Omega-3s: Are “Brain-Boosting” Effects Scientifically Backed?
No, but they’re probably good for you.
Given the current state of things, you’re far better off spending your money on quality food or fitness rather than pure omega-3s.
Of 14 comprehensive reviews covering hundreds randomized trials analyzed below, 13 showed inconclusive evidence to prove that omega-3s help brain function. The last one is standing on shaky ground (read the review if you want to evaluate it).
There is a good story for why omega-3s can help: they are related to child brain development, are used throughout the body, and are required for your brain to work. They also have antioxidant and anti-inflammatory properties that might help brain function.
Isolated findings within reviews have found things like a small boost to memory or attention in cognitively impaired people, but there aren’t enough of these findings to balance many other studies, or the only large trial which considered other lifestyle factors which found no impact (interestingly, a side result was that a program of brain training, fitness advice, and nutritional information did prevent cognitive decline).
But it might help your heart
On the other hand, there is better evidence about omega-3s reducing the number of people dying from heart-related problems. In general, researchers have found a small benefit in overall mortality rate from people who eat more omega-3s.
That being said, here’s a quote from one review: “If 1000 people without existing cardiovascular disease take this supplement for 5 years each then one person will avoid dying from coronary heart disease”.
They point out that the money spent on omega-3 supplements may be better spent buying running shoes, fruit and fish, or investing in your mental health.
Cheaper stuff works
For most people, cheaper, more popular things like caffeine for improving focus do the trick perfectly fine. I would argue the same thing for health: do eat more fish and nuts, but before considering specific supplementation think of the many other things you could spend your money on that have far greater proven impact.
Thanks for reading! If you want to take a look at the reviews I referenced in this article, here’s all of them:
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On Brain Function:
Omega-3, Omega-6, and Polyunsaturated Fat for Cognition: Systematic Review and Meta-analysis of Randomized Trials - ScienceDirect
(2020, Journal Impact Factor - 7.8) An assessment of 38 Randomized Controlled Trials: “This extensive trial data set enabled assessment of effects on neurocognitive illness and cognitive decline not previously adequately assessed. Long-chain omega-3 probably has little or no effect on new neurocognitive outcomes or cognitive impairment.”
Full article: Omega-3 polyunsaturated fatty acids and cognition throughout the lifespan: A review (tandfonline.com)
(2013, Journal Impact Factor - 5) Omega-3s can affect brain development during pregnancy, no research has clearly established link between better cognitive skills and dietary intake of n-3 PUFA. Few studies have looked at cognitive effects from childhood to middle age. “At later ages, multiple studies found evidence suggesting that n-3 PUFA can protect against neurodegeneration and possibly reduce the chance of developing cognitive impairment.”
Cureus | Effects of Omega-3 Polyunsaturated Fatty Acids on Brain Functions: A Systematic Review
(2022, Journal Impact Factor - 1.15) - “Natural omega-3 consumption through the diet should be promoted.” Findings to be taken with a grain of salt, particularly due to the fact that: results from underlying studies are cherry-picked to support conclusions, small sample size. Review included for completeness.
IJMS | Free Full-Text | Omega-3 Fatty Acids and Neurodegenerative Diseases: New Evidence in Clinical Trials (mdpi.com)
(2019, Journal Impact Factor - 6.2) Omega-3 fatty acids “may indeed represent a valuable and biologically plausible tool in the management of neurodegenerative diseases”. “Although dietary recommendations are far from being a treatment, they may be able to alleviate some of the symptoms”. Possible inconsistencies between observational and randomized studies may be due to time, nature of disease, lifestyle factors, differing individual responses.
Associations of Omega-3 fatty acids with brain morphology and volume in cognitively healthy older adults: A narrative review - ScienceDirect
(2021, Journal Impact Factor - 11.1) “However, most studies reviewed provided mixed findings regarding the presence or absence of the association of interest, and the findings were observed to be brain region-dependent. Current evidence is still insufficient to formulate recommendations for omega-3 intake to support brain health specifically.”
