Creatine is available in many forms, including as a pill, a chew, a powder, and as an ingredient in energy bars, sports drinks, and chewing gum. “The cellular uptake is enhanced if it’s in a liquid form with glucose in combination,” Dr. Harris said. “Uptake is decreased by caffeine.”
A loading dose of 5 g every 6 hours for 5 days is recommended. This increases creatine stores in muscles by 15%-30% and remains elevated for 2 weeks to 2 months. “That sounds impressive,” Dr. Harris said. “The problem is, most people don’t do a loading dose. There are a lot of GI side effects associated with that, so they just skip to the maintenance dose of 3-6 g per day. But slowly over time creatine decreases despite the supplementation, so you need to have times off, which is why you cycle. You go on for 5-8 weeks and off the 2-4 weeks.”
According to limited surveys of creatine use by high schoolers, 55% don’t know the dose they’re taking, and 23% report taking doses higher than recommended. Moreover, 13%-30% of people who take creatine are nonresponders, “so a lot of people are taking this and it’s no benefit to them,” Dr. Harris said.
Side effects include weight gain from water retention, anecdotal reports of muscle cramps, stiffness, muscle tension injury, dehydration, and heat illness. “The biggest concern is renal function, but we don’t know the long-term effects,” she said. “There are no effects on blood pressure, liver enzymes, electrolytes, uric acid, hematologic parameters, muscle enzymes, and lipid profiles. That’s reassuring.”
Even so, the use of creatine by adolescents hasn’t been formally studied, and its effects on the brain, cardiac muscle, testes, and other creatine-containing tissues is unknown, “so most medical organizations recommend against it, including the AAP and the American College of Sports Medicine,” Dr. Harris said.
Another concern about creatine is that adolescents “may assume that supplements can substitute for proper nutrition or good athletic training,” Dr. Harris said. “Some feel that it’s a slippery slope to the use of steroids and other harmful and banned substances. On the other hand, it’s not banned by any group and it’s not drug- tested because it’s a source of energy in the diet. It’s not an anabolic agent. Some liken it to caffeine; it’s part of the diet so only high levels should be banned.”
Dr. Harris reported having no financial disclosures.
On Twitter @dougbrunk