Background

Threonine is an essential amino acid. Amino acids are the building blocks the body uses to make proteins. The "essential" amino acids are those that cannot be made by the body and must be obtained from the diet.

People use threonine for conditions such as a muscle control disorder marked by involuntary movements and muscle tightness (spasticity), multiple sclerosis (MS), inherited disorders marked by weakness and stiffness in the legs (familial spastic paraparesis or FSP), and Lou Gehrig's disease (amyotrophic lateral sclerosis or ALS), but there is no good scientific evidence to support these uses.

Safety Safety definitions

When taken by mouth: Threonine is LIKELY SAFE when used in food amounts. It's been proposed that people need to get about 0.5 to 1 gram of threonine from their diet per day. This amount is considered to be safe. Threonine is POSSIBLY SAFE when used as a medicine. Doses of up to 4 grams of threonine daily have been used safely for up to 12 months. Some people experience minor side effects such as stomach upset, headache, nausea, and skin rash.

Special Precautions & Warnings:

Pregnancy and breast-feeding: There isn't enough reliable information to know if threonine is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Amyotrophic lateral sclerosis (Lou Gehrig's disease):There is some concern that threonine might decrease lung function in patients with ALS. In one study, ALS patients taking 1 gram of threonine four times per day for 6 months had significantly reduced lung function compared to patients who did not receive threonine. More evidence is needed to determine if threonine was actually at fault.

Effectiveness

Dosing & administration

The appropriate dose of threonine depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for threonine. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

Interactions with pharmaceuticals

Medications for Alzheimer disease (NMDA antagonists)

Interaction Rating=Major Do not take this combination.

There is some concern that threonine might decrease how well a medication used for Alzheimer's disease works. This medication is called memantine (Namenda).

Interactions with herbs & supplements

Alanine: Threonine might compete with other amino acids to gain access to the central nervous system (CNS) through a "gateway" called the blood-brain barrier. It's possible that high blood levels of amino acids such as alanine might decrease how much threonine enters the CNS. This could decrease the effectiveness of threonine.
Branched-chain amino acids: Threonine might compete with other amino acids to gain access to the central nervous system (CNS) through a "gateway" called the blood-brain barrier. It's possible that high blood levels of branched-chain amino acids might decrease how much threonine enters the CNS. This could decrease the effectiveness of threonine.
Phenylalanine: Threonine might compete with other amino acids to gain access to the central nervous system (CNS) through a "gateway" called the blood-brain barrier. It's possible that high blood levels of amino acids such as phenylalanine might decrease how much threonine enters the CNS. This could decrease the effectiveness of threonine.
Serine: Threonine might compete with other amino acids to gain access to the central nervous system (CNS) through a "gateway" called the blood-brain barrier. It's possible that high blood levels of amino acids such as serine might decrease how much threonine enters the CNS. This could decrease the effectiveness of threonine.
Tryptophan: Threonine might compete with other amino acids to gain access to the central nervous system (CNS) through a "gateway" called the blood-brain barrier. It's possible that high blood levels of amino acids such as tryptophan might decrease how much threonine enters the CNS. This could decrease the effectiveness of threonine.
Tyrosine: Threonine might compete with other amino acids to gain access to the central nervous system (CNS) through a "gateway" called the blood-brain barrier. It's possible that high blood levels of amino acids such as tyrosine might decrease how much threonine enters the CNS. This could decrease the effectiveness of threonine.

Interactions with foods

There are no known interactions with foods.

Action

Threonine is changed in the body to a chemical called glycine. Glycine works in the brain to reduce constant and unwanted muscle contractions (spasticity).