Omega-3 fatty acids and cognitive decline: a systematic review - PubMed (nih.gov)
(2019, Journal Impact Factor - 1.05) 10/14 studies showed positive outcome on at least one aspect of cognitive function. Evidence may be weaker for cognitively normal older adults: an 18-month “randomized, double-blind, placebo-controlled trail of DHA-rich fish oil” 403 people, did not support supplementation with fish oil to prevent cognitive decline.
Long-chain omega-3 polyunsaturated fatty acids and cognitive decline in non-demented adults: a systematic review and meta-analysis | Nutrition Reviews | Oxford Academic (oup.com)
(2019, Journal Impact Factor - 5.79) No effect on global cognitive function, “among the specific cognitive domains, only memory function showed a mild benefit”. Dosages did not significantly affect outcomes. Further studies required.
(2020, Journal Impact Factor - 8.1) DHA effect on mental health disorders. “Randomized clinical trials that have investigated the therapeutic effects of omega-3 fatty acids have yielded inconclusive results, which limit the use of these nutrients in psychiatric practice. Therefore, high-quality clinical trials that examine the efficacy of omega-3 fatty acids in preventing and treating mental disorders are needed.”
Is docosahexaenoic acid, an n−3 long-chain polyunsaturated fatty acid, required for development of normal brain function? An overview of evidence from cognitive and behavioral tests in humans and animals | The American Journal of Clinical Nutrition | Oxford Academic (oup.com)
(2005, Journal Impact Factor - 7.05) RCTs show weak possible causation, Breastfeeding trials show link between longer breastfeeding period and test scores, but does not account for large number of confounding factors, animal testing may provide the best evidence that big deficiency may cause small differences.
The Efficacy of Omega-3 Fatty Acids on Cognitive Function in Aging and Dementia: A Systematic Review (karger.com)
(2006, Journal Impact Factor - 3.28) “The available data are insufficient to draw strong conclusions about the effects of omega–3 fatty acids on cognitive function in normal aging or on the incidence or treatment of dementia. However, limited evidence suggests a possible association between omega–3 fatty acids and reduced risk of dementia.”
“Although the lay press and commercial advertisements have purported that omega–3 fatty acids are beneficial for cognitive function and the treatment of dementia, we were unable to find strong evidence to support these claims. A detailed systematic search of the literature identified only five articles that informed these topics.”
Omega 3 fatty acids and cognitive health in older people | British Journal of Nutrition | Cambridge Core
(2012, Journal Impact Factor - 4.2) “We identified seven relevant trials, four among cognitively healthy older people, and three among individuals with pre-existing cognitive decline or dementia, and overall conclude that there is no evidence to support the routine use of n-3 LCPs supplements for the prevention, or amelioration, of cognitive decline in later life.”
“Authors have also highlighted that fish intake is not equivalent to n-3 LCP intake and that the genetic heterogeneity among different populations with respect to both n-3 fatty acids metabolism and dementia susceptibility might weaken the benefits of these nutrients.”
“The strength of the epidemiologic associations and the proposed mechanisms underlying the effects of n-3 LCPs on brain function are increasing, and yet of seven trials included in our review, only one identified any potential benefits from n-3 LCP supplementation on cognitive function.”
Cognitive function after supplementation with B vitamins and long-chain omega-3 fatty acids: ancillary findings from the SU.FOL.OM3 randomized trial | The American Journal of Clinical Nutrition | Oxford Academic (oup.com)
(2011, Journal Impact Factor - 7) “No significant main effects of group assignment on cognitive function were found; however, we found some evidence of disease history– and age-specific effects. In the subgroup with prior stroke, for example, participants assigned to receive B vitamins plus omega-3 fatty acids were significantly less likely to have a decreased score on the temporal orientation task than were those assigned to receive placebo (odds ratio: 0.43; 95% CI: 0.21, 0.86).”
