What you carry at this position in your DNA and what research says about it.
Omega Fatty Acid Metabolism: 8/10 evidence, 16 publications.
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Sample genotype (not yours): C/C
Efficient Omega Conversion but Higher LDL
Efficient conversion of plant-based oils into active omega fatty acids occurs alongside a tendency for higher LDL cholesterol.
What this genotype means: Highly efficient conversion of plant-based ALA to EPA; Slightly elevated LDL cholesterol levels; Typical to lower triglyceride and glucose levels.
Sample genotype (not yours): C/T
Typical Metabolic Profile
Moderate conversion of plant-derived essential fatty acids occurs alongside typical lipid and glucose levels.
What this genotype means: Moderate conversion of plant-based ALA to EPA; Average circulating lipid and cholesterol levels; Typical fasting blood glucose levels.
Sample genotype (not yours): T/T
Reduced Omega Conversion and Higher Triglycerides
Inefficient conversion of plant-based fats into active omega fatty acids is paired with elevated triglycerides and glucose.
What this genotype means: Inefficient conversion of plant-based ALA to EPA; Elevated circulating triglyceride levels; Slightly higher fasting blood glucose levels.
Gene function and biological role
Gene Function: FADS2 encodes delta-6 desaturase, a rate-limiting enzyme in the biosynthesis of long-chain polyunsaturated fatty acids [1]. It converts plant-derived alpha-linolenic acid into active eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) [1]. It also converts linoleic acid into arachidonic acid, which is vital for cellular membrane structure and inflammatory signaling [2]. Variations in this gene can significantly alter circulating lipid levels and overall metabolic health [3].
Variant Impact: The rs174583 variant is located within an intron of the FADS2 gene and acts as a major regulator of desaturase activity [3]. The C allele is associated with high expression of the enzyme, leading to rapid conversion of plant-based fatty acids into arachidonic acid and EPA [1]. Conversely, the T allele reduces enzyme activity, resulting in an accumulation of precursor plant oils and lower levels of active long-chain omega-3 and omega-6 fatty acids [1]. This genetic difference also influences circulating cholesterol and triglyceride levels [4].
Key Insight: Your ability to convert plant-based flax or chia seeds into active omega-3 fats is highly dependent on this single genetic letter.
Location: FADS2. Chromosome 11 · 11q12.2 · 61.8 Mb
Estimated prevalence by population
Global 42.6%; European 42.7%; African 52.1%; East Asian 19.8%; South Asian 63.9%; Americas 22.8%; Ashkenazi 47.6%; Finnish 33.5%; Middle Eastern 34.6%; Amish 54.9%.
Estimated CC genotype frequency.
Global 44.2%; European 45.3%; African 40.2%; East Asian 49.4%; South Asian 32.1%; Americas 49.9%; Ashkenazi 42.8%; Finnish 48.8%; Middle Eastern 48.4%; Amish 38.4%.
Estimated CT genotype frequency.
Global 13.1%; European 12.0%; African 7.7%; East Asian 30.8%; South Asian 4.0%; Americas 27.3%; Ashkenazi 9.6%; Finnish 17.8%; Middle Eastern 16.9%; Amish 6.7%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Nutrition & Metabolism
Macronutrient Metabolism
Omega-3 Conversion. Evidence: 3/10. Source: PMID 18936223. Efficient.
Cardiovascular & Metabolic
Lipids & Cholesterol
Triglycerides. Evidence: 8/10. Source: PMID 29507422. Typical.
LDL Cholesterol. Evidence: 6/10. Source: PMID 29507422. Elevated.
Diabetes & Glycemic Traits
Blood Glucose. Evidence: 8/10. Source: PMID 31669095. Typical.
Showing effects for C/T genotype
Omega-3 Conversion. Evidence: 3/10. Source: PMID 18936223. Moderate.
LDL Cholesterol. Evidence: 6/10. Source: PMID 29507422. Typical.
Showing effects for T/T genotype
Omega-3 Conversion. Evidence: 3/10. Source: PMID 18936223. Reduced.
Triglycerides. Evidence: 8/10. Source: PMID 29507422. Elevated.
Blood Glucose. Evidence: 8/10. Source: PMID 31669095. Elevated.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Efficient conversion of dietary plant-based oils into active long-chain omega-3 and omega-6 fatty acids occurs with this genotype [1]. The delta-6 desaturase enzyme operates at high capacity, producing robust levels of arachidonic acid and eicosapentaenoic acid (EPA) in blood phospholipids and breast milk [1]. While this ensures an abundant supply of critical fatty acids for cellular health and infant development, it also leads to higher circulating levels of LDL cholesterol and cholesteryl esters [2]. Conversely, blood triglyceride levels and fasting glucose tend to remain lower and within typical ranges [3]. This metabolic profile is highly advantageous for individuals consuming a primarily plant-based or vegetarian diet, as it maximizes the synthesis of essential fats from plant sources [1]. However, monitoring cardiovascular health remains important due to the associated rise in LDL cholesterol [2].
Highly efficient conversion of plant-based ALA to EPA; Slightly elevated LDL cholesterol levels; Typical to lower triglyceride and glucose levels.
Sample genotype: CT (Heterozygous)
Moderate conversion of plant-derived essential fatty acids into active long-chain polyunsaturated fatty acids is typical for this heterozygous genotype [1]. Having one copy of each allele balances the high-efficiency desaturase activity of the C allele with the reduced activity of the T allele [1]. This results in intermediate levels of arachidonic acid, EPA, and DHA in both blood circulation and breast milk [1]. Metabolic markers such as LDL cholesterol, triglycerides, and fasting blood glucose generally remain close to population averages. This balanced profile provides adequate synthesis of essential fats without severely elevating cardiovascular or glycemic risk factors. Maintaining a balanced diet rich in both plant-based alpha-linolenic acid and direct marine sources of omega-3s supports optimal lipid levels.
Moderate conversion of plant-based ALA to EPA; Average circulating lipid and cholesterol levels; Typical fasting blood glucose levels.
Sample genotype: TT (Homozygous)
Reduced delta-6 desaturase enzyme activity significantly limits the conversion of plant-based fats into active long-chain omega-3 and omega-6 fatty acids [1]. Precursor plant oils like linoleic acid accumulate in the blood, while levels of vital downstream fats like arachidonic acid and EPA are markedly lower [1]. This reduction in active fatty acids is also reflected in lower concentrations within breast milk during lactation [1]. In addition to altered fatty acid profiles, this genotype is associated with elevated fasting blood glucose and higher circulating triglycerides. However, a notable metabolic benefit is a lower level of LDL cholesterol and cholesteryl esters [2]. To compensate for the inefficient conversion process, directly consuming pre-formed long-chain omega-3s from marine sources like fish oil can help maintain optimal cellular levels.
Inefficient conversion of plant-based ALA to EPA; Elevated circulating triglyceride levels; Slightly higher fasting blood glucose levels.
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
Genetic variation in lipid desaturases and its impact on the development of human disease.
A large electronic-health-record-based genome-wide study of serum lipids.
Content updated August 2026.
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