Note, appended 3/20/11: This was some research I did on energy drink ingredients. I never had anything close to an energy drink addiction and merely experimented with some. My conclusion was they are fairly harmless (apart from large amounts of sugar and questionable artificial colorings). The main active ingredient in most energy drinks is caffeine and most of the other ingredients are questionable. Since this was written I have completely stopped drinking coffee, because of caffeine dependency, discussed below. I drink 1-2 cups of black tea and 1-2 cups of green tea every day instead, and have concluded that tea is much more healthy than coffee (due to higher levels of antioxidants and stress-relief from theanine and other compounds). Tea provides ~45mg of caffeine per cup of black tea, (~15-30mg per cup of green) which is adequate to provide all  the beneficial effects of caffeine without committing to a major dependency.

Background & personal observations

There is a strong allure to energy drinks. It is now not uncommon to see a section in supermarkets marked “new-age beverages” and filled with a variety of concoctions with un-pronounceable ingredients which claim to improve everything from mental clarity  to sexual performance. Beverage giants such as Coca-Cola and Pepsi are now experiencing major competition from numerous small start ups taking advantage of this new and fast growing market. The concept of a drink that enhances cognitive performance is not new, however. For a long time people have been searching for “smart drugs” or nootropics — drugs which enhance cognitive performance but without side effects or significant dependency. This article will try to sift through the various claims of energy drinks to determine if what , if any, of he ingredients are true nootropics, and make an evidence-based evaluation of what energy drinks may be worth buying.

Energy drinks are marketed primarily towards males. This is for a number of reasons; on average more guys play sports, and guys are usually less sensitive about their health (you don’t usually see girls guzzling mountain dew). Once a gender-association such as this has been developed, it will likely continue to be re-enforced in society. So, energy drinks are now considered “machismo” and a source of identity among the male crowd. The fact is reflected in names such as “Monster”, “Khaos”, “M80”,  “No Fear” and “Pimp Juice”. There are also energy drinks marketed specifically towards gamers such as “Mountain Dew: Game Fuel”.  Exceptions to this trend include more “classy” energy drinks such as the Starbucks line and Bawls.

Within the predominantly male customer base, energy drinks attract two different crowds. The larger crowd is undoubtedly the sports (jock) crowd. They are looking for an energy / adrenal rush to improve athletic performance. The second crowd is the student (nerd) crowd. Here, energy drinks are used to help with “all-nighters”. I would like to further distinguish between the “student” crowd and the “intellectual” crowd. While energy drinks are popular amongst students cramming and pulling all-nighters, I don’t believe energy drinks have been picked up very much amongst intellectuals.

Among intellectuals, Coffee remains the beverage of choice. And as we will see, coffee has a lot of science in its favor. Coffee culture is also a factor. The growth in popularity of European coffeehouses helped start the Enlightenment. Coffee remains vital in most intellectual fields as a stimulant for increased focus. It is possible that we may be on the cusp of a new revolution similar to the original coffeehouse revolution of the enlightenment. So far, though, Coffee remains dominant and for good reason, as we will see.


** “Energy” must be differentiated into increases in physical and cognitive performance.

There are three cognitive metrics we will be interested in:

  1. Enhanced focus.

  2. Enhanced wakefulness. (clearing cognitive “fog”)

  3. Enhanced memory.

These will be compared with physical metrics:

  1. Enhanced physical energy (strength & stamina)

  2. Enhanced resistance to pain (adrenal rush)

Some of the ingredients in energy drinks will give you physical energy merely from calories (ie. sugar, amino acids), but will not enhance cognitive performance above baseline levels, and others may be vice-versa.

Many energy drinks claim to enhance all five metrics. But of course, advertisers are free to make whatever claims they want and even if they are totally false they can reap profits off the placebo effect. In this review we will be looking at scientific studies, in contrast to most other websites devoted to energy drinks. There are some pretty detailed sites dedicated to reviewing energy drinks, but they are primarily based on restatement of the marketing assertions and subjective experience. I’ve compared some reviews of identical energy drinks from different sites and found the reviews to be very subjective. One person might experience a huge rush of energy, which another person might become mildly nauseous. One person might claim to love the strong flavor of a drink while another person might find it pungy and disgusting. This review is different in that we will look for scientific research on each of the active ingredients found in energy drinks. Only then will we try to determine what beneficial effects can be found from energy drinks.

