When it comes to protecting the brain as we age, diet plays a critical role and few nutrients have sparked as much scientific interest as omega-3 fatty acids. Found primarily in oily fish like salmon, mackerel, and sardines, as well as in flaxseeds and walnuts, omega-3s are essential fats that support everything from heart health to inflammation regulation. But what about the brain? Could omega-3s help lower the risk of dementia or slow its progression? Here’s what the research tells us.
What are omega-3 fatty acids?
Omega-3s are a type of polyunsaturated fat that your body cannot produce on its own. There are three main types:
ALA (alpha-linolenic acid) – found in plant sources like flaxseeds and chia
EPA (eicosapentaenoic acid) – found in fatty fish
DHA (docosahexaenoic acid) – also found in fatty fish and a critical structural component of the brain
DHA, in particular, is the most relevant when it comes to brain function. It plays a major role in maintaining the health of brain cell membranes and supporting communication between neurons.
The link between omega-3 and dementia
Several studies have examined whether higher omega-3 intake, through diet or supplements, is associated with a lower risk of dementia, including Alzheimer’s disease. Here’s a summary of some key findings:
Population-based studies show promising associations
Large cohort studies have found that people with higher levels of omega-3s in their diet or bloodstream tend to have a lower risk of cognitive decline. A 2022 study published in Neurology found that people with higher blood DHA levels had a 49% lower risk of developing Alzheimer’s disease, particularly among those with a genetic predisposition (the APOE ε4 gene).
The Rotterdam Study (one of Europe’s largest long-term cohort studies) showed that individuals who consumed fish regularly had a significantly lower risk of dementia and Alzheimer’s. These findings suggest that omega-3s may have a protective effect, particularly when consumed over the long term.
Brain imaging studies offer clues
Some research using MRI brain scans shows that omega-3 intake is associated with greater brain volume and fewer signs of brain atrophy. In one study, older adults with higher blood levels of omega-3s had larger hippocampal volumes — the part of the brain responsible for memory and one of the first regions affected by Alzheimer’s disease.
Supplementation studies show mixed results
While observational studies are largely positive, clinical trials using omega-3 supplements have had mixed outcomes. Some trials have shown that omega-3 supplements help maintain cognitive function in people with mild cognitive impairment (MCI), especially when started early. Whereas other studies found no significant benefit in people already diagnosed with Alzheimer’s, especially in more advanced stages.
These inconsistencies suggest that timing matters. Omega-3s may be more effective as a preventative measure or during the early stages of cognitive decline, rather than as a treatment once dementia is well established.
How might omega-3s help the brain?
Researchers believe omega-3s protect brain health through several mechanisms:
Reducing inflammation – Chronic brain inflammation is believed to contribute to neurodegeneration
Supporting brain cell structure – DHA is a major component of brain cell membranes
Improving blood flow to the brain – Especially EPA, which supports vascular function
Promoting neuroplasticity – Helping the brain form new connections
Together, these effects may help delay or slow the processes that contribute to dementia.
What does this mean for people concerned about dementia?
While we can’t say that omega-3s prevent dementia outright, the evidence suggests they are a valuable part of a brain-healthy lifestyle. Incorporating omega-3-rich foods into your diet, like salmon, sardines, walnuts, flaxseeds, and chia seeds, is a smart and safe choice. For those who don’t consume fish, supplements containing DHA and EPA may be considered, especially under the guidance of a healthcare provider.
Research into omega-3 and dementia continues to evolve. The strongest benefits appear to come from long-term, consistent intake, especially before significant cognitive decline sets in. While omega-3s are not a cure, they’re one more tool in our growing understanding of preventative dementia care. A balanced, anti-inflammatory diet rich in omega-3s may not only support brain health but also enhance overall wellbeing as we age.