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Supplements · Amino acids

Threonine: Benefits, Food Sources, Daily Needs & Supplements

What threonine is, why your body can't make it, which foods supply the most, how it helps build the mucus that protects your gut lining, and what the human trials of threonine supplements found.

By Dr. Josh Axe, DC, DNM, CNS·19-min read
Meet the Medical Advisory Board
Evidence-based60 sources citedUpdated October 18, 2026
Published Oct 18, 2026Last updated Oct 18, 2026Editorial policyMedical review policyFact-checking policy
Two panels of protein foods: salmon steaks, raw beef, chicken breast, eggs, a wedge of cheese and bowls of beans and chickpeas above; milk, cottage cheese, yogurt and almonds below
Threonine comes with the protein in meat, fish, eggs, dairy, beans and seeds.
The Dr. Axe Score™
6.0/10
Overall Dr. Axe Score · Threonine

Threonine scores 6.0 as a supplement for its dependable uptake by mouth, its clean record at high doses and a set of older human trials, most of them in nerve-related muscle stiffness, where it eased the physical signs.

Scientific Evidence
4.6/10
At least seven trials in nerve conditions from 1982 to 1996, the largest with 95 people, a 12-patient PKU trial and a 2025 safety trial; strong human requirement studies.
Bioavailability & Absorption
7.8/10
Doses by mouth raised threonine in blood and spinal fluid; in adults, the gut and liver keep about 18% on the first pass.
Clinical Effectiveness
4.2/10
Protein foods cover the daily need; as a supplement, it eased spasticity signs in three trials.
Safety & Tolerability
8.0/10
No adverse effect at up to 12 g a day for 4 weeks; one ALS trial raised a lung-function concern.
Why this score?
Why Threonine scores 6.0 / 10

    Larger, longer trials of the uses people take it for would raise the score; in food, it comes with the protein you eat. Weighting: Evidence 30% · Bioavailability & Absorption 25% · Clinical Effectiveness 25% · Safety & Tolerability 20% (4.6×0.30 + 7.8×0.25 + 4.2×0.25 + 8.0×0.20 = 5.98, shown as 6.0). How we score

    A transparent, weighted index built for supplements. See how it’s calculated →

    Interaction check: Low. The human threonine studies on this page report no drug interactions.111213 Because threonine was tested for nerve-related muscle stiffness, if you take medicine for a brain or nerve condition, keep taking it as prescribed and clear any threonine supplement with your prescriber first. Interactions are rated separately and don't change the score.

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    Threonine at a glance

    Threonine is one of the nine essential amino acids your body can't make, and you get it from protein foods: a 3-ounce roasted chicken breast carries about 1,114 mg, roughly a full day's need for a 154-pound adult.12

    • Gut lining: threonine is one of the main building blocks of MUC2, the mucus protein that shields your intestinal lining3
    • Food: grass-fed bison, wild salmon, sardines, lentils, black beans and hemp seeds are rich sources456789
    • Muscle stiffness: in three controlled trials of 18 to 33 people, 4.5 to 7.5 grams a day eased the physical signs of spasticity101112
    • Safety: healthy men took up to 12 grams a day for 4 weeks with no adverse effect13

    The free Healing Leaky Gut protocol builds its Repair step around protein foods like bone broth, pasture-raised eggs and wild salmon.

    Every protein in your body, from the muscle in your legs to the lining of your gut, is built from amino acids, and threonine is one your body can't make on its own. It has to come from food, and it arrives with the protein you already eat: meat, fish, eggs, dairy, beans, lentils and seeds.

    One of its most important jobs happens in your gut. Your intestines are coated with a layer of mucus, and threonine is one of the amino acids its main protein is built around. Sugars attach to that protein so densely that researchers compare it to a bottle brush.3

    Protein builds and maintains every tissue in your body, even the lining of your gut.14 Eat enough high-quality protein and your threonine follows. Researchers have also tested threonine on its own as a supplement, mostly in nerve conditions such as muscle stiffness and ALS.

    Protein isn't just about muscle; it's about longevity at the cellular level. Amino acids, proteins, and peptides form the scaffolding and signaling system that keep your body biologically young. When you fall short, you accelerate organ aging.Dr. Josh Axe, DC, DNM, CNSFrom Heal Your Cells (2026), p. 131

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    Did you know?

