Research stemming from the National Institutes of Health’s Age-Related Eye Disease Study found no impact in older persons’ cognitive function from supplementation over a five-year period with omega-3 fatty acids or lutein/zeaxanthin.

Subjects participating in AREDS2 were evaluated in a related study on yearly change for composite scores from a battery of cognitive function tests from baseline. The study, identified as the largest and longest of its kind, found an annual score change of -0.19 for participants randomized to receive omega-3 long-chain polyunsaturated – docosahexaenoic and eicosapentaenoic – fatty acids compared to -0.18 for subjects randomized to receive no omega-3s.

Similarly, the score for participants randomized to receive lutein/zeaxanthin was -0.18, compared to -0.19 for the placebo group. Lutein/zeaxanthin have shown “a possible role” in the treatment of cognitive impairment in older adults in small random controlled trails, according to the study results published Aug. 25 in the Journal of the American Medical Association.

AREDS2 continues the original 2001 AREDS designed to investigate a combination of nutritional supplements for slowing age-related macular degeneration, a major cause of vision loss among the elderly in the US Also see "Bausch & Lomb OcuVite Line Extension Used In Natl. Eye Institute Study" - Pink Sheet, 15 October, 2001..

AREDS demonstrated that daily high doses of certain antioxidants and minerals, including lutein, could help slow the progression of advanced AMD. However, AREDS2, which commenced in 2006 and added omega-3 to the formula, found supplementation made no difference on AMD Also see "Vision Health Supplements Blurry On AREDS Formulation – Study" - Pink Sheet, 22 December, 2014..

“Contrary to popular belief, we didn’t see any benefit of omega-3 supplements for stopping cognitive decline,” said Emily Chew, the lead researcher and deputy clinical director at the National Eye Institute, in a release.

Omega-3s are common in supplements promoted for cognitive health. DHA is a structural component of brain cells and low levels of the nutrient have been found in persons with Alzheimer’s disease, estimated to have affected 5.2m people in the US in 2013 and projected by some estimates to triple in the next four decades, according to the researchers.

Cognitive health supplement sales grew 10% in 2013 to reach $1.5 billion globally compared to the overall supplement market which grew 6% that year ([A#05141013009]).

Two studies JAMA published in 2010 did not show omega-3s effective in treating dementia, though observational data suggested high dietary intake of saturated fat and low intake of vegetables could be linked to Alzheimer’s disease.

Caution On Extrapolating

Overall, the cognitive function testing scores decreased over time, but Chew and her colleagues cautioned against extrapolating the results of the study to long-term use of omega-3 supplements.

“It is possible that these supplements were started too late in the aging process since the mean age of the study population at baseline was 72.7 years. It is plausible that supplementation duration of five years may be insufficient,” as suggested in a cognitive ancillary study, Chew, who also is deputy director of NIH’s Division of Epidemiology and Clinical Applications, wrote in the study.

In their discussion of the study, the researchers added that the process of cognitive decline “may occur over decades, thus a short-term supplementation given too late in the disease may not be effective.”

They added that long-term diet also could have an influence.

“Studying dietary and food intake patterns rather than specific factors isolated with food sources may better reflect nutritional benefits because we have no knowledge of the actual factor(s) that may make an effect or of the interactions between nutrients that influence the physiologic effects of any one nutrient that may target tissues or pathways.”

The double-masked randomized clinical trial was conducted between October 2006 and December 2012. Cognitive function tests were administered at baseline and every two years. Adjusting for baseline age, sex, race, history of hypertension, education, cognitive score and depression score, researchers evaluated the differences in composite score between the treated and untreated groups.

Study participants, with a mean age of 72.7 and slightly more than half of them women, were randomly assigned to take one of four formulas – placebo; DHA/EPA 1 g; lutein 10 g/zeaxanthin 2 mg; or DHA/EPA and lutein/zeaxanthin – in formats matched in size, shape and taste. Approximately 1,500 subjects received omega-3s and 1,500 received a placebo or only lutein/zeaxanthin .

Researchers used an eight-test cognitive battery to collect data from subjects for a 30-minute period at three months after baseline and approximately every two years later. The battery included counting backwards and assessing delayed recall.

Changes in scores were captured from the eight tests from baseline to two and four years. A composite score ranging from -22 to 17 was constructed by converting the test results of the eight tests.

AREDS-Inspired Study Challenges Omega-3 Cognitive Benefit Claims

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