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Alpha-GPC illustration

Alpha-GPC

A choline source that crosses the blood-brain barrier. Acute cognitive and pre-workout growth-hormone effects supported by small RCTs. A 2021 Korean cohort study flagged a stroke association in elderly users; honest framing required.

Cholinergics Last verified 2026-05-06
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What it does

Alpha-glycerylphosphorylcholine (Alpha-GPC) at 300 to 600 mg supplies choline that converts to acetylcholine. Ziegenfuss 2008 reported a 44-fold pre-workout GH peak (n=7 small trial); Lee 2021 cohort raised cardiovascular safety concerns in elderly Korean prescription users (not yet confirmed in healthy adults).

  • Acute cognitive performance Moderate evidence

    Single doses of 200 to 630 mg improve Stroop performance and serial subtraction speed in healthy adults; mechanism via acetylcholine precursor that crosses the BBB.

    Sources: PMID 39683633 · PMID 26500463

  • Pre-workout growth hormone and peak force Preliminary evidence

    Ziegenfuss 2008 (n=7 small trial): 600 mg taken 90 minutes pre-resistance-exercise produced a 44-fold post-exercise GH peak vs 2.6-fold placebo, plus 14% greater peak bench-press force. Single-trial finding, replicated directionally in a 6-day isometric study.

    Sources: PMID 26582972

Top picks

  1. 1

    Jarrow Formulas

    Alpha GPC 300 mg (Veggie Capsules)

    300 mg per cap; titrate to 600 mg pre-workout if desired.

    Check on Amazon
  2. 2

    NOW Foods

    Alpha GPC 300 mg Veg Capsules

    Veg-cap format; widely available.

    Check on Amazon
  3. 3

    Life Extension

    Alpha GPC 300 mg

    60 vegetarian capsules.

    Check price

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How to use it

Dosage
300 to 600 mg per dose (cognitive); 600 mg (pre-workout).
Timing
30 to 90 minutes before mental work or training. Ziegenfuss protocol used 90 minutes pre-lift.
With food
Not required
Onset
Acute (single dose); motivation effects after ~14 days at 400 mg/day.

What to look for

  • Per-capsule dose: 300 mg standard; need 2 caps to hit the 600 mg pre-workout dose.
  • Hygroscopic stability: Alpha-GPC clumps fast in powder form; prefer capsules with desiccant.
  • AlphaSize (Chemi Nutra) branded raw material is the form used in Ziegenfuss 2008.
  • Verify the mg figure is the active, not the silica complex (many products list 'alpha-GPC 50%').
  • Third-party testing (NSF, USP, Informed Sport).

Formats: capsules, powder.

Skip if:
  • History of stroke or high cardiovascular risk. Lee 2021 (Korean cohort, N=12M) found a dose-response association with ischemic and hemorrhagic stroke at 10 years in elderly users prescribed alpha-GPC for cognitive decline. Honest framing: signal exists, magnitude in healthy adults unclear.
  • Anticholinergic medications or scopolamine therapy.
  • Pregnancy or lactation (insufficient safety data).
  • Pre-existing atherosclerosis (mouse model showed GPC promotes lesions via TMAO pathway).

FAQ

Should the stroke study scare me off?
It depends. Lee 2021 was an elderly Korean cohort prescribed alpha-GPC for cognitive decline - not the demographic of a healthy lifter taking 600 mg pre-workout. The mechanism (choline -> gut microbiota -> TMAO -> atherosclerosis) is biologically plausible. Treat as a real but unsettled signal: do not dismiss, but do not panic-sell either.

Related comparisons

Additional references