Alpha-GPC — full name L-alpha-glycerylphosphorylcholine — is a form of choline. Choline is an essential nutrient the body uses for several jobs, one of which is building acetylcholine, the neurotransmitter involved in attention and memory.
What makes Alpha-GPC worth naming separately is that it is highly bioavailable, and it is the form used in most of the clinical research on choline and cognition. When a study looks at choline and attention in healthy adults, Alpha-GPC is usually what was in the capsule.
How it differs from other choline on a shelf
Most supplements that say "choline" on the front use choline bitartrate. That is genuine choline and the label is not lying — it is chosen because it costs very little. In trials with healthy adults, bitartrate has not shown the cognitive benefits people buy it for.
Citicoline (CDP-choline) is a third form, also researched, often branded and often present in fairly small amounts.
All three appear on shelves at similar prices. The word on the back of the pack is the only way to tell which one is in your hand.
Where it comes from
Alpha-GPC occurs naturally in small quantities in food — organ meats and dairy among them — but supplement-grade Alpha-GPC is manufactured, usually from soy or sunflower lecithin.
One practical note
Alpha-GPC is hygroscopic, meaning it draws moisture out of the air. That is why products containing it should be sealed with a desiccant and kept somewhere cool and dry, and why a pouch left open on a counter is a bad idea.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Sources for every figure, with the population studied in each, are on our citations page.