L-Serine

Serine

Snapshot

Indications	Contraindications
Hereditary sensory neuropathy type 1¹ GRIN-related neurodevelopmental disorder² SARS1 deficiency febrile crises³ Amyotrophic lateral sclerosis⁴	Pregnancy or nursing⁵ High dose in serine synthesis defect⁶

L-serine is a dietary amino acid the body also synthesizes, serving as a precursor for membrane lipids such as phosphatidylserine⁷. Supplementation is used mainly where a genetic defect leaves serine or sphingolipid metabolism disturbed: hereditary sensory and autonomic neuropathy type 1 (HSAN1)^{1, 8}, neurodevelopmental disorders from glutamate receptor ionotropic NMDA type (GRIN) gene variants, and serine synthesis deficiency. It is also studied in amyotrophic lateral sclerosis (ALS)^{4, 9}. The typical patient has a genetically confirmed disorder.

Evidence is strongest in HSAN1, where a placebo-controlled trial found slower disease progression over one year. In ALS, a phase I trial found it generally well tolerated, with exploratory signals of slower decline against historical controls. For cognition or dementia in older adults, no clinical study has tested it⁷. In children with GRIN loss-of-function variants, a 2024 open-label single-arm trial found gains in adaptive behavior, motor function, and quality of life; no randomized trial has replicated it. Products are mostly capsules and powders; see Form comparison.

High-dose serine in one child with serine synthesis deficiency arrested head growth and lowered cerebrospinal fluid levels of other neutral amino acids, reversing on dose reduction¹⁰. Gastrointestinal effects led to withdrawals in the ALS trial⁹.

Last updated October 17, 2026. Read how we make monographs.

In the full monograph

27 sources, 20 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources