Comparison
Alpha-GPC vs N-Acetyl Cysteine
Side-by-side of Alpha-GPC and N-Acetyl Cysteine. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
Alpha-GPC
Alpha GPC supplement profile: 300 to 600 mg dosage, acetylcholine synthesis, attention and reaction-time evidence, side effects, and choline donor comparisons.
N-Acetyl Cysteine
NAC supplement benefits cover glutathione synthesis, liver and antioxidant support, and hangover recovery. Evidence strongest at 1200-2400 mg/day.
Effects at a glance
Alpha-GPC
- •Choline donor supplement, roughly 40% choline by weight; crosses blood-brain barrier efficiently
- •Replicated small gains in attention and reaction time at 300 to 600 mg in healthy adults
- •Standard prescription cognitive medication in much of Europe (Gliatilin) at 1,200 mg/day for vascular cognitive impairment
- •ASCOMALVA trial (n=210) showed cognitive preservation when added to donepezil over 24 months
- •Increases acute power output (~14%, single trial) and transient growth hormone secretion at 600 mg
- •TMAO production raises a contested cardiovascular concern at chronic high doses
N-Acetyl Cysteine
- •Replenishes intracellular glutathione by supplying cysteine, the rate-limiting amino acid for synthesis
- •First-line antidote for acetaminophen toxicity, restoring hepatic glutathione before fulminant injury occurs
- •Reduces sputum viscosity in chronic bronchitis and COPD at 600 to 1200 mg/day over months
- •Modest symptom reductions in OCD and trichotillomania at 1200 to 2400 mg/day across small RCTs
- •Mixed evidence for psychiatric adjunct use in bipolar depression and schizophrenia negative symptoms
- •Inhaled forms can trigger bronchospasm in active asthma; oral use is the standard biohacker route
Side-by-side
| Attribute | Alpha-GPC | N-Acetyl Cysteine |
|---|---|---|
| Category | supplement | supplement |
| Also known as | L-Alpha glycerylphosphorylcholine, choline alfoscerate, GPC, alpha-glyceryl phosphorylcholine | NAC |
| Half-life (hr) ↗ | 4 | 5.6 |
| Typical dose (mg) ↗ | 600 | 1200 |
| Dosing frequency | 1 to 3 times daily | 1 to 3 times daily, split dosing preferred |
| Routes | oral | oral, iv |
| Onset (hr) | 1 | 1 |
| Peak (hr) | 2 | 2 |
| Molecular weight | 257.22 | 163.19 |
| Molecular formula | C8H20NO6P | C5H9NO3S |
| Mechanism | Hydrolyzed to free choline and glycerophosphate after absorption; choline supports acetylcholine and phosphatidylcholine synthesis in CNS. | Deacetylated to cysteine, the rate-limiting precursor for glutathione synthesis; also directly scavenges reactive oxygen species and modulates glutamate signaling. |
| Legal status | Dietary supplement (US); prescription medication in much of Europe | OTC in most jurisdictions; restricted periods in US history (FDA reclassified 2022) |
| WADA status | allowed | allowed |
| DEA / Rx | OTC supplement | OTC supplement (US, post-2022); Rx indications also exist (acetaminophen overdose, mucolytic) |
| Pregnancy | Insufficient data; choline generally recommended in pregnancy | Used clinically in pregnancy for specific indications; consult clinician |
| CAS | 28319-77-9 | 616-91-1 |
| PubChem CID | 71920 | 12035 |
| Wikidata | Q411478 | Q413299 |
Safety profile
Alpha-GPC
Common side effects
- mild GI upset
- headache
- dizziness
- occasional insomnia with evening dosing
Contraindications
- established cardiovascular disease (TMAO concern)
- concurrent strong anticholinergic therapy
Interactions
- anticholinergic medications: partial mutual antagonism(minor)
- cholinesterase inhibitors (donepezil): additive cholinergic effect, basis for ASCOMALVA protocol(minor)
- scopolamine: partial counteraction of anticholinergic effect(minor)
N-Acetyl Cysteine
Common side effects
- sulfur-like taste or odor
- nausea
- flatulence
- diarrhea
Contraindications
- active asthma attack (inhaled form can trigger bronchospasm)
- known NAC hypersensitivity
Interactions
- nitroglycerin: potentiates vasodilation, risk of hypotension and headache(moderate)
- activated charcoal: reduces NAC absorption when used for acetaminophen overdose(moderate)
- anticoagulants: theoretical additive antiplatelet effect at high doses(minor)
Which Should You Take?
N-Acetyl Cysteine comes out ahead for most readers on the criteria we weight: 3 catalogued goals, OTC, oral dosing, with a Tier-A outcome catalogued. Alpha-GPC is the right call when one of the conditionals below applies.
- → If your priority is focus or working memory, pick Alpha-GPC.
- → If your priority is athletic performance, pick Alpha-GPC.
- → If your priority is healthspan extension, pick N-Acetyl Cysteine.
- → If your priority is post-training recovery, pick N-Acetyl Cysteine.
Default choice: N-Acetyl Cysteine. Wider use case, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for Alpha-GPC only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between Alpha-GPC and N-Acetyl Cysteine?
Alpha-GPC and N-Acetyl Cysteine differ in category (supplement vs supplement), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Alpha-GPC or N-Acetyl Cysteine?
Alpha-GPC half-life is 4 hours; N-Acetyl Cysteine half-life is 5.6 hours.
Can you stack Alpha-GPC with N-Acetyl Cysteine?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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