L-Threonine

Essential amino acid crucial for protein synthesis, immune function, and digestive health support

Scientific nameL-Threonine FormulaC4H9NO3 Molecular weight119.12 g/mol CAS72-19-5

90 absorption score

9 safety / 10

20 USD per month

5 documented interactions

Check it against something

Evidence level B

L-Threonine with:

78 out of 100

Works better together Compatible. Timing differs, so follow each supplement's own window.

Check it against your whole stack →

What it does

mechanism and evidence for each claim

Enhanced immune system function

Supports immune cell production and antibody synthesis

Essential for immunoglobulin and immune protein synthesis Evidence A-grade 2-4 weeks

Improved digestive health

Supports gut barrier function and intestinal health

Essential for mucin production and gut lining integrity Evidence B-grade 2-6 weeks

Enhanced protein synthesis

Critical for proper protein formation and muscle building

Essential amino acid required for all protein synthesis Evidence A-grade Ongoing with protein synthesis

Collagen and elastin support

Important for healthy skin, joints, and connective tissue

Essential component of structural proteins Evidence B-grade 4-12 weeks

Liver function support

Helps prevent fatty liver and supports liver health

Important for liver protein synthesis and fat metabolism Evidence B-grade 4-8 weeks

Others take these for the same thing

Same goal, different mechanism — check any of them against this one

Probiotics for Autoimmune Disease Support Gut health & immune modulation 10-100 billion CFU daily B 60% Magnesium Glycinate Superior absorption sleep & muscle support 200-600 mg A 90% Vitamin D3 Bone health & immune support 1000-2000 IU A 85% Magnesium Citrate Balanced absorption & digestive support 300-600 mg A 35% Chloride Electrolyte & digestive support 2300mg A 95% Bone Broth Collagen Gut healing & collagen support 20-40g powder B 85%

Every pair we checked

12 combinations scored by the engine

L-Threonine + Caffeine No documented interaction either way No known interaction 70

L-Threonine + Creatine Monohydrate No documented interaction either way No known interaction 70

L-Threonine + Calcium Carbonate No documented interaction either way No known interaction 70

L-Threonine + Whey Protein No documented interaction either way No known interaction 70

L-Threonine + Lactase No documented interaction either way No known interaction 70

L-Threonine + Bovine Collagen No documented interaction either way No known interaction 70

L-Threonine + DHA No documented interaction either way No known interaction 70

L-Threonine + Turmeric No documented interaction either way No known interaction 70

L-Threonine + Fish Oil (EPA/DHA) No documented interaction either way No known interaction 70

L-Threonine + Magnesium Oxide No documented interaction either way No known interaction 70

L-Threonine + Vitamin D3 Required for amino acid metabolism Works better together 78

L-Threonine + Zinc Gluconate Both support immune function and protein synthesis Works better together 78

Dosage

With food

Daily500-1500mg

Maintenance300-800mg daily

Immune support500-1500mg daily

Digestive health500-1500mg daily

Athletic performance500-1000mg daily

Before you take it

VeganYes

When to expect it

First Effects1-2 weeks for immune and digestive benefits

Peak Benefits4-8 weeks for structural and long-term benefits

Deficiency DevelopmentWeeks to months with inadequate protein intake

Toxicity OnsetVery rare, mainly digestive upset

How to measure it

$80-150

MarkerPlasma threonine levels

Optimal100-250 μmol/L

Deficient below<80 μmol/L

FrequencyOnly if monitoring protein status or immune function

What actually reaches you

The label counts the carrier, your body does not

Absorption Very high 90 of 100 · best absorbed form of this compound

Delivered daily 900 mg

Cost per 100 mg delivered $0.07 comparative — uses the absorption score, not a measured percentage

