Creatine
CREATINE
OFFICIAL NAMES: Creatine monohydrate, creatine phosphate
STREET NAMES: Legal steroid, muscle candy, ergogenic aid, performance-enhancing substance
DRUG CLASSIFICATIONS: Not scheduled, dietary supplement
OVERVIEW
Creatine was first discovered and isolated in muscle tissue in 1832 by French chemist Michel Chevreul. The compound is a naturally occurring, non-essential amino acid found in red meat, pork, dairy products, and fish. Most people take in approximately 1–2 grams (g) of dietary creatine from these sources daily (vegetarians somewhat less). Together, the kidneys, liver, and pancreas produce an additional 1–2 g of creatine daily, synthesized from the amino acids L-arginine, glycine, and L-methionine. Both creatine and phosphocreatine (which is creatine bound to phosphate; PCr, Crphos) are stored in skeletal muscle, organs, and body tissues. Phosphocreatine helps to power muscle contractions and decrease the amount of time the muscle takes to recover and "refuel."
Oral creatine supplements first gained popularity among athletes in the early 1990s following the publication of a Karolinska Institute study that found that subjects who took creatine supplements experienced a significant increase in total muscle creatine content. In theory, increased creatine stores would increase PCr stored in the muscles, which would in turn provide a larger power supply for anaerobic muscle activity and exercise (short bursts of exercise which don't require oxygen).
Creatine was thrust onto the global athletic scene in 1992 when British sprinters Linford Christie and Sally Gunnel won Olympic gold in Barcelona after reportedly training with the aid of creatine supplementation. Since that time, a number of clinical studies have looked at both the ergogenic (output enhancing effect) and therapeutic benefits of creatine.
Because creatine is considered a nutritional supplement, it is available legally and without a prescription in the United States. As of early 2002, creatine supplementation was not explicitly prohibited by the U.S. Olympic Committee (USOC), the National Collegiate Athletic Association (NCAA), the Major League Baseball (MLB), the National Football League (NFL), and other major national athletic organizations. However, a lack of well-designed clinical studies of creatine's long-term effects combined with loose regulatory standards for creatine supplement products manufactured in the United States has caused some athletic associations, including the USOC, to caution against its use without banning it outright.
Despite these issues, creatine remains well-known as a nutritional, performance-enhancing supplement used by athletes to improve high-intensity muscle endurance and performance. Bodybuilders and weightlifters supplement with creatine to bulk up muscles, and athletes involved in team sports train with creatine to increase their energy for sprints and other short and intense muscular tasks. Statistics show that the use of creatine by adolescent and adult athletes is growing. Yet research is still largely inconclusive on exactly how and in what situations supplements help athletes out of the laboratory and on the field.
CHEMICAL/ORGANIC COMPOSITION
Endogenous creatine is creatine that is synthesized, or manufactured, within the body by the liver, kidneys, and pancreas. It is produced from the amino acids arginine and glycine, and methionine, and is then transported throughout the body where it is stored in the organs, tissues, and muscles. The body can biosynthesize, or manufacture, up to 2 g of creatine daily. However, animal studies have shown that when supplemental creatine is taken regularly, the amount of endogenous creatine produced by the body is reduced. This tendency is thought to reverse itself once creatine supplementation stops.
The majority of creatine in the body (over 95%) is stored in skeletal muscle. About two-thirds of this is bound with phosphates, forming the compound creatine phosphate (PCr).
PCr acts on anaerobic adenosine triphosphate (ATP), the substance that powers muscle contractions. When ATP powers a muscle contraction, it loses one of its three phosphate molecules, changing from a triphosphate to a diphospate. The phosphate loss converts ATP to ADP (or adenosine diphosphate). Creatine phosphate provides an extra phosphate molecule for the ADP to convert or regenerate quickly back to ATP again and refuel muscle performance. Storing extra creatine in the skeletal muscles theoretically will provide for faster, more frequent ATP conversion.
Creatine monohydrate, the most popular form of off-the-shelf creatine supplementation, is an odorless, white, water-soluble powder. Its chemical name is N-(aminoiminomethyl)-N-methylglycine monohydrate.
In addition to unadulterated creatine monohydrate, special formulations of the supplement are available in the U.S. market which may include supplemental phosphates, amino acids, carbohydrates, and other dietary additives. There have also been laboratory reports of creatine that has been altered during the manufacturing process with other unlabeled and potentially harmful substances.
INGESTION METHODS
Creatine is sold in powdered, liquid, tablet, capsule, and chewing-gum formulations. The most popular formulation of creatine is creatine monohydrate, which is also the creatine formula that has been most extensively tested in clinical studies. Pure creatine monohydrate is a white, odorless, crystal powder with a faintly sweet taste. Other variations of creatine supplements are available, including creatine citrate and creatine phosphate. However, the clinical data on the effectiveness of these formulas is limited.
There are two types of dosing techniques commonly used. The first is to start with a large loading dose of 20 g, taken in 5-g increments four times a day, for 2–5 days. This is followed by a lower daily maintenance dose of 2 g or less for up to six weeks. The second method is to forgo the loading dose and simply use the smaller daily dose. The latter method may avoid some of the gastrointestinal distress and cramping that has been occasionally reported with loading doses.
Oversupplementation with creatine is common, and can be harmful to individuals with existing kidney problems or to athletes who don't properly hydrate themselves during workouts. Human skeletal muscle can only store up to 160 millimoles (mmol)/kg per day. After this limit is reached, any excess dietary or supplemental creatine will be excreted in the urine. When the body is already demanding fluids to replace those naturally lost during physical activity, severe dehydration can be a very real danger. For this reason, anyone taking creatine should always maintain adequate fluid intake of at least six to eight glasses of water daily.
Creatine is sometimes mixed or taken with sports drinks or other carbohydrate-heavy beverages. This practice is based on results of a 1996 clinical study published in the American Journal of Physiology, which reported that carbohydrate solutions increased uptake of creatine by skeletal muscle in study subjects. The American College of Sports Medicine recommends against regular heavy carbohydrate loading of 100 g or more along with creatine dosing because of the potential negative health affects of high sugar intake over time.
Some creatine products currently on the market are also "enriched" with other nutrients, including protein, glucose, vitamins, herbal ingredients, and other amino acids. Again, no hard data exists on the effectiveness of taking creatine in combination with other dietary supplements or herbals.
THERAPEUTIC USE
Children with guanidinoacetate methyltransferase (GAMT) deficiency require long-term treatment with creatine supplementation. GAMT deficiency is a rare inborn error of metabolism caused by an insufficient amount of stored creatine along with an excessive accumulation of guanidinoacetate (GAA) in the brain. GAA is one of the building blocks of creatine formed through a chemical reaction of the amino acid arginine. GAMT deficiency, which is typically diagnosed in infancy, causes seizures and developmental delays that can be at least partially reversed with high doses of supplemental creatine.
