Evidence-based·Last reviewed May 30, 2026·How we grade evidence

L-Threonine

Amino-acidL-threonineBest in the morning

Useful mainly for correcting dietary threonine deficiency; a research-level option for spasticity.

Quick decision guide

May help most

correcting dietary threonine deficiency; a research-level option for spasticity

Common dosing range

500–2,000 mg/day (RDA ~1,400 mg for a 70 kg adult)

When to expect effects

Weeks

Watch out for

Avoid in hereditary disorders of threonine metabolism

What is it

L-threonine is an essential amino acid that the body cannot synthesize and must obtain from food. It supports protein synthesis, immune function, intestinal mucus production, and connective tissue and tooth enamel structure.

Is it worth it for you?

Use this as a quick fit check, not a diagnosis.

Worth considering if…

You have inadequate intake of this essential amino acid
You are exploring high-dose use for spasticity under clinical guidance

Probably skip if…

You already eat adequate complete protein
You expect proven gut, immune, or wound-healing benefits
You have a hereditary threonine metabolism disorder

Evidence at a glance

threonine deficiency / nutritional repletion

Strong Evidence
Effect
Corrects deficiency
Best fit
people with inadequate essential amino acid intake
Time
Weeks

gut barrier / mucin production

Limited Evidence
Effect
Mechanistic
Best fit
not established in humans
Time
Unknown

immune function (antibody synthesis)

Limited Evidence
Effect
Mechanistic
Best fit
not established in humans
Time
Unknown

Evidence for 3 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

threonine deficiency / nutritional repletion

Corrects deficiency
Strong Evidence

Threonine is an essential amino acid required for protein synthesis, intestinal mucin, and antibody production, and the body cannot make it. Severe deficiency causes growth impairment, immune dysfunction, and GI problems, all of which repletion addresses. Correcting an established deficiency is a well-accepted use.

Effect size
Corrects deficiency
Time to effect
Weeks
Best fit
people with inadequate essential amino acid intake
Less likely
people already replete from complete dietary protein

Bottom line: Supplementation reliably corrects threonine deficiency when intake is inadequate.

SourceMalinovsky et al., 2018 — PubMed

gut barrier / mucin production

Mechanism only
Limited Evidence

Threonine is heavily incorporated into intestinal mucin proteins that maintain the protective gut mucus layer, and animal studies link threonine availability to mucin synthesis. Human clinical outcomes for gut-barrier supplementation are not established. The support is mechanistic rather than clinical.

Effect size
Mechanistic
Time to effect
Unknown
Best fit
not established in humans

Bottom line: Biologically central to gut mucin, but human benefit from supplementation is unproven.

SourceZhang et al., 2019 — PubMedPuiman et al., 2011 — PubMed

immune function (antibody synthesis)

Mechanism only
Limited Evidence

Threonine is a key component of immunoglobulins, so adequate supply supports humoral immunity. Evidence that supplementing above dietary needs improves clinical immune outcomes in people is lacking. This is a mechanistic rationale, not a demonstrated clinical benefit.

Effect size
Mechanistic
Time to effect
Unknown
Best fit
not established in humans

Bottom line: Needed for antibody production, but extra intake is not shown to boost immunity clinically.

SourceZhang et al., 2019 — PubMed

How it works

L-threonine is absorbed in the small intestine and used in protein synthesis throughout the body. It is particularly abundant in mucin proteins that line the gut, where it helps maintain the protective mucus layer of the intestinal wall. Threonine is also a key component of immune system proteins, particularly antibodies, supporting humoral immunity. In metabolism, threonine can be converted to glycine and acetyl-CoA via the threonine dehydrogenase pathway, contributing to energy production and one-carbon metabolism. Its hydroxyl group makes threonine a target for protein phosphorylation, an important regulatory mechanism in cell signaling. Threonine is also notable for its role in collagen and elastin synthesis, supporting connective tissue health, and is incorporated into tooth enamel proteins. Severe deficiency causes growth impairment, immune dysfunction, and gastrointestinal problems.

How to take it

1. Typical dose
500–2,000 mg/day
2. Higher studied dose
4.5–6 g/day in spasticity studies
3. Timing
No strict preferred time; morning is well tolerated
4. With food
With or without food; empty-stomach dosing may improve absorption
5. Split dosing
Split larger doses across the day for steady availability
6. How long to try
Ongoing for repletion; trial several weeks for spasticity

What to track

dietary protein adequacy
muscle spasticity if that is the goal
GI tolerance

1 commercial form

Compare the main delivery options and what they’re best suited for.

L-threonine (free form)

The natural isomer used in proteins.

Standard supplement form; well absorbed.

Safety

Know the common side effects, key cautions, and who should avoid it.

Common side effects

GI upsetheadacheskin rash in sensitive individuals at higher doses

Who should avoid it

  • people with hereditary disorders of threonine metabolism
  • children without medical guidance for high-dose use

Pregnancy & breastfeeding

Pregnant and lactating women should not exceed dietary amounts unless directed by a clinician.

Interactions

other amino acidsMinor

May compete for transport at high doses

Food sources

Chicken breast (3 oz, cooked)

Amount
1,200 mg
%DV
—

Beef (3 oz, cooked)

Amount
1,100 mg
%DV
—

Tuna (3 oz, cooked)

Amount
1,100 mg
%DV
—

Salmon (3 oz, cooked)

Amount
950 mg
%DV
—

Eggs (1 large)

Amount
300 mg
%DV
—

Cottage cheese (1/2 cup)

Amount
560 mg
%DV
—

Lentils (1 cup, cooked)

Amount
660 mg
%DV
—

Soybeans (1 cup, cooked)

Amount
1,200 mg
%DV
—

Choosing a product

What to look for on the label — and what to be skeptical of.

Look for…

pure L-threonine form
stated amount per serving
free of unnecessary fillers

Be skeptical of…

'cures leaky gut'
'immune booster'
'builds muscle' overstatement

Frequently asked questions

Do I need a threonine supplement?⌄

Probably not. Most omnivorous diets provide ample threonine. Supplementation may be considered for specific clinical situations like inflammatory bowel disease, malnutrition, or research protocols.

Does threonine help my gut?⌄

Threonine is concentrated in intestinal mucin proteins, which form the protective gut barrier. Adequate intake supports gut integrity, but supplementation in healthy adults has limited direct evidence.

Can threonine help with spasticity?⌄

Older studies of high-dose threonine for spasticity in MS or ALS showed mixed results. It is not part of standard care.

Is threonine safe?⌄

Yes, at dietary and typical supplement doses. Long-term high-dose safety is less well-characterized.

What foods are high in threonine?⌄

Animal proteins (meat, fish, poultry, dairy, eggs), legumes (lentils, soybeans), and certain seeds. Vegetarians and vegans can get enough from varied plant proteins.

References by claim

threonine deficiency / nutritional repletion

Malinovsky et al., 2018 — PubMed (2018) link

gut barrier / mucin production

Zhang et al., 2019 — PubMed (2019) link

Puiman et al., 2011 — PubMed (2011) link

Track L-Threonine with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

Coming to App Store
Evidence-based·Last reviewed May 30, 2026·Evidence current as of May 30, 2026·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.