    • Biochemist William C. Rose is credited with discovering threonine: in 1935, his laboratory reported isolating and identifying a new essential amino acid in feeding experiments with purified amino acids.1516

    • In the one-letter code scientists use to write out protein sequences, threonine is T. Its three-letter abbreviation is Thr.17

    • Arctic fish survive in supercooled water with the help of antifreeze glycoproteins, built from a repeating three-amino-acid unit that ends in a sugar-coated threonine. When researchers swapped that threonine for serine, the antifreeze effect disappeared.18

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    What is threonine?

    Quick answer

    Threonine is one of the nine essential amino acids, the protein building blocks your body can't make, so it has to come from food.1413 The form in food, and the form your body builds into protein, is L-threonine.19

    Your body strings 20 amino acids together to make its proteins. Nine of them are essential: they must come from your diet, and without them your body can't function properly.14 Threonine is one of those nine, along with lysine, leucine, methionine and tryptophan.2 It's a small molecule, with the chemical formula C4H9NO3.19

    Its closest chemical relative is serine, another protein building block. Both carry a hydroxyl group on their side chain, the spot where sugars and phosphate groups attach, and threonine has one extra methyl group. A 2023 review traces how that single methyl group changes the way those attachments behave.18 That hydroxyl group is where the sugar coating on your gut's mucus attaches.3

    What does threonine do in your body?

    Threonine does two main jobs: it's built into proteins throughout your body, and your gut uses it to make the mucus that protects your intestinal lining.3

    1It arrives with protein food

    A 3-ounce roasted chicken breast carries about 1,114 mg of threonine, roughly a day's need for a 154-pound adult.12

    2Your gut takes its share first

    Before the rest reaches your bloodstream, your gut and liver keep part of the threonine you eat, far more in preterm babies than in adults. The chart below shows how much.2021

    3Goblet cells build mucus with it

    MUC2, the main mucus protein of the intestine, has two long central stretches rich in threonine, serine and proline, and the goblet cells that make it attach sugars at the threonine and serine sites.3

    4The mucus shields the lining

    In the colon, the inner mucus layer normally keeps gut bacteria off the cells of the lining. When bacteria get through it, they reach those cells and trigger inflammation.322

    5The rest builds protein everywhere else

    Beyond the gut, threonine goes into proteins throughout your body, and what isn't used is broken down. In a study of 6 healthy men, only 7% to 11% of that breakdown took the route that makes glycine,23 and in two of the trials below, threonine supplements raised threonine in blood and spinal fluid while glycine stayed the same.1012

    The share your gut claims depends on your age. In 8 preterm babies, the gut took 82% of the threonine they were fed on its first pass while part of their nutrition still came by IV, and 70% once they were fed entirely through the gut.20 In 6 healthy men on an amino acid formula, the gut and liver together took 17.9%, about the same share they took of lysine (18.5%).21 So in adults, most of the threonine you eat travels on to the rest of your body.

    A preterm baby's gut keeps most of its threonine; an adult's gut and liver keep less than a fifth

    A preterm baby's gut keeps most of its threonine; an adult's gut and liver keep less than a fifth8 preterm babies fed entirely through the gut · 6 healthy men on an amino acid formula · two separate studies. Preterm babies: 70 % kept on first pass; Healthy adult men: 17.9 % kept on first pass8 preterm babies fed entirely through the gut · 6 healthymen on an amino acid formula · two separate studies
    70 % kept on first pass
    PRETERM BABIES
    17.9 % kept on first pass
    HEALTHY ADULT MEN
    Source: van der Schoor et al. · American Journal of Clinical Nutrition, 2007; Chapman et al. · Journal of Nutrition, 2013 [20]Share of dietary threonine taken up on its first pass, by the gut in the babies and by the gut and liver in the men, before the rest reached the body.

    Which foods are highest in threonine?