Creatine has also been shown to be of some benefit in neurological and musculoskeletal diseases and conditions that involve muscle wasting or deterioration of muscle function, such as amyotrophic lateral sclerosis (ALS), myasthenia gravis, muscular dystrophy, Huntington's disease, Parkinson's disease, and McArdle's disease.
Several studies have demonstrated that creatine may improve muscle function and increase exercise capacity in older adults experiencing age-related strength and exercise capacity loss. As of early 2002, only a handful of clinical studies had explored this phenomenon, and further research is needed to confirm and explain this finding. It should be noted, however, that there is some research that suggests creatine may not be as effective in older users as it is in younger individuals.
Individuals who face extended bedrest or immobilization in order to recover from surgery may also benefit from creatine supplementation. One study, which looked at knee surgery patients in rehabilitation, found that subjects who received creatine intravenously during their recovery gained leg strength faster than those who did not. Further research published in the Archives of Physical Medicine and Rehabilitation in 2002 found that creatine supplementation improved upper body exercise capacity in patients with cervical spinal cord injuries.
Creatine may also be a promising treatment for other types of physical rehabilitation. Research conducted at Catholic University Leuven (Belgium) looked at the role of creatine in the recovery of university students who had been immobilized in full leg casts for two weeks. The students who received creatine monohydrate supplements had greater muscle function and mass than the students who received a placebo at both three weeks and 10 weeks of physical rehabilitation.
New research on the antioxidative properties of creatine shows that the supplement may have even therapeutic properties beyond the treatment of musculoskeletal disease and injury. A 2000 study in Annals of Neurology reported that creatine had a protective effect against traumatic brain injury (TBI) in animal studies, reducing brain damage in mice and rats by up to 50%.
In other animal research, clinical studies have demonstrated that creatine inhibits the growth of solid tumors in rats. No data on the effects of creatine supplementation on cancer in humans had been published as of early 2002.
Finally, creatine supplements may be useful in the treatment of heart problems. Creatine has improved exercise capacity in patients suffering from congestive heart failure, and lowered blood cholesterol in animal studies. Limited study of creatine's effect on blood cholesterol levels in healthy humans has had mixed results, with one study reporting a positive impact and another reporting no effect at all. Further research is needed to determine if creatine is beneficial in improving blood cholesterol and preventing atherosclerosis.
USAGE TRENDS
Worldwide demand for nutritional supplements is projected to reach $162 billion by 2004. Sports supplements in particular are a rapidly-growing market in the United States. According to Nutrition Business Journal, a dietary supplement trade group publication, Americans spent $1.6 billion on creatine and other performance-enhancing dietary products in 2000.
Scope and severity
Market research analysts Frost & Sullivan report that the U.S. creatine market is growing an estimated 15–20% each year, and sales of the product are projected to exceed $350 million by 2006. The American College of Sports Medicine has estimated the national consumption of creatine in 1999 was 2,755 tons (2,500 metric tons).
Age, ethnic, and gender trends
Several studies and surveys have found that creatine use is on the rise among adolescent athletes in middle and high schools, with use of the supplement being reported in every grade from the sixth through the twelfth. Creatine use and awareness of use by peers was more common among boys, and at least one study published in the Southern Medical Journal (2001) found that the majority of student athletes were misinformed about the proper dosing or "loading method" of the supplement and consumed excessive amounts of creatine.
The University of Wisconsin's Department of Sports Medicine found that 30% of high school football players surveyed in that state used or had used creatine, and the use of the supplement tended to increase with age. Similarly, a survey of high school and middle school athletes in Westchester County, New York, reported creatine use among 44% of high school seniors surveyed.
Another large-scale national survey conducted by the Blue Cross and Blue Shield Association's Healthy Competition Foundation in 2001 found that an estimated one million adolescents surveyed (12–17 years of age) had tried performance-enhancing substances such as creatine. In addition, 55% of those surveyed knew someone who took supplements to improve sports performance.
A 2001 National Collegiate Athletic Association report entitled "NCAA Study of Substance Use Habits of College Student-Athletes" revealed that among the 29.8% of NCAA athletes who admitted using dietary supplements in the past 12 months, creatine was taken by 25.8% (second only to protein supplements). Fifty-seven percent of these athletes first used nutritional supplements in high school.
The Third National Health and Nutrition Examination Survey (NHANES III), a national study conducted by the National Center for Health Statistics (NCHS) and the U.S. Centers for Disease Control (CDC) reported that 40% of Americans had used a dietary supplement in the month before they were interviewed for the study. Although NHANES did not break down supplement use into specific subtypes, the data gives some interesting insights into the growing acceptance of dietary supplement products in America.
Thirty percent of African Americans surveyed in NHANES III reported supplement use, as did 29% of Mexican Americans. Supplement use was highest among Caucasians (43%), and women were more likely to take them than men (44% vs. 35%). Interestingly, this gender gap appears to be reversed in the use of creatine and other performance-enhancing sports supplements, where males have a higher incidence of use. This is likely attributable to the fact that overall, U.S. high school and collegiate athletic programs have a larger population of male athletes than female. In 2001, there were 232,000 male athletes playing at the college level compared to 163,000 female. Similarly, 2.7 million girls took part in high school athletic programs during the 1998-99 school year, compared to 3.8 million boys.
MENTAL EFFECTS
There are no known long-term psychological effects from creatine supplementation. However, at least one study has linked the use of performance-enhancing supplements to an increased incidence of health risk behaviors. The 2001 study, which surveyed approximately 500 men and women between the ages of 17 and 35, found that study participants who took ergogenic nutritional supplements such as creatine were more likely to get drunk, drink and drive, and become involved in physical confrontations. However, since the research was limited by the fact that it involved a very specific population (subjects were new recruits entering military service), further study is needed to determine if ergogenic aids such as creatine are directly linked to an increase in these behaviors.
PHYSIOLOGICAL EFFECTS
Creatine is an ergogenic aid, increasing energy output for short, rapid bursts of muscle contractions (anaerobic exercise). More simply put, creatine recharges the muscles for activities requiring short, strong, and repetitive bursts of activity, such as sprints or weight lifting. It also minimizes muscle fatigue during contractions.
However, study results have been mixed as to exactly for which activities creatine has an ergogenic effect. For example, studies involving stationary cycle sprints have demonstrated positive performance enhancing results for creatine, but it is still unknown whether these results can be consistently reproduced in actual competition outside of the laboratory. In addition, some cycling studies have not shown any significant benefit to creatine supplementation.
The literature does reach a consensus on one point—creatine does not enhance aerobic activity, which is required in endurance sports such as cross-country running, basketball, or long-distance cycling. However, to the extent that these sports may require short bursts of activity, such as sprints at the end of a cycling or running race, creatine may offer athletes some performance gains.
Creatine supplementation causes rapid weight gain, mostly likely via water retention by skeletal muscles. The typical weight gain during the loading period of creatine supplementation is 1–4 lb (0.45–1.8 kg). Whether this weight gain comes from water retention, an increase of lean body mass, or a combination of both has not been conclusively established. Research has shown that individuals taking creatine urinate less during the first several days of the loading dose period, which may support the water retention theory. Further studies are again needed to determine the exact mechanisms by which creatine increases overall weight.
