How are MTHFR and Sport related?

The relationship between MTHFR and sport is primarily based on the enzyme's role in folate and homocysteine metabolism. Variants such as MTHFR C677T can reduce enzyme activity, leading to elevated homocysteine levels—a risk factor for cardiovascular issues. In sports, it is hypothesized that this could affect endurance, recovery, and injury susceptibility. However, the evidence is weak: large meta-analyses show no significant association between MTHFR variants and athletic performance or training adaptations. Most studies are small, heterogeneous, and not replicated. Moreover, many direct-to-consumer tests overstate the clinical relevance. In the EU, such health-related genetic tests are subject to strict regulations (GenDG, IVDR), requiring physician involvement and counseling; without it, they are illegal in Germany. In summary, while mechanistically plausible, the link between MTHFR and sport is not evidence-based. Individualized training or dietary adjustments based solely on MTHFR SNPs are currently not recommended.