If you look at the ingredients in redbull you'll find it's mostly a glorified coffee. It has sugar, and caffeine, but with only 80mg, it pales in comparison to a starbucks grande coffee which has 372mg. You can find caffeine in just about any drink, and don't be fooled, theine, guaranine, and matteine are just caffeine by another name, referring to the source (over 60 plants), rather than the chemical. You can compare here different varieties of soft drinks and energy drinks for their caffeine content.
Other than caffeine, redbull has a few vitamin Bs (B3, B5, B6, B12), I suppose deficiencies in these vitamins can lead to fatigue, but such deficiencies are extremely rare in our western societies since they are very abundant (or supplemented) in most foods, especially dairies.
It also contains inositol, for your PIP signaling needs. Inositol is very useful for drug dealers that use it to cut cocaine and crytal meth, since it has the same appearance, same melting point and no taste or smell. Inositol may also be effective against bulimia, bipolar disorders, panic attacks, obsessive compulsive behaviour and even polycystic ovarian syndrome (PCOS). Yet there is little evidence to support any energy-boosting properties. Inositol can counter-act the serotonin effects of lithium in rat models, so it may even be doing the exact oppposite.
Taurine (1000mg) and its precursor, glucuronolactone are supposed to be the main active ingredients. Taurine is actually an amino acid, and part of the cysteine metabolism. It is present in every living organism, but was originally isolated in ox bile, hence the name. You may also find taurine and creatinine in body building supplements, and both are about as ineffective at reducing muscle fatigue. To be fair it may increase muscular ouput, if it is in limiting quantities .Another place where you might find it is in contact lens solution, where it supposedly inhibits protein denaturation and prevents them from sticking to the lens. Most animals can metabolize their own taurine, although there is a rare condition in humans where they cannot produce taurine nor cysteine, which explains why it is added to infant formula as a precaution. Cats also lack this enzyme and will develop blindness (central retinal degeneration) if it is not supplemented in their diet. Taurine may also reduce blood pressure and be helpful in combating the manic portion of bipolar disorders, both of which argue against energy boosting properties.
Conclusion: So what does science have to say about Reb bull?
Intake of Energy Drinks in Association With Alcoholic Beverages in a Cohort of Students of the School of Medicine of the University of Messina.
"Our data indicate that association of ED (energy drinks) + alcohol is very popular among students. This behavior can be dangerous. In fact, the combination of ED + alcoholic drinks can reduce adversive symptoms of alcohol intoxication including the depressant effects. As consequence, users of ED + alcoholic beverages might not feel the signs of alcohol intoxication, thus increasing the probability of accidents and/or favoring the possibility of development of alcohol dependence."
Talk about overstating results, puleaaase, all they found was that 56.9% of students used rebull, and of those 48.4% often mix it with alcohol. There is no indication that they drink more or are less likely to drive. In my experience the only difference is that I am less sleepy. Is this the only adverse effect of mixing those two?
Most studies seem to imply that it's better to feel drunk and suffer the side effects of alcohol. How bizarre, why would this turn me away from the mix? It seems all good to me:
"the ingestion of alcohol plus energy drink significantly reduced subjects' perception of headache, weakness, dry mouth, and impairment of motor coordination. However, the ingestion of the energy drink did not significantly reduce the deficits caused by alcohol on objective motor coordination and visual reaction time."
And it also helps against drowziness while driving (hopefully not drunk), stimulates cognitive performance and mood, may help for exams, although it doesn't help with memory or performance. There is even some potential in taurine derivatives to help combat alcoholism. So I find very little evidence to support the urban legend that alcohol + redbull is dangerous, or why it is banned in many countries.