Once creatine phosphate is metabolized, it is converted to creatinine, a waste product, which is cleared
from the bloodstream by the kidneys. Excess free creatine (or creatine unbound to phosphate) is also cleared from the body this way. Elevated serum (or blood) creatinine levels of over 1.2 mg/dL for women and 1.4 mg/dL for men may indicate the onset of kidney disease. Anyone taking creatine supplements for therapeutic or athletic purposes should do so under a doctor's care. Regular serum creatinine tests may be recommended for these individuals to monitor their kidney function.
Anyone with existing kidney disease, or with health conditions that put them at high risk for kidney problems (such as diabetes) should avoid creatine supplements.
Pregnant women, women who breastfeed, and children and adolescents under 18 years of age should avoid creatine use, as its long-term effect on these populations has not been adequately studied. Individuals with chronic medical conditions should consult with their healthcare professional before taking creatine or any other dietary supplement.
Harmful side effects
Some athletes using creatine supplements for training have reported muscle cramping and gastrointestinal distress (i.e., diarrhea, stomach cramps, vomiting), particularly with loading doses. At this time, all reports are anecdotal, which means that they are reported by individual users or healthcare providers but have not been conclusively proven through clinical research or controlled studies.
Creatine supplementation causes water retention by muscle tissue, which may be the source of muscle cramps. It has also been theorized that athletes who experience this side effect have a fluid or electrolyte imbalance due to dehydration. In some cases, adequate water intake may eliminate the muscle cramping.
As of early 2002, controlled clinical studies had not discovered any direct link between creatine use and muscle pain or strains when supplements are taken according to generally accepted guidelines. In fact, preliminary results from an Arkansas State University study of college baseball players found that those who used creatine did not have any more cramping or muscle injuries than nonsupplementing players.
Gastrointestinal side effects, such as nausea, vomiting, diarrhea, and stomach cramps, have also not been conclusively linked to creatine supplements that are taken following generally accepted guidelines. The practice of taking creatine during or immediately prior to a workout has been found to cause gastrointestinal distress after exercise, as has taking creatine with large amounts of sugar or glucose, which has a tendency to slow digestion. Neither of these ingestion methods is recommended by the American College of Sports Medicine. Further controlled clinical studies are needed to determine the mechanisms and prevalence of these side effects.
The Special Nutritionals Adverse Event Monitoring System (SN/AEMS) of the U.S. Food and Drug Administration (FDA), a database of consumer reactions to nutritional supplements and substances, has had 31 reports of adverse reactions to products containing creatine between 1993–1998. Reported symptoms include (but were not limited to):
- seizures
- headache
- shortness of breath
- nausea
- rash
- irregular heartbeat
- fatigue
Some of the SN/AEMS incidents involved creatine monohydrate that was mixed with or taken with other supplements and substances, so it is difficult to determine to what extent creatine played a role in these reactions. There have also been anecdotal case reports of hypertension (high blood pressure) and elevated liver enzymes in athletes taking creatine supplements.
Dehydration may also be a risk for creatine users. Creatine causes skeletal muscle to absorb intercellular fluid from bodily tissues and into the muscle where it is retained. For this reason, athletes who are already losing fluid during physical activity may be further dehydrated by creatine supplementation.
In addition, muscle can only absorb up to 160 mmol/kg of creatine. All excess dietary and supplemental creatine must be excreted out of the body, which can increase urinary output and put undue stress on the kidneys.
There have also been published reports of fatalities in individuals using creatine monohydrate. During November and December of 1997, three collegiate wrestlers in three different states died during training to "make weight" for upcoming wrestling meets. Although there was initially widespread media speculation that creatine played a major role in their sudden deaths, it was later determined by the U.S. Centers for Disease Control (CDC) that the fatalities were directly attributable to severe hyperthermia (overheating, or heat exhaustion) and dehydration. All three had been attempting rapid weight loss by "sweating off" the pounds, wearing rubber suits to undertake a strenuous workout regimen, and refusing adequate fluid intake.
Although the CDC did not cite creatine use as a factor in these dehydration-related deaths, the American College of Sports Medicine (ACSM) notes that preliminary clinical evidence indicates that creatine does appear to affect fluid balance in athletes. In a consensus statement on the use of creatine supplementation, the ACSM has said that "The potential acute effects of high-dose creatine supplementation on body fluid balance has not been fully investigated, and ingestion of creatine before or during exercise is not recommended." The ACSM also recommends that creatine supplementation should be avoided by anyone exercising or participating in sports in extremely high temperatures due to the dehydration risk.
Because creatine is regulated by the FDA as a dietary supplement and not a drug, the purity of the product is a concern. A test of 100 popular nutritional supplements conducted by the International Olympic Committee (IOC) at the German Sports University in Cologne found that 16 were adulterated with nandrolone, a steroid. Nandrolone was not a listed ingredient on the product label, and most of the creatine products tested originated in the United States.
In other independent tests, ConsumerLab.com, a privately held U.S. company that specializes in laboratory analysis of nutritional and herbal supplements for purity, strength, and truth in labeling, found that 15% of creatine supplements tested did not meet industry standards for creatine content, purity, and label claims.
Long-term health effects
The data on the long-term health effects of creatine supplementation is extremely limited. However, at least one animal study has found that creatine caused a decline in kidney function in rats with existing renal (kidney) disease. In addition, published case reports have indicated that creatine can cause further renal impairment in people with pre-existing kidney disease. However, several studies of healthy athletes have shown that both short-term and extended creatine supplementation had no effect on kidney function.
Creatine is not recommended for use by individuals with kidney problems, or by anyone at risk for kidney disease (such as those with a family history of kidney problems or diabetes). Again, further controlled clinical studies are needed to determine the long-term impact and safety of creatine supplement use on human renal function.
REACTIONS WITH OTHER DRUGS OR SUBSTANCES
According to the Physician's Desk Reference (PDR) for Nutritional Supplements, there are no known adverse interactions between creatine monohydrate supplements and prescription drugs, herbs, and/or other dietary supplements. However, the effects of creatine may be decreased or altered by the use of other drugs or supplements, so anyone considering taking the supplement should consult a physician first.
Creatine has a dehydrating affect, and ingestion of other diuretic substances such as caffeine may increase the chance of rapid and dangerous fluid loss. In addition to enhancing this diuretic affect, caffeine may also interfere with the ergogenic activity of creatine. A small Belgian study published in the Journal of Applied Physiology in early 2002 found that caffeine ingestion of three or more days interfered with the ability of creatine supplementation to shorten muscle relaxation time between isometric muscle contractions. Caffeine is a common ingredient in soft drinks, coffee, tea, chocolate, and other foods and beverages, and is used by some endurance athletes as a training aid.
