Evidence check: FADS1 in the context of fertility

FADS1 encodes delta-5 desaturase, a key enzyme in the conversion of alpha-linolenic acid (ALA) to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These long-chain omega-3 fatty acids are critical for reproductive health: DHA is a major structural component of sperm and the developing fetal brain, while EPA influences prostaglandin synthesis and inflammation. Variants in FADS1 (e.g., rs174547) have been associated with altered blood levels of EPA and DHA. However, direct evidence linking FADS1 variants to fertility outcomes (e.g., time to pregnancy, IVF success, sperm parameters) is sparse and mostly based on observational or mechanistic studies. A few small studies suggest that women with certain FADS1 genotypes may have different omega-3 status and possibly altered fertility, but no large-scale replication or clinical trials exist. Therefore, while the biological plausibility is strong, the evidence for a direct, actionable role of FADS1 in fertility is currently weak. Consumers should not make dietary changes solely based on FADS1 genotype without measuring actual omega-3 levels. Evidence grade: mechanistic. Safety note: Omega-3 supplementation is generally safe, but high doses may have anticoagulant effects.