Citicoline results in clearer, more focused thinking. One recent Harvard study found that healthy men and women taking 500 or 2,000 mg of citicoline daily for six weeks showed increased energy in the part of the brain responsible for focus and concentration. Other research indicates that citicoline increases production of acetylcholine in the brain, a major neurotransmitter responsible for brain processing speed.

How to take: For a general brain boost, try the lower dose of 500 mg a day. Higher amounts (up to 2,000 mg) are safe and give a stronger mental boost. Results should be immediate, and this supplement can be continued for as long as desired.