Water should be the main source of hydration for young athletes. But high-carb sports drinks have "a specific limited function" for teen athletes, according to the American Academy of Pediatrics’ Committee on Nutrition and Council on Sports Medicine and Fitness. They say sports drinks and water can help with quick replenishment of carbohydrates and/or electrolytes during intense physical activity.

For children and teens, this is "the most appropriate use of a commercial sports drink."

Most people -- including most teen athletes -- get more than enough protein from their diet. In most cases, extra protein from a supplement won't help build muscles and probably won't have any other constructive purpose. Too much protein can harm the body, causing unnecessary weight gain (from extra calories), dehydration, or kidney problems.

However, supplements may be helpful for strict vegetarians or other people who don't get enough protein from their diet. Eggs, dairy, fish, meat, poultry, soy, nuts, and peanut butter are good protein sources.

Although most teen athletes get enough protein from their diet, the American Academy of Pediatrics approves the use of protein supplements "for muscle recovery" after prolonged vigorous exercise "if a food source of protein is unavailable."

Because protein does help repair muscles when eaten or drunk soon after exercise, supplements might be especially helpful when dietary sources of protein are not on the post-workout menu.

Energy drinks aren't the same thing as sports drinks. Sports drinks are flavored beverages with carbohydrates and electrolytes (and sometimes vitamins or other nutrients). Energy drinks usually contain stimulants such as caffeine.

Although sports drinks may be recommended for teen athletes in limited circumstances, energy drinks are not recommended at all. The American Academy of Pediatrics says "energy drinks pose potential health risks, primarily because of stimulant content; therefore, they are not appropriate for children and adolescents and should never be consumed."

The stimulants in most energy drinks can have potentially harmful effects on young people. Caffeine can cause nervousness, anxiety, insomnia, and gastrointestinal problems. At very high doses it can be toxic, causing tremors, seizures, rapid heartbeats, and in rare cases, death.

And it can be hard to tell how much caffeine is in an energy drink, because some manufacturers don't list the amount on the label. Some drinks have more than 500 mg of caffeine, equal to about 14 caffeinated soft drinks.

The sugar and acids in energy drinks can damage tooth enamel.

Sports drinks should be used only for replenishing lost fluids and electrolytes and providing energy in combination with water during intense physical activity. Drinking too much is pointless and can hurt you. "Frequent consumption adversely affects the appropriate balance of carbohydrate, fat, and protein intakes,” according to the American Academy of Pediatrics. The extra calories may make you fatter.

Your teeth also may be damaged, because of the acidic nature of most sports drinks.

Creatine has not been shown to increase endurance or improve aerobic performance. Some studies have shown that creatine improves strength during weight lifting, sprinting, and other high-intensity, short-duration exercise. But creatine had no effect for almost a third of all people studied, researchers found.

Long-term effects of creatine on teens are completely unknown, and the American College of Sports Medicine says people younger than 18 shouldn't use it. Weight gain, diarrhea, abdominal pain, and muscle cramps are some of the possible side effects. At high doses, there's a risk of kidney damage.

According to the American College of Sports Medicine, "no evidence supports nutritional supplement use for performance enhancement in adolescent athletes."

Anabolic steroids are illegal and dangerous. Suicide and heart attack are the two most common causes of premature death associated with steroids. Steroids also are a risk for stroke, liver disease, increased aggression, shrinking testicles, testicular cancer, high cholesterol, high blood pressure, and many other bad effects on your health. Teens especially should steer clear of any substances, such as anabolic steroids, that could mess up their hormonal development.

Androstenedione and dehydroepiandrosterone (DHEA) are testosterone precursors -- also called "prohormones" or "natural steroids." They aren't safe and they aren't effective. Studies have shown that they don't increase testosterone levels, strength, muscle size, or performance. In large doses, experts believe, they cause the same kind of problems that anabolic steroids cause: shrinking testicles, testicular cancer, breast enlargement, infertility, and an increased risk of heart disease.

Prohormones and natural steroids are not recommended for teens under any circumstances.

Vitamins are not dangerous unless you get too much, and you can get too much -- especially fat-soluble vitamins such as vitamins A and D.  Because they can’t be excreted by the body, these can build up in your system and cause nausea, vomiting, digestive issues, and other problems. Vitamin supplements also can interfere with medical tests or prescription medications.

The best way to get vitamins is to eat a balanced diet, including fresh fruits and vegetables, nuts, whole grains, dairy products, eggs, and meats. If you think you may not be getting enough of a particular vitamin, talk to your doctor.

Teens in general don't get enough calcium and iron, and teen athletes need even more of both than other adolescents. Calcium keeps your bones strong and helps prevent fractures. Iron is important in delivering oxygen to muscles.

Dairy foods, such as low-fat milk, yogurt, and cheese, are a rich source of calcium. Iron is found in green leafy vegetables, iron-fortified cereals, and meats.