L-Serine

Emerging interest for neuroprotection, particularly in ALS and hereditary sensory neuropathy, but clinical evidence is very early-stage.

A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.

A small Phase I/II trial in ALS patients suggested possible slowing of functional decline at high doses (30 g/day). Research in hereditary sensory neuropathy type 1 (HSAN1) showed correction of neurotoxic deoxysphingolipid levels. Large-scale efficacy trials are lacking.

• Precursor to glycine and D-serine in the brain
• Preliminary ALS data suggesting possible neuroprotection
• Corrects toxic lipid profiles in HSAN1

General: 1–3 g/day. Research trials used 15–30 g/day for neurological conditions.

• GI discomfort at high doses
• Nausea

Very high doses (15–30 g/day used in trials) may cause GI distress. Not an established treatment for any neurological condition.

ALS data is from a very small, Phase I-level trial. Broader neuroprotection claims are speculative.

• Longevity30
• Mood20