Définition
BHMT (betaine-homocysteine methyltransferase) is an enzyme that clears homocysteine by attaching a methyl group from betaine (TMG). It is an alternative methylation pathway to the folate cycle — particularly important for people with MTHFR variants or elevated homocysteine.
The body has two parallel pathways for converting homocysteine back into methionine. The folate-dependent pathway uses methionine synthase with 5-MTHF and B12 as co-factors. The folate-independent pathway uses BHMT, which transfers a methyl group from betaine (trimethylglycine, TMG) to homocysteine. Both pathways operate simultaneously, but their relative importance varies by tissue — BHMT is highly expressed in the liver and kidneys.
BHMT becomes particularly important when the folate-dependent pathway is compromised. Roughly 40% of the population carries at least one variant in the MTHFR gene (C677T or A1298C), which reduces the efficiency of converting folate to its active form 5-MTHF. In these individuals, the BHMT pathway can compensate — provided adequate betaine is available.
Dietary betaine sources include beets (where the compound was originally identified), spinach, quinoa, and whole grains. Supplemental TMG is commonly used in methylation support protocols at doses of 500–2000mg daily. TMG also serves as an osmolyte (supporting cellular hydration) and has evidence for supporting exercise performance and liver health.
For women specifically, supporting BHMT is relevant during the perimenopausal decade (when homocysteine often rises) and for those with elevated homocysteine despite adequate folate and B12 intake. Checking MTHFR status through genetic testing (commonly included in 23andMe raw data) clarifies whether targeted BHMT support is likely to help. The combined approach — methylfolate, methylcobalamin, and TMG — is a conservative and effective methylation support stack.
Termes associés
Ava Longevity · Built on the Ava Method · MMXXV