Tuesday May 31 2011
Energy and sports drinks can be high in caffeine and calories
"Children should avoid energy drinks due to ‘toxic’ levels of caffeine," reported the Daily Mail. The news is based on a clinical report of the ingredients of sports and energy drinks and a review of previous research into their effects on children. The researchers combined these findings with expert opinion to make recommendations about the suitability of these drinks for children and teenagers.
The researchers convincingly argued that sports drinks are unnecessary for children and adolescents doing average amounts of physical activity, and that energy drinks are also unsuitable for them because of their high caffeine content.
This was a US study, but many of the results are probably applicable to the UK. The researchers concluded that sports drinks are no more beneficial than water after normal exercise for children. They also say that both energy and sports drinks have high levels of sugar, increasing the risk of obesity, and that their acidity can damage teeth enamel. They stated that the very high caffeine content of energy drinks (sometimes equivalent to 14 cans of common caffeinated soft drinks) makes them unsuitable for children.
The Food Standards Agency recommends that children should only "consume in moderation drinks with high levels of caffeine".
Where did the story come from?
The study was carried out by researchers from the American Academy of Pediatrics Committee on Nutrition (CON) and Council on Sports Medicine and Fitness (COSMF). Sources of funding were not given. The study was published in the peer-reviewed journal Pediatrics.
The research was generally covered well by the Daily Mail and The Independent.
What kind of research was this?
This review examined the ingredients of sports and energy drinks, and the similarities and differences between the products. The researchers then carried out a systematic review of the evidence of the effects of these drinks on children and adolescents.
The researchers said that sports and energy drinks are a large and growing beverage industry, and sports drinks are marketed to children and adolescents for “optimisation of performance and replacement of fluid and electrolytes lost during exercise”. Energy drinks, meanwhile, are marketed as being able to boost energy, decrease fatigue and enhance concentration. The researchers say that sports drinks and energy drinks are two different products, but the two may be confused with each other. For example, “energy” can be thought to imply calories only (which sports drinks also contain), but energy drinks also contain stimulants such as caffeine or guarana, a South American plant extract also containing caffeine.
What did the research involve?
The researchers defined and categorised popular sports and energy drinks and reviewed their ingredients.
The sports drinks that were assessed were All Sport Body Quencher, All Sport Naturally Zero, Gatorade, Gatorade Propel, Gatorade Endurance, Gatorade G2, Powerade Zero, Powerade, Powerade Ion4 and Accelerade.
The energy drinks assessed were Java Monster, Java Monster Lo-Ball, Monster Energy, Monster Low Carb, Red Bull, Red Bull Sugar Free, Power Trip Original Blue, Power Trip “0”, Power Trip the Extreme, Rockstar Original, Rockstar Sugar Free and Full Throttle.
The researchers conducted a systematic review of the evidence relating to the effect of the ingredients of these drinks on children’s health. They then discussed the evidence for and against the use of sports and energy drinks in children and adolescents. The researchers aimed to produce guidelines for parents, government policy makers, schools and youth sports clubs on the appropriate use of sports drinks for children doing average amounts of activities. Where there was a lack of evidence, the authors instead considered the expert opinions of the American Academy of Pediatrics Committee on Nutrition (CON) and Council on Sports Medicine and Fitness (COSMF).
The researchers highlighted that their report was not intended to be a guide for the effectiveness of sports drinks in children and adolescents involved in competitive endurance, repeated-bout sports such as tournaments, or other prolonged vigorous physical activities.
What were the basic results?
Water 'best for hydration'
The researchers first looked at the effect of the drinks on hydration. They said that dehydration can be associated with premature fatigue, impaired sports performance, cognitive changes, possible abnormalities in the body’s salt balance (electrolytes), and an increased risk of heat illness. However, they say that water is generally the best first choice for hydration before, during and after most exercise, rather than sports or energy drinks.
High-carb content 'raises obesity risk'
The researchers then looked at the carbohydrate content of sports drinks, such as sugar. With the exception of the sugar-free sports drinks, the drinks contained 2–19g of carbohydrate (glucose and fructose) per 240ml serving. This corresponds to 10–70 calories per drink. The researchers said that although carbohydrates are the most important source of energy for an active child or adolescent, in general there is little need for children to drink carbohydrate-rich drinks other than the recommended daily intake of fruit juice and low-fat milk.
