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Energy drinks, whey protein, and more: Dietary supplements and teen athletes

According to some studies, as many as 30% to 40% of young athletes take at least one dietary supplement such as creatine, protein, or amino acids. In a competitive world where every athlete is striving to be the best and nobody seems to have enough time to eat right, it is hardly surprising that substances touted to build strength and endurance, burn fat, or increase testosterone production are popular.

Many of these supplements, though, are useless at best and harmful at worst. They are not held to the same standards as prescription drugs. They are often manufactured by companies with murky backgrounds and sold over the Internet. The safety and effectiveness of some products have not been tested. Other products have serious side effects. Still others may be contaminated with harmful or banned substances such as steroids, contain more or less than the labelled dose, or contain no active ingredients at all.

Where scientific studies have been done, some products have been found to lack the effect the manufacturer claims. In addition, most studies look at the short-term use of dietary supplements by adult or elite athletes, so we have little information about their possible risks over the long term or in teenagers.

For all these reasons, many health care professionals do not recommend dietary supplements at all, especially for adolescents.

The position of the Dietitians of Canada, the American Dietetic Association, and the American College of Sports Medicine, which has been endorsed by the Coaching Association of Canada, is that dietary supplements “should be used with caution, and only after careful evaluation of the product for safety, for efficacy, for potency, and to determine whether or not it is a banned or illegal substance…. These products should not be recommended until the athlete’s health, diet, nutrition needs, current supplement and drug use, and energy requirements have been evaluated.”

If your teen is considering taking dietary supplements to improve athletic performance, both of you should think carefully and critically about them beforehand.

Popular dietary supplements


Dr. Brian Shaw of The Hospital for Sick Children, who is an advisor on substance abuse to many athletic organizations, observes that caffeine is “the number one drug of abuse at present” and is even encouraged by some official sport associations. Most popular energy drinks contain high levels of caffeine, sometimes in combination with other stimulants such as ephedra. It has been shown to increase endurance, improve alertness and concentration, reduce perceived exertion and pain, and enhance performance in some sports. However, at high doses it poses a number of risks, including increased heart rate, changes in heart rhythm, dehydration, sleep problems, and addiction.


Creatine, one of the most popular supplements, is supposed to improve strength and performance in intermittent, high-intensity activities such as weight lifting, wrestling, or baseball. Studies do suggest that it is effective in the short term, when used in combination with a carefully designed training program. However, there are still no studies showing that it is safe over the long term, and it has not been tested in teenagers. Creatine’s known side effects include weight gain, muscle cramps, and an increased risk of heat illness associated with dehydration. There have also been individual reports of kidney problems, high blood pressure, and heart problems from creatine use. As a result, major sports organizations strongly discourage young athletes from using it.

Protein (whey or casein)

Protein supplements in the form of whey powder and casein are also popular, especially in athletes trying to build muscle. While athletes who are doing intense endurance or strength training may need slightly more protein than average, these supplements are probably no better at building muscle than protein from normal sources, such as milk, lean meat, fish, and legumes. They are certainly much more expensive. Note that even athletes who are training hard should not eat more than 2 g of protein per kilogram of body weight per day; the body cannot make use of it, and it may be harmful in excess amounts.

Some other popular supplements are listed below, together with the claims made for them, the evidence regarding these claims, and known adverse effects.




Beta-hydroxy-beta-methylbutyrate (HMB)

Suppress protein breakdown, increase muscle mass, enhance repair process following intense resistance training

No known adverse effects; little evidence for performance improvement

Ephedrine and ephedra (ma huang)

Boost metabolism, burn fat, increase alertness, increase endurance

Risk of anxiety, heart rhythm problems, high blood pressure, hallucinations, seizures, addiction; effects increased by caffeine; banned by many sports organizations; ephedra has caused a number of deaths


Increase testosterone production

Unknown; may pose a cardiovascular risk; associated with increases in estrogen; most studies do not find increased muscle mass, increased levels of testosterone, or improved sport performance


Release growth hormone, increase lean body mass and strength, prevent overtraining syndrome

No serious side effects reported; very limited evidence to support claims


Intravenous arginine releases more growth hormone with exercise

Oral arginine causes gastrointestinal problems; no evidence that it increases growth hormone levels or improves sport performance

Conjugated linoleic acid

Reduce body fat, increase lean body mass, enhance bone mineral density, enhance immune function

Adverse effects unknown; no evidence to support claims

Using nutritional supplements wisely

Encourage teens to think critically about any supplement that is recommended to them, whether by a friend, a coach, a health food store employee, or a training magazine or website. It’s their bodies and their athletic performance that are at stake, and often their wallets as well. The supplement industry makes millions of dollars a year promoting unproven products. Teens don’t have to add to those profits at the expense of their health.

Before taking any nutrition supplement, your teen should consider the following:


What effect is the product supposed to have? Who is making the claim? Does the product really have that effect? What evidence is there? Do the claims come from testimonials, or from scientific studies? Do the results of the study apply to athletes like your teen? Does the product have an actual effect on athletic performance, or are the effects only measurable in the lab? Was the product tested at the dose that is recommended on the label?


Has anyone evaluated the safety of the product? Does it have side effects? What are they? Has the product been studied over the long term, or only for short periods (weeks or months)? Has it been banned by any athletic organization or government body?

Product quality

Do you know what you’re getting? Is the package properly labelled and sealed? Are the manufacturer and the retailer trustworthy, and can you contact them? Does the package contain the dose that it claims? Where did it come from? Can you trust the source? Could it be contaminated with heavy metals or other drugs?


How much does the product cost? Is it worth taking? Could you get the same results from a properly balanced diet and training program?

Teens should also discuss any supplements they are considering with their coach or trainer. A good, ethical coach will not recommend a product that is banned or illegal or that could be harmful. A sport nutritionist can help your teen with information on how to plan a training diet and evaluate dietary supplements. A sports medicine physician or your family doctor can also provide valuable information.

Your teens’ first priority needs to be their health, now and in the long term.

Hugh O’Brodovich, MD, FRCP(C), was Paediatrician-in-Chief at The Hospital for Sick Children from 1996 to 2006.


Patel DR, Greydanus DE. Nutritional supplement use by young athletes: An update. International Pediatrics. 2005;20(1):15-24.

Tokish JM, Kocher MS, Hawkins RJ. Ergogenic aids: A review of basic science, performance, side effects, and status in sports. The American Journal of Sports Medicine. 2004;32(6):1543-1553.

Position of Dietitians of Canada, the American Dietetic Association, and the American College of Sports Medicine: Nutrition and athletic performance. Canadian Journal of Dietetic Practice and Research. 2000;61(4):176-192.