← Omega-3 Fatty Acids

What Are EPA and DHA?

Understanding the two most important omega-3 fatty acids and what they do in your body

Omega-3 fatty acids come in several forms, but two matter most for your health: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Your body can't make enough of these on its own, so you need to get them from food or supplements.

EPA helps manage inflammation throughout your body, while DHA is a major building block of your brain and eyes. Together, they support everything from heart health to mood regulation.

Think of them as essential maintenance tools your body needs but can't manufacture in sufficient quantities.

EPA and DHA are long-chain polyunsaturated fatty acids, each with distinct biological roles. While both belong to the omega-3 family, they serve different functions at the cellular level [1].

EPA (eicosapentaenoic acid) is a 20-carbon fatty acid that serves as a precursor to a class of signaling molecules called eicosanoids. These include prostaglandins and resolvins that help regulate the inflammatory response. When your body has adequate EPA, it produces more anti-inflammatory signals and fewer pro-inflammatory ones [1][2].

DHA (docosahexaenoic acid) is a 22-carbon fatty acid that is a structural component of cell membranes, particularly in the brain and retina. DHA makes up roughly 40% of the polyunsaturated fatty acids in the brain and about 60% of those in the retina [4]. It contributes to membrane fluidity, which affects how well cell receptors function and how efficiently neurons communicate.

Your body can technically convert ALA (alpha-linolenic acid, found in flaxseed and walnuts) into EPA and DHA, but the conversion rate is extremely low -- typically less than 5% for EPA and less than 0.5% for DHA [3]. This is why dietary intake of preformed EPA and DHA is considered important.

The biological essentiality of EPA and DHA is well-established across decades of research. Swanson et al. (2012) conducted a comprehensive review demonstrating that EPA and DHA exert health benefits across the entire lifespan, from fetal development through aging, with mechanisms including anti-inflammatory eicosanoid production, cell membrane structural support, and gene expression modulation [1].

The distinct roles of EPA and DHA arise from their differing chain lengths and double-bond configurations. EPA (20:5n-3) is the primary substrate for Series-3 prostaglandins and Series-5 leukotrienes, which are substantially less inflammatory than their arachidonic acid-derived counterparts. EPA also gives rise to E-series resolvins, specialized pro-resolving mediators that actively terminate inflammatory responses rather than merely suppressing them [2].

DHA (22:6n-3) plays an irreplaceable structural role. Innis (2008) documented that DHA accumulates preferentially in neural tissue, where it modulates membrane properties including fluidity, phase behavior, and the formation of lipid rafts that organize signaling proteins. DHA deficiency during development has been associated with impaired visual acuity and cognitive function in both animal models and human observational studies [4].

The NIH Office of Dietary Supplements notes that while ALA-to-DHA conversion exists as a metabolic pathway, it is insufficient to meet physiological demands in most individuals. Stable isotope tracer studies show conversion rates of ALA to EPA at approximately 0.2-8% and ALA to DHA at less than 0.05-4%, with considerable interindividual variability influenced by sex, genetics, and background diet [3]. This evidence underpins the recommendation for direct dietary intake of preformed EPA and DHA.

References

  1. Omega-3 fatty acids EPA and DHA: health benefits throughout lifeSwanson D, Block R, Mousa SA. Advances in Nutrition, 2012. PubMed 22332096 →
  2. Essential Fatty Acids as Functional Components of Foods- a ReviewKaur N, Chugh V, Gupta AK. Journal of Food Science and Technology, 2014. PubMed 28900017 →
  3. Omega-3 Fatty Acids - Fact Sheet for Health ProfessionalsNational Institutes of Health, Office of Dietary Supplements. NIH Office of Dietary Supplements, 2023. Source →
  4. DHA effects in brain development and functionInnis SM. Nutrients, 2008. PubMed 20439549 →

Transparency

View edit history

Every change to this page is tracked in version control. If you have conflicting research or think something is wrong, we want to hear about it.

Weekly Research Digest

Get new topics and updated research delivered to your inbox.