What you carry at this position in your DNA and what research says about it.
Omega-3 Synthesis: 8/10 evidence, 15 publications.
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Sample genotype (not yours): C/C
Efficient Omega-3 Synthesis
Efficient conversion of plant-based fats into active omega-3 fatty acids characterizes this metabolic profile.
What this genotype means: Highly efficient synthesis of DHA and EPA; Lower circulating triglyceride levels; Slightly higher LDL and total cholesterol.
Sample genotype (not yours): A/A
Reduced Omega-3 Synthesis
Less efficient conversion of plant-based fats into active omega-3s makes dietary sources of DHA more important.
What this genotype means: Inefficient synthesis of DHA and EPA; Higher circulating triglyceride levels; Slightly lower LDL and total cholesterol.
Sample genotype (not yours): C/A
Typical Omega-3 Synthesis
A balanced, intermediate rate of fatty acid conversion helps maintain typical lipid levels.
What this genotype means: Moderate synthesis of DHA and EPA; Typical triglyceride and cholesterol levels; Balanced overall lipid profile.
Gene function and biological role
Gene Function: The FADS2 gene encodes delta-6 desaturase, a rate-limiting enzyme crucial for lipid homeostasis [1]. This enzyme catalyzes the first step in converting plant-derived short-chain fatty acids into active long-chain polyunsaturated fatty acids [1]. These end products include docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are vital for brain function and cardiovascular health [1]. FADS2 works in tandem with FADS1 within a highly regulated gene cluster on chromosome 11 [2]. Variations in this gene directly alter how efficiently the body synthesizes these essential fats from dietary sources [2].
Variant Impact: The rs174577 variant is an intronic change in the FADS2 gene that acts as a strong modifier of gene expression [3]. This genetic change alters DNA methylation patterns in the FADS cluster, directly impacting desaturase enzyme levels [3]. The C allele is associated with highly efficient conversion of dietary fats into long-chain omega-3 and omega-6 fatty acids [4]. Conversely, the A allele reduces this enzymatic conversion, leading to lower circulating levels of active polyunsaturated fatty acids [4]. This single change thus shifts the entire systemic balance of blood lipids and metabolic markers [3].
Key Insight: Your body's ability to create brain-essential DHA from plant oils like flaxseed depends heavily on this genetic variant.
Location: FADS2. Chromosome 11 · 11q12.2 · 61.8 Mb
Estimated prevalence by population
Global 39.4%; European 43.0%; African 39.9%; East Asian 19.9%; South Asian 66.9%; Americas 22.0%; Ashkenazi 48.6%; Finnish 33.4%; Middle Eastern 35.5%; Amish 54.9%.
Estimated CC genotype frequency.
Global 45.8%; European 45.2%; African 46.5%; East Asian 49.4%; South Asian 29.8%; Americas 49.8%; Ashkenazi 42.3%; Finnish 48.8%; Middle Eastern 48.2%; Amish 38.4%.
Estimated CA genotype frequency.
Global 14.7%; European 11.9%; African 13.6%; East Asian 30.6%; South Asian 3.3%; Americas 28.2%; Ashkenazi 9.2%; Finnish 17.8%; Middle Eastern 16.3%; Amish 6.7%.
Estimated AA genotype frequency.
Showing effects for C/C genotype
Nutrition & Metabolism
Macronutrient Metabolism
Omega-3 Fatty Acids. Evidence: 8/10. Source: PMID 41044249. Higher Levels.
Cardiovascular & Metabolic
Lipids & Cholesterol
Triglycerides. Evidence: 8/10. Source: PMID 29507422. Lower Levels.
Cholesterol Levels. Evidence: 8/10. Source: PMID 29507422. Higher LDL.
Diabetes & Glycemic Traits
Blood Sugar Control. Evidence: 8/10. Source: PMID 28898252. Higher HbA1c.
Showing effects for A/A genotype
Omega-3 Fatty Acids. Evidence: 8/10. Source: PMID 41044249. Lower Levels.
Triglycerides. Evidence: 8/10. Source: PMID 29507422. Higher Levels.
Cholesterol Levels. Evidence: 8/10. Source: PMID 29507422. Lower LDL.
Blood Sugar Control. Evidence: 8/10. Source: PMID 28898252. Lower HbA1c.
Showing effects for C/A genotype
Omega-3 Fatty Acids. Evidence: 8/10. Source: PMID 41044249. Typical Levels.
Triglycerides. Evidence: 8/10. Source: PMID 29507422. Typical Levels.
Cholesterol Levels. Evidence: 8/10. Source: PMID 29507422. Typical LDL.
Blood Sugar Control. Evidence: 8/10. Source: PMID 28898252. Typical HbA1c.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Possessing two copies of the C allele leads to highly active delta-6 desaturase enzymes [1]. This allows for the efficient conversion of short-chain plant fats into critical long-chain polyunsaturated fatty acids like DHA and EPA [1]. Studies show these individuals maintain higher circulating levels of omega-3 and omega-6 fatty acids [1]. They also tend to have lower fasting triglyceride levels [2]. However, this highly active metabolic state is a double-edged sword, as it is also associated with slightly higher total cholesterol, LDL cholesterol, and fasting blood glucose levels [2]. Ensuring a balanced diet rich in natural antioxidants can help optimize this metabolic profile.
Highly efficient synthesis of DHA and EPA; Lower circulating triglyceride levels; Slightly higher LDL and total cholesterol.
Sample genotype: AA (Homozygous)
Two copies of the A allele significantly reduce the activity of the delta-6 desaturase enzyme [1]. As a result, the body struggles to convert plant-derived short-chain fatty acids into active, long-chain polyunsaturated fatty acids like DHA [1]. This inefficient conversion often leads to lower circulating levels of essential omega-3 fatty acids [1]. Additionally, this genotype is linked to higher fasting triglyceride levels [2]. On the positive side, these individuals often benefit from lower total cholesterol, lower LDL cholesterol, and better blood sugar control [2]. To compensate for the reduced synthesis, focusing on direct dietary sources of preformed DHA and EPA is highly recommended.
Inefficient synthesis of DHA and EPA; Higher circulating triglyceride levels; Slightly lower LDL and total cholesterol.
Sample genotype: CA (Heterozygous)
A single copy of each allele provides a balanced metabolic middle ground [1]. The body converts plant-based alpha-linolenic acid into active DHA and EPA at a typical, moderate rate [1]. Circulating levels of omega-3 fatty acids and triglycerides generally fall within the average range for the population [2]. This intermediate desaturase activity also means that cholesterol and blood sugar levels are typically balanced, avoiding the higher extremes seen in other genotypes [2]. While there is no urgent need for high-dose supplementation, maintaining a diet with consistent sources of preformed omega-3s remains beneficial.
Moderate synthesis of DHA and EPA; Typical triglyceride and cholesterol levels; Balanced overall lipid profile.
Variants with shared genetic architecture
rs174570 · FADS2 Gene · Chr 11 · Fatty Acid Metabolism
rs174574 · FADS2 Gene · Chr 11 · Fatty Acid Metabolism
rs99780 · FADS2 Gene · Chr 11 · Omega-3 Metabolism
Rare and common genetic determinants of metabolic individuality and their effects on human health.
A genetic map of human metabolism across the allele frequency spectrum.
A large electronic-health-record-based genome-wide study of serum lipids.
Content updated August 2026.
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