Alpha-GPC

Alpha-GPC (Alpha-glycerophosphocholine or sometimes just glycerophosphocholine) is a choline-containing supplement that, although found in a variety of food products that are also rich in choline, appears to be pharmacologically active at higher doses.

Alpha-GPC is mostly marketed due to it conferring dietary choline to the body following oral ingestion, and being the most efficient choline prodrug at doing so (able to influence both systemic and brain concentrations of choline). Due to the provision of the other half of the alpha-GPC molecule (glycerophosphate), alpha-GPC also appears to support the structure of cellular membranes, which is not a common mechanism attributed to choline prodrugs (only CDP-choline is associated with lipid membranes in this sense).

Oral supplementation of alpha-GPC is of interest for nootropic purposes, as it appears to have cognitive-enhancing properties (no human evidence exists to support this in otherwise-healthy youth, but it does have support in rodents) and attenuate the rate of cognitive decline in the elderly. In regards to reducing the rate of cognitive decline, alpha-GPC at high doses (1,200 mg) does appear to be somewhat effective in mild to moderate Alzheimer's disease and works nicely with the standard therapy (acetylcholinesterase inhibitors).

Athletes are at times interested in alpha-GPC due to its ability to enhance growth hormone production (of which only acute spikes have been reported so far, so it may fall to the same problems that arginine has on growth hormone) and to enhance power output, which has a lone pilot study in support of 600 mg alpha-GPC prior to exercise. Although ergogenic properties of alpha-GPC cannot be ruled out and look promising, it requires more evidence.

Alpha-GPC is approximately 40% choline by weight, and as such 1,000 mg alpha-GPC confers about 400 mg of dietary choline.

A standard dosage of alpha-GPC is 300-600 mg, according to the most common label doses. This dose is in accordance with the study using alpha-GPC to enhance power output (600 mg) and the two studies noting an increase in growth hormone secretion, and is likely a good dose to take for athletes.

For the usage of alpha-GPC in attenuating symptoms of cognitive decline, almost all studies use a dosage of 1,200 mg daily, divided into three doses of 400 mg. It is unsure how lower doses would benefit cognition, but the 1,200 mg appears to be consistently associated with benefit.

Rat studies suggest that the effects of alpha-GPC oral ingestion peak at 300-600 mg/kg, which is an estimated human dose of 48-96 mg/kg (and for a 150lb human, 3,272-6,545 mg daily).

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects alpha-gpc has on your body, and how strong these effects are.

Grade	Level of Evidence [show legend]
	Robust research conducted with repeated double-blind clinical trials
	Multiple studies where at least two are double-blind and placebo controlled
	Single double-blind study or multiple cohort studies
	Uncontrolled or observational studies only

Level of Evidence ? The amount of high quality evidence. The more evidence, the more we can trust the results.	Outcome	Magnitude of effect ? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.	Consistency of research results ? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.	Notes
	Cognitive Decline	Notable	- See study	The rate of cognitive decline of either degenerative or vascular origin appears to be significantly reduced with Alpha-GPC supplementation
	Power Output	Notable	- See study	The lone pilot study noted a 14% increase in power output as assessed by bench throws, requires replication but seems stronger than caffeine based on this study.
	Symptoms of Alzheimer’s	Notable	- See study	At least among nutraceuticals, Alpha-GPC appears to significantly improve cognition in persons with Alzheimer's disease at the dose of 1,200mg when taken as a daily supplement over a prolonged period of time.
	Fat Oxidation	Minor	- See study	Some biomarkers of hepatic fat oxidation increased at rest, no indication as to the potency of this relative to reference drugs.
	Growth Hormone	Minor	Very High See 2 studies	Has noted an increase in circulating growth hormone, but measurements were acute (whole-day measurements of growth hormone are more reliable due to hourly fluctuations)
	Iron Absorption	Minor	Moderate See 2 studies	It is possible that Alpha-GPC increases iron absorption from non-meat sources (nonheme iron), but the evidence is currently mixed and a very low dose of 46mg may be required (which would render supplementation irrelevant).

Studies Excluded from Consideration

• Confounded with caffeine and phosphatidylserine^[1]

• Excluded due to using intramuscular injections rather than oral intake^[2][3]

• Paired with donepezil^[4]