**Caffeine–Benefits–(100-400mg/ day)

** –Decreased risk in developing Parkinson’s.[1] **and slows/reverses development of Alzheimer’s[link][link2][link3]

–General neuroprotective effects.[link]

–Increased attention :  “the information processing system seems more sensitive to relevant stimulus characteristics after caffeine.”[1]

–Improved motor response:

“Rees, Allen, and Lader (1999) found improvements in psychomotor performance in human subjects after a moderate dose of caffeine.”[1]     “ supported in several investigations illustrating that caffeine reduced the time required to execute a response (e.g., Jacobson & Edgley, 1987; Smith, Tong, & Leigh, 1977). However, the effects of caffeine on motor performance are not always beneficial; negative or no effects are reported, as well (see B€attig, 1985; Fredholm et al., 1999; Van der Stelt & Snel, 1998).”[1]

–Increased preference for left hemisphere :  “A relative dominance of left compared to right frontal activation has been linked to activity in the mesocorticolimbic dopaminergic system mediating approach motivation (Davidson, 1999). This dopaminergic system projects more densely to left than right frontal cortex.”[1]**

** –Increased growth of dendric spines (may aid memory formation) [link]

–Improved short term memory retention. (small fMRI study ~15 people) Increased activation of prefrontal lobe.[link]

–Increased “plasticity” in short term memory and phonological loop.[link]

–Reduces mistakes made by shift workers.[link]

–Improved athletic performance (“A small increase in performance via caffeine could mean the difference between a gold medal in the Olympics and an also-ran”) [link][link2]

–slightly decreased risk of death from heart disease.[link]

–Aids carbohydrate uptake, re-fueling after work outs.[link]

–Reduced risk of hospitalization for heart rhythm disturbances [link]

–Decreased risk of gout. [link]

–Decreased risk of skin cancer.[link]

–No correlation between caffeine and increased risk for heart disease or cancer.[2][link]

–Helps prevent decline in memory in older women.[link]

–May help prevent multiple sclerosis.[link][link2]

–Panel of experts concludes moderate coffee drinking decreases many risks.[link]

–Helps treat asthma and improves lung function.[link]**


–Dangerous to drink when pregnant. May damage heart of child. [link]

–Increased risk of miscarriage.[link]

–The benefits of caffeine follow an upside down U shaped response curve. Doses above 500mg (the top of the “U”) start to result in a decrease in performance.[1]

–May not be good for diabetics — greater blood sugar level fluctuation.[link]

–There is evidence that the body develops a tolerance and that beneficial attention effects may be illusions. “While frequent consumers may feel alerted by coffee, evidence suggests that this is actually merely the reversal of the fatiguing effects of acute withdrawl”.[link]

–Causes short term increases in blood pressure. Not recommended for those prone to heart attacks.[link]

–Increased tendency for hallucinations. (>500mg/day)[link]

–Symptoms of caffeine overdose (generally >1000mg) include “everything from nausea, vomiting and a racing heart to hallucinations, panic attacks, chest pains and trips to the emergency room”. [link]

–At least one study shows caffeine to be a moderate risk factor for “chronic daily headache onset”.[link]

very slight addiction. Caffeine consumption is described as “self-limiting” — there are diminishing returns on continuing to consume caffeine. People do not usually increase their consumption of caffeine gradually over time.  Experiments with rats show that only very high doses of caffeine are able to activate “reward circuits”. Thus, caffeine has very little addictive properties.[1]**

** —Withdrawal symptoms–“caffeine withdrawal is often characterized by a headache, fatigue, feeling less alert, less energetic and experiencing difficulty concentrating.**” [link]

** According to an article on CNN, experts estimate 40-45% of people “will experience headaches and other symptoms from caffeine withdrawal syndrome.”[link]

