The BHMT gene is central to the ‘short cut’ through the methylation cycle, again helping to convert homocysteine to methionine, using betaine as a methyl donor. In this way, the BHMT pathway acts as a backup pathway in folate deficiency.
The activity of this gene can be affected by stress, cortisol levels and may play a role in ADD/ADHD by affecting norepinephrine levels. BHMT plays a role in the GUT-brain axis, playing a role in how an individual is able to concentrate while under the effects of stress.
Some genetic variations in this gene have been associated with increased homocysteine levels in the blood. Elevated homocysteine can be very damaging to tissue, particularly the specialised endothelial tissue which lines the blood vessels and heart.
It's better to have this gene increased/upregulated most of the time as it leads to lower homocysteine levels as well as less dependency on folate and B12.
BHMT can be upregulated with TMG (trimethylglycine), betaine, zinc, phosphatidylcholine/choline, selenium, taurine, and B9 (folate).