Most people have heard of omega 3. Far fewer are getting enough of it.
EPA and DHA, the two omega 3 fatty acids most closely linked to human health, aren't just dietary extras. They become structurally embedded in cell membranes throughout the body, particularly in the brain, eyes, and cardiovascular system. When intake is consistently low, those systems may not function as effectively as they could.
For most of human history, omega 3 was relatively easy to obtain through fish, seafood, wild plants, and animals raised on natural diets. Modern diets have shifted that balance significantly. Most people today consume far less omega 3 and substantially more omega 6, largely from refined seed oils and ultra-processed foods. Because omega 3 and omega 6 fats compete for some of the same metabolic pathways, this shift may influence inflammatory signalling (3).
The result is that many people consume less omega 3 than is considered optimal for long-term health.
The ALA Problem
Omega 3 fats are classified as essential fatty acids. The body cannot produce alpha-linolenic acid (ALA) on its own, so it must come from food.
Plant sources like flaxseeds, chia seeds, walnuts, and hemp seeds are rich in ALA, but ALA is not the same as EPA and DHA. The body has to convert it, and that conversion is inefficient. Current estimates suggest only around 5-12% of ALA becomes EPA, and less than 1% becomes DHA (8,9).
Women appear to convert ALA more efficiently than men, likely due to the influence of oestrogen on omega 3 metabolism. Vegetarians and vegans may also show marginally greater conversion when no direct sources of EPA or DHA are present. But even accounting for this, achieving a good amount of EPA and DHA through plant foods alone can be difficult.
Direct sources remain the most reliable route. SMASH fish (salmon, mackerel, sardines, anchovies, and herring) are among the richest, but many people eat them infrequently, and some prefer to avoid relying on fish due to concerns about mercury and other contaminants.
This is why omega 3 has become a focus in longevity and preventive health research. For most people, the question isn't whether omega 3 matters, but how to reliably get enough of the right forms.
What EPA and DHA Actually Do
EPA and DHA show up across so many areas of health because they influence multiple systems at once.
Cardiovascular Health. EPA and DHA have been extensively studied for their role in supporting triglyceride levels, vascular function, blood flow, and inflammatory balance, particularly in people with lower baseline omega 3 intake (2,5).
Brain Function and Cognition. DHA is highly concentrated in the brain, where it maintains membrane fluidity and the efficiency of neuronal communication. Adequate intake has been associated with cognitive health and healthy brain aging (4).
Inflammation Regulation. Omega 3-derived compounds help regulate inflammatory signalling pathways. While inflammation is a normal part of repair and adaptation, chronically elevated levels are associated with cardiovascular disease, metabolic dysfunction, and accelerated biological aging (3).
Mood and Emotional Wellbeing. EPA-rich formulations have shown improvements in depressive symptoms in some individuals, particularly as a complement to standard treatment rather than a replacement for it (6,7).
Eye Health. DHA is highly concentrated in the retina, where it contributes to the structure and function of photoreceptor cell membranes. Low omega 3 intake has been associated with dry eyes and age-related visual health concerns in some populations (10).
The effects aren't always dramatic in people already eating a nutrient-dense diet. But for those with low omega 3 intake, which remains common, maintaining adequate EPA and DHA levels may be considerably more important (1).
The Takeaway
For most people, omega 3 supplementation isn't about optimisation. It's about restoring a balance that modern diets have shifted.
EPA and DHA play structural and regulatory roles across multiple systems, from the brain to the cardiovascular system to the inflammatory response. The challenge is getting enough of them from food.
When diet alone isn't reliable, direct supplementation with EPA and DHA remains the most practical solution.
Read More
The impact of omega-3 fatty acids on brain aging
What is an optimal longevity diet?
Literature Sources
- National Institutes of Health Office of Dietary Supplements. Omega-3 Fatty Acids Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/
- Siscovick DS, Barringer TA, Fretts AM, et al. Omega-3 Polyunsaturated Fatty Acid (Fish Oil) Supplements and the Prevention of Clinical Cardiovascular Disease. Circulation. 2017;135(15):e867-e884. doi:10.1161/CIR.0000000000000482
- Calder PC. Omega-3 Fatty Acids and Inflammatory Processes: From Molecules to Man. Biochem Soc Trans. 2017;45(5):1105-1115. doi:10.1042/BST20160474
- Dyall SC. Long-chain omega-3 fatty acids and the brain: a review of the independent and shared effects of EPA, DPA and DHA. Front Aging Neurosci. 2015;7:52. doi:10.3389/fnagi.2015.00052
- Aung T, Halsey J, Kromhout D, et al. Associations of Omega-3 Fatty Acid Supplement Use with Cardiovascular Disease Risks. JAMA Cardiol. 2018;3(3):225-234. doi:10.1001/jamacardio.2017.5205
- Mocking RJT, Harmsen I, Assies J, et al. Meta-analysis and Meta-regression of Omega-3 Polyunsaturated Fatty Acid Supplementation for Major Depressive Disorder. Transl Psychiatry. 2016;6(3):e756. doi:10.1038/tp.2016.29
- Liao Y, Xie B, Zhang H, et al. Efficacy of Omega-3 PUFAs in Depression: A Meta-Analysis. Transl Psychiatry. 2019;9:190. doi:10.1038/s41398-019-0515-5
- Burdge GC, Calder PC. Conversion of Alpha-linolenic Acid to Longer-chain Polyunsaturated Fatty Acids in Human Adults. Reprod Nutr Dev. 2005;45(5):581-597. doi:10.1051/rnd:2005047
- Takić M, Ranković S, Girek Z, et al. Current Insights into the Effects of Dietary α-Linolenic Acid Focusing on Alterations of Polyunsaturated Fatty Acid Profiles in Metabolic Syndrome. Int J Mol Sci. 2024;25(9):4909. doi:10.3390/ijms25094909
- SanGiovanni JP, Chew EY. The role of omega-3 long-chain polyunsaturated fatty acids in health and disease of the retina. Progress in Retinal and Eye Research. 2005;24(1):87–138. DOI: 10.1016/j.preteyeres.2004.06.002