Influence on blood sugar levels some research seems to indicate that caffeine may disrupt the insulin system used to control blood sugar levels. People with diabetes are usually advised to keep caffeine intake low. [link]


** References: [1] Caffeine, fatigue, and cognition Monicque M. Lorista and Mattie Topsa 21 July, 2003.**

**  [2] Caffeine The Encyclopedia of Psychoactive Drugs.


Caffeine is highly water soluble. It is destroyed in the liver and has a half life of 3-5 hours. Caffeine works by blocking adenosine receptors. At the “A1” receptors it leads to the well known effect of delaying tiredness. At the “A2” receptors, caffeine leads to increased transmission of dopamine. This is supported by the fact that “intact dopaminergic neurotransmission is necessary for caffeine to be stimulatory.” As shown in the picture to the left, Caffeine is broken into three different compounds in the liver which have secondary effects in the body. From Wikipedia:

–Paraxanthine (84%): Has the effect of increasing lipolysis, leading to elevated glycerol and free fatty acid levels in the blood plasma.

–Theobromine (12%): Dilates blood vessels and increases urine volume. Theobromine is also the principal alkaloid in the cocoa bean, and therefore chocolate.

–Theophylline (4%): Relaxes smooth muscles of the bronchi, and is used to treat asthma. The therapeutic dose of theophylline, however, is many times greater than the levels attained from caffeine metabolism.

More information on the mechanisms of caffeine can be found on Wikipedia and other websites. **


After this literature review it is clear that moderate caffeine consumption (100-300mg/day) or 1-2 cups of coffee a day has many beneficial effects and no reported detriments, except for withdrawal symptoms and in the special cases of pregnant women and diabetics. If you plan to drink coffee regularly, it may be worth buying caffeine tablets. Then you can take a tablet if are unable to get a cup of coffee to prevent withdrawal symptoms. If you are a regular drinker and plan to go without caffeine, you can avoid withdrawal symptoms by slowly cutting back consumption several days in advance. **

** See also: Guide to getting optimally wired on Developing Intelligence blog.**

** The Complete Guide to Starbucks Caffeine Complete Guide to Starbucks Caffeine


–Not much hard data available on this.**

** –It is claimed it serves a “de-toxificant” but there is no scientific evidence of this.**

** –It is naturally produced by the synthesis of glucose in the liver.

–European Food Safety Authority **determined the amounts found in energy drinks are safe.

** –Conclusion–not enough data available. **



** –claims to aid metabolism.**

** –known to be an antioxidant**

** –Conclusion–may be a useful antioxidant but don’t expect energy from this.


** –Technically a amino-sulfonic-acid but usually described as a “non-essential amino acid”..

–First isolated in ox bile in 1827. (an ox is a castrated bull)

–A key ingredient in Red Bull, and found in large amounts (1000-4000mg) in other energy drinks.

–Taurine is naturally found in meat and fish. Average daily taurine consumption is 58mg according to one study. Another estimated between 40-400mg daily.(refs on Wikipedia)

–“L-Taurine” denotes the natural form of taurine. Many amino acids exhibit only the left isomeric form when produced biologically. When produced naturally, they may exhibit both forms. The Greek words denoting left and right are “Levo” and “Dextro”, so the letters L and D are used to distinguish the two forms.

–A “literature review” seeks to debunk the marketing claims about Taurine. The article notes that caffeine can freely cross the blood-brain barrier. Taurine, however, is regulated, so it is unlikely consumption of taurine leads to higher taurine levels in the brain.[link]**

** –Taurine has anxiolytic (anti-anxiety) effects.[link] **(see  refs. on Wikipedia)

** –A literature survey reports: “Taurine appears to have multiple functions and plays an important role in many physiological processes, such as osmoregulation, immunomodulation and bile salt formation. Taurine analogues/derivatives have recently been reported to have a marked activity on various disorders.” [link]

–Higher heart rate and blood pressure was observed in those who consumed high-taurine energy drinks for several days. May be harmful to those with heart disease or hypertension.[link]