    Quick answer

    Animal proteins lead: a 3-ounce roasted chicken breast has about 1,114 mg of threonine, and 3 ounces of lean beef, grass-fed bison or wild salmon carries about 950 to 1,040 mg.12445 A cup of cooked black beans or lentils supplies about 640 mg.87

    Values from USDA FoodData Central (SR Legacy). Per-serving amounts are calculated from the per-100-gram values for the serving shown. USDA's grass-fed beef records don't list amino acids, so the beef row uses its lean top sirloin record.

    FoodServingThreonineProteinThreonine per 100 g

    Chicken breast, roasted (choose pasture-raised)

    3 oz (85 g)

    1,114 mg

    26.4 g

    1,310 mg1

    Beef, top sirloin, lean, broiled (choose grass-fed)

    3 oz (85 g)

    1,037 mg

    26.0 g

    1,220 mg24

    Bison, grass-fed, ground, cooked

    3 oz (85 g)

    986 mg

    21.6 g

    1,160 mg4

    Lamb, ground, broiled

    3 oz (85 g)

    901 mg

    21.1 g

    1,060 mg25

    Turkey breast, roasted (choose pasture-raised)

    3 oz (85 g)

    832 mg

    25.6 g

    979 mg26

    Sardines, Atlantic, canned in oil, with bone

    1 can (3.75 oz), drained (92 g)

    994 mg

    22.6 g

    1,080 mg6

    Salmon, Atlantic, wild, cooked

    3 oz (85 g)

    952 mg

    21.6 g

    1,120 mg5

    Halibut, cooked

    3 oz (85 g)

    944 mg

    19.1 g

    1,110 mg27

    Cod, Atlantic, cooked

    3 oz (85 g)

    850 mg

    19.4 g

    1,000 mg28

    Cottage cheese, full-fat (choose A2)

    1 cup (225 g)

    1,125 mg

    25.0 g

    500 mg29

    Goat milk

    1 cup (244 g)

    398 mg

    8.7 g

    163 mg30

    Goat cheese, hard

    1 oz (28.35 g)

    323 mg

    8.6 g

    1,140 mg31

    Egg, hard-boiled (choose pasture-raised)

    1 large (50 g)

    302 mg

    6.3 g

    604 mg32

    Black beans, cooked

    1 cup (172 g)

    642 mg

    15.2 g

    373 mg8

    Lentils, cooked

    1 cup (198 g)

    640 mg

    17.9 g

    323 mg7

    Chickpeas, cooked

    1 cup (164 g)

    540 mg

    14.5 g

    329 mg33

    Hemp seeds, hulled

    3 tbsp (30 g)

    381 mg

    9.5 g

    1,270 mg9

    Pumpkin seeds, dried

    1 oz (28.35 g)

    283 mg

    8.6 g

    998 mg34

    Spirulina, dried

    1 tbsp (7 g)

    208 mg

    4.0 g

    2,970 mg35

    Threonine in one serving: animal proteins lead, and beans, lentils and seeds add a solid share

    Threonine in one serving: animal proteins lead, and beans, lentils and seeds add a solid shareUSDA FoodData Central values for one stated serving · a 154-pound adult needs about 1,050 mg a day. Cottage cheese, 1 cup (choose A2): 1125 mg per serving; Chicken breast, 3 oz roasted: 1114 mg per serving; Beef top sirloin, 3 oz lean: 1037 mg per serving; Sardines, 1 can (3.75 oz): 994 mg per serving; Grass-fed bison, 3 oz cooked: 986 mg per serving; Wild Atlantic salmon, 3 oz cooked: 952 mg per serving; Lamb, 3 oz broiled: 901 mg per serving; Black beans, 1 cup cooked: 642 mg per serving; Lentils, 1 cup cooked: 640 mg per serving; Hemp seeds, 3 tbsp: 381 mg per servingUSDA FoodData Central values for one stated serving · a154-pound adult needs about 1,050 mg a dayCottage cheese,1 cup (chooseA2)1125 mg per servingChicken breast,3 oz roasted1114 mg per servingBeef topsirloin, 3 ozlean1037 mg per servingSardines, 1 can(3.75 oz)994 mg per servingGrass-fed bison,3 oz cooked986 mg per servingWild Atlanticsalmon, 3 ozcooked952 mg per servingLamb, 3 ozbroiled901 mg per servingBlack beans, 1cup cooked642 mg per servingLentils, 1 cupcooked640 mg per servingHemp seeds, 3tbsp381 mg per serving
    Source: USDA FoodData Central (SR Legacy): FDC 172179, 171477, 168634, 175139, 173847, 171998, 172544, 173735, 172421, 170148; daily need: WHO/FAO/UNU, 2007 [1]Milligrams of threonine in one serving of each food. A longer bar means more threonine.