There are reports of illness and adverse reactions arising in individuals taking creatine in conjunction with other supplement products. One such case study involved a man suffering a stroke after consuming both ma huang extract and creatine monohydrate. It is difficult to determine the exact role creatine plays in cases involving the use of more than one supplement product, but these incidents emphasize the need for anyone taking dietary or nutritional supplements to do so with extreme caution and consult their doctor or pharmacist about possible interactions. Just like prescription drugs, "natural" and herbal products can trigger dangerous interactions with other supplements and with prescription or over-the-counter medications.
TREATMENT AND REHABILITATION
None.
PERSONAL AND SOCIAL CONSEQUENCES
Because creatine is a legal dietary supplement and a non-addictive substance, the social pressures accompanying its use are not as intense as those that surround controlled substances and illicit drugs. And since the major professional U.S. sporting organizations allow its use in training, it does not have the stigma that steroids and other banned substances have. In addition, since the creatine use of a number of famous and talented professional athletes has been well-publicized by the media, many amateur athletes view the supplement as a miracle-drug of sorts.
The use of creatine by high-profile athletes around the world has also increased its popularity among youth and adolescents, who are taking the supplement in record numbers. A recent survey by the Healthy Competition Foundation found that 390,000 children between 10 and 14 years of age had taken performance-enhancing supplements of some type, and 57% of all respondents had used creatine. Unfortunately, there has not been a similar rise in education efforts about the supplement, and many who supplement with creatine do so in a manner that is inconsistent with the current clinical research (i.e., over-supplementation, use for non-anaerobic activities, etc.), possibly endangering their health.
In recent years, there has been a trend against the use of creatine and other performance-enhancing supplements among high school and collegiate athletic organizations. The National Federation of State High School Associations developed a position statement that states that "coaches should never supply, recommend or permit the use of any drug, medication, or food supplement solely for performance-enhancing purposes."
And in August 2000, the National Collegiate Athletic Association (NCAA) released a list of permissible and nonpermissible nutritional supplements that institutions and coaching staffs may provide their athletes. Under the NCAA policy, only those supplements that are considered non-muscle building substances can be provided to an NCAA athlete by a coach or institution. Creatine is considered a nonpermissible substance, however, athletes may still purchase and take the supplement on their own initiative and at their own risk.
LEGAL CONSEQUENCES
As previously stated, creatine is not a controlled substance and is available for over-the-counter retail purchase in the United States.
Legal history
As of early 2002, creatine supplementation was not on the list of banned or prohibited supplements of the International Olympic Committee, the United States Olympic Committee, or the NCAA. However, since nutritional supplements are not closely regulated by the FDA, the United States Anti-Doping Agency (the USADA, which oversees drug testing for the USOC) warns that ingestion of any nutritional supplement is at the athlete's own risk.
A number of prominent international sports and sports medicine organizations—including the International Olympic Committee, the Federation Internationale de Nation Amateur (FINA, the world governing body of swimming), the Sport Nutrition Advisory Committee of the Coaching Association of Canada, the U.S. Anti-Doping Agency, and the UK Sports Council—also maintain a "take at your own risk" policy for the use of creatine and other nutritional supplements by athletes. Some associations such as the Irish Sports Council have taken a stronger stance, advising athletes against creatine and performance supplement use of any kind. The French Rugby Federation (FFR) has an outright ban on creatine. In addition, France has classified creatine as a performance-enhancing drug, and its sale is banned in that country.
There have been cases of Olympic athletes taking adulterated supplement products they assumed were pure and later testing positive for steroids and other banned substances not listed on the product label. American bobsledder Pavle Jovanovic and Norweigan Greco-Roman wrestler Fritz Aanes are just two of the dozens of Olympic athletes banned in recent years for positive steroid drug tests. Both Jovanovic and Aanes claimed they took the banned substance unintentionally when they ingested contaminated dietary supplements. Subsequent testing of Aanes's dietary supplement did indeed find the banned steroid precursor nandrolone. However, even if steroid ingestion is unintentional, the athlete is still assumed to be responsible for its use, and Jovanovic and Aanes were banned from competition for two years as a result.
In 2001 the International Olympic Committee announced that 15–20% of the approximately 600 nutritional supplements the agency tested were adulterated with substances that could lead to positive doping tests. The IOC and the World Anti-Doping Agency (WADA), called upon the U.S. government for stricter regulation and labeling of supplements.
Federal guidelines, regulations, and penalties
Creatine is classified as a nutritional or dietary supplement, and as such it is regulated by the United States Food and Drug Administration (FDA) as a dietary supplement. Dietary supplements do not have to meet the same stringent manufacturing and clinical testing and approval requirements that are required of drugs before reaching the U.S. consumer market. Federal legislation known as the Dietary Supplement Health and Education Act (DSHEA) was passed in 1994 in an effort to standardize the manufacture, labeling, composition, and safety of botanicals, herbs, and nutritional supplements. In January 2000, the FDA's Center for Food Safety and Applied Nutrition (CFSAN) announced a 10-year plan for establishing and fully implementing these regulations by the year 2010.
But DSHEA is very different then the standard approval process for drugs and medical devices, and emphasizes the regulatory enforcement of label claims and advertising and marketing issues rather than the efficacy and quality of the supplements themselves. Unlike new drug and medical device applications, controlled clinical trials aren't part of the supplement review process, nor is any FDA inspection of a company's manufacturing facilities or quality control systems.
Under the act, a dietary supplement manufacturer is required to make certain submissions or notifications to the FDA only when specific health claims are made for the product. And the primary responsibility for the safety of the supplement rests with the product manufacturer; any required regulatory submissions can be made up to 30 days after the supplements are already available for sale to the general public. There are also no regulatory restrictions on the serving size a manufacturer chooses for the supplement, nor on the amount of included active ingredients. As such, the potency and dosage of creatine supplements may vary widely from manufacturer to manufacturer.
Anyone deciding to take creatine monohydrate should obtain the supplement from a reputable manufacturer that observes stringent quality control procedures and industry-accepted good manufacturing practices (GMPs). A good way to determine the quality of a supplement is to look for the designations "USP" or "USP Verified" on the product label. This designation indicates that the supplement meets the guidelines of the U.S. Pharmacopeia dietary supplement verification program (DSVP). Dietary supplements prepared under USP guidelines meet nationally recognized strength, quality, purity, packaging, and labeling standards as recommended by the FDA. The USP seal also tells the consumer that the supplement manufacturer is in compliance with FDA-prescribed GMPs.
See also Steroids
RESOURCES
Books
Burke, Edmund R. Creatine: What You Need to Know. New York: Avery Penguin Putnam, 1999.
Hendler, Sheldon, and David Rorvik, eds. PDR for Nutritional Supplements. Montvale, NJ: Medical Economics/Thomson Healthcare, 2001.
Periodicals
Murphy, Dee. "What You Should Know About Creatine." Current Health 26, no. 6 (Feb 2000): 13.
"Sports Supplement Dangers." Consumer Reports 66, no. 6 (June2001): 40.
Other
U.S. Food and Drug Administration. Center for Food Safety & Applied Nutrition. Office of Nutritional Products, Labeling, and Dietary Supplements (ONPLDS). <http://www.cfsan.fda.gov/~dms/supplmnt.html>. (April 1, 2002).
