L-Threonine
Compiled from published pharmacological and botanical literature. Not independently verified by Herbuno. Spotted an error or have a correction? Flag it below →
| Compound | L-Threonine |
|---|---|
| Chemical class | Essential α-amino acid — hydroxyl-bearing side chain; two chiral centres |
| CAS | 72-19-5 |
| Primary source | Microbial fermentation, typically Escherichia coli or Corynebacterium strains |
| Key applications | Mucin and glycoprotein synthesis, intestinal barrier, collagen and elastin, glycine precursor |
| Claim strength | High for mucin biochemistry and gut demand; Emerging for supplementation outcomes |
| Typical form | Crystalline powder at 98–99% |
| Buy from Herbuno | L-Threonine Powder |
| Origin | Processed / Sourced from India |
| MOQ | R&D 100 g / 250 g (subject to stock) · Pilot batch 1–5 kg · Bulk 10 kg, 25 kg and above |
| Lead Time | Dispatch within 72 hrs from stock · fresh-batch production (typically 50 kg+): 10 working days |
| Documentation | CoA & MSDS standard with every lot |
Name origin: Named for its structural resemblance to threose, a four-carbon sugar. William Cumming Rose identified it in 1935, making it the last of the essential amino acids to be discovered — which it was, because its absence from the known set was what explained why diets apparently complete in all other amino acids still failed to support growth in Rose's rat experiments. Like isoleucine, it carries two chiral centres.
Discovery and production history: Threonine's biological significance is concentrated in an unusual place: the gut. Mucin, the glycoprotein that forms the protective mucus layer lining the intestine, is exceptionally rich in threonine, and mucin turnover consumes a disproportionate share of dietary threonine. Estimates from tracer studies suggest a large fraction of dietary threonine is extracted by the intestine on first pass and never reaches systemic circulation. Commercial production is by fermentation at very large scale, driven principally by swine and poultry feed demand where threonine is typically the second or third limiting amino acid.
Research trajectory: Research has followed the gut. Work in animal models has examined threonine requirement under conditions of intestinal challenge — infection, inflammation, weaning stress — consistently finding that mucin demand rises and that threonine becomes limiting sooner than other amino acids. Human work is thinner. A separate line concerns threonine's role as a precursor of glycine and its contribution to collagen and elastin, both of which contain threonine, though at lower abundance than mucin.
Commercial source: L-threonine is produced by fermentation, commonly using engineered Escherichia coli, and crystallised to 98% or above. Because feed demand dominates the market, a substantial proportion of available material is feed grade, and the specification gap between feed and supplement grade is meaningful — particularly on microbiological limits, residual protein from the fermentation organism, and heavy metals. Substrate and organism determine certification eligibility.
Evidence for L-Threonine Applications
The mucin relationship is threonine's genuinely distinctive feature and the strongest biochemical case available. Intestinal mucins are heavily O-glycosylated glycoproteins in which sugar chains attach to threonine and serine hydroxyl groups, and threonine content in mucin far exceeds its abundance in most other proteins. Mucin is secreted continuously and turned over rapidly, so the intestinal demand for threonine is large and ongoing. Tracer studies indicate the gut extracts a substantial proportion of dietary threonine on first pass, which is unusual among amino acids and has real implications for systemic availability. Claim strength: High.
Intestinal challenge raises threonine requirement, demonstrated consistently in animal models. Infection, inflammation, weaning stress and dietary fibre load all increase mucin secretion, and under those conditions threonine becomes limiting sooner than other amino acids — growth and barrier integrity respond to threonine supplementation specifically. This is well replicated in pigs and poultry, which is why threonine is a standard feed additive. Direct human intervention trials testing whether threonine supplementation improves intestinal barrier outcomes are sparse. Claim strength: Moderate in animal models, Emerging for humans.
The gut-first-pass extraction has a counterintuitive consequence worth stating. Because the intestine takes a large share of dietary threonine before it reaches the systemic circulation, oral threonine is relatively more available to the gut than to peripheral tissue. For a product targeting intestinal barrier support this is an advantage rather than a limitation; for one targeting systemic protein synthesis it means less of the dose arrives than the label implies. The same property that makes threonine interesting for gut applications makes it inefficient for others. Claim strength: High.
Threonine is also a glycine precursor, which connects it to a separate set of applications. Threonine catabolism via threonine dehydrogenase yields glycine, contributing to the glycine pool used for collagen synthesis, glutathione production and bile acid conjugation. Given the argument that glycine supply may be marginal relative to total demand, threonine's contribution there is not trivial. This is a mechanistic connection rather than a demonstrated clinical one. Claim strength: Emerging.
There is little evidence for standalone threonine supplementation in healthy people eating adequate protein, as with the other individual essentials. Threonine deficiency does not occur in normal diets. The case for supplementation rests on conditions of elevated demand — intestinal inflammation, high fibre intake, recovery from gut injury — and that case is built largely on animal data. Positioning threonine for general wellness extends beyond what the literature supports. Claim strength: Emerging.
The feed-grade question deserves specific attention because of market structure. Threonine is produced overwhelmingly for animal feed, and feed-grade material is considerably cheaper and more readily available than supplement grade. The specification differences are real: microbiological limits, residual host-cell protein from the fermentation organism, endotoxin and heavy metals are all controlled more tightly for human-grade material. A price that looks unusually attractive in this category is worth interrogating. Claim strength: High.
