggests several ways to help keep your memory sharp (see box, above).[21]

References

[1] Vitacost.com. Bluebonnet Nutrition Natural Omega-3 Brain Formula – 60 softgels. http://www.vitacost.com/bluebonnet-nutrition-natural-omega-3-brain-formula-60-softgels-1?csrc=PPCADW-[keyword]&mtp=s8TmJsKp2-dc|pcrid|95700665531|mt|b&gclid=CNixqN6uvcgCFUUXHwodtWwASw. Accessed October 12, 2015.

[2] Pureformulas. Extreme Omega – 60 softgels. https://www.pureformulas.com/omega3-extreme-3020-60-softgels-by-natrol.html?CUSTOMTRACKING=CUSTOMTRACKING&CAWELAID=1550462415&CAGPSPN=pla&catargetid=530005240002497768&cadevice=c&gclid=CPOXgcCfuMgCFZOGaQodo7sHIw. Accessed October 12, 2015.

[3] National Institutes of Health, Office of Dietary Supplements. Omega-3 fatty acids and health: Fact sheet for health professionals. Last reviewed October 28, 2005. https://ods.od.nih.gov/factsheets/Omega3FattyAcidsandHealth-HealthProfessional/. Accessed October 10, 2015.

[4] Ibid.

[5] Ibid.

[6] Ibid.

[7] National Institutes of Health, Office of Dietary Supplements. Omega-3 fatty acids and health: Fact sheet for health professionals. Last reviewed October 28, 2005. https://ods.od.nih.gov/factsheets/Omega3FattyAcidsandHealth-HealthProfessional/. Accessed October 10, 2015.

[8] Chew EY, Clemons TE, Agron E, et al. Effect of omega-3 fatty acids, lutein/zeaxanthin, or other nutrient supplementation on cognitive function: The AREDS2 randomized clinical trial. JAMA. 2015;314(8):791-801.

[9] National Institutes of Health, Office of Dietary Supplements. Omega-3 fatty acids and health: Fact sheet for health professionals. Last reviewed October 28, 2005. https://ods.od.nih.gov/factsheets/Omega3FattyAcidsandHealth-HealthProfessional/. Accessed October 10, 2015.

[10] Chew EY, Clemons TE, Agron E, et al. Effect of omega-3 fatty acids, lutein/zeaxanthin, or other nutrient supplementation on cognitive function: The AREDS2 randomized clinical trial. JAMA. 2015;314(8):791-801.

[11] Abdel-Aal EM, Akhtar H, Zaheer K, Ali R. Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health. Nutrients. 2013;5(4):1169-1185.

[12] Ribaya-Mercado JD, Blumberg JB. Lutein and zeaxanthin and their potential roles in disease prevention. J Am Coll Nutr. 2004;23(6 Suppl):567S-587S.

[13] Abdel-Aal EM, Akhtar H, Zaheer K, Ali R. Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health. Nutrients. 2013;5(4):1169-1185.

[14] Ribaya-Mercado JD, Blumberg JB. Lutein and zeaxanthin and their potential roles in disease prevention. J Am Coll Nutr. 2004;23(6 Suppl):567S-587S.

[15] Ibid.

[16] Chew EY, Clemons TE, Agron E, et al. Effect of omega-3 fatty acids, lutein/zeaxanthin, or other nutrient supplementation on cognitive function: The AREDS2 randomized clinical trial. JAMA. 2015;314(8):791-801.

[17] Ibid.

[18] Age-Related Eye Disease Study 2 Research Group. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. JAMA. 2013;309(19):2005-2015.

[19] National Eye Institute. For the Media: Questions and Answers about AREDS2. https://nei.nih.gov/areds2/MediaQandA. Accessed November 6, 2015.

[20] Gill SS, Seitz DP. Lifestyles and cognitive health: What older individuals can do to optimize cognitive outcomes. JAMA. 2015;314(8):774-775.

[21] National Institute on Aging. Understanding Memory Loss: What to Do When You Have Trouble Remembering. October 2015. https://www.nia.nih.gov/alzheimers/publication/understanding-memory-loss/introduction. Accessed October 26, 2015.