Energy drinks (those with added caffeine) generally had more carbohydrates than sports drinks: 0–67g per serving with a calorie content of 10–270 calories. The researchers said that routinely drinking these sports and energy drinks (and soft drinks) will result in excessive calorie intake and substantially increase the risk of becoming overweight or obese.
'Risks of high caffeine'
The researchers said that caffeine has been found to enhance physical performance in adults by increasing aerobic endurance and strength, improving reaction time and delaying fatigue. The size of the effects can vary, however, and there have been no studies in children. Caffeine can have a wide range of effects on the body, including increasing the heart rate and blood pressure. It also reportedly increases speech rate, attentiveness and motor activity as well as body temperature and the secretion of gastric juices. Caffeine is also a diuretic. Psychological effects include effects on mood, increasing anxiety in people who are prone to this and sleep disturbances in some people.
The researchers say that energy drinks can contain large amounts of caffeine, often more per serving than cola. It can be hard to determine the amount of caffeine in the drink from the packaging as the serving size may be different from the packaging size. They say that the total amount of caffeine in some cans or bottles of energy drinks can exceed 500mg, which they say is equivalent to 14 cans of common caffeinated soft drinks. To put this in context, they say that a lethal dose of caffeine is considered to be 200–400mg per kg of weight (about 6g for a 30kg child).
They say that caffeine has other dangers for children, and can affect the developing brain and heart and the risk of developing addiction. They recommend that children should be discouraged from consuming caffeine. They also highlight that the most common way children would be exposed to caffeine is in soft drinks, which have around 24mg of caffeine per serving.
Guarana 'adds even more caffeine'
Energy drinks often include the plant extract guarana. This extract contains caffeine, and 1g of guarana is equivalent to 40mg of caffeine. Therefore, guarana will increase the total caffeine content in the beverage. In the energy drinks that the researchers sampled, they found that the drinks contained up to 30mg of guarana per 240ml.
Electrolyte needs 'met by the diet'
Sports and energy drinks may contain electrolytes (sodium and potassium salts). The sodium content of the drinks was 25–200mg and the potassium content was 30–90mg per serving (240ml). However, the researchers say that most children and adolescents get enough electrolytes from a healthy, balanced diet and that sports drinks offer “little to no advantage over plain water”.
Added protein and vitamins ‘not needed’
Proteins are often added to sports drinks based on the idea that protein can enhance muscle recovery when consumed soon after exercise. However, the researchers say that most children can easily get their recommended intake (1.2–2.0g of protein per kg of body weight a day) from a well-balanced diet, which is sufficient even for those who are regularly sporty. Likewise, vitamins that are sometimes added to sports drink can be obtained in the required amounts from a balanced diet without the need for supplements.
High acidity 'erodes teeth'
The researchers say that there is some concern that these sports and energy drinks will cause tooth decay in children and adolescents. They say that most of these drinks are acidic and can contain citric acid, which is highly erosive to the teeth. They report a study that found that 57% of 11- to 14-year-olds had erosion to the enamel of their teeth.
How did the researchers interpret the results?
The researchers said, “for the average child engaged in routine physical activity, the use of sports drinks in place of water in the sports field or school lunchroom is generally unnecessary. Stimulant-containing energy drinks have no place in the diets of children or adolescents.”
This review delivers a well-argued and convincing case that energy and sports drinks are unnecessary and possibly unsuitable for children and adolescents doing average amounts of physical activity. The researchers say that, in the US, there is a drive to stop schools selling high-calorie fizzy drinks, but that sports drinks have been marketed as a “healthier alternative”.
The researchers make a series of recommendations for parents, schools and policy makers. Though these recommendations are intended for the US, some translate to the UK. These include educating parents, children and paediatricians about the risks of these drinks, including the risks of caffeine, obesity and tooth erosion. They suggest that water should be promoted as the best source of hydration for children and adolescents.
A similar review, published by a group of American researchers in February 2011, looked at research on energy drinks and their consumption by children and adolescents. This research, examined by Behind the Headlines, described in further detail the potential dangers of energy drinks for younger people.
The Food Standards Agency recommends that “children, or other people sensitive to caffeine, should only consume in moderation drinks with high levels of caffeine.”