    Where your protein comes from matters as much as how much you eat. Grass-fed and pasture-raised meats provide more amino acids per calorie, along with more omega-3s and CLA, and wild-caught fish deliver complete proteins alongside EPA and DHA.14

    Keep red meat fresh, unprocessed and grass-fed. The WHO's cancer agency classifies processed meat of every kind, processed beef included, as a Group 1 carcinogen, largely on colorectal cancer data, and rates red meat itself Group 2A, probably carcinogenic.3637 As I've said on my show, the studies that link red meat to poor health mostly reflect grain-fed and processed meat, not the fresh, grass-fed red meat I recommend.38

    For dairy, the kind matters too. In The Biblio Diet, Jordan Rubin and I put goat milk, goat milk hard cheese and full-fat A2 cottage cheese on the list of dairy to enjoy, and cow's milk products that aren't A2 on the list to avoid.39 Plants carry threonine as well. On my show, I've said that for plant protein, beans, lentils, chickpeas, nuts and seeds are the best,40 and the table shows how much threonine they bring. For more ideas, see our guides to high-protein foods and plant-based protein foods.

    How much threonine do you need a day?

    Quick answer

    Healthy adults need about 15 mg of threonine per kilogram of body weight a day, roughly 1,050 mg for a 154-pound adult, by the World Health Organization's estimate.2 A 3-ounce chicken breast or a can of sardines supplies about that much on its own.16

    That figure rests on careful human studies. In 16 healthy men in India, each tested at three of six intakes, the body's protein balance leveled off at 15 mg per kilogram a day, and the researchers concluded that the older 1985 international figure of 7 mg per kilogram was too low.41 A 2023 study of 11 healthy young men put the requirement at 10.5 to 12.1 mg per kilogram, whether they had 1, 3 or 7 days to adjust to each intake.42 In everyday numbers, 15 mg per kilogram works out to about 820 mg a day if you weigh 120 pounds and about 1,360 mg at 200 pounds.

    You don't need to count threonine itself, because it comes packaged with protein. I recommend 0.7 to 1 gram of protein per pound of body weight a day, closer to 1 gram if you're over 40,43 and most of you want at least 30 to 40 grams of protein three times a day.44 Hit that, from the foods above, and you've covered your threonine several times over. Our guide to how many grams of protein per day walks through the math for your body.

    Severe protein deficiency is rare in the U.S., but falling short on amino acids is common and quietly speeds aging.14 If you eat only plants, legumes and seeds can cover your threonine: a cup of cooked lentils, a cup of black beans and 3 tablespoons of hemp seeds together supply about 1,660 mg.789 Over the long term, though, I see major deficiencies in people on all-plant diets, so if you eat this way, I recommend a B complex, with vitamin B12 most important, and a DHA and EPA supplement.45 Our guide to protein deficiency covers the signs to watch for.

    What is threonine good for?

    Quick answer

    Threonine's clearest role is as an essential building block of protein, including the mucus that protects your gut lining.143 As a supplement, it eased the physical signs of muscle stiffness in three controlled trials and lowered blood phenylalanine in a 12-patient PKU trial.10111246

    Where the research stands

    The human research on threonine supplements is small and mostly older: at least seven trials in nerve-related conditions between 1982 and 1996, the largest with 95 people, a 12-patient trial in PKU and a 2025 safety trial in 30 healthy men. The gut research is mostly in animals, so each result below names its species, and every trial names its dose and design.

