L-Tyrosine
Compiled from published pharmacological and botanical literature. Not independently verified by Herbuno. Spotted an error or have a correction? Flag it below →
| Compound | L-Tyrosine |
|---|---|
| Chemical class | Conditionally essential aromatic α-amino acid — phenolic side chain |
| CAS | 60-18-4 (L-tyrosine) · 537-55-3 (N-acetyl-L-tyrosine) |
| Primary source | Microbial fermentation; endogenously from phenylalanine via phenylalanine hydroxylase |
| Key applications | Catecholamine precursor, thyroid hormone backbone, melanin synthesis, acute stress cognition |
| Claim strength | Moderate under acute stressors such as sleep deprivation and cold; low at baseline |
| Typical form | Crystalline powder at 98%, or N-acetyl-L-tyrosine for solubility |
| Buy from Herbuno | L-Tyrosine 98% Powder · N-Acetyl-L-Tyrosine |
| 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: From the Greek tyros, cheese. Justus von Liebig obtained it in 1846 from casein, and the name records the source. Tyrosine is conditionally essential rather than essential: the body makes it by hydroxylating phenylalanine, so dietary tyrosine is required only when phenylalanine supply is inadequate or when the hydroxylase is defective, as in phenylketonuria — where tyrosine becomes strictly essential.
Discovery and production history: Tyrosine's biological importance lies in what is built from it. It is the precursor for dopamine, noradrenaline and adrenaline in sequence, for thyroid hormones, which are iodinated tyrosine residues, and for melanin. Few amino acids sit upstream of so many distinct signalling systems. Commercial production moved to fermentation during the twentieth century. N-acetyl-L-tyrosine was developed specifically to address tyrosine's poor water solubility, initially for parenteral nutrition where the free amino acid cannot be adequately concentrated.
Research trajectory: The cognitive literature developed from military research. Investigators examining performance degradation under extreme conditions — cold exposure, sleep deprivation, sustained operations — hypothesised that catecholamine depletion contributed, and tested tyrosine as a precursor. The results established a consistent pattern that has shaped the field: tyrosine helps when the catecholamine system is being depleted faster than it can be replenished, and does essentially nothing in rested, unstressed subjects.
Commercial source: L-tyrosine is produced by microbial fermentation and crystallised, typically to 98% or above; the slightly lower assay than other amino acids reflects its poor solubility during purification. N-acetyl-L-tyrosine is manufactured by acetylating the amino group, which substantially improves water solubility. Both are supplied as free-flowing powders.
Evidence for L-Tyrosine Applications
The acute-stressor finding is consistent and it defines the legitimate claim. Trials in sleep-deprived personnel, in cold exposure, during sustained military operations and under demanding multitasking have shown tyrosine preserving working memory, cognitive flexibility and reaction time relative to placebo. The mechanism is precursor supply: under sustained catecholamine demand, tyrosine hydroxylase activity becomes substrate-limited, and providing tyrosine supports continued synthesis. The effect is protective against decline rather than enhancing above normal. Claim strength: Moderate.
At baseline, in rested unstressed people, tyrosine does little, and this should be stated rather than implied away. Trials in well-rested subjects performing ordinary cognitive tasks have generally found no meaningful effect on attention, memory or mood. This follows directly from the mechanism: if catecholamine synthesis is not substrate-limited, adding substrate changes nothing. Nootropic positioning that implies general cognitive enhancement is extending the evidence beyond the conditions that produced it. Claim strength: High for the absence of baseline effect.
N-acetyl-L-tyrosine is a solubility solution with a bioavailability problem, and it is widely mis-sold. NALT dissolves far better than free tyrosine, which is why it appears in liquid and high-concentration formats. However, human studies indicate that a substantial proportion of an oral NALT dose is excreted unchanged in urine rather than deacetylated to tyrosine, so it raises plasma tyrosine less efficiently than free tyrosine at equivalent weight. It is a reasonable choice where solubility is the binding constraint, provided the dose is adjusted upward and no superiority claim is made. Claim strength: Moderate.
Thyroid positioning is mechanistically true and clinically misleading. Thyroid hormones are built from iodinated tyrosine residues, so tyrosine is structurally required. Thyroid hormone synthesis in healthy people is limited by iodine availability and by regulatory control, not by tyrosine supply, and supplementing tyrosine does not increase thyroid hormone output in people with adequate iodine. Marketing tyrosine as thyroid support invites the inference that it treats hypothyroidism, which it does not, and may delay appropriate diagnosis. Claim strength: Emerging, and the claim is misleading as usually framed.
Mood and depression applications have been tested and have not succeeded. The precursor logic is the same as for the cognitive work, and small trials examined tyrosine in depression on the basis of catecholamine hypotheses. Results have been largely negative, and tyrosine is not an established antidepressant adjunct. Where mood effects appear in the literature, they tend to accompany the acute-stress protective effect rather than representing a separate antidepressant action. Claim strength: Emerging, trending negative.