Works better with

3 documented

Other Essential Amino Acids

Works with other amino acids for complete protein synthesis

Synergistic effects for optimal protein formation · level A

Vitamin B6

Required for amino acid metabolism

Cofactor for amino acid processing and utilization · level B

Zinc

Both support immune function and protein synthesis

Complementary roles in immune and tissue health · level B

What not to take with L-Threonine

2 documented

High Protein Meals

Large protein meals may reduce threonine absorption

Competition with other amino acids · mild significance

Alcohol

Alcohol may interfere with threonine metabolism

Impairs amino acid processing and protein synthesis · moderate significance

Medication interactions

Discuss these with a pharmacist before combining

immunosuppressive-drugs Minor

May support immune function counter to drug effects

What to do: Monitor immune function

antibiotics Beneficial

May support gut health during antibiotic treatment

What to do: May help maintain gut barrier function

Available forms

bioavailability compared

L-Threonine (Free Form) 90

L-Threonine (Free Form): Immune support, Digestive health, Well-tolerated, Essential for growth

Food sources

before you supplement

Meat and poultry 0.8-1.2g per 100g · 90

Fish and seafood 0.7-1.0g per 100g · 90

Dairy products 0.4-0.8g per 100g · 85

Eggs 0.6g per 100g · 95

Too little

deficiency signs

Impaired immune function and frequent infections
Poor gut health and digestive issues
Slow wound healing and tissue repair
Poor growth and development in children
Muscle weakness and protein deficiency
Fatty liver development
Skin and hair problems

Too much

toxicity signs

Very rare with oral supplementation:
Mild digestive upset
Nausea with very high doses
Generally excellent safety profile

Who benefits most

immune-support

Essential for optimal immune system function

500-1500mg daily

digestive-gut-health

Supports gut barrier function and intestinal health

500-1500mg daily

athletes-muscle-building

Essential for protein synthesis and muscle development

500-1000mg daily

collagen-skin-health

Important for structural protein and collagen synthesis

500-1000mg daily

liver-health-support

Helps prevent fatty liver and supports liver function

500-1500mg daily

Where to buy it

compare forms first

Look for L-Threonine at 500-1500mg per serving. The form that matters here is L-Threonine (Free Form).

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What else affects it

Beyond other supplements

High protein meals

Large protein meals may reduce threonine absorption

Competition with other amino acids

Alcohol

Alcohol may interfere with threonine metabolism

Impairs amino acid processing and protein synthesis

How it works

Essential component of all protein synthesis
Required for immunoglobulin and antibody production
Important for mucin production in gut lining
Essential for collagen and elastin formation
Required for proper liver protein synthesis
Important for glycine and serine amino acid production

Key findings

what the evidence supports

Essential for immune system function and antibody production
Important for gut barrier function and digestive health
Critical for proper protein synthesis and structural proteins
Generally well-tolerated with excellent safety profile

Sources: NIH Examine.com · data reviewed 2026-08-01

Compiled by Denis, who maintains this database and holds no medical qualification — every figure here is sourced or derived, never asserted. How we calculate it →

Common questions

What are the benefits of L-Threonine?

Documented effects: Enhanced immune system function; Improved digestive health; Enhanced protein synthesis; Collagen and elastin support. Supports immune cell production and antibody synthesis

How much L-Threonine should you take per day?

The common daily range is 500-1500mg. By goal — maintenance: 300-800mg daily; immune support: 500-1500mg daily; digestive health: 500-1500mg daily; athletic performance: 500-1000mg daily.

When is the best time to take L-Threonine?

With food. First effects are typically reported within 1-2 weeks for immune and digestive benefits.

What are the side effects of L-Threonine?

At excessive doses: Very rare with oral supplementation:, Mild digestive upset, Nausea with very high doses, Generally excellent safety profile. Safety rating at normal doses is 9 out of 10.

What should you not take with L-Threonine?

Separate it from High Protein Meals, Alcohol by two to four hours. Large protein meals may reduce threonine absorption

Does L-Threonine interact with medications?

Documented interactions with immunosuppressive-drugs, antibiotics. Discuss these with a pharmacist before combining.

How do you know if you need L-Threonine?

The marker is Plasma threonine levels, optimal range 100-250 μmol/L. Common deficiency signs: Impaired immune function and frequent infections, Poor gut health and digestive issues, Slow wound healing and tissue repair, Poor growth and development in children.

Taken for

59 Immunity

Vitamin D3 · Vitamin C (Ascorbic Acid) · Comprehensive Immune Support Complex

74 Digestion

Lactase · Lactobacillus acidophilus · Protease