Myths vs facts: FADS1 and Fruchtbarkeit

FADS1 encodes delta-5 desaturase, a key enzyme in polyunsaturated fatty acid (PUFA) metabolism. Genetic variants in FADS1 (e.g., rs174547) affect the conversion of alpha-linolenic acid to EPA/DHA and linoleic acid to arachidonic acid. Since arachidonic acid is a precursor for prostaglandins involved in ovulation, implantation, and uterine contractions, an indirect influence on fertility is discussed. However, the evidence is moderate: there are GWAS linking FADS1 variants to fatty acid levels and some observational studies on fertility outcomes, but no randomized controlled trials proving a causal effect. MyBody-X DNA tests may include such variants, but effect sizes are small and clinical relevance is unclear. Fertility is multifactorial (age, hormones, lifestyle, nutrition). A single FADS1 variant has no diagnostic or predictive value. Consumers should not rely on such genetic tests for family planning and should consult a physician. Evidence: human-moderate.