Tolerability is good with specific interaction cautions worth carrying on label. Doses of 100 to 150 milligrams per kilogram, which is 7 to 10 grams for most adults, have been used in trials without serious adverse effects, though gastrointestinal upset occurs at the upper end. Tyrosine competes with other large neutral amino acids for blood-brain barrier transport, so taking it with a protein meal reduces its effect — an empty-stomach instruction is functional, not arbitrary. There are theoretical interactions with MAO inhibitors and with thyroid medication, and people with phenylketonuria require it under medical supervision rather than as a supplement. Claim strength: Moderate.
Sourcing L-tyrosine from Herbuno. We supply free L-tyrosine at 98% and N-acetyl-L-tyrosine where solubility is the binding constraint.
If you are choosing NALT for a liquid format, plan the dose upward rather than matching free tyrosine gram for gram, since a meaningful fraction is excreted unchanged. All lots ship with CoA and MSDS as standard; request a quotation for pilot or bulk volumes.
Dosage & Formulator Specification
L-tyrosine is dosed as the free amino acid at 98%. Trial doses for acute-stress cognitive endpoints are high: 100 to 150 milligrams per kilogram of body weight, which is 7 to 10 grams for a typical adult, taken 30 to 60 minutes before the stressor. Many consumer products carry 500 milligrams to 2 grams, which is well below what the supporting literature used, and that gap should inform what the product claims. N-acetyl-L-tyrosine is roughly 80% tyrosine by weight before accounting for incomplete conversion, so matching a free tyrosine dose requires more than the weight arithmetic suggests.
Timing and food matter more for tyrosine than for most actives. Because it competes with other large neutral amino acids for the blood-brain barrier transporter, a dose taken with or shortly after a protein-containing meal will deliver substantially less tyrosine to the brain. The trial protocols dose on an empty stomach ahead of the stressor, and a product replicating those effects needs to carry that instruction. For products positioned around shift work, travel or sleep deprivation, this fits the use occasion naturally.
Solubility is the dominant handling constraint. Free tyrosine is poorly soluble — around 0.45 grams per litre in water at room temperature — which makes it effectively unusable in ready-to-drink formats and difficult even in powders intended for reconstitution, where it will settle rather than dissolve. This is the sole reason NALT exists. For capsules, tablets and dry sachets taken as a slurry, free tyrosine is fine. Tyrosine is also prone to oxidative discolouration, developing a pink or brown tint in the presence of oxygen and light, which is cosmetic but noticeable in pale formulations.
For analytical control, specify identity and assay by HPLC with optical rotation confirming L-configuration, and state clearly whether the specification is for free tyrosine or NALT, since the two are often conflated under the single word tyrosine. Standard amino acid specifications cover heavy metals, residual solvents, microbiological limits and loss on drying, and the certificate should name the fermentation organism and substrate. Tyrosine is fermentation-derived rather than plant-extracted, so phytosanitary certification does not apply; CoA and MSDS ship as standard.
Two further points shape how a tyrosine product should be built. The use occasion is narrow and should drive the format: this is an ingredient for shift work, overnight travel, examinations and operational demand, taken ahead of the stressor on an empty stomach, which suits a single-serve sachet or capsule far better than a daily tub. And the gap between trial doses and market doses is wide enough to be a positioning decision rather than a detail. A product carrying 500 milligrams can be honest about being a modest contribution; one carrying 7 grams can cite the trials but must first solve a real palatability and format problem. Choosing deliberately between those is better than landing between them.
Frequently Asked Questions — L-Tyrosine
When does tyrosine actually work?
Under acute stressors that deplete catecholamines faster than they can be replenished — sleep deprivation, cold exposure, sustained operational demand, demanding multitasking. In those conditions it preserves working memory and reaction time. In rested, unstressed people it does essentially nothing, because catecholamine synthesis is not substrate-limited. The effect is protective, not enhancing.
Is NALT better than free tyrosine?
More soluble, less bioavailable. A substantial fraction of an oral N-acetyl-L-tyrosine dose is excreted unchanged in urine rather than deacetylated, so it raises plasma tyrosine less efficiently per gram. Use it when solubility is the binding constraint, adjust the dose upward, and do not claim superiority.
Why are trial doses so much higher than product doses?
Because the literature uses 100 to 150 mg/kg — 7 to 10 g for most adults — while typical consumer products carry 500 mg to 2 g. That gap should shape what the product claims. A 500 mg serve is not replicating the acute-stress trials and should not imply it is.
Does tyrosine support thyroid function?
Thyroid hormones are built from iodinated tyrosine, so it is structurally required. But synthesis in healthy people is limited by iodine and by regulatory control, not by tyrosine supply, and supplementing it does not raise hormone output when iodine is adequate. Framing it as thyroid support invites the inference that it treats hypothyroidism, which it does not.
Can I put tyrosine in a ready-to-drink product?
Not free tyrosine — solubility is around 0.45 g per litre, so it will not dissolve and will settle. That is the entire reason NALT exists. Also note tyrosine discolours on oxidation, developing a pink or brown tint under oxygen and light, which shows in pale formulations.
Why source tyrosine 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 rather than a price exercise. India has established fermentation capacity with the certification infrastructure these buyers typically require.