Trimethylglycine (TMG / betaine anhydrous)

Tier 3 — weak evidence · Methyl donor · Homocysteine · Performance

Also known as betaine. Acts as a direct methyl donor in the methionine cycle, lowering elevated homocysteine. The performance literature (separate from the cardiovascular literature) shows small but consistent strength and power benefits at 2.5 g/day. Relevant for users on high-dose niacin or other methylation-depleting compounds. Generally well tolerated; very high doses can mildly raise LDL.

Dose: 1.5–3 g/day for homocysteine; 2.5 g/day for performance endpoints