A can of Red Bull contains 1,000 mg taurine, more than many supplements. (Photo by kamshot)
Taurine is found in most energy drinks right alongside caffeine, but nobody seems to know exactly why. Do the manufacturers of Red Bull and Battery know something we don't, or is taurine added simply out of habit?
Since finding any useful information on taurine as a brain stimulant is difficult, in this post, we'll look at what the studies say on taurine's effect on cognitive function and mood. Specifically, the problem areas we'll be focusing on are aging, depression, brain damage, and alcohol.
Taurine and the aging brain
With age, the neurotransmitter system performs progressively worse, resulting in problems with memory, learning and mood, among other things. A key part of this system is the main inhibitory neurotransmitter GABA, or gamma-Aminobutyric acid. Drugs that increase the amount of available GABA in the brain typically have a relaxing and anti-anxiety effect.
There is some evidence that taurine may increase GABA levels by acting as a GABA receptor antagonist. In one study, aged mice supplemented with taurine showed less decline in memory acquisition and retention, which was associated with increased levels of GABA and glutamate (link). Taurine may also protect from Huntington's disease through its indirect antioxidant effect and by increasing GABA levels (link).
Not all studies have found similar benefits, however. One experiment showed that when old rats were given taurine in their drinking water, brain taurine levels increased, but oxidative stress parameters improved only in the liver (link).
Taurine, depression and anxiety
Since taurine is found in energy drinks, one might expect it to have at least a temporary positive effect on mood, similar to caffeine. Indeed, there is some evidence that this is the case. In mice, intraperitoneally administered taurine was shown to increase social interaction and have an anti-anxiety effect in doses between 14-126 mg/kg (link).
However, one study showed that only supplementary taurine increased increased locomotor activity and anxiety while taurine injections had the opposite effect (link). This is contrast to the previously mentioned study. Similarly, in one study 200 mg/kg given orally had a significant anti-anxiety effect (link), but in another one, taurine had no effect on anxiety or depression and even resulted in a decrease in activity in higher doses (link).
Taken together, the animal studies don't give us a very clear picture of how taurine affects mood, if it does so at all. Unfortunately, human studies are scarce and equally confusing. In a study on Korean college students, taurine intake inversely correlated with stress in female but not in male subjects (link). Unlike the rodent studies, however, the study didn't use taurine supplements and only measured taurine intake from food sources.
Taurine and brain damage
Whereas the studies on taurine's effect on brain aging and mood remain inconclusive, the case for protecting the brain from sudden damage is quite strong. Brain ischemia, a condition where there is insufficient blood flow to the brain, causes neuronal death in part through apoptotic pathways mediated by calpain and caspase-3, caspase-8 and caspase-9; taurine appears to dose-dependently protect the neurons from cell death by blocking the pathways (link, link, link).
Other ways taurine may protect the brain is by improving mitochondrial function (link), and by reducing damage from excessive calcium overloads (link) and cadmium-induced oxidative impairment (link). Tryptophan administration also increases oxidative stress in the brain cortex of rats, but pre-treatment with taurine prevents the increase (link). Based on these studies, taurine may be helpful in protecting from short-term damage to the brain.
Taurine and alcohol
Taurine has been suggested as a possible treatment for alcoholism (link), and acamprosate, a promising drug used to treat alcoholism and alcohol withdrawal, contains a synthetic compound similar to the naturally occuring homotaurine (link). One possible reason for helping with alcohol withdrawal is that taurine increases dopamine levels in the brain similarly to ethanol (link).
In addition to helping with staying away from alcohol, taurine also appears to reduce some of the harmful effects of alcohol in the brain. For example, taurine shields from alcohol-induced damage by reducing programmed cell death through a decrease in the immunoreactivity of caspase-3 (link). Taurine may also reduce the lack of coordination of muscle movements resulting from ethanol (link), which can be a good thing or a bad thing, depending on how you ask.
For those who enjoy the short-term effect of alcohol but are worried about the long-term effects, it's interesting to note that taurine reduces the urinary loss of selenium, chromium and manganese in rats chronically consuming alcohol (link). This suggests taurine might be useful as an anti-hangover supplement.
Taurine is a common ingredient in energy drinks, because it is believed to have a cognition- or mood-boosting function. However, the evidence behind these claims is controversial. While taurine appears to protect from acute neurological damage, including alcohol, its other effects are less clear. Nonetheless, at least a few studies have shown that taurine increases GABA levels in the brain, which may help with memory, learning and anxiety.
For more information on aging and the brain, see these posts:
Does Ginkgo Biloba Improve Cognitive Performance?
L-Carnitine, Acetyl-L-Carnitine and Cognitive Function in Humans
Increasing Intelligence by Playing a Memory Game – Experiment Update
Caloric Restriction Improves Memory in the Elderly