–Chronic doses help prevent age-related memory decline in rats. Leads to increases in the GABA neurotransmitter.[link]

–Taurine was tested in monkeys– taurine-free monkeys showed greater attention and scored better on cognitive tasks.[link]

–Taurine is an antioxidant, protects liver [link] and protects brain tissue.[link]

–The European Food Safety Authority found no adverse effects for up to 1,000 mg of Taurine per kilogram of bodyweight per day.(refs on Wikipedia)

–Helps repair neurovascular/ neurological defects from type II diabetes.[link][link2]

–An essay on the effects of taurine cites studies showing synergistic effects between caffeine and taurine, for instance, improved performance of athletes.  An excerpt:: “other studies by Alford, et al. (2001) and Warburton, et al. (2001) in which caffeinated taurine drinks improved information processing and increased subjective alertness, concentration, and physical endurance compared to the placebo group (no caffeine or taurine). Again, the same problems are encountered. The sample size is too small (36 and 42 respectively), and possibility of the positive effects being solely due to caffeine are not accounted for.”[link]

–Another study found that “The combination of caffeine and taurine had no effect on short term memory, but did cause a significant decline in heart rate and an increase in mean arterial blood pressure.”[link]

–France banned Taurine. Norway and Denmark also banned it, but lifted the ban recently.

–A key study was done by Dr. Neil L. Harrison at Cornell Medical College . “We have discovered that taurine is a strong activator of what are known as GABA receptors in a regulatory area of the brain called the thalamus.”….”We had discovered these receptors two years ago and showed that they interact with a neurotransmitter called gamma-aminobutyric acid (GABA) — the brain’s key inhibitory transmitter — that is also involved in brain development. It seems that taurine shares these receptors.” The effect is unknown. In conclusion: “Remarkably little is known about the effects of energy drinks on the brain. We can’t even be sure how much of the taurine in the drink actually reaches the brain!” Dr. Harrison says. “Assuming that some of it does get absorbed, the taurine — which, if anything, seems to have a sedating effect on the brain — may actually play a role in the ‘crash’ people often report after drinking these highly caffeinated beverages. People have speculated that the post-Red Bull low was simply a caffeine rebound effect, but it might also be due to the taurine content.” [news article][original paper]

–Conclusion–There is no evidence that taurine is energy-giving. There is only circumstantial evidence, based on the fact that it is found in many energy-rich foods. Additionally, a number of studies (not cited) show it is useful for skeletal and muscle maintenance. It seems doubtful there are cognitive benefits from taurine, one study actually showed a decrease in cognitive performance in monkeys and in the last study mentioned Dr. Harrison noted that he thought it showed sedative effects. My preference (and recommendation) is to stay away from large amounts of taurine (greater than 1000mg). However, 4000mg, (the amount found in some drinks) is probably safe, perhaps even healthy, based on the safety studies, but its hard to be sure. I am not sure why many energy drinks contain large amounts of taurine. Part of it may be because it sounds like “Taurus” (the bull). Most likely it is because it was popularized by Red Bull, and the marketing hype grew on itself. Additionally, it may be responsible for the taste of Red Bull, so many other energy drinks might want to achieve a similar taste. Of course, a person’s response to the taste of Red Bull is very subjective.

**GABA (gamma-Aminobutyric acid)

** –It is described as “is the chief inhibitory neurotransmitter in the mammalian central nervous system”. It is very important for brain function.

–GABA does not cross the blood-brain barrier.[link]

–However, some areas of the brain are not behind the blood-brain barrier, such as the periventricular nucleus. As a result, increased GABA can mess with the endrocrine system. At least one study shows that orally administered GABA results in acute increases in human growth hormone (HGH) secretions.[link]

–A neuroscientist writes on his blog that “GABA is a gimmick” and that it won’t have any effect since it doesn’t cross the blood-brain barrier.[link2]

–Injection of GABA directly into the brain is being studied for some therapeutic applications, mostly as an anti-convulsant and to reduce anxiety.

