Folate metabolism (MTHFR gene)

The MTHFR gene makes an enzyme that helps your body process folate (vitamin B9) and clear a substance called homocysteine. A common version of the gene lowers that enzyme's activity, though its health importance is usually mild and often overstated online.

Possible results

Normal folate metabolism. You have two standard copies of MTHFR, so the enzyme that processes folate (vitamin B9) works at full strength. Your body clears a substance called homocysteine normally, and this gene gives you no special reason to worry about folate. A balanced diet is plenty.

Slightly reduced folate metabolism. You have one standard and one slower copy of MTHFR, so the enzyme runs at roughly two-thirds of its usual speed. For almost everyone this makes no real difference, and a normal diet with folate from greens, beans and grains covers it.

Reduced folate metabolism. You have two copies of the slower MTHFR variant, so this enzyme runs at roughly 30% of its usual speed. That can let a substance called homocysteine build up a little, which is why some people make a point of getting enough folate from leafy greens, beans and fortified grains. For most people the effect is mild, and this gene's health impact is often exaggerated online.

Evidence & sources

Across global populations, about 11% of people carry two copies of this variant, and about 47% carry none.

This variant appears in 11 published genetic studies: PubMed 20031578 · PubMed 23696881 · PubMed 23754956 · PubMed 23824729 · PubMed 29953918 · PubMed 30339177 · PubMed 34707639 · PubMed 37479695 · PubMed 38626723 · PubMed 39024449 · PubMed 39414775.

Common questions

What does reduced folate metabolism mean? It means the MTHFR enzyme that converts dietary folate into its active form works more slowly than average. With one slower copy (CT) it runs at roughly two-thirds speed, and with two (TT) at roughly a third. In practice this only means your body is a little less efficient at processing folate, which a folate-rich diet easily makes up for.

Is the MTHFR C677T variant dangerous? For most people, no. The T version of MTHFR C677T lowers the enzyme's activity and can raise homocysteine slightly, but the health impact is usually mild and is often exaggerated online. Getting enough folate from leafy greens, beans and fortified grains covers it for the large majority of carriers, even those with two copies.

Should I take methylfolate if I have the MTHFR gene variant? Usually it is not necessary. A normal diet with folate from food is enough for most people with the CT or TT genotype, and ordinary folic acid is still processed effectively by the body. Some clinicians suggest methylfolate in specific situations, such as pregnancy planning with elevated homocysteine, but that is an individual medical decision. This result is educational and not a prescription, so discuss supplements with a doctor.

Related

Adult lactose digestion · Beta-carotene to vitamin A conversion (BCO1) · Caffeine metabolism speed · Fat taste sensitivity (CD36) · LDL cholesterol · Sweet tooth / carbohydrate preference (FGF21) · Vitamin D status (low-D genetic burden)