L-Serine

Tier 3 — weak evidence · Neuroprotection · ALS · Sleep

A non-essential amino acid that plays a critical role in brain phospholipid synthesis and nerve cell function. A Dartmouth safety/tolerability trial (Levine et al., JAMA Neurology 2017) showed 30 g/day was tolerated in ALS patients, with preliminary hints of slowed ALSFRS-R decline versus historical controls — no controlled efficacy trial has replicated this, so treat as experimental. Also a precursor to glycine and D-serine, both important for sleep and NMDA receptor function. Clinical evidence remains early-stage with only small trials. Very safe even at high doses.

Dose: 15–30 g/day in ALS trials (high dose); 3–5 g/day for general neuroprotection; very early-stage evidence