Universal methyl donor for >100 methyltransferases — DNMT (DNA methylation), HMT (histones), COMT (catecholamine inactivation), GNMT (creatine synthesis), PEMT (phosphatidylcholine synthesis). Donates a methyl group to become S-adenosyl-homocysteine (SAH), then demethylated to homocysteine. SAMe/SAH ratio is the 'methylation potential.' Clinical antidepressant effect comparable to TCAs in some RCTs.
Half-Life (t½)
PO: 6.17h, IV: 4.1h
Dosing Guidelines
PO: Typical 800 mg (Range: 400–1600 mg)
IV: Typical 800 mg (Range: 400–1600 mg)
IM: Typical 800 mg (Range: 400–1600 mg)
Target Organ Systems
nervous
Interactions
Methionine (synergistic): SAMe is one step downstream of methionine.
L-Methylfolate (synergistic): Folate / B12 cycle regenerates methionine from homocysteine, replenishing the SAMe pool.
TMG (Betaine) (synergistic): Alternate methyl donor for homocysteine → methionine via BHMT.