U.S. Anti-Doping Agency (USADA): The Independent Anti-doping Agency for Olympic Sports in the U.S. <http://www.usantidoping.org/>. (April 1, 2002).
Organizations
Healthy Competition Foundation, PO Box 81289, Chicago, IL, USA, 60681-0289, (312) 297-5824, healthycompetition@ bcbsa.com, <http://www.healthycompetition.org>.
Paula Anne Ford-Martin
Creatine
Creatine
What Kind of Drug Is It?
Creatine monohydrate can be found in numerous dietary supplements, in pill, powder, liquid, or even chewing gum form. It is a combination of three amino acids that are found in the muscles of humans and all animals with backbones. Creatine provides fuel to muscles during moments of rapid exertion, working within the muscle cells as a substance called creatine phosphate. Some studies suggest that it helps to repair and restore muscles after intense physical activity.
Human beings and other animals store creatine naturally in their muscle cells. The body manufactures it in the liver, kidneys, and pancreas. Additionally, creatine can be absorbed from natural outside sources such as meat and fish during the digestion process. According to Robert Monaco and Terry Malloy in Creatine and Other Natural Muscle Boosters, "the average man has about 120 grams [or 4 ounces] of creatine in his body, with about 95 percent in skeletal muscles." New creatine is created within the body at a rate of about two grams per day.
Safety Concerns, Especially for Teens
Some athletes have begun to use dietary supplements containing creatine to build muscle mass and reduce recovery times between workouts. Creatine supplements can be found in health food stores, on the Internet, and through mail-order companies. No one breaks the law by buying or selling creatine. It is not a controlled substance. Short-term studies have proven that creatine does contribute in a small way to increased strength during short bursts of activity, such as weight lifting, shot put, or batting a baseball.
Official Drug Name: Creatine monohydrate (KREE-uh-teen or KREE-uh-tin mon-oh-HY-drate)
Also Known As: Dietary supplements, supps
Drug Classifications: Creatine is not a controlled substance
Since creatine is not regulated by the U.S. Food and Drug Administration (FDA), many questions remain not only on its true effectiveness, but also on the possible damage it can do to the body, especially with prolonged use. How it affects the growing bodies of teenagers and younger children is not known. Although it is legal, creatine should be used by adults with extreme caution, under the close supervision of a medical doctor. Children and adolescents should avoid it.
Overview
Creatine was first isolated and named in 1832 by French chemist Michel-Eugène Chevreul (1786–1889). By the end of the nineteenth century, scientists had determined that intense muscular activity caused concentrations of creatine to build up in—and strengthen—muscle tissue. Further study determined that creatine levels could be raised in the body by eating a diet rich in meat. Eating great quantities of meat is not considered a healthy habit, so in the 1950s an Illinois company named Pfanstiehl Laboratories created and marketed the first synthetic, or manufactured, creatine.
Use by Olympic Athletes
As early as the 1960s, competitive athletes in the former Soviet Union were using creatine, along with anabolic steroids, to increase their strength and durability. (An entry on steroids is available in this encyclopedia.) In those years competitors were not tested for drugs prior to the Olympic Games. However, the apparent physical superiority of the Soviet, Eastern European, and Chinese athletes raised many suspicions. As the 1970s progressed, sports authorities in many nations, as well as the International Olympic Committee, instituted blood tests to check for performance-enhancing substances.
It is possible to test athletes for elevated levels of anabolic agents such as testosterone, androstenedione (ann-druh-STEEN-dee-ohn), and dehydroepiandrosterone (dee-HY-droh-epp-ee-ann-DROSS-tuh-rone). No tests, however, exist for measuring creatine levels. By the end of the twentieth century, a number of famous professional and amateur athletes and bodybuilders were using creatine supplements legally. In fact, they were even touting the substance's powers. Home run champions Mark McGwire and Sammy Sosa
have both admitted taking creatine. Use of the supplement has been linked to former professional quarterbacks Troy Aikman and John Elway and Olympic runner Michael Johnson, to name only a few.
A June 2000 article for Time magazine discussed the safety of creatine. The writer reported that half of the athletes surveyed by the magazine, "many of them Olympians, admitted … that they'd be willing to take a drug even if it was sure to kill them eventually, so long as it would let them win every event they entered five years in a row." This "win at all costs" mindset filters down from the professional and Olympic level to high school and even middle school athletes. Many youth are feeling that they will have no chance of succeeding at the highest levels if they do not use supplements such as creatine.
What Is It Made Of?
endogenous, or natural, creatine is produced from three amino acids: arginine (AHR-juh-neen), glycine (GLY-seen), and methionine (meh-THY-uh-neen). It can be found in most of the body's organs. However, the vast majority of it resides within the muscle cells that power the body's movements.
Creatine is part of a complex chemical process that creates and restores adenosine triphosphate (atp), the fuel that muscles feed on as they contract. In quick movements, ATP converts to adenosine phosphate (ADP), releasing a burst of energy in the process. As Monaco noted in his book, "Normally, muscles contain only enough ATP to provide energy for between five and ten seconds, depending on the amount of effort required for the activity. Then, the muscles need creatine to make more ATP."
About two-thirds of the creatine in the body is creatine phosphate. This chemical comes into play when the muscle's store of ATP has been depleted, or used up. Creatine phosphate breaks down into creatine and phosphate, restoring the levels of ATP. The reason muscles ache after a difficult workout is that levels of ATP and creatine have fallen. As the body restores the chemical balance, the aches fade and the muscles become stronger.
Endogenous creatine is manufactured in the liver, kidneys, and pancreas. A normal, active human being manufactures about two grams of creatine daily, taking in perhaps one or two grams more through foods. Vegetarians tend to store less creatine in their bodies, since they do not eat meat.
Mark McGwire
In September of 1998, while working toward setting a new single-season home run record, St. Louis Cardinals slugger Mark McGwire talked with reporters at his locker in the stadium clubhouse. A photographer snapped a shot of McGwire's locker, showing a bottle of creatine supplements.
On March 17, 2005, McGwire was called to testify in Washington, D.C., before the House Committee on Governmental Reform. Facing tough questions from members of Congress, McGwire dodged the issue about whether he used performance-enhancing products. As reported in the Philadelphia Daily News, McGwire stated: "I cannot answer these questions without jeopardizing my friends, my family, and myself." McGwire wept when parents whose sons had died of complications of steroid abuse told the committee that their sons idolized McGwire and wanted to be like him.
How Is It Taken?
Supplemental creatine is available in pill form, as a powder dissolved into beverages, or as a gum or candy. Because it is not considered a drug, the substance is not regulated for purity in its many different products. Sometimes the dosage per unit varies from the information printed on the label. Sometimes extra ingredients are added to the pills or powders, and some of these can act as steroids in the body.