–Conclusion–GABA is not a useful ingredient for energy drinks. GABA-based energy drinks do exist and have been repudiated by reviewers and energy drink connoisseurs. The effects of GABA on growth hormone levels should be worrisome. I would stay away from this ingredient, at best it is not very useful and at worst could be harmful.

**Ginseng Panax

** –Found to have anti-inflammatory action.[link]


** –Found in Green tea, it is believed to be a relaxing antioxidant.

–A study in rats found that L-Theanine counteracts some of the effects of caffeine.[link]

–A study found that it reduces stress [link]

–It increases levels of GABA (discussed above) in the brain. (wikipedia)

–In 2006 a study found no consistent, statistically significant treatment-related adverse effects on behavior, morbidity, mortality, body weight, food consumption and efficiency, clinical chemistry, hematology, or urinalysis in rats fed high doses of theanine for 13 weeks [link]

-L-Theanine may help the body’s immune response to infection by boosting the disease-fighting capacity of gamma delta T cells. The study, published in 2003 by the Brigham and Women’s Hospital, included a four-week trial with 11 coffee drinkers and 10 tea drinkers, who consumed 600 milliliters of coffee or black tea daily. Blood sample analysis found that the production of anti-bacterial proteins was up to five times higher in the tea-drinkers, an indicator of a stronger immune response.[link]


** –contains caffeine (2-4.5% by weight).**

** –used by Brazilian tribes as a stimulant.**

** –study of 45 adults over 60 gave them 1000mg a day for 120 days. No observed cognitive alternation.[link]**

** –slight memory improvements and increased physical endurance observed in rats with low doses over long periods.[link]

–improved cognition observed with low doses (37.5mg, 75mg) compared with higher doses in humans.[link]

–improved attention and performance in human subjects age 18-24. Speed of cognitive tasks increased, accuracy slightly decreased or remained constant. [link]

–anti-oxidant action observed in high doses in rats. No toxicity or risks found. [link]

–reduced platelet aggregation found in several studies. Ramifications for heart disease unknown.[link]

–Conclusion–Most of the claims about guarana are highly exaggerated. There may be some small cognitive effects but results are conflicting. It is difficult to isolate the effects of guarana from the caffeine it contains. It is thus understandable how it may have been used by Brazilian tribes — the beans contain twice as much caffeine than coffee beans by weight. On the other hand, two studies reported no evidence of toxicity or increased mortality in rats and there is no reason to believe it is unsafe in the quantities found in energy drinks.

B vitamins (in particular, niacin and inositol)

–To help reduce confusion, here are the B vitamins:

  • Vitamin B1 (thiamine)

  • Vitamin B2 (riboflavin)

  • Vitamin B3 (niacin or niacinamide, sometimes also known as vitamin PP)

  • Vitamin B5 (pantothenic acid)

  • Vitamin B6 (pyridoxine, pyridoxal, or pyridoxamine, or pyridoxine hydrochloride)

  • Vitamin B7 (biotin)

  • Vitamin B8 (inositol)

  • Vitamin B9 (folic acid)

  • Vitamin B12 (various cobalamins; commonly cyanocobalamin in vitamin supplements)

–B1-B9 + B12 are all essential, there are many other “B vitamins” that are non-essential. They are essential for cell metabolism.

–One study finds that B vitamins, in particular folate, B12, and B6 are important for maintaining cognitive function into old age. Other studies theorize there is a deficiency in these vitamins amongst a large percentage of Americans. [link]

–A study of 70 male subjects, aged 50-70 found that lower blood level concentrations of vitamin B-12 and folate were associated with poorer spatial copying skills. Higher levels of B6 were found to be linked to better performance in two measures of memory.[link]


** –Increased cerebral blood flow found in stroke patients after 2 week exposure.[link]**

** –May serve as neuroprotective against stroke.[text]**

** –Inhibits inflammation.[link1][link2]**

** –Conclusion–no evidence of improved energy. Not sure.**

Huperzine A

–“Hup A” is found to be a promising drug for treating Alzheimer’s.[link]**

** –Another study found that Huperzine A helped heal damaged brain tissue and may be useful for combating dementia.[link]

-A study found some neuroprotective effects.[link]

DMAE (Dimethylethanolamine)

–After 3 months, some positive effects on mood found in humans.[link]**

** –led to decreased lifespan in quails. (49 vs 69 weeks) [link]**


Ginkgo Biloba

–Ginkgo Biloba is a big beautiful tree that has been cultivated in China and parts of Japan for thousands of years.

