How Genetics Affect EPA Levels and Your Dietary Needs

Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

This article is part of the PlexusDx Education Hub — your resource for evidence-based guidance on diet & genetics. Browse all Diet & Genetics education

Eicosapentaenoic acid (EPA) is a long-chain omega-3 fatty acid that supports cell membranes and the body's production of signaling molecules involved in inflammation resolution. Blood levels of EPA vary widely from person to person, and that variation is driven by two things working together: how much omega-3 a person eats and how efficiently their genes convert plant-based omega-3 into EPA. Understanding both helps explain why the same diet produces different omega-3 status in different people.

EPA and the omega-3 pathway

Dietary omega-3s come in two broad forms. Alpha-linolenic acid (ALA), found in flaxseed, walnuts, and canola, is a shorter-chain omega-3 the body must elongate and desaturate to make EPA and then DHA. Preformed EPA and DHA come directly from oily fish and algae. The conversion of ALA to EPA runs through a series of enzyme steps, and in most people that conversion is inefficient — often only a few percent of ALA becomes EPA. That inefficiency is where genetics makes a large difference.

FADS1 and FADS2: the conversion genes

The rate-limiting steps in making EPA are controlled by the desaturase enzymes encoded by FADS1 and FADS2. A common variant near these genes, tagged by rs174537, is strongly associated with how efficiently the body performs this conversion. People carrying the lower-activity version tend to have lower blood levels of EPA for the same ALA intake, while higher-activity variants convert more readily. The gene ELOVL2, which elongates fatty-acid chains further along the pathway, also shapes downstream omega-3 status. These variants differ markedly in frequency across populations, which is one reason omega-3 needs are not identical for everyone.

What this means for dietary needs

The practical implication is that people with lower-efficiency FADS1 and FADS2 variants may not raise their EPA much by eating more ALA-rich plant foods alone, because the conversion bottleneck limits how much EPA they produce. For these individuals, preformed EPA and DHA from oily fish or algae-based sources can be a more direct route to adequate omega-3 status. This is a general nutritional consideration, not a prescription — individual needs depend on overall diet, health status, and goals.

Diet still matters as much as genes

Genetics sets the efficiency of the machinery, but the raw material comes from food. Total omega-3 intake, the balance between omega-6 and omega-3 fats in the diet, and how regularly a person eats fish or algae-derived sources all influence EPA status independently of genotype. Someone with efficient conversion genes still needs dietary omega-3 to work with, and someone with less efficient genes can improve status through food choices. Genes and diet are partners, not competitors.

What a genetic test can and can't tell you

A genetic test offers pathway-level context about how your biology handles nutrients, not a diagnosis or a meal plan. The Precision Peptide Genetic Test analyzes 14 pathways, 49 peptides, 150+ genetic insights across peptide-related biological pathways. Variants in genes like FADS1 show how much of omega-3 metabolism is written into DNA, but a test does not tell you what to put in your body. It provides information you can bring to a qualified provider or dietitian — genetics as a guide, not a guarantee.

Frequently Asked Questions

Why are my EPA levels low even though I eat healthy?

Blood EPA depends on both intake and conversion efficiency. If you rely on plant-based ALA from flax or walnuts, common lower-activity FADS1 and FADS2 variants may convert only a small fraction into EPA. Preformed EPA and DHA from fish or algae bypass that bottleneck more directly.

What do FADS1 and FADS2 genes do?

FADS1 and FADS2 encode desaturase enzymes that perform the rate-limiting steps of converting plant-based ALA into the long-chain omega-3s EPA and DHA. Common variants, tagged by rs174537, strongly influence conversion efficiency, so two people eating identical omega-3 can end up with different EPA levels.

Do I need fish oil if I have low-efficiency variants?

Not necessarily, but preformed EPA and DHA from oily fish or algae can be a more direct source if conversion from plant omega-3 is limited. This is general nutritional context, not medical advice. Discuss supplements and dietary changes with a qualified provider or registered dietitian.

Can a genetic test tell me exactly how much omega-3 to take?

No. A wellness genetic test gives pathway-level context about how efficiently your body may process omega-3, not a dosage or prescription. It does not predict drug or supplement response. Use the insight to inform a conversation with a qualified provider about your individual dietary needs.

Curious how your genetics fit into the bigger picture? The Precision Peptide Genetic Test offers pathway-level insight you can bring to a conversation with your healthcare provider — genetics as a guide, not a guarantee.

This article is part of the PlexusDx Education Hub. Browse all Diet & Genetics education

The Precision Peptide Genetic Test analyzes how your genes influence peptide-related biological pathways. It does not recommend, prescribe, or determine which peptides you should use. Consult a qualified healthcare provider before beginning any peptide protocol.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.