Threonine Interactions Overview

Additional Details

Is L-Threonine Safe? Are There Any Warnings?

L-Threonine is considered safe when taken orally in food amounts. Daily doses of 7-14 mg/kg (about 0.5-1 gram) of L-threonine are generally safe and necessary for maintaining a positive nitrogen balance in humans.

Taking up to 4 grams daily of L-threonine for up to 12 months is also likely safe when used medicinally. However, during pregnancy and lactation, it's best to avoid using L-threonine due to insufficient information available. Some reported side effects include minor gastrointestinal upset, headaches, rhinorrhea, flatus, constipation, and skin rash. One patient experienced increased serum ammonia levels with high doses of L-threonine.

How Does L-Threonine Work? What Is the Mechanism of Action?

L-Threonine, an essential amino acid, has garnered interest for its potential in addressing spasticity and amyotrophic lateral sclerosis (ALS). It serves as a precursor to glycine, a major inhibitory neurotransmitter in the spinal cord.

Unlike glycine, which has limited central nervous system (CNS) penetration, L-threonine can better enter the CNS. By increasing glycine levels in the spinal cord, L-threonine might help reduce spasticity associated with spinal cord injury. In ALS cases, where excessive excitatory amino acids like glutamate play a role, boosting glycine as an inhibitory neurotransmitter could counteract these excitatory effects.

Pharmacokinetics

After oral consumption, L-threonine levels in the plasma rise swiftly. Fasting threonine levels are around 113 mcgMol/L, and with a daily intake of 6 grams over two weeks, these levels can reach an average of 498 mcgMol/L. Peak threonine concentrations occur within about 2 hours after ingestion.

Interaction Overview

Interactions with Drugs

L-Threonine's interaction with NMDA antagonists, like memantine, can have a notable impact due to its ability to increase glycine levels in the central nervous system. This might diminish the effects of NMDA receptor antagonists.

Interactions with Supplements

L-Threonine's interaction with certain amino acids, including alanine, branched-chain amino acids, phenylalanine, serine, tryptophan, and tyrosine, can compete for passage through the blood-brain barrier into the CNS. This competition may affect how much L-threonine enters the CNS and consequently influence its effectiveness.

Common Side Effects To Watch For

Minor gastrointestinal discomfort, headaches, rhinorrhea, flatus, constipation, and skin rash are among the reported side effects of L-threonine use.

Are Supplements Standardized?

Reliable information about the standardization of L-threonine supplements is lacking.

What Is L-Threonine Typically Used For?

L-Threonine finds use in addressing conditions such as spasticity, multiple sclerosis (MS), familiar spastic paraparesis (FSP), and amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). However, its effectiveness is still being studied and more evidence is needed to establish its benefits in these areas.

Dosing & Administration

For familial spastic paraparesis (FSP), dosages of 1.5 to 2 grams of L-threonine taken three times daily for 2 weeks have been utilized. In the case of spasticity, 2 grams of L-threonine taken three times daily for 2 weeks has been employed.

Drugs that interact with Threonine