–The large seeds have culinary applications and the leaves are used for Ginkgo tea. **Ginkgo leaves are rich in flavanoids.

** –A literature review finds some positive effects in the treatment of “cerebral insufficiency”.[link]**

** –A study finds a small beneficial effect for the long-term treatment of Alzheimer’s Disease.[link]**

** –A study finds no effect of Ginkgo Biloba on cognitive impairment and dementia.[link]

–A 6 month study finds slightly beneficial effects on the treatment and stabilization of dementia.[pdf]**

** –A study found no effects on heart disease , but possible slight benefits to vascular disease.[link]

–A multi-year study found no effect of GB on preventing cognitive decline.[link]

–Several studies found no effect on memory problems.[link][link2]**

** –A $30 million study found no effects on memory, cognition, dementia or preventing Alzheimer’s.[link]

–A study found that administration of 240mg of GB improves attention and speed after 2.5 hours.[link]

–In another study, GB led to accute improvements in attention and memory. However, after 6 weeks the improvements went away, suggesting the brain developed a tolerance to the effects.[link]

–Another study found no improvement of cognitive function among patients with MS.[link]

–A review which references 155 studies can be found here. They cite studies investigating possible benefits in preventing cancer. They also note that in a study with 160mg/day, no adverse reactions were found compared to placebo groups, so it is generally safe. There are side effects with larger quantities, though.

–Conclusion–As far as preventing long-term mental decline and boosting health, Ginkgo Biloba appears to be another case of a traditional herbal remedy that doesn’t stand up to scientific scrutiny. Some research shows some minor effects on treatment of specific conditions but no over-arching effects have been found. As far as acute short-term effects, it appears that **it does have some effects, which is probably why it has been used by monks and yogis for centuries. In conclusion, in the small quantities found in a cup of tea, Ginkgo may help lift mental fog and probably has some healthy antioxidant properties. However, it is not the disease-preventing panacea that is often claimed by marketers and given the possible chance of side effects it doesn’t seem worth taking as a supplement. **


–Citicoline is a main ingredient in “5 Hour Energy”. It makes “5 Hour Energy” unique among energy drinks.

–Helps prevent age-related memory decline in mice.[link]**

** –1000mg/day improves verbal memory in aging seniors.[linklink]**

** –Conclusion–this ingredient looks promising, but not enough research has been done to make a judgment. There is no direct evidence it is energy-giving, although it is described in some sources as a “psychoactive stimulant”. **

“luo han guo” fruit

–A unique sweetener / antioxidant found in Guru energy drink. Extract is 300x sweeter than sugar.

–Has antioxidant properties.[link]

–Generally recognized as safe by the FDA.**

Acai Berry

–Açaí berry juice has mid-range antioxidant content. It has less than Concord grape, blueberry, and cherry juice, but more than cranberry, orange and apple. (Wikipedia

**Milk Thistle

** –A traditional herbal medicine for liver problems.

–Studies have been mixed. One double-blind study found it “does not seem to significantly influence the course of patients with alcoholic and/or hepatitis B or C liver diseases”[link] A literature review reached no conclusion. Other studies indicate that in small quantities there are no effects but in large quantities there are effects at helping liver function. Other studies support the claim it prevents liver cancer and is healthy and helps repair liver damage. (references on Wikipedia)

**Yerba Mate

—**A south american drink. Contains caffeine.

**Artificial Sweeteners found in Energy Drinks

Acesulfame-K (Ace-K)

** –Some health-advocacy groups call for more studies.**

** –Generally recognized as safe (GRAS) by FDA.**


–Has been the source of major controversy, mostly related to conflicts of interest between the FDA and corporations. (see long Wikipedia article on the subject which I didn’t read in entirety..)

