Food and diet

Energy drinks 'no better than a strong coffee'

“Forget energy drinks – they’re no more effective than a cup of coffee”, the Daily Mail reports.

The story comes from research looking at evidence for claims that the ingredients in popular energy drinks, other than caffeine, have any benefits on physical or mental performance.

Energy drinks, including popular brands such as Red Bull and Rockstar, are heavily marketed as improving physical and mental performance and are a multi-billion pound global industry. They all contain significant amounts of caffeine, but much of the marketing for these drinks also highlights the fact that they contain other, alleged energy-boosting ingredients such as taurine, guarana, and ginseng. 

However, this study cites “an overwhelming lack of evidence” to substantiate claims that such ingredients have any effect. The research concludes that any effects from energy drinks are due to their caffeine content, rather than the other ingredients.

While it is important to note that the study is not a systematic review of the type that might be used in assessing medical treatments, the available evidence seems to suggest that a double espresso is as likely to help performance as an energy drink.

Those looking for a healthy stimulant-free refreshment need look no further than the nearest drinking water tap. If you are feeling tired all the time it may be worth considering whether you are suffering from one of the medical causes of tiredness.

Where did the story come from?

The study was carried out by researchers from TM McLellan Research Inc, Canada, and the US Army Research Institute of Environmental Medicine.

It was funded by The US Army and the US Department of Defense.

The study was published in the peer-reviewed journal Nutrition Reviews.

The findings of the study were reported accurately by the Daily Mail.

What kind of research was this?

This was a review of research that aimed to evaluate whether the purported effects of energy drinks are greater than those of caffeine alone.

The study points out that these drinks represent a huge industry, with more than half the US market consisting of adolescents and young adults.

Energy drinks are marketed as improving physical and mental performance as well as promoting weight loss through increased energy expenditure. A typical 235ml energy drink provides between 40 and 250mg of caffeine, which the researchers say equates to doses that improve cognitive performance and at higher levels, physical performance. However, they commonly contain other ingredients, such as:

  • Taurine – an amino acid found naturally in muscle
  • Glucuronolactone – a naturally occurring compound formed from glucose 
  • Glucose – a naturally occurring sugar
  • Vitamins – many such drinks contain B vitamins, claiming these will increase energy levels
  • Guarana extract – from a plant native to Brazil, thought to contain caffeine as well as other compounds
  • Yerba mate – from a plant native to South America, thought to contain caffeine and other compounds
  • Carnitine – a naturally occurring compound that can help the body turn fat into energy
  • Ginseng – a herbal supplement

The researchers point out that previous studies documenting the effectiveness of such drinks have often compared them with placebo drinks, but these types of studies do not make it possible to look at the potential effects of any single ingredient, say the researchers. Such research has predominantly been funded by the drinks manufacturers.

While there is no evidence of wrongdoing on the part of drinks manufacturers, industry-funded research is notorious for producing results favourable to the companies providing the funding.

What did the research involve?

The researchers searched the scientific literature across several electronic databases, using keywords that included caffeine and other common ingredients of energy drinks, and physical and cognitive performance.

They searched PubMedPsych Info and Google Scholar with keywords that included caffeine with the other common ingredients, such as those listed above, either alone or in combination. They combined these terms with phrases such as “physical performance” or “cognitive performance”.

Only articles or abstracts published in English were used. They searched for peer-reviewed publications, but some government reports and non-peer-reviewed publications were also looked at.

It’s important to point out that this was not a systematic review of randomised controlled trials of the kind often used to evaluate the effectiveness of healthcare treatments. However, the researchers did try to evaluate the quality of the evidence using an established system.

What were the basic results?

They identified 243 articles, of which 63 were reviews dealing with adverse events and the safety and efficacy of the use of energy drinks as well as herbal, nutritional and dietary supplements.

Among these, they found 32 relevant studies on the effects of the ingredients of energy drinks, alone or in combination with caffeine. Of these studies, 20 involved humans, 11 were animal studies and one used cell cultures in the laboratory. The researchers used established guidelines to document the quality of the evidence in each study.

The study found that with the exception of “some weak” evidence for glucose and guarana, there is “an overwhelming lack of evidence” to substantiate claims that the ingredients found in energy drinks other than caffeine, enhance physical or cognitive performance.

How did the researchers interpret the results?

The researchers point out that there is an overwhelming lack of evidence to substantiate claims that energy drinks enhance performance through ingredients other than caffeine. They say that - on the contrary - there is excellent evidence that small amounts of caffeine exert positive effects on cognitive function and that larger doses can enhance physical performance. Further well-designed studies are needed to support claims that energy drinks enhance performance through a mechanism other than caffeine.


This study implies that any effects from energy drinks are due to their caffeine content, rather than other ingredients. It is useful in that it looks at evidence for each separate ingredient and evaluates the evidence in line with established guidelines.

The research does not assess the effectiveness of energy drinks, rather the effectiveness of the compounds they commonly contain. As such, it cannot ultimately refute the claims that the manufacturers make, however, it does seem to be the case that having a cup of coffee (or more) is as likely to enhance performance as much as any expensive energy drink.

This research also serves as a reminder that these drinks can contain large amounts of caffeine, and that anyone wanting to limit their caffeine intake – particularly pregnant women – should bear this fact in mind.

NHS Attribution