Sourcing L-threonine from Herbuno. We supply fermentation-derived L-threonine at 98% to supplement-grade specification.
Because threonine is produced at scale for feed, specification discipline matters more here than for most amino acids — confirm microbiological limits, residual host-cell protein and endotoxin rather than assuming they are controlled. All lots ship with CoA and MSDS as standard; request a quotation for pilot or bulk volumes.
Dosage & Formulator Specification
Threonine is dosed as the free amino acid at 98% or above. Adult requirement is around 15 milligrams per kilogram daily, met comfortably by adequate protein. There is no established supplemental dose for gut applications in humans, because the human intervention work has not been done; animal studies have used requirements well above maintenance under intestinal challenge. In an essential amino acid blend, threonine is dosed against the target profile rather than to a standalone figure.
For gut-targeted formulations the first-pass property should shape the design rather than be worked around. Because the intestine extracts a large share of oral threonine before it reaches circulation, there is no need for delivery technology to protect it — the site of action is where the absorption occurs. This is unusual and convenient. Conversely, if a formulation needs threonine systemically, the effective dose is higher than the arithmetic suggests, and that should be factored in rather than discovered.
Handling is straightforward. Threonine is freely soluble in water at around 9 grams per 100 millilitres, stable to heat and across a broad pH range, not notably hygroscopic, and has a mild, faintly sweet taste that is among the more palatable of the essential amino acids. It blends uniformly and is compatible with common excipients. Its hydroxyl group participates in Maillard reactions with reducing sugars, so thermally processed formats containing sugars warrant the usual browning check, though threonine is less reactive in this respect than lysine.
For analytical control, specify identity and assay by HPLC or ion-exchange chromatography with optical rotation confirming configuration, and note that threonine has two chiral centres, so allo-threonine is a relevant specified impurity in the same way allo-isoleucine is for isoleucine. Given the feed-grade market structure, explicitly specify microbiological limits, residual host-cell protein, endotoxin and heavy metals rather than relying on a general amino acid specification. The certificate should name the fermentation organism and substrate.
Co-formulation for gut-targeted products has a reasonably clear logic. Threonine supplies the mucin backbone; glutamine is the primary fuel for the enterocyte itself; glycine and proline contribute to the structural proteins of the mucosa; and serine shares threonine's role as a glycosylation attachment site in mucin. A formulation built around intestinal barrier support therefore has a mechanistic rationale for combining them that does not depend on any one of them having standalone clinical evidence, which most do not. State that honestly in the technical documentation: the biochemistry of mucin composition is well characterised and the animal data on threonine requirement under intestinal challenge are consistent, while human intervention outcomes remain to be demonstrated. That is a defensible position for a B2B specification and a poor one for a consumer claim, and the distinction is worth drawing explicitly for customers who may not make it themselves.
One further formulation consideration follows from the first-pass property. Because the intestine extracts threonine from the lumen as it is absorbed, delivery timing matters less than it does for amino acids with systemic targets, and enteric or delayed-release technology is unnecessary and arguably counterproductive — bypassing the proximal small intestine bypasses part of the site of action. Simple immediate-release powders and capsules are appropriate. Conversely, where threonine is included in a general essential amino acid blend intended for systemic protein synthesis, the first-pass extraction means the delivered systemic dose is lower than the label figure, and if the blend is dosed to a target plasma profile rather than to a label ratio, threonine inclusion should be adjusted upward to compensate.
Frequently Asked Questions — L-Threonine
What makes threonine different from other amino acids?
The gut takes most of it. Intestinal mucin — the glycoprotein forming the protective mucus layer — is exceptionally threonine-rich, and mucin turns over continuously. Tracer studies show the intestine extracts a large share of dietary threonine on first pass, which is unusual and means less reaches systemic circulation than the dose implies.
Is that first-pass extraction a problem?
It depends what you are formulating for. For gut barrier support it is an advantage — the site of action is where the absorption happens, so no delivery technology is needed to protect it. For systemic protein synthesis it means the effective dose is higher than the arithmetic suggests. The same property cuts both ways.
Is there human evidence for threonine and gut health?
Sparse. The mucin biochemistry is solid and the animal data are consistent — under intestinal challenge, infection or weaning stress, threonine becomes limiting sooner than other amino acids and supplementation improves barrier outcomes in pigs and poultry. Direct human intervention trials have not been done. We would call it Emerging for humans.
Why is threonine so cheap sometimes?
Because it is produced overwhelmingly for animal feed, and feed grade is considerably cheaper than supplement grade. The specification differences are real — microbiological limits, residual host-cell protein from the fermentation organism, endotoxin, heavy metals. An unusually attractive price in this category is worth interrogating.
What should I specify beyond assay?
Microbiological limits, residual host-cell protein and endotoxin explicitly, given the feed-grade market structure. Also allo-threonine as an impurity — threonine has two chiral centres, like isoleucine, so a diastereomer can be present without a standard assay catching it.
Why source threonine from India?
Around 80% of raw nutraceutical ingredients originate in China and amino acids are among the most concentrated categories, so a second qualified origin is a continuity measure. India has established fermentation capacity, and for threonine specifically the ability to supply to supplement rather than feed specification is the distinction that matters.