— “FDA officials describing aspartame as “one of the most thoroughly tested and studied food additives the agency has ever approved” and its safety as “clear cut””

— A scientific literature review backs the claim that it is completely safe.[link]



** –First artificial sugar substitute.

–Study found it caused bladder cancer in rats in 1960. Long story short, it was later found the mechanism for cancer formation does not occur in humans.**

** –Still, its probably worth being wary of this one.**

Sucralose (aka “Splenda”)

–“In determining the safety of sucralose, the FDA reviewed data from more than 110 studies in humans and animals. Many of the studies were designed to identify possible toxic effects, including carcinogenic, reproductive, and neurological effects. No such effects were found…” (FDA final ruling quoted on Wikipedia)**

** –Generally recognized as safe (GRAS) by FDA.**

Stevia –(Aka “Rebaudioside A” aka “Truvia”) **— found in “Guru” **

** –from Wikipedia: “In a 2008 review, 14 of 16 studies cited showed no genotoxic activity for stevioside, 11 of 15 studies showed no genotoxic activity for steviol, and no studies showed genotoxicity for Rebaudioside A. No evidence for stevia constituents causing cancer or birth defects has been found.”

–One study found that stevia has anti-hypertension effects.[link] Another study found no such effects.[link2]

–Generally recognized as safe (GRAS) by FDA.**


General Scientific Research on Energy Drinks:

–Mood and cognitive performance effects of “energy” drink constituents: caffeine, glucose and carbonation.” — “The results showed caffeine to be the main energy drink constituent responsible for the effects found, with possible minor, relatively weak effects of carbohydrates.”**

** —Diuretic potential of energy drinks –“Taurine played no significant role in the fluid balance in moderately dehydrated healthy young consumers. Consequently, the diuretic potential of energy drinks will not differ significantly from other caffeine containing beverages.”**

** —“Party Like a Rockstar: The Effect of Energy Drinks on Cognitive Ability**— a group of college students found that Rockstar energy drink did not improve cognitive performance, but did improve speed. (most likely to be due to caffeine).

–“A survey of energy drink consumption patterns among college students“–results: “Fifty one percent of participants (n = 253) reported consuming greater than one energy drink each month…The majority of users consumed energy drinks for insufficient sleep (67%), to increase energy (65%), and to drink with alcohol while partying (54%). The majority of users consumed one energy drink to treat most situations although using three or more was a common practice to drink with alcohol while partying (49%). Weekly jolt and crash episodes were experienced by 29% of users, 22% reported ever having headaches, and 19% heart palpitations from consuming energy drinks. There was a significant dose effect only for jolt and crash episodes.”**

** —_Efficacy of a ‘functional energy drink’ in counteracting driver sleepiness  –“_It was concluded that the FED (Functional Energy Drink) is beneficial in reducing sleepiness and sleep-related driving incidents under conditions of afternoon monotonous driving following sleep restriction the night before.**”

** —The effects of Red Bull Energy Drink on human performance and mood –“Significant improvements in mental performance included choice reaction time, concentration (number cancellation) and memory (immediate recall), which reflected increased subjective alertness…”**

** —New-onset seizures in adults: Possible association with consumption of popular energy drinks — “We report a series of four patients who had discrete seizures on multiple occasions, following heavy consumption of energy drinks.

—_The effects of energy drinks on cognitive performance — “_CONCLUSION: The findings suggest that most of the effects of energy drinks on cognitive performance are related mainly to the presence of caffeine. Further investigation is needed into the effects of the lesser known ingredients of energy drinks (taurine, glucuronolactone) if we are to obtain a better understanding of the possible interactions.”**

** —The effects of Red Bull Energy Drink on human performance and mood Significant improvements in mental performance included choice reaction time, concentration (number cancellation) and memory (immediate recall), which reflected increased subjective alertness. These consistent and wide ranging improvements in performance are interpreted as reflecting the effects of the combination of ingredients.**

** —Effects of ‘energy’ drinks on mood and mental performance: critical methodology**