Picking a choline form starts with its real choline content; the cheaper forms mainly supply the body, while α-GPC and CDP are used in cognition and stroke trials.Choosing a choline form starts with how much of the capsule is actually choline (elemental fraction is chemistry): bitartrate ~41%, α-GPC ~40%, CDP-choline ~18%, phosphatidylcholine ~13%. The cheaper two mainly supply the body; α-GPC and CDP are the forms used in cognition / stroke trials — Zeisel 2009 does not rank crossing as high vs medium.
2 · Six forms compared
Comparing six forms by choline content, use and price shows that is not choline, DMAE has weak evidence, and third-party certification is the quality floor.bitartrate 41%/body/$; PC 13%/body/$$; CDP 18%/cognition trials/$$$; α-GPC 40%/cognition trials/$$$; is not choline but often stacked; DMAE has weak evidence. Cognizin (CDP) and AlphaSize (α-GPC) are -used brands; third-party certification (USP/NSF) is the quality floor.
3 · Dosing and time to effect
CDP is dosed at 250-500mg twice daily and α-GPC at 300-600mg/day; exercise effects come 30-60 min after one dose, cognitive effects over weeks.CDP: 250-500mg twice daily (nootropic). 2000 mg/day was the acute-stroke trial dose (ICTUS, Dávalos 2012, N=2298, 6 weeks); global recovery was null ( 1.03) — not a proven post-stroke regimen. α-GPC: 300-600mg/day; exercise performance 600mg 30-60 min pre-training. Onset: exercise single dose 30-60 min; cognitive subjective 1-4 weeks, objective 4-12 weeks.
4 · Safety and marketing debunk
Common side effects are nausea, headache, insomnia and, at high doses, tachycardia, and one-week brain-boost marketing is mostly placebo.Common side effects: nausea, headache, insomnia, tachycardia (high dose). Bipolar disorder: may trigger mania; long-term high-dose TMAO worth watching; stop one week before surgery. Lee 2021 is a 10-year Korean α-GPC prescription-cohort stroke signal (matched total-stroke aHR 1.43), not a CDP common-side-effect item. One-week brain-boost marketing is mostly placebo — the real focus levers are sleep, exercise, nutrition, less screen time, less stress.