Effects of omega-3 fatty acids on cognitive performance: a meta-analysis - ScienceDirect
(2012, Journal Impact Factor - 5.13) For cognitively impaired individuals there was a small benefit in immediate recall and attention, but no significant results for healthy people.
Full article: How does high DHA fish oil affect health? A systematic review of evidence (tandfonline.com)
(2018, Journal Impact Factor - 11.2) “DHA is likely to play important roles in brain development and function”, “Nevertheless, there is currently not enough robust information available to draw conclusions on the actual roles and effects of DHA on brain development and physiological function, or on visual function.”
Some non-review articles that are still very useful:
Effect of long-term omega 3 polyunsaturated fatty acid supplementation with or without multidomain intervention on cognitive function in elderly adults with memory complaints (MAPT): a randomised, placebo-controlled trial - ScienceDirect
(2017, Journal Impact Factor - 44.18) Randomized, placebo controlled, multidomain intervention on cognitive function in elderly adults with memory complaints on1680 participants over 3 years 2008-2011. Multidomain intervention was basically a group that did 60 min of cognitive training, 45 min of physical activity advice, and 15 min of nutritional advice. A 1 hour session was held each month to reinforce the key messages.
“In a post-hoc analysis, in which all participants who received the multidomain intervention were pooled, cognitive decline from baseline to 36 months, as measured with the composite Z score, was significantly less in those who had received the multidomain intervention than in those who did not receive this intervention (data not shown; p=0·015) in the modified intention-to-treat population. In a separate analysis in which all participants who received polyunsaturated fatty acids were pooled, cognitive decline did not differ significantly between those who received polyunsaturated fatty acids and those who did not (data not shown; p=0·715) in the modified intention-to-treat population.”
“The multidomain intervention and polyunsaturated fatty acids, either alone or in combination, had no significant effects on cognitive decline over 3 years in elderly people with memory complaints.”
Nutrients | Free Full-Text | Beneficial Outcomes of Omega-6 and Omega-3 Polyunsaturated Fatty Acids on Human Health: An Update for 2021 (mdpi.com)
(2021, Journal Impact Factor - 6.7) “In addition to their antioxidant and anti-inflammatory roles, omega-3 fatty acids are considered to regulate platelet homeostasis and lower risk of thrombosis, which together indicate their potential use in COVID-19 therapy.”
Omega-3 and dementia | Alzheimer's Society (alzheimers.org.uk)
Not a journal article, but a good and well-balanced report.
On Health Benefits:
Effect of omega-3 fatty acids on cardiovascular outcomes: A systematic review and meta-analysis - PubMed (nih.gov)
(2021, Journal Impact Factor - 17) Modest cardiovascular mortality benefit associated with use of omega-3 FA. “Omega-3 FA was associated with reducing cardiovascular mortality (-1.4 incident cases per 1000 person-years), but not all-case mortality.”
Omega‐3 fatty acids for the primary and secondary prevention of cardiovascular disease - Abdelhamid, AS - 2020 | Cochrane Library
(2020, Journal Impact Factor - 11.9) “Moderate and low-certainty evidence suggests increasing LCn3 slightly reduces risk of coronary heart disease mortality and events” Coronary heart disease mortality - LCn3: NNTB (number needed to treat for an additional beneficial outcome) 334, Risk of cardiovascular disease events - ALA: NNTB 500. More figures in the review itself.
Full article: How does high DHA fish oil affect health? A systematic review of evidence (tandfonline.com)
(2018, Journal Impact Factor - 11.2) Evidence for DHA improving cardiovascular health and reducing total cholesterol. Big differences in sex-specific responses, recommended further testing on specific testing population.
Omega-3 Fatty Acids Effects on Inflammatory Biomarkers and Lipid Profiles among Diabetic and Cardiovascular Disease Patients: A Systematic Review and Meta-Analysis | Scientific Reports (nature.com)
(2019, Journal Impact Factor - 4.996) Omega-3s may be related to inflammatory biomarkers, but no clear benefits identified in the review.