Are sports drinks good or bad for you? A medical analyst explains

Sports drinks
The main purpose of sports drinks is to restore water and electrolytes lost during exercise and sweating. Photo credit: cmannphoto / iStockphoto / Getty Images

By Katia Hetter of CNN

In the United States, Senate Majority Leader Chuck Schumer has called on the US Food and Drug Administration to investigate the high caffeine content of the Prime Energy drink and the company's marketing efforts to children.

This beverage, which is sold in cans, contains 200 milligrams of caffeine per 12 ounces, which is equal to the caffeine content of nearly two Red Bulls or an entire six-pack of Coca-Cola. Prime also sells another drink, Hydration, which is sold in bottles, that is similar in appearance to Energy but does not have caffeine.

That prompted Schumer to say that "because the product is billed as a hydration and sports drink in its other, near-identical form, kids are likely to ingest cans of this stuff with the parents being unaware."

In response to Schumer's comments, Prime said that its energy drink contains a "comparable amount of caffeine to other top selling energy drinks, all falling within the legal limit of the countries it's sold in."

The situation brings up the larger question of sports drinks, including their ingredients - such as caffeine. Does anyone need sports drinks, and who should stay away? What should parents look for when considering sports drinks for their children? Is it better to buy ready-to-drink beverages or electrolyte powder and mix it yourself? What else should people, including endurance athletes, keep in mind?

I spoke with CNN medical analyst Dr Leana Wen, an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She previously served as Baltimore's health commissioner.

Wen is also an endurance athlete who enjoys trail runs, open-water swims and triathlons.

CNN: What are sports drinks? How are they different from energy drinks, and what ingredients do they each contain?

Dr Leana Wen: It's important to distinguish between sports drinks and energy drinks.

Sports drinks are electrolyte-enhanced beverages. Their main purpose is to restore water and electrolytes that are lost during heavy exercise and sweating. They will contain electrolytes like sodium, potassium, calcium and magnesium. Many are carbohydrate-based, with added sugars like fructose, glucose and sucrose. Sometimes they contain caffeine.

There are also energy drinks that are often, and unfortunately, confused with sports drinks. Energy drinks typically contain large amounts of caffeine. Many contain other legal stimulants like taurine, guarana and L-carnitine. These energy drinks could reduce fatigue and enhance performance in the short term. However, they are not sports drinks and should not be used when the purpose is to replenish electrolytes and fluids.

Energy drinks can be dangerous when consumed in large quantities. According to the US Centers for Disease Control and Prevention, 1499 adolescents ages 12 to 17 went to the emergency room for an energy-drink related emergency in 2011. High amounts of caffeine can induce irregular and rapid heartbeats. Individuals may become anxious and develop sleeping problems. Those consuming energy drinks instead of sports drinks or water may become dehydrated. Also, although many ingredients in these energy drinks are marketed as being "natural," they may be present in much larger quantities that people normally consume.

The American Academy of Pediatrics recommends that children and adolescents do not use energy drinks. However, 30 percent to 50 percent of adolescents report consuming them. This could be because of confusion between sports drinks and energy drinks, so people should be careful to choose the beverage that's appropriate for their purpose.

CNN: Is it good to have caffeine in a sports drink, and how much is too much? 

Wen: The primary reason for using a sports drink is to replenish electrolytes and fluids. Caffeine does not have a role in replenishing electrolytes, and in fact is a diuretic that leads to more fluid being lost, so in general, I would advise to stay away from sports drinks that have caffeine.

Some adult athletes may choose drinks with caffeine as an added boost to their performance. If so, they should be aware of the risk and of exactly how much they are using. Caffeine is a stimulant that can increase heart rate and have adverse effects on performance, too. It also has addictive potential. People can become tolerant to it, meaning that the effect decreases with regular consumption, and individuals may need more of it to achieve the same effect.

The negative impacts of caffeine are even more profound when it comes to young people. The American Academy of Pediatrics recommends that children under 12 do not consume any caffeine. Children ages 12 to 18 should not exceed 100 milligrams of caffeine every day.

Parents should keep in mind that there are other beverages that contain caffeine, including coffee and many sodas, and that many sports drinks contain very high levels of caffeine that would far exceed the daily recommended amount. Given that sports drinks really are intended to replace electrolytes and not to be used as a stimulant, it's best for children to avoid sports drinks with added caffeine.

CNN: Who needs sports drinks, and who should stay away?

Wen: Most people do not need sports drinks. Water is sufficient for hydration, and the food people eat will usually contain the electrolytes they need. Athletes engaging in mild to moderate activity and children playing on the playground or engaging in recreational after-school sports generally do not need additional electrolyte replacement drinks.

The key concern for these individuals is hydration. Especially if it's hot outside, they need to be drinking lots of water before, during and after exercise. They can also aim to eat foods packed with nutrients and electrolytes. Some examples include watermelon, milk, cheese, bananas, coconut water and avocados. If they are engaging in heavier activity for longer, they could also eat a snack of salted nuts.

Individuals who should consider sports drinks are athletes who are doing vigorous exercise for at least an hour or longer. Whether they need it depends on the climate, type and intensity of exercise, and whether they are prone to sweat heavily.

CNN: What do kids in sports camps that last an entire afternoon or a whole day need?

Wen: It depends on the intensity of the camp and how it's organised. If there are regularly scheduled breaks, and a lot of the focus is on drills that aren't always at maximum intensity, it could be sufficient to eat small snacks during the breaks, in addition to copious hydration with water, instead of sports drinks.

CNN: What should parents look for when considering sports drinks for their children?

Wen: I would caution most children and adolescents against using sports drinks. These are not needed for most kids, unless they are doing endurance sports or training intensively, in which case I'd recommend that they develop a sports drinks plan with their coach and paediatrician. If children are using sports drinks, stay away from drinks that have high caffeine content. They could also use drinks that just contain electrolytes, without added sugar, unless the carbohydrate content is specifically needed.

CNN: Is it better to buy ready-to-drink beverages or electrolyte powder and mix it yourself?

Wen: It's usually cheaper to buy electrolyte powder or tabs that then dissolve in water, rather than ready-to-drink beverages. Which one is better depends on personal preference. Be sure to read the label to check for caffeine and stimulants, and for presence of added sugar if that's something you are aiming to avoid.

CNN: As an endurance athlete yourself, do you use sports drinks? What else should athletes keep in mind?

Wen: While hydration is crucial, it doesn't mean that you must use sports drinks. And really distinguish between sports drinks that replenish electrolytes and fluids versus energy drinks. Personally, I stay away from energy drinks. I do not want to have to depend on caffeine. And given the lack of long-term research into other stimulants, I wish to avoid them. I would not want my kids to use energy drinks.

Before engaging in physical activity, I make sure that I'm well-hydrated with water. Generally, if I'm going for a run, swim or bike ride that's under an hour and a half in duration, I'd just drink water. If it's over an hour and a half in very hot weather, or over two hours in milder climates, I'd probably bring a drink with electrolyte and energy replacement. I'd make sure to eat a snack, like a pack of salty nuts or an energy bar, right after this kind of heavy exercise and of course refuel with lots of water, too.

People should tailor regimens that work for them. Someone who sweats heavily or recently had vomiting and diarrhoea will need more electrolytes and may benefit from sports drinks rather than just water. Cramping and early fatigue may also indicate that they need electrolyte replacement. Endurance athletes routinely training or competing in events more than two hours in duration should have a full nutrition and hydration plan in consultation with a coach. Always check the ingredient label and, when in doubt, speak with your healthcare provider.