Alpha GPC is the most bioavailable form of Choline currently available. Choline is a water soluble nutrient which acts as a precursor to the neurotransmitter acetylcholine.
Acetylcholine plays an important role in many cognitive processes including memory, intelligence, and mood. Alpha GPC is generally regarded as the most potent form of Choline due to its ability to rapidly pass the blood brain barrier.
While there is no real consensus on an optimal dose, and no health organizations have provided any dosage guidelines it is generally not recommended to exceed a dosage of 1200 mg per day.