At John F. Kennedy High School in La Palma, Mitch Olson warns football players and other athletes that anyone caught using a performance-enhancement product will be barred from playing. The rule goes for everyone — and it includes creatine, a legal but controversial dietary supplement.

Olson, the school's athletic director, knows students could use creatine without his knowledge, perhaps even with the blessing of their parents. "I'm not naive enough to think that some kids aren't doing it," he said, while expressing hope that none of his athletes are doing so.

It's easy to see why many young athletes might feel tempted. Advertisements promoting creatine are everywhere, from bodybuilding magazines to the local pharmacy and nutrition store. And if not swayed by ads, athletes probably have heard friends' claims that creatine makes you bigger, stronger and faster. Some young athletes may not recall the controversy that surrounded creatine in the late 1990s, when the substance was briefly implicated — though later found not to be a factor — in the deaths of three college wrestlers.

Thousands of young athletes across the country have decided that a substance that promises to give them a competitive edge — on the field and, for some, in the chase for a college athletic scholarship — is worth it, even if it means bending the rules.

In recent years, any concerns over creatine have been overshadowed by the controversy over steroids, an illegal substance, and ephedra, an herbal supplement that was legal until the federal government banned its sale earlier this year after linking its use to more than 100 deaths. Although ephedra and steroids have received most of the attention, school officials, medical researchers and amateur and professional athletes have quietly debated the use of creatine, which has continued to rack up strong sales. With its benefits well-established and potential dangers merely anecdotal, creatine has become the table salt of the performance-enhancement world.

Used mostly by men, creatine is available in powder, capsule, chew tablet, effervescent tablet and liquid forms — sold under such brand names as Twinlab's Creatine Fuel and Dymatize's Crea-Fizz. Creatine sales totaled $193 million in 2003 — or roughly 10% of the $1.9-billion sports supplement market, according to the San Diego-based Nutrition Business Journal. Among sports supplements, only protein powder is more popular.

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A '90s powerhouse

Since creatine became widely available in the mid-1990s, "nothing has really captured that hard-core sports nutrition enthusiast — their imagination and attention — quite as well," said Patrick Rea, research director for the Nutrition Business Journal.

Creatine supplementation began several decades ago in the Soviet Union and gained worldwide attention in 1992, when several British Olympians used it during the Barcelona Summer Games. The same year, researchers in Sweden reported in the British medical journal Clinical Science that creatine supplements could indeed increase muscle creatine levels.

Creatine products began to show up on retailers' shelves, and the cottage industry was soon the powerhouse of the sports nutrition business. Denver Broncos tight end Shannon Sharpe touted Phosphagen HP, a creatine-based product, as early as 1996. Former St. Louis Cardinals slugger Mark McGwire credited creatine in 1998, when he hit 70 home runs to shatter the Major League Baseball record. Days before boxer Oscar De La Hoya fought Felix Trinidad in 1999, a public relations photo of his favorite supplements showed a bottle of creatine.

In 1997, however, three college wrestlers enrolled at three universities died within a six-week span while on crash weight-loss diets. When autopsies determined all three athletes had been using supplemental creatine, which promotes weight gain, the FDA vowed to investigate its role in the fatalities. (A 1998 review by the federal Centers for Disease Control and Prevention found that exercise in high temperatures and severe fluid restriction had caused lethal hyperthermia and vascular collapse in each of the wrestlers. Creatine was not a factor, the researchers found.)

Other alarms were raised. A case study published in the New England Journal of Medicine in 1999 told of a 20-year-old man who suffered kidney trouble one month after going on creatine, and then recovered after he stopped using the supplement.

Media coverage of creatine quickly soured. A Fortune magazine article referred to it as "nature's steroid." When asked by a newspaper reporter about creatine use by pro baseball players in 1998, San Francisco Giants pitcher Orel Hershiser was quoted as saying: "I just hope and pray there aren't a lot of heart attacks in another 10 years."

Scientists have performed hundreds of studies, some following creatine users for as long as five years; none have found convincing evidence linking it to heart attacks or any other ill effects in healthy people, said Jeff Volek, an assistant professor of kinesiology at the University of Connecticut. Studies have also failed to correlate the cramping and diarrhea often reported by athletes and trainers.

"I think a lot of this media coverage of creatine has been responsible for the idea that creatine is dangerous in some way," Volek said. Whereas steroid abuse causes acute and immediate changes in the body that presage the life-threatening problems, "that's just not the case with creatine," he said.

Creatine, formally known as creatine monohydrate, is neither a steroid nor a steroid precursor. It is not an herb, such as ephedra, nor is it a hormone, such as androstenedione. It is a nonessential dietary element produced naturally by many animals, including humans. It was discovered by French chemist Michel Chevreul in the 1830s, and its essential role in building and maintaining muscle tissue has been scrutinized ever since. Manufactured from amino acids by the liver, pancreas and kidneys, creatine is found primarily in the skeletal muscles — a 150-pound man typically maintains about 120 grams. It is also found in meat and fish. A pound of beef contains a gram or two. A pound of herring can have up to 5 grams.

In muscle cells, creatine is converted into creatine phosphate and works to replenish the body's supply of adenosine triphosphate (ATP), the cellular energy source into which all proteins, carbohydrates and fats are eventually converted. The problem for athletes is that intense physical exercise can deplete stored ATP faster than creatine can renew it. Humans manufacture about 2 grams of creatine per day. Hence the rationale behind supplementation.

If used this way, creatine is considered an ergogenic aid — that is, a performance enhancer. The regimen usually begins with a loading phase lasting about five days, during which 20 grams is taken per day in 5-gram doses. Then follows the maintenance phase, when the dosage drops to a single 5-gram dose daily. This cycle is usually repeated once a month.

