Choline, in some form, is a component of most people’s nootropic stack, and rightly so. Choline is an essential nutrient which is vital for the production of neurotransmitter acetylcholine and is used to form phosphatidylcholine (PC), a building block of cell membranes.
While the benefits of ensuring optimal choline intake are usually highlighted across the internet, it’s difficult to find a comparison of the various choline supplements. This article will cover the differences between Alpha GPC, CDP Choline and Choline Bitartrate.
Choline Bitartrate and Lecithin
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Choline bitartrate is an economical / inexpensive form of choline which contains 40% choline by weight. That is to say that a gram typically contains 400-410mg of actual choline. This form of choline doesn’t seem able to specifically raise brain levels of choline beyond that of “general” choline rich foods (such as lecithin). It’s probably reasonable to group choline bitartrate and choline citrate with other “dietary” forms of choline such as lecithin. Lecithin has specifically been found to be ineffective at treating dementia (Ref), while CDP choline is regarded as effective (Ref).
CDP Choline (Citicoline)
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CDP choline is only 18% choline by weight, but packs a nice punch as a nootropic as it’s essentially a uridine supplement as well. CDP Choline is naturally found within the body as an intermediary form of choline created during PC synthesis, whereas Alpha-GPC is created as a by-product of PC breakdown (discussed below).
The chemical structure of citicoline is cytidine 5′-diphosphocholine. Upon digestion CDP Choline is broken into its constituent parts cytidine and free choline (Ref). In humans cytidine is quickly converted to uridine. Uridine is a nootropic in its own right that lends a hand in PC creation. This makes citicoline a two-in-one nootropic.
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Alpha GPC naturally occurs in the brain as a catabolic byproduct of PC breakdown. When the brain needs acetylcholine and free choline stores are running low, it breaks down phosphatidylcholine from cell membranes into GPC choline (a process known as autocannibalisation). In my head (no pun intended) this explains why oral GPC is such an effective cholinergic; it’s effectively a compound the brain makes when it is savaging its own cell membranes for choline.
Alpha GPC is 40% choline by weight and is able to cross the blood brain barrier intact. It has been shown to reliably increase choline levels in brain tissue, which enhances PC and acetylcholine synthesis.
Aside from impacting brain choline levels, Alpha GPC is known for increasing growth hormone by (theoretically) inhibiting somatostatin release in the brain via cholinergic mechanisms. Regardless of the exact explanation, growth hormone is raised for 2 hours following GPC ingestion. (Ref)
Choline Bitartrate vs GPC vs CDP Choline (Citicoline)
If budget is a concern, then choline bitartrate wins hands down. It’s 1/10th the cost of the other choline supplements and will certainly prevent a deficiency.
Budget aside, most people will be interested in the optimal form, or, in other words, which choline is the best: GPC or CDP?
GPC and CDP Similarities:
- Both are able to raise brain levels of choline
- Both contribute to acetylcholine and PC synthesis
- Both are naturally occurring intermediary forms of choline
- Both support youthful levels of cell membrane fluidity (Ref)(Ref)
- Both increase AhCE (Ref) (Ref)
- Both have been found helpful in dementia, though GPC more so (Ref)
- Both have been shown to restore muscarinic acetylcholine receptors in aged rodent models (Ref) (Ref)
GPC and CDP Differences:
- GPC is 40% choline by weight, while CDP is 18-19% – a pretty major difference
- CDP choline is essentially a uridine supplement as well as a choline supplement
- CDP has been shown to restore dopamine receptor densities in aged rodents (Ref)
- CDP was shown to improve symptoms of Parkinson’s, presumably through increasing dopamine receptor density (Ref)
- Alpha-GPC has been studied and shown to enhance GH release (Ref)
One study comparing the two involved 120 patients with mild-moderate dementia (Ref). An intramuscular injection of 1 gram GPC or CDP was given once per day for 90 days. Researchers concluded that GPC was superior at increasing various markers of cognition, though both choline supplements were helpful at reducing symptoms. The only caveat of this study is that it featured an intramuscular injection rather than the choline supplements by mouth. Avoiding the gut may have increased GPC’s efficacy as it’s thought some GPC is metabolised during digestion.
Desert island scenario: If I could have unlimited quantities of either and I had to pick, CDP would be my winner, as it’s essentially a two in one nootropic (uridine and choline) and looks like it has the edge with dopamine receptors. That said, if I could only have a kilogram of each GPC would probably be my choice as it contains vastly more choline.
Whichever you choose, GPC or CDP are both fantastic forms to supplement and both will raise brain levels of choline, thereby optimising cell membrane and neurotransmitter synthesis.
Questions? Feel free to leave a comment below!