How Genetics Affects Arachidonic Acid Levels: FADS1 and FADS2

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

Arachidonic acid (AA) is an omega-6 fatty acid your body uses to build cell membranes and to make signaling molecules that govern inflammation, immune response, and blood clotting. How much AA circulates in your blood is not just a product of what you eat — it is strongly shaped by genetics. A cluster of fatty-acid desaturase genes controls the enzymes that convert dietary fats into AA, and common variants there create meaningful differences between people. Understanding this can inform how you think about your diet, though it does not diagnose or treat any condition.

What arachidonic acid does in the body

Arachidonic acid sits at the center of omega-6 metabolism. It is incorporated into cell membranes and released on demand, then converted by enzymes into eicosanoids — prostaglandins, thromboxanes, and leukotrienes — that regulate inflammatory and immune signaling. Because these downstream molecules are so biologically active, the amount of AA available influences the tone of the body's inflammatory pathways.

The body makes AA from linoleic acid, a fat abundant in many vegetable oils, through a multi-step enzymatic conversion. The efficiency of that conversion is where genetics has a large say.

FADS1 and the fatty-acid desaturase cluster

The FADS1 and FADS2 genes, located together on chromosome 11, encode delta-5 and delta-6 desaturase — the rate-limiting enzymes that build AA from its dietary precursors. The FADS1 variant rs174537 is one of the strongest and most reproducible genetic determinants of blood AA levels ever identified. People carrying different genotypes convert precursor fats into AA at different rates, which can substantially change circulating AA even on similar diets.

These variants also affect omega-3 fatty acids that share the same enzymes, so the FADS cluster shapes the overall balance of omega-6 to omega-3 metabolism, not just AA in isolation.

ALOX5, PTGS2, and what happens downstream

Once AA is available, genes governing its conversion into signaling molecules add another layer of individual variation. ALOX5 encodes 5-lipoxygenase, which produces leukotrienes, and PTGS2 encodes COX-2, which produces prostaglandins. Variants in these genes have been studied for their influence on inflammatory signaling. So genetics affects both how much AA you make and how your body uses it once it is there.

How diet and genes work together

Diet still matters — it supplies the raw materials. But the FADS genotype determines how efficiently those raw materials become AA. This is why blanket dietary advice does not fit everyone: two people eating the same omega-6-rich diet can end up with different AA levels because their desaturase enzymes work at different rates. Knowing your genetic tendency can make dietary choices about omega-6 and omega-3 fats more personalized and less guess-driven.

Turning genetic insight into informed choices

The PlexusDx Precision Peptide Genetic Test analyzes 14 pathways, 49 peptides, 150+ genetic insights, including pathways tied to inflammation, metabolism, and nutrient processing that intersect with fatty-acid biology. This is educational context about your predispositions — it does not diagnose any condition, does not prescribe a diet, and is not a treatment plan. Decisions about nutrition and any related health concerns belong with a qualified provider or registered dietitian.

General, evidence-based guidance — a balanced intake of omega-3 and omega-6 fats, whole-food-forward eating, and individualized advice from a clinician — applies regardless of genotype. Genetic insight simply helps you understand why your body handles these fats the way it does.

Frequently Asked Questions

What genes control arachidonic acid levels?

The FADS1 and FADS2 genes on chromosome 11 are the main genetic controllers of arachidonic acid levels. They encode desaturase enzymes that convert dietary fats into AA. The FADS1 variant rs174537 is one of the strongest known determinants of how much arachidonic acid circulates in blood.

Can I change my arachidonic acid levels through diet?

Diet influences AA levels by supplying precursor fats, but your FADS genotype sets how efficiently those fats convert to arachidonic acid. That means dietary changes affect people differently. Balancing omega-6 and omega-3 intake, guided by a clinician or dietitian, is the evidence-based approach.

Does high arachidonic acid cause disease?

Arachidonic acid is essential and not inherently harmful; it fuels normal immune and signaling functions. Its downstream products influence inflammatory pathways, which is why balance matters. Genetic testing offers pathway context, not a diagnosis, and any health concern should be evaluated by a qualified provider.

Is a genetic test the same as measuring my fatty acids?

No. A genetic test reveals inherited tendencies in genes like FADS1 that shape how you process fats. A blood fatty-acid panel measures your current levels. The two are complementary: genetics explains predisposition, while lab testing reflects your present status, interpreted by a provider.

Curious how your inflammation and nutrient-processing pathways are wired? Take the Precision Peptide Genetic Test to understand your genetic pathway context, then bring that insight to a conversation with your provider.

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, diagnose, or determine which peptides or treatments you should use. Consult a qualified healthcare provider before making decisions about your health or 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.