Two athletes, American bobsledder Pavle Javanovic and Norwegian wrestler Fritz Aanes tested positive for steroid use prior to the Olympic Games and received two-year suspensions. Both men claimed they used only creatine. A test of Aanes's dietary supplement revealed that it contained a banned substance called nandro-lone, which was not listed on the label. In a random test of creatine supplements conducted by ConsumerLab.com in 2003, only half of the products tested were found to have the ingredients they listed at the dosages they claimed. The other half made false claims of dosages or were found to contain other unlabeled ingredients.
Are There Any Medical Reasons for Taking This Substance?
A very small number of children are born with a condition called guanidinoacetate methyltransferase deficiency (GMAT; pronounced GWAN-ih-deen-oh-AH-suh-tate METH-uhl-TRANZ-fuh-rase). This extremely serious illness causes muscle wasting and seizures from the time of birth onward. Some of its symptoms are eased by high doses of supplemental creatine.
Small research studies show creatine supplements benefit people who have diseases that cause muscle degeneration, such as amyotrophic (ay-my-oh-TROH-fik) lateral sclerosis (ALS, or "Lou Gehrig's Disease"), myasthenia gravis (my-us-THEE-nee-uh GRAH-vuss), muscular dystrophy, Huntington's disease, Parkinson's disease, and McArdle's disease. It is important to note that creatine supplementation may slow the symptoms of these diseases, but it does not cure them.
Fast Facts about Creatine
Did you know the following facts about creatine supplements?
- Half of the athletes surveyed by Time magazine in 2000 said they would be willing to take a deadly drug if it would allow them to win every event they entered for five years.
- In 2001, $400 million worth of creatine supplements were sold in the United States.
- Creatine supplements have not been banned by any professional or amateur sports authority, except the National Collegiate Athletic Association (NCAA), where it is classified as a "non-permissible" substance.
- In 2001, survey findings suggested that 390,000 children between the ages of ten and fourteen had tried some sort of performance-enhancing product.
People who face long periods in bed recovering from surgery or from multiple broken bones may speed the restoration of their muscles by taking extra creatine. Creatine also appears to improve the exercise capacity in patients suffering from heart problems. Also, there is some evidence to suggest that the supplement helps elderly people retain balance and muscle control later in life.
Usage Trends
Since the late 1990s, there has been a huge surge in the purchase of creatine supplements. According to the Knight Ridder/Tribune Business News, Americans purchased $400 million worth of creatine in 2001. A Sports Illustrated piece claimed that over- the-counter dietary supplements for sports nutrition were a $1.7 billion industry in 2003. Most of the buyers are teenagers and grown men and women who want to build muscle. Some creatine products are especially targeting "the upmarket youth," according to Suhit Kelkar in the Asia Africa Intelligence Wire. In a survey conducted by Time magazine in 2000, 44 percent of high school seniors said they used creatine to improve athletic performance. No legal restrictions exist on the purchase of creatine, so teenagers can buy it without the advice or consent of their parents. Peer pressure, along with the desire to win in competition, can be powerful agents of persuasion for those considering creatine supplementation.
Effects on the Body
Creatine supplement use has been shown to raise the levels of stored creatine in muscles. Plus, research has revealed it does lead to modest gains in strength during anaerobic exercise. In most people, use of creatine supplements does not improve performance in aerobic exercises or sustained periods of activity. Creatine users claim that the substance helps them to "bulk up," or gain muscle mass. This is the case, but the weight gain stems only from retained water within muscle cells.
Not Enough Information Available
The water retention is just one of the dangers of creatine use. One of the most common side effects of using creatine supplements is dehydration, or a drying-out of body tissues. Taking creatine mixed in a caffeinated beverage, such as coffee or some soft drinks, increases the risk of dehydration. Athletes who work out briskly at higher temperatures risk heat stroke and, ultimately, kidney damage due to dehydration. Other reported side effects of high doses of creatine include nausea, diarrhea, indigestion, and an increased risk of muscle strain.
Whether muscle strain is linked to creatine use is highly debated. Some studies suggest that creatine use encourages athletes to work out harder and longer, while their bodies reap little benefit from the extra creatine. This psychological component of creatine use can be a factor in painful muscle strains or cramping.
How does using creatine affect children and teens who are still growing? As of 2005, no answers were available. Long-range studies of creatine use had not been completed. Doctors recommend that children and teens avoid all use of creatine, no matter how tempted they might be to "bulk up." A Sports Illustrated story on sports supplements quoted Dr. Arthur Grollman of the State University of New York at Stony Brook. He observed: "Basically, anyone who uses these products is a human lab rat."
Case in point: In the Journal of Toxicology: Clinical Toxicology, Christine A. Haller and her colleagues discussed whether seizures are linked to dietary supplements. They noted that although creatine has not been linked with seizures in published studies, "the California Poison Control System has received a few … reports of seizures in young athletes who were allegedly taking only creatine. This potential association between creatine use and seizures requires further investigation."
Reactions with Other Drugs or Substances
Creatine and caffeine do not mix well. Both tend to dehydrate the body. Taken together, they can lead to heat stroke. Few studies have been done about the body's reaction to creatine supplements when taken with prescription medications, over-the-counter medications, or even other dietary supplements. Some fitness magazines warn against mixing creatine powder with drinks that are high in sugar or glucose content. Sweetened beverages carry their own dangers, including encouraging diabetes and weight gain.
Although the purchase of creatine is legal, the substance has not been proven safe, even for adults. Before taking creatine supplements, adults should first consult a licensed doctor and carefully review any other medications that they are using daily. People with kidney problems should never take creatine supplements. Doctors will take periodic blood tests to make sure that creatine use is not damaging internal organs such as the liver and kidneys. Coaches, personal trainers, and sports nutritionists are not qualified to recommend creatine supplementation. They do not have the extensive medical education and training that licensed medical doctors have.
Creatine Chronology
1832 French chemist Michel-Eugène Chevreul isolates creatine within muscle cells and names it after the Greek word for "flesh."
1926 An article in a British medical journal links creatine consumption in meats to weight gain as muscle mass.
1954 Pfanstiehl Laboratories Inc. of Illinois produces synthetic creatine in bulk and markets it to catalog resellers.
1992 British sprinters Linford Christie and Sally Gunnel win Olympic gold medals after having trained using creatine supplements.
1998 Mark McGwire, working toward breaking the single-season home run record for Major League Baseball, is photographed with a bottle of creatine supplements in his stadium locker.
2005 Mark McGwire testifies before Congress about steroid use in Major League Baseball. He dodges questions about whether he used performance-enhancing products.
Treatment for Habitual Users
The use of creatine supplements has not been shown to cause the human body to stop making its own endogenous
creatine. Also, creatine monohydrate is not a habit-forming substance. Withdrawal from creatine supplements does not plunge the user into a period of muscle weakness or other difficulties. Still, users can develop a psychological dependence on the drug and become convinced that extra creatine will make them better athletes. This may cause them to use the substance longer, or in higher doses, than anyone would recommend.
As of 2005, no studies had been done on the long-term use of creatine supplements. Experts suggest that young athletes never begin using creatine supplements at all. Those who have already begun should consult a doctor about continued use.
