What to watch with MTHFR and skin aging?

The link between MTHFR variants (e.g., C677T) and skin aging is often overstated in marketing contexts. Mechanistically, reduced MTHFR activity can affect folate and methylation metabolism, potentially increasing homocysteine levels, which may promote oxidative stress and collagen cross-linking. However, evidence for a direct, clinically meaningful effect on skin aging is weak. Most studies are associative, do not adequately control for UV exposure, diet, and lifestyle, and show small effect sizes. MTHFR variants are very common (30–50% carry at least one copy), so a single consumer DNA test cannot predict skin aging. Established factors—sun protection, antioxidants (vitamin C, E), adequate dietary folate (leafy greens, legumes), and avoiding smoking—are far more impactful. Do not start supplementing with folic acid or methylfolate based solely on a genetic test without medical guidance. Evidence level: mechanistic/unclear. Consumer tests overstate clinical relevance.