Are energy drinks bad for you?

Next, discover how much caffeine you should drink and if coffee is good for you. Plus, see the best supplements for energy and find out why you're waking up tired with no energy.

What is an energy drink and what are the most common ingredients?

Energy drinks typically combine sugar (glucose and sucrose) alongside ingredients that boost energy metabolism, like the B group of vitamins, as well as stimulants such as caffeine, and amino acids like taurine, carnitine or theanine. These ingredients reputedly sharpen focus, boost energy and enhance performance.

Energy drinks are not to be confused with sports drinks or vitamin waters, both of which are water-based drinks with added electrolytes or vitamins and are designed to provide superior hydration; these are distinct from energy drinks because they don’t contain caffeine.

Indeed, it’s caffeine that is the most common stimulant in energy drinks, with most products containing 80-200mg per serving – that’s the equivalent of two to five cans of regular cola. By law, products containing over 150mg caffeine per litre are required to carry a warning on the label, although their sale is not restricted. Other ingredients in energy drinks may include electrolytes (sodium, potassium and calcium), herbal extracts like ginseng or guarana, colourings, flavourings and preservatives.

Following the introduction of the UK’s soft drink industry levy (‘sugar tax’) in 2018, a number of manufacturers chose to reformulate their products, replacing sugar with sweeteners. These 'zero' or ‘diet’ versions of energy drinks contain fewer calories but they still maintain high levels of caffeine and other stimulants.

Do energy drinks work?

There’s inconsistent evidence to determine how effective energy drinks might be, with a lack of sufficiently robust studies.

What we do know is that glucose is the key fuel source for muscles, and that drinking a glucose-based beverage before, during and after prolonged exercise is likely to postpone fatigue.

We also know that caffeine fights fatigue and is the ingredient responsible for sharpening concentration and enhancing alertness, with some studies reporting improvements in memory and enhanced aerobic endurance (maintaining 65-75 per cent maximum heart rate) and anaerobic performance (maintaining maximum speed).

When combined with glucose, caffeine appears to improve reaction time, most notably during the hour after consumption. However, it’s worth bearing in mind that the human body develops a tolerance to caffeine very quickly, usually after 3-5 days of regular use. This means if you are consuming an energy drink for a specific purpose or event, abstaining from caffeine for at least seven days beforehand may heighten its effects. In fact, caffeine’s performance effects are such that the World Anti-Doping Agency has included it on its watch list – this means athletes are only allowed to consume caffeine within certain limits.

Despite this, other studies report no improvement from the consumption of energy drinks on exercise performance or the onset of fatigue. As for hydration, although many energy drinks contain electrolytes, which help manage the amount of water in cells, the sugar and caffeine they contain means the drinks have a net diuretic effect so are not an effective solution for restoring hydration levels.

Are energy drinks unhealthy?

The health implications of energy drinks have not been fully established. The negative effects of high amounts (over 200mg in a single dose) of caffeine are known to be problematic, but the effects of other ingredients, like taurine, remain unconfirmed. One aspect that may not be fully appreciated is that regular consumption of these drinks may be a risk factor for alcohol and other substance abuse, even when consumed without alcohol.

Although the sugar tax encouraged re-formulation, the amount of sugar in regular versions of some brands may be considerable. For example, a regular 500ml can (such as Monster Original) is likely to contain about 54g or 13 teaspoons of sugar. UK guidelines for sugar consumption recommend no more than 30g or seven teaspoons of ‘free’ sugar per day, with long-term exposure to higher amounts potentially leading to obesity and increasing the risk of heart disease and type 2 diabetes.

We all react to the stimulatory effects of caffeine differently, dependent on our age and our genes. However, consuming high amounts, may cause agitation and anxiety for some as well as dizziness, tremors and an inability to sleep. Adolescence is the time of maximum bone deposition and high levels of caffeine interferes with this by reducing calcium absorption.

Consistent exposure to stimulants like caffeine may also lead to changes to the cardiovascular system. This is because caffeine acts on the cells of the heart making it beat faster and stronger, and also increases blood pressure and arterial stiffness. It is worth bearing in mind that some additives in energy drinks may naturally contain caffeine (for instance guarana). Manufacturers are not required to list the caffeine from these sources which means the dose from a single serving may exceed that listed on the label.

For these reasons, if you have a medical condition, including high blood pressure, you should check with your GP before consuming energy drinks. Based on current evidence, children and other people sensitive to caffeine should consume it in moderation only (a single dose being no more than 3mg caffeine per kg body weight) with healthy adults consuming up to 200mg in a single serving and up to 400mg over the day. However, pregnant and breast-feeding women are advised to have no more than 200mg caffeine over the course of a day.

Is Prime Energy bad for you?

Introduced with a social media frenzy, this relatively recent entrant to the market has established itself as a core product. Prime Energy* combines electrolytes (calcium, sodium, potassium) with caffeine (140mg per 330ml can), glucaronolactone, L-theanine, taurine as well as vitamins B6 and B12. While Prime Energy may be safe for some adults to consume, those with lower body weights should avoid or limit consumption to minimise adverse effects including sleeplessness, anxiety and serious heart complications.

Is Red Bull bad for you?

The market leader, Red Bull* supplies caffeine (80mg per 250ml can) combined with taurine, B vitamins and sugar; a sugar-free ‘Zero’ version is also available. When drunk in moderation, the combination of taurine and caffeine may improve mental performance and mood, however, when drunk frequently and in excess, this drink may have negative and potentially serious implications.

Is Lucozade good for you?

Originally developed to replace lost energy after illness, Lucozade* was the go-to ‘tonic’. Fast-forward 90 years and a significant reformulation (replacing some glucose with sweeteners) has resulted in new versions of this old favourite in the form of Lucozade ‘Energy,’ ‘Alert’ and ‘Zero’. No longer famed for its recuperation effects, these caffeinated drinks (approx. 46mg caffeine per 380ml bottle) also include food colourings linked to hyperactivity in some children.

So, are energy drinks bad for you?

While consuming moderate levels of these drinks may provide useful effects for some, their regular consumption is likely to increase blood pressure, quicken heart rate and trigger nervousness and agitation. They may also lead to insomnia and detrimental changes in mood. If you enjoy energy drinks, are over 18 years old, your health is good and you are not in one of the vulnerable groups (listed above) – then avoid frequent consumption (5-7 cans per week), reduce caffeine from other sources, avoid binge consumption and don’t mix with alcohol. If you don’t currently consume energy drinks, the evidence suggests you are better off not doing so.

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*Product information relates to the brands retailed in the UK market.

Kerry Torrens BSc. (Hons) PgCert MBANT is a BANT Registered Nutritionist® with a post graduate diploma in personalised nutrition and nutritional therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including Good Food.

All health content on goodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.