NAC and NALT: two different amino acid derivatives sold as one entry

The app holds these as one entry and they are not one compound. One is a glutathione precursor with a genuine approved use; the other is a catecholamine precursor with a much weaker case. Separating them is most of what this page is for.

NAC: the one with an approval behind it

Established clinical use N-acetylcysteine is a cysteine donor, and cysteine is the rate-limiting amino acid for glutathione synthesis — the cell’s principal antioxidant. That is not a supplement claim: intravenous NAC is the standard antidote for paracetamol overdose, where it works by restoring hepatic glutathione, and it is on the WHO essential medicines list for that reason. It is also used as a mucolytic.

Off-label or community practice The uses people take it for — psychiatric conditions, compulsive behaviours, respiratory health, liver support — rest on a mixed body of trials. There is reasonable randomised evidence in trichotillomania and some in obsessive-compulsive and substance-use disorders; results elsewhere are inconsistent. It is one of the better-evidenced supplements in this reference and that is a low bar being cleared rather than a strong claim.

Its regulatory position in the United States has been contested, because it was approved as a drug before being marketed as a supplement — which is what the app’s own string means by "in flux". It remains widely available.

NALT: a different molecule with a narrower case

Established clinical use N-acetyl L-tyrosine is a more soluble form of tyrosine, the precursor to dopamine, noradrenaline and adrenaline, and also to thyroid hormone. The case for supplementing it is specific: tyrosine appears to help cognitive performance under conditions that deplete catecholamines — cold, sleep deprivation, sustained stress — and much less under ordinary conditions.

Animal-only or theoretical Whether the acetylated form is actually better is questionable. It is more water-soluble, and there is evidence that a substantial fraction is excreted unchanged rather than deacetylated to free tyrosine, which would make it a worse delivery vehicle rather than a better one. Plain L-tyrosine is cheaper and is what most of the trials used.

It also competes with other large neutral amino acids for transport across the blood-brain barrier, which is why it is taken away from protein-containing meals. That detail is in the app’s own drawbacks list and it is the one that most often explains a disappointing result.

What each is worth watching

NAC’s common effect is gastrointestinal at higher amounts. The interaction worth knowing is that it may reduce the efficacy of some chemotherapy, which is the app’s own note and is a conversation for anyone in oncology care rather than a footnote. It also has mild antiplatelet activity.

NALT’s constraint is that it feeds a pathway shared with thyroid hormone synthesis and with catecholamines, so anyone on thyroid medication, on a monoamine oxidase inhibitor, or with hyperthyroidism should be raising it with a clinician rather than treating it as inert.

The app records liver enzymes on the panel, noting NAC is hepatoprotective. That is reasonable and it is also worth saying plainly that "hepatoprotective" does not make an oral androgen safe — taking NAC alongside something that stresses the liver is not a licence, and the compounds where that argument gets made are ones this site does not publish.

The dosing rows the app records

Off-label or community practice Reproduced from the app’s reference so you can see what it holds, not as a recommendation. Which row applies to a particular person, if any, is a clinical decision this page does not make — and rows describing supraphysiological or post-cycle use are filtered out before this table is built, so what you see here is a subset.

What the app monitors alongside it

The panel below is the app’s own monitoring note for NAC / NALT, verbatim. None of the analytes it names has a page here yet.

Drawbacks and risks the app records

From the app’s own entry, and it covers both compounds at once — which is exactly the conflation this page is trying to undo.

• NAC: FDA regulatory uncertainty as supplement in US
• NALT: requires adequate cofactors (B6, iron, folate)
• NAC: can cause nausea at higher doses
• NALT: best taken away from protein-rich meals
• Individual response varies significantly
• NAC may reduce efficacy of some chemotherapy drugs

Questions people actually ask

Is NAC actually a medicine?

Intravenously, yes — it is the standard antidote for paracetamol overdose and is on the WHO essential medicines list. The oral supplement use for other purposes is a separate and much weaker evidence base.

Is NALT better than plain tyrosine?

Probably not, and possibly worse. It is more soluble, and evidence suggests a substantial fraction is excreted unchanged rather than converted to free tyrosine. Most of the trials used plain L-tyrosine.

When does tyrosine actually help?

Under conditions that deplete catecholamines — cold, sleep deprivation, sustained stress — more than in rested ordinary conditions. That is a narrower claim than it is usually sold with.

Why take NALT away from food?

Because it competes with other large neutral amino acids for transport into the brain. Taken with a protein meal, most of it loses that competition.

Where the load-bearing numbers come from

Named rather than linked. Publisher URLs move, and a citation that resolves to a 404 two years from now is worse than one you can search for by name — every entry below is findable from the title and year alone.