Table 1.

This table summarizes the functions of methyl donors that contribute to the one-carbon metabolism.

Methyl Donors	Function	References
Methionine	Precursor for SAM formation, maintenance of the redox state, and brain health.	[57]
Choline	Regulation of cholinergic signaling, maintaining cellular membrane integrity, and contributing to the formation of SAM.	[58,59,60,61]
Betaine	Choline precursor, a methyl-donor in the BHMT pathway, and anti-inflammatory functions.	[62,63,64]
Folic acid	Normal brain development, nucleotide synthesis, and prevention of neural tube defects.	[65,66,67]
Vitamin B12	Nucleotide synthesis, antioxidant properties, and maintaining brain health.	[68,69,70]
Vitamin B6	Maintenance of the redox state and brain health. Role in transamination and decarboxylation reactions required for the metabolism of several neurotransmitters. Nucleotide synthesis and protein/lipid metabolism.	[71,72,73]