Supplements to avoid with MTHFR
In people with MTHFR gene variants, the MTHFR enzyme functions less efficiently depending on the severity of the mutation. For example, people with two copies of the C677T mutation (homozygous) have significantly less function than those with one copy (heterozygous). Those with a less functional enzyme should avoid certain supplements, especially folic acid and high-dose methylated nutrients.
- Folic acid is the synthetic form of folate. It must be converted into its active form by the enzyme methylenetetrahydrofolate reductase before it can be used for various metabolic functions, including homocysteine metabolism and neurotransmitter production.1
If folic acid cannot be properly metabolized, less methylfolate is produced overall. It also means that folic acid accumulates in the blood, leading to unmetabolized folic acid syndrome (UMFA). UMFA has been associated with vitamin B12 deficiency, cognitive and psychiatric disorders, and pregnancy complications.2
High doses of folic acid (more than 1 mg/day) can mask the symptoms of vitamin B12 deficiency, which can lead to serious neurological damage, especially in people with megaloblastic anemia.3
It should be noted that folate is essential during pregnancy to support fetal development. Women with MTHFR variants are advised to supplement with methylfolate, the active form of folate, which requires no conversion in the body.
- High intake of methylated B vitamins is reported to cause feelings of overstimulation in some people with MTHFR variants. However, this is mostly based on anecdotal evidence.