    Threonine benefits, graded by evidence (updated October 2026). Evidence labels are editorial judgments that compare these uses with each other; they aren't formal certainty ratings.
    UseEvidenceProduct studiedWhat the research shows

    Building protein

    		Strong

    Threonine in the diet

    Adults need about 15 mg per kilogram a day; the older figure of 7 mg fell short41422

    Muscle stiffness (spasticity)

    		Emerging

    L-threonine, 500 mg to 7.5 g a day

    Fewer physical signs of spasticity on examination and rating scales; 29% better motor performance in the 6-person study11101247

    Phenylalanine control in PKU

    		Emerging

    L-threonine, about 50 mg per kg a day

    Lower blood phenylalanine after 8 weeks46

    Gut-lining mucus

    		Preclinical

    Threonine in the diet or feed; an amino acid mix in rats

    Less mucin when threonine ran short; with added threonine, more mucus protein in piglets and more goblet cells in piglets and rabbits; slower recovery in mice given it as colitis began48495051

    Threonine benefits, ranked by evidence

    Ordered by the strength of the human research, threonine's benefits start with building protein, followed by easing muscle stiffness, phenylalanine control in PKU and gut-lining mucus.

    1

    Building and repairing protein

    Strong evidenceHuman studyRequirement studies · 16 and 11 healthy men; WHO estimate

    Threonine is one of the nine amino acids your body can't make, and your body builds it into proteins throughout your body, from muscle to the mucus proteins of your gut lining.143 In careful human studies, adults needed about 15 mg per kilogram of body weight a day, and the daily-needs section shows how easily food covers it.412

    Study takeaway: threonine is essential, and adults need about 15 mg per kilogram of body weight a day.

    2

    Easing muscle stiffness (spasticity)

    Emerging evidenceHuman study3 controlled trials · 18 to 33 people; 1 study of 6 without a comparison group

    Spasticity is the tight, overactive muscle tone that can come with multiple sclerosis, spinal cord disease and some inherited nerve conditions. Researchers tested threonine for it because, in rats, it raised glycine, a messenger that quiets nerve signals in the spinal cord.1012

    In a placebo-controlled trial in which each person tried both, 6 grams a day had what the researchers called a modest but definite antispastic effect on leg muscle tone, and the trial reached its conclusion in threonine's favor after 33 patients.11 In 18 people with familial spastic paraparesis, an inherited form, 4.5 and 6 grams a day for 2 weeks each lowered motor impairment and spasticity on rating scales compared with placebo.10 In a randomized trial of 26 people with multiple sclerosis who could walk, in which each person had a threonine period and a comparison period, 7.5 grams a day reduced the signs of spasticity on examination.12 In both of those trials, the patients and examining physicians didn't notice a change in overall symptoms.

    A 1982 pilot study used the lowest dose: in 6 people with inherited spasticity and no comparison group, 500 mg a day for 12 months improved measured motor performance by 29% on average, 19% in the arms and 42% in the legs.47

    Study takeaway: in three controlled trials, 4.5 to 7.5 grams of threonine a day eased the physical signs of spasticity.

    3

    Phenylalanine control in PKU

    Emerging evidenceHuman studyPlacebo-controlled trial · 12 patients · each tried both

    People with phenylketonuria (PKU) and related forms of hyperphenylalaninemia have to keep blood phenylalanine from building up. In a trial in which 12 patients each took about 50 mg of threonine per kilogram of body weight a day and a maltodextrin placebo, 8 weeks each with 8 weeks off between, threonine lowered blood phenylalanine, and the drop wasn't explained by more phenylalanine leaving in urine. The researchers want the reason clarified before threonine is used as a treatment.46

    Study takeaway: in 12 patients, threonine lowered blood phenylalanine over 8 weeks compared with placebo.

    4

    Gut-lining mucus

    Preclinical evidenceAnimal studyAnimal studies · rats, minipigs, piglets, rabbits and mice

    Threonine is one of the main building blocks of MUC2, the mucus protein that keeps gut bacteria off your intestinal lining.3 In a study of 32 rats, too little threonine slowed mucus production, and in piglets from 18 litters, added threonine raised the main mucus protein; the gut section has the full research and how to put it to work.4849

    Study takeaway: threonine builds gut mucus, and in animal studies its supply kept mucus production up.

    Does threonine help your gut lining?

