The guide / Part 26

Omega-3 and memory: do fish oil supplements work?

By The Prolongeva Editorial Team Written from the published research cited in each article Updated October 2026

Affiliate disclosure: we are an independent site and may earn a commission if you buy Neuro Serge through links on this site, at no extra cost to you.

Fish oil is one of the most common supplements on the shelf, and the box often hints at a sharper mind. If you are in your late 40s or 50s and have noticed small slips, it is natural to wonder whether a daily capsule is worth it. This guide sticks to what the reviews say, and who they studied.

What is omega-3, and where do you find it?

An NCCIH fact sheet (last updated August 2015, now archived, so details may have changed) describes omega-3 fatty acids as a group of polyunsaturated fatty acids with a number of functions in the body. It names three main types: ALA, EPA and DHA.

ALA comes mainly from vegetable oils, such as canola, soybean and flaxseed oil. EPA and DHA are found in seafood, including fatty fish and shellfish. That fact sheet says the body can convert ALA into EPA and DHA, usually in small amounts.

It also says DHA is important for brain development and function. That is a statement about the nutrient, not about whether taking extra helps an adult brain. The studies below address that second question.

What do the reviews say about omega-3 supplements and memory?

We read an NCCIH clinical digest on supplements and cognitive function (the page is dated July 2022). It summarizes three reviews that bear on omega-3 supplements.

• 2012 Cochrane review, older people without dementia. The digest says the available evidence shows no benefit of omega-3 supplementation on the cognitive functioning of older people without dementia. We opened the review itself (Sydenham, Dangour and Lim, 2012). It covered 3 randomized trials in adults aged 60 and over who were cognitively healthy at the start, with 4,080 people randomized. Its authors wrote that the trials showed no benefit on cognitive function, and that direct evidence on dementia was lacking.
• 2016 Cochrane review, people who already have Alzheimer's disease. The digest says there was no convincing evidence for omega-3 supplements in mild-to-moderate Alzheimer's disease, based on 3 randomized trials with 632 participants. This is a different group of people from most readers of this site.
• 2020 systematic review and meta-analysis. As the digest describes it, 38 randomized trials with 49,757 participants, found that long-chain omega-3 probably has little or no effect on new neurocognitive outcomes or cognitive impairment. We read the digest summary, not the paper.

The same archived NCCIH fact sheet (last updated August 2015) adds one trial. It says a large NIH-sponsored study, published in 2015, found that EPA and DHA supplements did not slow cognitive decline in older adults. All of those participants had the eye disease AMD, so the result may not carry over to everyone.

How far can these findings be stretched?

Not very far, in either direction. In our reading, the honest summary is that the reviews found no cognitive benefit from omega-3 supplementation (capsules or fortified margarine) in the groups they studied. That is not the same as proof of harm, or proof that no one could ever benefit.

• Age. The 2012 trials enrolled people aged 60 and over. Most readers here are in their late 40s to 50s, and we found no review we opened that tested supplements in that age group for memory.
• Length. The Cochrane authors said longer studies are needed, because longer follow-up might detect changes that shorter trials miss.
• Different questions. The reviews looked at test scores and at dementia or impairment outcomes. They do not tell you whether a capsule changes how you feel day to day.

If forgetfulness is what worries you, a capsule is not where the evidence points us. For what the broader picture looks like, see nootropic supplements for memory.

Is eating fish different from taking a capsule?

The archived NCCIH fact sheet (last updated August 2015) treats them separately. It says there is moderate evidence for the health benefits of eating seafood, while the benefits of omega-3 supplements are unclear. That statement is general, dates from 2015, and in the passage we read the heart was the main example, not memory. We did not open the current NCCIH page, which may word this differently.

The NHS says a healthy, balanced diet should include at least 2 portions of fish a week, including 1 of oily fish. It defines a portion of oily fish as around 140 g cooked, and lists herring, pilchards, salmon, sardines, sprats, trout and mackerel. It says fresh and canned tuna do not count as oily fish.

The NHS describes oily fish as high in long-chain omega-3 fatty acids that can help keep your heart healthy. We did not open a source that tests fish meals for memory specifically, so we will not claim they protect it. For ideas on eating patterns, see foods for memory after 45.

Prefer no fish? NCCIH says algae oils are a vegetarian source of DHA. We found no memory trial results for them in the sources above.

What are the risks and interactions?

The archived NCCIH fact sheet (last updated August 2015) says omega-3 supplements usually do not have negative side effects, and that when they occur they are typically minor gastrointestinal symptoms, such as belching, indigestion or diarrhea. The 2012 Cochrane review similarly reported mild gastrointestinal problems as the most common side effect.

The same 2015 fact sheet lists these points. NCCIH has since revised its page and we did not check the current wording, so treat them as questions for your clinician rather than a complete list:

• Omega-3 supplements may extend bleeding time. People who take anticoagulants (blood thinners) or NSAIDs should discuss omega-3 supplements with a health care provider.
• It is uncertain whether people with fish or shellfish allergies can safely consume fish oil supplements.
• Fish liver oils, such as cod liver oil, are not the same as fish oil. They contain vitamins A and D, which can be toxic in large doses, and amounts vary by product.

Fish oil is easy to forget to mention because it is sold as a food supplement. Tell your clinician and pharmacist about it anyway, especially if you take blood thinners.

When should you talk to a doctor?

Before starting fish oil, if you take blood thinners or NSAIDs, are pregnant or nursing, or have a fish or shellfish allergy. The archived NCCIH sheet advised talking to a health care provider in those cases, and we think that is sensible.

Separately, if memory slips are new, getting worse, or noticed by people close to you, a check-up matters more than any supplement. Common, but we cannot judge your case; a clinician can. See normal aging vs. early dementia and midlife forgetfulness for what to watch for, and questions to ask your doctor about memory to prepare.

This article is general information, not medical advice. Please talk to a doctor or pharmacist before starting a supplement, especially if you take blood thinners or have allergies, and see a doctor if you are worried about your memory.