Are supplements appropriate for the growing swimmer?


By Jill Castle, MS, RDN

Sam was a pre-adolescent swimmer who wanted to get faster, bigger and stronger. Kelly was a senior swimmer carrying some extra weight and wanted to get leaner. Sam started incorporating extra protein powder and creatine in his nightly shake. Kelly pulled out food sources of carbohydrate like pasta and bread, and ate as much protein as she could, even adding a high-protein powder to her morning shake.

These stories may seem familiar, or even drastic or alarming, but the use of supplements in an effort to enhance musculature or improve performance amongst growing athletes is gaining ground.

According to the National Health Interview Study, published in 2012, many growing athletes are using some kind of supplement, including multivitamin and mineral supplements, creatine, fiber and omega-3 fatty acids.

Another study, published in 2012 in Pediatrics, looked at muscle-enhancing behaviors in girls and boys (the average age of participants was 14.4 years).

According to their findings, it was common practice to use unhealthy substances such as protein powders, steroids and other muscle-enhancing substances like creatine or amino acids. While most behaviors were more common in boys than in girls, an impressive 34.7% of all participants used protein powders or shakes, and almost 6% used steroids.

Yet, the scientific evidence for the use of these supplements is missing, especially for youth athletes. As a result, many organizations, including the American Academy of Pediatrics (AAP) advise against any supplement use among children and teens under the age of 18.

USA Swimming maintains a “take these at your own risk” policy for all athletes of any age. (Editor’s note: For more information on USA Swimming’s “Take at Your Own Risk” policy regarding supplements, please visit our Dietary Supplements page in our Doping Control section). 

I’ve briefly summarized some key information for the growing athlete (<18 years) below:

Vitamins and Minerals

Vitamin and mineral supplementation for children and teens is generally not needed when kids are active, have access to food and healthcare. If there is a documented deficiency like iron deficiency, or a missing food group from the typical diet such as the dairy food group (or non-dairy substitutes), then a doctor should be consulted for proper treatment. It is best to get vitamins and minerals from natural food sources, especially fruit, vegetables, grains and dairy products. Many of the foods in our food supply are fortified (vitamins and minerals added after processing), making them an appreciable source of certain vitamins and minerals.

Management Tip: Use food first—a healthy, balanced diet. Any deficiencies should be addressed by a licensed healthcare professional.


Creatine, a nitrogenous acid (made from amino acids within the body), supplies energy to all cells in the body, especially muscles. About half of all creatine in the body comes from food sources, mainly meat and fish. Creatine supplements are not recommended for use in children or teens under 18 years, mainly because of a lack of evidence that proves it is safe, and the association of its use with other unhealthy substances.

(Editor’s Note: USA Swimming would never recommend a swimmer (of any age) take Creatine. There is really no evidence that it would be beneficial for the type of training our athletes do [in and out of the water] and there is obviously a lack of long-term studies. Again, see our Dietary Supplements page in our Doping Control section for more information on our Take at Your Own Risk policy).

Management Tip: Go for the natural sources of creatine: a variety of meats and fish!


Anabolic steroids, a synthetic version of testosterone, are used to bulk up muscle, something that naturally occurs during puberty when testosterone levels are peaking. Perhaps due to a desire to have an athletic edge or build muscle mass, growing athletes are experimenting with this substance increasingly. According to the CDC, up to 11 percent of all high school males try steroids, and 6 percent have “cycled” (taking them for an 8- to 12-week period). The side effects of high dose anabolic steroids include mood swings (“roid rage”), and in teens, stunting (arrested height growth) and accelerated pubertal development. Use of steroids is banned in the sport of swimming and use will lead to sanctions against the athlete.

(Editor’s note: For more information on banned substances, check out our Resources page in our Doping Control section). 

Management Tip: Know the signs of steroid use: acne, moodiness, isolation, suddenly bigger muscles, an increased interest in one’s own body and working out. Talk with athletes about the side effects and consequences of steroid use, and ‘Just say no!’ 

The Bottom Line

The safest way to enhance muscle building is to include a healthy diet and regularly exercise. My advice is always to use real food, and never experiment, or push nutrients and nature beyond its natural pace.

Jill Castle, MS, RDN is a registered dietitian/nutritionist and child nutrition expert. She is the co-author of Fearless Feeding: How to Raise Healthy Eaters from High Chair to High School, and creator of Just The Right Byte, a child and family nutrition blog. She lives with her husband and four children (two swimmers!) in New Canaan, CT. Find more about her at www.JillCastle.com  Questions? Contact Jill at Jill@JillCastle.com.