    Quick answer

    Threonine is one of the main building blocks of MUC2, the mucus protein that shields your gut lining, and in animal studies, too little of it slowed mucus production, while added threonine raised it in piglets.34849 Pasture-raised eggs and wild salmon, two threonine-rich foods, are part of the Repair step in my gut-healing protocol.52325

    My gut-healing protocol takes away what irritates the gut first, then rebuilds the lining. In the Repair step, the lining rebuilds, and your job is to give it the building blocks: bone broth every day, pasture-raised eggs, wild salmon and sardines, and collagen peptides.52 The eggs and fish on that list are rich in threonine, as the food table shows. Needs vary, too: a woman with gut inflammation may need more protein, in more digestible forms like collagen peptides or bone broth.14

    Animal research shows why supply matters. A review of the research, much of it in pigs and poultry, explains that the gut can't digest and reuse its own mucin proteins, so the mucus it sheds carries threonine away for good.53 In a study of 32 rats, when the animals ate 30% of the threonine they needed for 14 days, mucin production fell in the small intestine and colon while the lining's other proteins kept being made at the normal pace; at 60%, mucin production held.48 Inflammation raises demand: in a study of 8 minipigs, the 4 with an inflamed small intestine drew nearly seven times more threonine from the blood into the gut than the 4 healthy ones, and made more mucin.54

    Adding threonine has helped in several animal studies. In a study of rats with chemically induced colitis, 8 per group, a diet with extra threonine, serine, proline and cysteine raised mucin production in the colon by 95% and promoted the bacterial populations the colitis had disrupted.55 In piglets born small, from 18 litters, adding 2 grams of threonine per kilogram of feed for 3 weeks raised Muc2, the antibody secretory IgA and the number of goblet cells, and calmed inflammation in the small intestine.49 In a study of 180 young rabbits, more threonine in the diet raised secretory IgA and goblet cells and lowered inflammatory signals in those given a bacterial toxin to inflame the gut.50 Timing may matter: in a study of mice with chemically induced colitis, 5 per group, threonine given as the colitis began impaired mucus production and delayed recovery, while threonine started on day 8 didn't.51

    None of this has been tested as a gut treatment in people yet. What you can do today is eat enough protein from the foods that carry threonine, and our guides to leaky gut and gut health go deeper.

    Should you take a threonine supplement?

    Quick answer

    Food comes first: a few servings of protein foods cover a day's threonine, and supplement trials have tested it mainly in nerve-related conditions, at 500 mg to 7.5 grams a day.14712 Each study's dose is in the table below.

    There's no established supplement dose for threonine. Each trial used its own amount for its own question:

    What the study looked atWho took partDaily threonineHow longDesign

    Spasticity

    6 people with inherited spasticity

    500 mg

    12 months

    No comparison group47

    Spasticity

    18 people with familial spastic paraparesis

    4.5 g and 6 g

    2 weeks at each dose

    Placebo-controlled; each person tried both10

    Spasticity

    33 people with spinal spasticity

    6 g

    Not reported in the study summary

    Placebo-controlled; each person tried both11

    Spasticity

    26 people with multiple sclerosis

    7.5 g

    Not reported in the study summary

    Randomized; each person had a threonine and a comparison period12

    ALS

    15 people who finished, on threonine or placebo

    2 g

    1 year

    Placebo-controlled56

    ALS

    30 people, 13 of whom finished

    Not reported in the study summary

    1 year

    Compared with vitamin B or carnitine; people knew which treatment they got57

    ALS

    95 people, 77 of whom finished

    4 g, with 160 mg pyridoxal phosphate

    6 months

    Placebo-controlled58

    PKU

    12 patients

    About 50 mg per kg of body weight

    8 weeks

    Placebo-controlled; each person tried both46

    Safety

    30 healthy men, 24 of whom finished

    3, 6, 9 and 12 g

    4 weeks at each dose

    Placebo-controlled; the men took placebo and each dose in turn13

    Three of those trials tested threonine in amyotrophic lateral sclerosis (ALS), and none slowed the disease. In a year-long placebo-controlled trial of 2 grams a day, which 15 people finished, people on threonine declined at the same rate as those on placebo.56 In a year-long trial in which people knew which treatment they got, 30 people with ALS took threonine, vitamin B or carnitine, and 13 finished; their scores fell at the same pace, though the threonine group complained less often of breathing failure despite having more swallowing and speech involvement at the start.57 In the largest, 95 people took 4 grams of threonine a day with 160 mg of pyridoxal phosphate, a mix of three branched-chain amino acids or a placebo for 6 months, and 77 finished; neither amino acid treatment changed strength, function or timed tasks, and the safety section covers its lung-function finding.58

    For most people, the simplest way to get more threonine is more high-quality protein, and the food table shows what each serving adds. If you add a protein powder, I recommend a high-quality animal or plant source. I use protein powder every day: a bone broth protein and an organic plant protein made from seeds, peas and sprouted grains.14

    Want help fitting threonine into your plate?

