Table 3.

Potential ergogenic nutrients contained in energy drinks that may affect cognition and/or mental performance

Ingredient	Potential ergogenic value	Scientific support
Taurine	Improved mental focus, concentration, serve as antioxidant, glucose homeostasis [21-24]	Some supportive evidence with ED and fed animals [25-35]
Gingko Biloba	Improve memory and mental concentration	Some supportive evidence on memory (e.g., 120 mg/d) [36-39]. No known effects at dosages found in ED or ES.
L-Tyrosine	Prevents depletion of catecholamines, may ameliorate declines in cognition with acute stress [40-47]	Some supportive evidence on cognition (e.g., 2 g/d, 150 mg acute ingestion with cold exposure) [41,43,46,48,49]. No effects on performance capacity [42,50]. No known effects at dosages found in ED or ES.
Citicoline	Intermediate in the generation of phosphatidylcholine from choline. Increase dopamine receptor densities and delay memory impairment [51,52].	Some supportive evidence with large doses (8.5 g prior to and during exercise) and in fed animals [52]. No known effects at dosages found in ED or ES.
5-Hydroxy-L-Trypotophan (5-HTP)	Precursor to serotonin [53,54]. Purported antidepressant, appetite suppressant, & sleep aid [53,55-58].	Some evidence in treatment of depression [53,55-58]and 5-HT fed animals on muscle performance [54,59,60]. Role on exercise performance at dosages found in ED and ES is unknown.
St. John’s Wort	Anti-depressant [56-58].	Some supportive evidence [56-58]. No known effects at dosages found in ED or ES.