Introduction
Your brain needs more than just energy molecules like glucose or ketones to run. Neurotransmitters are depleted by use, for example. While they can be synthesized to an extent, your brain will work more efficiently if you consume them or their precursors. There are others, like acetylcholine, that you cannot completely synthesize, and have to consume. Baseline amounts from a basic balanced diet will keep you going, but getting spike doses can help clear thinking. Most generally defined, a nootropic is a cognitive enhancer that is not a stimulant and has very low toxicity.
Other supplements may not be found in a natural diet but will enhance or feed existing metabolic pathways. L-Alpha Glycerylphosphorylcholine is more readily absorbed (though it’s found in milk so it’s not entirely unnatural). Dimethylaminoethanol is man-made, very easily absorbed, and is methylated in the brain to produce choline. Choline is one of the most essential building blocks of a nootropic regimen, and often has a significant effect alone.
Some may be concerned with a distinction between supplements and drugs. As noted above, synthetic substances that produce effects identical to natural substances are readily found, and many will know that natural substances that produce effects outside of necessary metabolism are readily found in nature (caffeine and THC are good examples). The natural/synthetic thus seems a poor line to divide “supplements” from “drugs”. For the purposes of these discussions, the “natural effect” versus “synthetic effect” line will be used, when any distinction is made. It is necessarily informal, and individual distinctions may later be found to be incorrect. If you have qualms about drug use, thoroughly research the compounds before you use them and make the decision for yourself.
Choline Sources
As a near direct goal of most nootropic supplementation is to increase neural activity in the brain, increased consumption of essential nutrients used to make neurotransmitters is necessary. Choline is one of primary concern. One issue of note with choline is that it competes with protein to cross the blood brain barrier – thus spike choline supplementation should be done on an empty stomach. Generally, an adult male’s adequate intake of choline is about 550 mg/d, slightly less for most females, but significantly higher for pregnant or breastfeeding females. Listed amounts of the supplements target the ingestion of 100 mg of choline.
Dietary: eggs, chicken, cruciferous vegetables such as cauliflower, milk, fish, and liver, in increasing levels, contain significant amount of choline (varies).
Lecithin (3000 mg): usually available from an all natural source such as soy or sunflower oil.
Choline Bitartrate (1500 mg): Synthetic
Alpha GPG (L-Alpha Glycerylphosphorylcholine) (1200 mg): Hard to find now, but very effective.
DMAE (Dimethylaminoethanol) (1200 mg ?): Dosages not as well documented, but presumed from structure. Tested and know to be safe well past 1600 mg/day.
Centrophenoxine (1200 mg): Not well documented.
Citicholine (cytidine diphosphate-choline, CDP Choline) (1200 mg): More expensive but one of the best sources.
Racetams
Racetams seem to work by activating glutamate receptors that are colocated with cholinergic receptors, increasing the firing of the cholinergic receptors. The specific mechanisms are generally not well understood. They all seem to increase working memory, memory recall, and cognition to various degrees. Racetams are synergistic with choline sources – that is, the results of taking both is improved when they are used concurrently. It is important to note racetam solubility. It varies, and consuming a racetam with a small amount of food with which it is soluble will significantly increase uptake. For example, consume a dose of a fat soluble racetam like aniracetam with 8 oz of milk. Each is listed with solubility and a commonly recommended starting dose.
Piracetam: Improves cognition and working memory through increased cross-hemisphere communication within the brain. Half life is 4-5 hours. (water, 1000 mg 2bd)
Oxiracetam: Improves cognition, logical performance, memory, and spatial awareness. (water, 750 mg 2bd)
Aniracetam: Improves cognition, more potent and easily absorbed than piracetam or oxiracetam. Half life is 1.5-2 hours. (fat, 250 mg 3bd)
Pramiracetam: Similar to piracetam. Half life of 4.5-6 hours. (fat, 50 mg 1/2bd)
Nefiracetam: Antidepressant effects, may improve cognitive function and memory. Reduction in testosterone and sperm motility associated with extremely high doses. Half life 3-5 hours. (fat, 600 mg 2bd)
Stimulants
Mild stimulants are regularly used. Caffeine, in the form of tea, coffee, and soft drinks, is consumed almost universally. Most mild stimulants are plant alkaloids. They often show synergistic effects with other compounds.
Caffeine: Practically ubiquitous. Dosing with pills may be more effective in order to minimize uptake competition and standardize dose.
Ephedrine: More difficult to find due to FDA meddling. Look for Ephedrine-HCL or Ephedrine Sulfide in Bronkaid or Primatene at a pharmacy.
Nicotine: Improves cognition and working memory. Generally taken as a transdermal patch.
Other
Some compounds show significant benefit but are not members of families with similar marked benefit. Theanine, for example, has a mild psychoactive effect and appears to improve cognition and mood.
Theanine: Improves cognition and mood. Found in tea, especially green tea (~10 mg per 8 oz serving) or isolated in pills.
Ginkgo biloba: Improves memory, concentration, and reduces the effects of vertigo.
Stacking
Taking supplements with synergistic effects or precursors is called stacking.
Simple stack
Below are the components of a very simple stack that will result in moderate improvements of cognition, memory, and energy. It is important that these be taken with a small amount of milk or almond milk or other food (about four ounces of milk is all that is necessary).
800 mg piracetam
1200 mg lecithin
200 mg theanine
100 mg caffeine
Take that twice a day on an empty stomach.
Jordan's space 
Interesting perspective on “stacking.” I’ve heard of a number of positive effects related to choline supplementation. Stimulants seem to be the most commonly used method of spiking neural activity, however their diminishing effect after heightened tolerance levels seems to be the only major drawback. Very nicely done post. Cheers.
Simulants do that. But these aren’t stimulants and don’t work the same way. Think of them more like vitamins.
nice post. i know ecetams have been studied and considered to be risk free. But what we know is, the racetam supplement family is being used by many people who wish to enhance their brain and thinking capacity.