    Ask Dr. Axe AI. Answers are grounded in this library, with sources shown.

    Is threonine safe? Side effects and who should be careful

    Quick answer

    At food amounts, threonine is simply part of the protein you eat, and as a supplement it has been well tolerated: in a 2025 trial, healthy men took up to 12 grams a day for 4 weeks with no adverse effect.13 People with ALS or PKU, and anyone pregnant or nursing, should read the list below first.

    The newest safety data come from a 2025 trial funded by an amino acid manufacturer, which employed two of its four authors. Thirty healthy men, average age 43, took a placebo and doses of 3, 6, 9 and 12 grams a day in turn, 4 weeks at each with at least 2 weeks off between, and neither the men nor the researchers knew who got what; 24 finished. No dose changed body measurements, diet, blood pressure, heart rate or blood tests, apart from a small rise in two enzymes, AST and creatine kinase, at 9 grams that didn't appear at 12. Side effects such as stomach complaints and cold-like symptoms came up as often on placebo (7) as on all four doses combined (7), with none at 12 grams, and all of them cleared while the men kept taking their capsules. The researchers set 12 grams a day as the highest dose with no observed adverse effect.13

    The older trials point the same way: the randomized 26-person multiple sclerosis trial found no side effects, the placebo-controlled 33-patient spasticity trial reported minimal ones, the 6-person pilot study, which had no comparison group, found no toxic effects over 12 months, and in the placebo-controlled 95-person ALS trial, which 77 finished, the amino acids were well tolerated.12114758 In the multiple sclerosis trial, the researchers set that clean record against the sedation and added muscle weakness of the antispasticity drugs commonly used in MS.12

    Good to know before you take threonine

    • ALS: in the placebo-controlled ALS trial of 95 people, 77 of whom finished, breathing capacity fell about 2.5 times faster on threonine, and on the branched-chain amino acid mix, than on placebo, and the threonine group lost 3.2 kg over 6 months against 1.1 kg on placebo. The researchers said this may have been chance but couldn't rule out harm, so if you have ALS, don't add threonine supplements on your own; decide with the neurologist who manages your care.58

    • PKU or high phenylalanine: threonine lowered blood phenylalanine in the 12-patient trial above, so keep any threonine within the diet your metabolic specialist manages.46

    • Pregnancy and nursing: threonine supplements haven't been studied in pregnancy or while nursing, so get your threonine from protein foods.

    • Kidney disease with a protein limit: the protein foods on this page, and any threonine supplement, count toward your limit, so keep to the target set for your condition.

    The bottom line

    Is threonine good for you?

    Yes. Threonine is one of the nine essential amino acids, built into the proteins of every tissue and into the mucus that shields your gut lining, and your body depends on food to supply it. As a supplement, it eased the physical signs of muscle stiffness in three controlled trials, and its role in the gut lining is promising.

    Build your plate around grass-fed and pasture-raised meats, wild-caught fish, pasture-raised eggs, goat or A2 dairy, beans, lentils and seeds, and aim for 30 to 40 grams of protein at each meal. Your body was designed to rebuild itself every day, and the protein on your plate supplies the materials.

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    Threonine: frequently asked questions

    What is threonine?

    Threonine is one of the nine essential amino acids, the protein building blocks your body can't make, so it has to come from food.14 The form in food and in supplements is L-threonine.1913

    Is threonine an essential amino acid?

    Yes. Your body can't make threonine, so you need it from food every day, about 15 mg per kilogram of body weight for healthy adults.132

    What does threonine do in the body?

    It's built into proteins throughout your body, and your gut uses it to make MUC2, the main protein of the mucus that shields your intestinal lining.3

    Which foods are highest in threonine?