Consequences
Are creatine supplements safe? As of 2005, the bodybuilding industry and its periodicals claimed creatine was safe. However, various medical journals offered a different opinion. They noted that nothing was known about the long-term effects of creatine use, particularly for young people. Plus, since creatine was already available on the market and fairly inexpensive, drug companies have been reluctant to conduct trials to prove the medical benefits of taking the supplement.
What this means is that those using creatine supplements in the early twenty-first century will provide the only long-term data on creatine's possible ill effects, since these users were the first to buy the supplement in great numbers. Because the long-term effects of creatine are not yet known, users could learn one day that the substance has various health risks.
Building Muscles without Supplements
All athletes should be wary of any substance that promises quick results. Health professionals note that there is simply no substitute for a carefully chosen exercise program and good dietary habits. In its August 2003 edition, Prevention magazine offered teens various tips for building muscle without the pills and the powders. For example, the editors recommended:
- When exercising vigorously, add twenty-eight grams of protein to your diet daily. Instead of protein powders, consume larger quantities of milk, eggs, lean meats, and beans.
- After exercising, eat a snack high in carbohydrates, such as trail mix, apples, fruit juices, or whole grain breads.
- Cramped, sore, or stiff muscles are the body's sign that it is being overworked. Take longer breaks between intense workouts, and vary the types and duration of exercise routines. A long run or bike ride one day might be followed by some weight lifting the next day.
The Law
Anyone of any age can buy creatine supplements and use them. They are legal. The burden of keeping them out of the hands of growing children and young adults falls on parents, doctors, coaches, and the young people themselves. Nutritional supplements have not been proven to turn an average, or even above-average athlete, into a sports star, like Mark McGwire. The odds of receiving a contract to play professional sports—in any sport—are very slim. A study published in NCAA News Online in 2000 stated that only 2 percent of college football players go on to play professional football. The percentage of high school players who win pro contracts is far smaller than that.
For More Information
Books
Clayman, Charles B., editor. The American Medical Association Encyclopedia of Medicine. New York: Random House, 1989.
Monaco, Robert, and Terry Malloy. Creatine and Other Natural Muscle Boosters. New York: Dell Publishing, 1999.
Periodicals
Anderson, Nicki. "Creatine for a 14-Year-Old? It's Not a Good Idea, Parents." Arlington Heights, IL Daily Herald (December 13, 2004): p. 2.
Beckham, Lauren. "Your S.T.U.F.F.: Healthy or Health Hazard?: Teens and Families Need to Do Their Homework When It Comes to Dietary Supplements." Boston Herald (November 27, 2000): p. 40.
Christie, Tim. "Eugene, Oregon-Area High School Athletes Use Performance Booster with Creatine." Knight Ridder/Tribune Business News (November 20, 2003).
"Crazy for Creatine: Everyone from Mark McGwire to Kiddie Jocks Is Using This Muscle Builder. But Is It Safe?" Time (June 12, 2000): p. 93.
Donnellon, Sam. "Swearing Thin." Philadelphia Daily News (March 18, 2005).
Fauber, John. "Performance Enhancers Might Harm Your Child." Milwaukee Journal Sentinel (September 3, 2001): p. 1.
Fragakis, Allison Sarubin. "Your Teen: The Terminator: Pills Promise Kids Bulging Muscles—but at a Price." Prevention (August, 2003): p. 66.
Haller, Christine A., Kathryn H. Meier, and Kent R. Olson. "Seizures Reported in Association with Use of Dietary Supplements." Journal of Toxicology: Clinical Toxicology (January, 2005): p. 23.
Kelkar, Suhit. "Creatine a Monster." Asia Africa Intelligence Wire (August 24, 2004).
Kubetin, Sally Koch. "Demand Swells for Sports Supplements." Family Practice News (February 15, 2002): p. 1.
"A Little Chip on His Big Shoulder." Time (September 7, 1998): p. 23.
O' Neil, John. "Creatine and Boys in Pursuit of Bulk." New York Times (December 19, 2000): p. F8.
Schneider, Mary Ellen. "Screen Teens for Use of Performance Enhancers: Steroids, Ephedra, Creatine, More." Family Practice News (February 15, 2004): p. 62.
Song, Bonita. "Stanford U.: Creatine May Be More Hype than Help, Doctor Says." America's Intelligence Wire (February 5, 2004).
Splete, Heidi. "Creatine Popular with Student Athletes." Family Practice News (February 15, 2002): p. 5.
Wertheim, L. Jon. "Jolt of Reality: Following the Lead of Elite Athletes, Teenagers Are Increasingly Juicing Their Workouts with Pills and Powders—Sometimes with Tragic Results." Sports Illustrated (April 7, 2003): p. 68.
Web Sites
"A History of Innovation." Ferro.http://www.ferro.com/Our+Products/Pharmaceuticals/About+Us/_Time+Line.htm (accessed June 30, 2005).
"Probability of Competing in Athletics Beyond the High-School Interscholastic Level." NCAA News Online.http://www.ncaa.org/news/2000/20000814/digest.html (accessed June 30, 2005).
"Product Review: Muscular Enhancement Supplements: Creatine, HMB, and Glutamine." ConsumerLab.com.http://www.consumerlab.com/results/creatine.asp (accessed June 30, 2005).
U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition.http://www.cfsan.fda.gov/ (accessed June 30, 2005).
Creatine
Creatine
Description
With its promises of bigger muscles and improved athletic performance, creatine has generated more interest and controversy than almost any other dietary supplement. It is widely used by body builders and athletes of all levels, from famous baseball sluggers to high school jocks. Even without taking supplements, all people have a small amount of this protein in their bodies. Some of it comes from food, especially meat and fish, while the rest is made by the body from amino acids . No one disputes the fact that creatine plays an important role in converting food into energy. The real question is whether taking extra amounts of creatine can make muscles bigger, boost athletic performance, or improve the health of people with muscle or nerve disease.
Creatine is considered important because it can increase the amount of energy available to working muscles. The protein is used by the body to make a chemical compound called adenosine triphosphate (ATP), the immediate fuel source used by muscles during short but intense bursts of activity. Through its conversion into phosphocreatine, a related substance, creatine appears to delay muscle fatigue by re-supplying muscles with ATP. Because creatine can be stored for later use by cells, consuming extra amounts of the protein may create a deeper energy reserve for muscles and other tissues. Excess creatine is eliminated by the kidneys. This means that creatine supplements may be of little value in people who have sufficient levels of the protein, since the kidneys automatically remove extra amounts.
A significant amount of research is still required to determine the long-term effects of taking creatine, proper dosage, and whether age, gender, or the presence of existing diseases can affect use of the supplements. However, as of 2002, studies found a lower risk of training-related injuries in athletes who used the supplement and new therapeutic uses of the supplement were being tested.