By raising the total amount of creatine stored in muscle tissue by about 20%, supplementation increases the size, but not the number, of muscle cells, said Dr. Doug McKeag, director of the Indiana University Center for Sports Medicine. This can benefit athletic performance, but in a narrower way than many users realize. It applies only to the short, high-intensity bursts of energy that characterize bodybuilding, football, sprinting, shot-putting and other anaerobic activities. The weight gain — mostly retained water — that accompanies creatine use makes it ill-suited for endurance sports, such as distance running.

Plus, the effects don't manifest themselves on the first burst — only subsequent ones, such as the latter repetitions during a weightlifting set. The extra creatine will speed the replenishment of the body's ATP supply, effectively delaying fatigue. A motivated weightlifter can seize this extra energy to work harder — and may find himself able to heft more weight or do more sets a few days later as a result.

Creatine supplementation has shown promise treating diseases involving muscle weakness, such as Huntington's disease, muscular dystrophy and congestive heart failure. One 1996 study at Texas Woman's University indicated creatine may lower blood triglycerides significantly. Another, conducted last year at the University of Sydney and Macquarie University, both in Australia, found that it boosts the brainpower needed for computational tasks.

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Uncertainty over quality

Because creatine is classified as a nutritional supplement, manufacturers do not have to demonstrate to the Food and Drug Administration that their products are safe or effective for humans, as is the case with prescription drugs. An analysis last year by Consumer Lab, an independent testing firm in White Plains, N.Y., found that the seven brands of creatine powders and pills tested were free of impurities, but some other forms were contaminated with creatinine (the useless end product into which creatine breaks down) or contained less creatine than claimed on the label. One liquid version had less than 1% of the claimed amount.

Uncertainty over quality control is one reason why many public school officials want to keep supplements away from young athletes. Both the National Federation of State High School Associations and the California Interscholastic Federation have issued statements that discourage the use of performance enhancers. "Whether it's andro or creatine, or the other ones out there, we don't support the use of any of them," said Emmy Zack, a spokeswoman for the California Interscholastic Federation. "If [student athletes] need to get bigger for their sport, this is not the safest and best method to be following."

Thousands of teens across the country evidently are following the method anyway. A survey of Wisconsin high school athletes published in 2002 found that nearly 17% of 4,011 high school athletes — and more than 30% of football players — said they had used creatine. A total of 36% said their coaches had discouraged such use; 26% said their coaches had encouraged it.

The chief concern, say some experts, is that little information exists regarding creatine's effect on young bodies. "They're not done growing yet," said Eric Rawson, an assistant professor of exercise science and athletics at Bloomsburg University of Pennsylvania. He is skeptical that research will ever progress beyond surveys, because that would require administering creatine to minors. "It's unethical to conduct a study on this substance to see if it stunts growth," he said. "We can't address that. My personal opinion is that people under 18 should not use nutritional supplements like creatine, and I think that would be a general consensus of the scientific community."

McKeag disagrees. "It does not appear to be harmful at this point…. In a high school setting, it's probably a reasonable drug to use," he said.

Would he allow his son to take it? "No, I don't think I'd encourage him to use it," he said. "But I'm not so sure I would discourage it if he came home one day and said he was using it."

Researchers also disagree over whether supplemental creatine might eventually cause the body to curtail or halt internal creatine synthesis, leaving the user permanently dependent on outside sources.

While Rawson called this a "theoretical concern," McKeag said creatine's place of residence — inside cells, not floating free in the bloodstream — eliminates any threat of such biofeedback.

Tanner Elliott, 17, a wide receiver on the varsity football team at Kennedy High School, has friends at other schools who take creatine. "I get the impression that a lot of kids use it," he said. Some tell him they buy it with their parents.

Elliott, who is 5 feet 8 and weighs 150 pounds, said he was happy with his training progress. Nevertheless, if supplements weren't forbidden at Kennedy, he said he might be inclined to try creatine to "see what it does."

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Dreams of the NFL

Legislation proposed by state Sen. Jackie Speier (D-Hillsborough) would discourage the use of creatine and other performance-enhancement supplements by mandating that school officials not sell or distribute such products; and it would prohibit the use of such supplements by student athletes, dependent on funding for such a program.

The bill also would bar schools from accepting sponsorship money from supplement makers and would require that student athletes undergo testing to detect the use of performance enhancers beginning in 2006.

Speier expects stiff resistance from the supplement industry. "The power of the dietary supplement industry is overwhelming," she said. "When I first carried legislation on ephedra, I was being mocked. There is a collective denial around this issue."

Many teen football players use creatine to bulk up with dreams of playing in the NFL, yet Mark Asanovich, the strength and conditioning coach of the Jacksonville Jaguars, would tell them not to bother. He first banned the supplement's use by players while with the Tampa Bay Buccaneers in 1987 after noticing a pattern of cramping, dehydration and lowered endurance. "Creatine supplementation may be advantageous to a bodybuilder interested in ornamental muscular development, but a disadvantage to a football player interested in functional muscular development," he said.

Across the league, however, the message is muddled. After Asanovich left the Buccaneers in 2002, the ban was lifted.

He said parents were, in part, responsible for not discouraging the use of supplements by teen athletes. In the Wisconsin survey, more than 18% of high school students using creatine said their parents had encouraged them.

"I live next door to a guy who's got a 9-year-old baseball player, and he's pushing him toward creatine," Asanovich said. "The proper way to get bigger is progressive resistance exercise and a good dietary plan. I just sat down and had some prime rib a little while ago. I got all the creatine I needed."