    Animal proteins lead: a 3-ounce roasted chicken breast has about 1,114 mg, 3 ounces of grass-fed bison about 986 mg and 3 ounces of wild salmon about 952 mg. A cup of cooked lentils or black beans has about 640 mg.14578

    How much threonine do you need a day?

    About 15 mg per kilogram of body weight, or roughly 1,050 mg a day for a 154-pound adult, by the World Health Organization's estimate.2 A 3-ounce chicken breast supplies about that much.1

    Can you get enough threonine on a plant-based diet?

    For threonine, yes: a cup of cooked lentils, a cup of black beans and 3 tablespoons of hemp seeds together supply about 1,660 mg, more than a 154-pound adult needs in a day.789 Long term, though, I see major deficiencies on all-plant diets, so if you eat only plants, I recommend supplementing a B complex, with vitamin B12 most important, and DHA and EPA.45

    What is L-threonine?

    L-threonine is the form of threonine in food, the form your body builds into protein and the form sold in supplements.1913

    Is L-threonine the same as L-theanine?

    No. L-theanine is a different amino acid, a form of glutamine found in green tea, while L-threonine is an essential amino acid that comes with the protein in your food.5919

    Is magnesium L-threonate the same as threonine?

    No. Magnesium L-threonate is magnesium bound to L-threonic acid, a different molecule that contains no nitrogen, so it doesn't supply threonine or any other amino acid.60

    What is the difference between serine and threonine?

    Threonine carries one more methyl group than serine. Both have a hydroxyl group where sugars attach in mucus proteins, and that small difference changes how sugars and phosphate groups bind to each.183

    What is the abbreviation for threonine?

    Threonine's three-letter abbreviation is Thr, and its one-letter code is T.17

    Who discovered threonine?

    Biochemist William C. Rose is credited with discovering threonine. In 1935, his laboratory reported isolating and identifying a new essential amino acid in feeding experiments with purified amino acids.1516

    Does threonine help with spasticity?

    It eased the physical signs of spasticity in three controlled trials of 4.5 to 7.5 grams a day, including one in 26 people with multiple sclerosis.101112

    Does threonine help ALS?

    No. In three trials in people with ALS, lasting 6 months to a year, threonine didn't slow the disease.565758

    Does threonine help leaky gut?

    Threonine is one of the main building blocks of the mucus that shields your gut lining, and in animal studies, getting enough of it kept mucus production up.348 Pasture-raised eggs and wild salmon, two threonine-rich foods in the Repair step of my gut-healing protocol, supply it along with the rest of their protein.52

    Is threonine safe to take?

    For healthy adults, it has been well tolerated: in a 2025 trial, men took up to 12 grams a day for 4 weeks with no adverse effect.13 If you have ALS or PKU, or you're pregnant or nursing, read the safety section first.

    Freshness & update log

    October 18, 2026 — Rewrote the page in full under Dr. Axe's byline. Retitled it and replaced the collagen-production framing with threonine's role in the mucus that protects the gut lining; added the Dr. Axe Score under the current supplement weighting (6.0) with an Interaction check; replaced the food list, which included carrots and bananas, with USDA threonine values per serving for 19 foods; added the World Health Organization's daily requirement; named each human trial of threonine for spasticity, ALS and PKU with its design, size, dose and result; replaced the statement that threonine raises glycine in the nervous system with the trial measurements; replaced the 500 to 1,000 mg daily dose and the four-grams-a-day safety statement with the doses each study used and a 2025 safety trial; removed the T-cell, fatty liver, anxiety and depression, wound healing and collagen-percentage claims, which human research doesn't support; replaced the memantine warning, for which we found no published report, with an interaction note; and added a mechanism diagram and two charts.

    Originally published August 19, 2019. —

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    Dr. Josh Axe

    Dr. Josh Axe, DC, DNM, CNS

    Doctor of Natural Medicine · Founder, DrAxe.com

    Dr. Axe is a certified doctor of natural medicine, clinical nutritionist, and multiple New York Times bestselling author. He has spent 20+ years in clinical practice helping people heal at the root cause and founded one of the most-visited natural-health platforms in the world.

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    This article is for educational purposes. See our medical disclaimer.