General use
Creatine supplements are generally used by weight lifters and athletes who wish to optimize their workouts or enhance athletic performance. It is important to distinguish fact from myth regarding the possible benefits of creatine. The scientific evidence suggests that creatine may not have much usefulness as a muscle-enhancing agent, though it does appear to moderately improve performance in exercises or sports that require short, repeated bursts of high-energy activity. For example, creatine may provide a slight energy boost to the muscles of a weight lifter during extended repetitions or a basketball player who makes yet another drive to the hoop. However, creatine does not appear to increase aerobic capacity or improve performance in endurance-type activities such as marathon running. Apart from its uses in body building and athletics, creatine may prove beneficial in the treatment of certain diseases involving the muscles or nerves.
In one study of 16 physical education students, for example, those who received 20 g a day of creatine for about a week were more capable of maintaining speed during a cycling exercise . The students peddled on a stationary bike for six seconds at a stretch, repeating the exercise 10 times and taking 30-second breaks between attempts. A study of 14 active men, published in the Journal of the American Dietetic Association in 1997, investigated creatine supplementation and repetitive, high-intensity resistance exercises involving the bench press and jump squats. The authors reported that taking 25 mg a day of creatine for one week enhanced muscular performance during the resistance exercises and also increased body mass. It is not certain if the higher body mass reflected increases in muscle or simply excess water weight, which may give the impression of bigger muscles.
In addition to individual studies, several articles in medical journals have reviewed the scientific literature concerning creatine. According to an article published in the Journal of the American College of Nutrition in 1998, creatine supplements may boost performance during certain physical exercises that require repeated, intense efforts and allow only a short interval of rest between attempts. The author noted that using the protein appears to increase body mass in men (though the initial increase is probably water) and may increase lean body mass when combined with resistance exercises over a long period of time. A meta-analysis published in the International Journal of Sports Medicine in 1997 discussed the possible benefits of creatine supplements and how the protein may produce its effects. The authors suggest that creatine may be able to delay muscle fatigue and quicken recovery during repetitive, high-intensity exercises by helping the body to re-supply muscles with ATP. Once ATP reserves get low due to exertion, the higher levels of creatine and phosphocreatine in muscles facilitate the speedy production of new ATP. The authors conclude that creatine supplements may be useful during repetitive training exercises and could provide a competitive edge in sports that require repeated, explosive bursts of activity such as basketball or soccer.
One of the most thorough and authoritative investigations of creatine supplementation was conducted by a panel affiliated with the American College of Sports Medicine (ACSM). This group, which reviewed over 100 studies involving creatine, published some of their findings in early 2000 in Medicine and Science in Sports and Exercise. The panel found that creatine can boost performance in certain repetition-type exercises that involve brief but powerful exertion. They noted that creatine does not appear to make people stronger or improve aerobic capacity. Creatine can produce weight gain after only a few days, but this is most likely due to water retention. Since most of the creatine research has been conducted in healthy young men, there is limited information about how age or gender may affect use of the protein. The panel pointed out that, while creatine may produce a small but significant boost in performance in very specific exercises, it usually cannot satisfy the overly high expectations of most people who use the supplement.
A 2002 European study reported that creatine supplements could actually speed rehabilitation for injured athletes. Patients who were immobilized in a leg cast for two weeks were given a dietary supplement of creatine before immobilization and then daily throughout the rehabilitation. They showed faster recovery of strength and muscle mass than subjects not receiving creatine.
Aside from sports, research also suggests that creatine may be helpful in the treatment of certain diseases affecting the muscles or nerves, including Huntington's disease, Lou Gehrig's disease (amyotrophic lateral sclerosis), and congestive heart failure. Creatine is not considered a cure for these diseases, but may help to alleviate symptoms (such as muscle weakness and fatigue) or possibly extend survival. In one study involving mice, conducted by researchers from Harvard Medical School and Cornell University Medical College, creatine appeared to provide protection against Lou Gehrig's disease. The protein worked twice as well as Riluzole, a prescription drug approved by the FDA for treatment of the disease.
Preparations
Dosage of creatine usually consists of a loading dose of 10–30 g a day (divided into several doses) for four to six days, followed by a maintenance dose of 2–5 g a day. It is not clear if the high loading dosage is actually necessary. The ACSM panel noted that smaller dosages (3 g a day) achieve the same effects if taken for several weeks.
Even without taking supplements, most people get about 1 g of creatine through their diets . Some authorities believe it is safer for people to avoid creatine supplements altogether in favor of eating foods that contain the protein. The best sources of creatine are meat, poultry, and fish. Getting too much dietary creatine is not considered a significant risk because only small amounts of the protein are contained in food.
Precautions
Creatine supplements are not known to be harmful when taken in recommended dosages, though there are some precautions to consider. People with kidney disease should not use creatine without medical supervision. Due to lack of sufficient medical study, creatine should be used with caution in children under age 16, women who are pregnant or breast-feeding, and people with liver disease.
The long-term health risks associated with taking creatine are unknown. Surprisingly, though, use of the supplement is increasing, even among children and adolescents. Some adults have used the drug on a long-term basis without knowing the effects of long-term use.
Side effects
A slight weight gain due to water retention is probably the most common side effect. Nausea , cramping, dehydration, diarrhea , and increased blood pressure have also been reported.
To avoid possible side effects, do not take creatine immediately before or during exercise.
Drink plenty of fluids (six to eight glasses a day) while using creatine in order to prevent dehydration.
Interactions
Taking creatine with large amounts of carbohydrates may increase its effectiveness. Caffeine may decrease the effects of the supplement.
Resources
BOOKS
Paoletti, Rodolfo. Creatine: From Basic Science to Clinical Application. Boston: Kluwer, 1999.
PERIODICALS
"Creatine Supplementation Speeds Rehabilitation." Health and Medicine Week (January 21, 2002): 6.
Kubetin, Sally Koch. "Demand Swells for Sports Supplements." Family Practice News (February 15, 2002): 1.
Mujika, I., and S. Padilla. "Creatine Supplementation as an Ergogenic Acid for Sports Performance in Highly Trained Athletes: A Critical Review." International Journal of Sports Medicine 18, no. 7 (1997): 491-6.
"Studies Say Creatine is OK." Obesity, Fitness & Wellness Week (January 12, 2002): 12.
Terjung, R. L., P. Clarkson, E. R. Eichner, et al. "The Physiological and Health Effects of Oral Creatine Supplementation [In Process Citation]."Medicine and Science in Sports and Exercise 32, no. 3 (2000): 706–17.
Volek, J. S., W. J. Kraemer, J. A. Bush, et al. "Creatine Supple-mentation Enhances Muscular Performance During High-Intensity Resistance Exercise."Journal of American Dietetic Association 97, no. 7 (1997): 765–70.
Williams, M. H., and J. D. Branch. "Creatine Supplementation and Exercise Performance: An Update."Journal of the American College of Nutrition 17, no. 3 (1998): 216–34.
ORGANIZATIONS
American College of Sports Medicine. 401 W. Michigan St., Indianapolis, IN 46202-3233. cheister@acsm.org. <http://www.acsm.org>.
Grand Forks Human Nutrition Research Center. 2420 2nd Ave N., Grand Forks, ND 58202. <http://www.gfhnrc.ars.usda.gov>.
Greg Annussek
Teresa G. Odle