Why DHA and EPA are key to long-term brain health

DHA and EPA, also known as omega-3 fatty acids, are widely recognised for their benefits to both physical and cognitive health. Yet despite their importance, many people remain unclear about what these nutrients are, why they matter, and how they support long-term brain health.

DHA and EPA stand for docosahexaenoic acid and eicosapentaenoic acid. They are healthy (essential) fats that the body needs to function and perform at its best. Of the many omega-3 fatty acids identified, DHA and EPA are the most important and biologically significant, as the body is unable to produce the quantities needed for optimal brain health. 

DHA is the primary structural fat within the neuronal membrane – the outer layer of brain cells. It plays a critical role in the brain by maintaining the membrane integrity and communication between neurons, working to support the processes underpinning neuroplasticity.

As Professor Jeremy Spencer, Nutritional Biochemist at the University of Reading, explains, “the more DHA there is in the neuron’s membrane, the easier it is for these new connections to form. This process, known as neuroplasticity, is key to learning new things and forming new memories. Building new connections also helps us build cognitive reserve, which is thought to help make the brain more resilient to dementia.”

What is important to understand is that DHA levels decline with age, not suddenly in later life. It is a gradual process which begins far earlier than people think, as early as young adulthood. As these DHA levels lower there is a gradual loss of synaptic pathways and connections, which in turn has been associated with impaired neuronal function. This has been increasingly linked to neurodegenerative diseases including Alzheimer’s disease and dementia. 

Maintaining adequate levels of DHA is therefore critical to maintaining good brain health, but because the body is unable to produce enough in terms of quantity, we need to ‘supplement’ the shortfall. A degree of responsibility will fall on our daily lifestyle choices, notably our daily diets – “sources of preformed DHA include oils from microalgae and fatty fish (especially salmon, mackerel, sardines and herring) – think of the acronym SMASH to remember this – which are commonly found in dietary patterns such as the Mediterranean and MIND diets.” In addition, taking a daily supplement of omega-3 has been shown to positively impact and maintain cognitive ability. The European Food Safety Authority (EFSA) recommends at least 250mg per day of DHA to contribute to the maintenance of normal brain function. 

Like DHA, EPA is also incorporated into cell membranes, influencing both structure and function. However, while DHA upholds cell integrity, EPA plays a more complementary role. It helps to regulate inflammation.

Omega-3 fatty acids, including EPA, work to help modulate the production of pro-inflammatory cytokines (small signalling proteins) that can drive chronic, low-grade inflammation, while at the same time, promoting specialised mediators called resolvins and protectins. These resolvins and protectins, derived from omega-3 fatty acids, actively work to resolve inflammation rather than simply suppressing it.

By helping to create a calm environment and regulate inflammation, EPA supports the conditions required for optimal brain function. It further contributes to vascular health and blood flow, ensuring a consistent delivery of oxygen and nutrients to the brain, for the brain demands high amounts of energy using 20% of the blood pumped by the heart. This brain perfusion is distributed by arteries which are modulated by vasoactive molecules, some of which are also derivatives from EPA and DHA, and the only way for the brain to receive these compounds is through the bloodstream. It is therefore not surprising that a higher omega-3 index (a measure of how much EPA and DHA are in the red blood cells) was found to be related to higher regional cerebral blood flow. 

It is clear to see that DHA and EPA are individual powerhouses, but when combined, they have a significant impact on brain health. Studies have even found that people with higher levels of DHA and EPA have better overall brain health, with one study from 2023 revealing that people aged 55-plus who took omega-3 supplements were 64% less likely to develop dementia in later life. 

It therefore goes to show that investment in long-term brain health matters, for by the time cognitive symptoms become noticeable, the underlying biological changes have often been developing for decades. As both medical and research advancements continue within the field of brain health, it is apparent and as emerging studies suggest, that higher levels of omega-3 are associated with better cognitive outcomes. In the long run this helps to slow down aspects of age-related decline.

For more information on brain health and how to get more DHA and EPA into your diet, visit our nutrition pillar and read the article, “Mediterranean, DASH and MIND diets: a beginner’s guide” to help better your brain health.