The two long-chain omega-3s most important for human health are DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid). These fats are especially concentrated in the eye and the brain, where they play structural and protective roles, it is why omega-3 nutrition is important to my research.
DHA is a structural fat found in high concentrations in the retina and in the brain’s grey matter, where it supports fast and flexible communication between cells. EPA complements DHA by helping to resolve inflammation and supporting cardiovascular and immune health.
DHA is a vital component of the retina, making up a large proportion of the light-sensitive cells (photoreceptor membranes) that allow us to see. It helps maintain the structure of these delicate tissues and ensures that signals are transmitted quickly and accurately. Without adequate DHA, the performance of the retina can decline, affecting visual function.
Our brain is made up largely of fat, and one of the most important of these fats is DHA, a type of omega-3. DHA is found in high amounts in the grey matter of the brain, where it supports memory, learning and quick thinking. Together with EPA, another key omega-3, it helps protect brain cells from damage caused by inflammation and oxidative stress.
Higher levels of DHA and EPA in the brain are linked to sharper memory, better attention, and healthier ageing. Without enough of these essential fats in our diet, our brain cannot function at its best.
At the Nutrition Research Centre Ireland (NRCI), we have studied omega-3s in both healthy adults and patients with early Alzheimer’s disease. Our studies including the re-MIND clinical trial (which you can read here) shows that:
The best dietary sources of DHA and EPA are oily fish such as salmon, sardines, and mackerel. Eating fish one to two times per week can help, but many people still fall short of recommended intakes. Vegetarians and vegans can use algal oil, which provides a plant-based, bioavailable source of DHA.
Supplements offer a reliable way to maintain consistent daily intake.
Modern diets are low in oily fish, and plant sources of omega-3 such as flaxseed or canola provide only ALA, which the body converts into DHA and EPA at a very low rate (often less than 5%). At the same time, demands for omega-3s are high throughout life, from pregnancy and early development through to healthy ageing. For most people, supplementation is the only practical way to achieve the levels of DHA and EPA needed for optimal eye, brain and heart health.
However, I can’t stress enough the importance of using a supplement product that has been rigorously third-party tested and certified for ingredient quantity, quality and purity. My research has shown that not all supplements are the same – look for the published clinical evidence and quality certifications.
Regulatory bodies, including the European Food Safety Authority (EFSA), have approved the following claims for DHA and EPA when consumed at adequate levels:
These claims are legally recognised when products provide sufficient daily amounts (typically 250 mg DHA and/or EPA for general benefits; higher intakes for specific outcomes).
