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Overview:

Creatine is a naturally occurring amino acid (protein building block) that's found in meat and fish, and also made by the human body in the liver, kidneys, and pancreas. It is converted into creatine phosphate or phosphocreatine and stored in the muscles, where it is used for energy. During high-intensity, short-duration exercise, such as lifting weights or sprinting, phosphocreatine is converted into ATP, a major source of energy within the human body.

Creatine supplements are popular among body builders and competitive athletes. It is estimated that Americans spend roughly $14 million per year on creatine supplements. The attraction of creatine is that it may increase lean muscle mass and enhance athletic performance, particularly during high-intensity, short-duration sports (like high jumping and weight lifting).

However, not all human studies have shown that creatine improves athletic performance. Nor does every person seem to respond the same way to creatine supplements. For example, people who tend to have naturally high stores of creatine in their muscles don't get an energy-boosting effect from extra creatine. Preliminary clinical studies also suggest that creatine's ability to increase muscle mass and strength may help combat muscle weakness associated with illnesses such as heart failure and muscular dystrophy.

Uses:

Athletic performance

Although not all clinical studies agree, some conducted in both animals and people have shown that creatine supplements improve strength and lean muscle mass during high-intensity, short-duration exercises (such as weight lifting). In these studies, the positive results were seen mainly in young people (roughly 20 years of age). Most human studies have taken place in laboratories, not in people actually playing sports. Creatine does not seem to improve performance in exercises that requires endurance (like running) or in exercise that isn't repeated, although study results are mixed.

Although creatine is not banned by the National Collegiate Athletic Association (NCAA) or the International Olympic Committee, using it for athletic performance is controversial. The NCAA prohibits member schools from giving creatine and other muscle building supplements to their athletes, although it doesn't ban athletes from using it. The French Agency of Medical Security for Food (AFSSA) asserts that the use of creatine supplements is "against the spirit of sportsmanship and fair competition."

Creatine appears to be generally safe, although when it is taken at high doses there is the potential for serious side effects such as kidney damage and the risk of inhibiting the body's natural formation of creatine.

Also of concern is the marketing of creatine-containing supplements directly to teens, with claims about changing one's body with little effort. One survey conducted with college students found that teen athletes frequently exceed the recommended loading and maintenance doses of creatine. Meanwhile, neither safety nor effectiveness in those under 19 has ever been tested.

Heart disease

A preliminary clinical study suggests that creatine supplements may help lower levels of triglycerides (fats in the blood) in men and women with abnormally high concentrations of triglycerides.

In a few clinical studies of people with congestive heart failure, those who took creatine (in addition to standard medical care) saw improvement in the amount of exercise they could do before becoming fatigued, compared to those who took placebo. Getting tired easily is one of the major symptoms of congestive heart failure. One clinical study of 20 people with congestive heart failure found that short-term creatine supplementation in addition to standard medication lead to an increase in body weight and an improvement of muscle strength.

Creatine has also been reported to help lower levels of homocysteine. Homocysteine is a marker of potential heart disease, including heart attack and stroke.

Chronic Obstructive Pulmonary Disease (COPD)

In one double-blind study, people with COPD who took creatine increased muscle mass, muscle strength and endurance, and improved their health status compared with those who took placebo. They did not increase their exercise capacity. More studies are needed to see whether creatine has any benefit for people with COPD.

Muscular dystrophy

People who have muscular dystrophy may have less creatine in their muscle cells, which may contribute to muscle weakness. One study found that taking creatine resulted in a small improvement in muscle strength. However, other studies have found no effect.

Parkinson's disease

People with Parkinson's disease have decreased muscular fitness including decreased muscle mass, muscle strength, and increased fatigue. A small clinical study found that giving creatine to people with Parkinson's disease improved their exercise ability and endurance. In another clinical study, creatinine supplementation improved patients' moods and led to a smaller dose increase of drug therapy. More research is needed in this area.

Dietary Sources:

About half of the creatine in our bodies is made from other amino acids in the liver, kidney and pancreas, while the other half comes from foods we eat. Wild game is considered to be the richest source of creatine, but lean red meat and fish (particularly herring, salmon, and tuna) are also good sources.

Available Forms:

Supplements are commonly sold as powders, although liquids, tablets, capsules, energy bars, fruit-flavored chews, drink mixes, and other preparations are also available.

How to Take It:

Pediatric

Safety and effectiveness have not been tested in those under 19. Creatine supplements are not recommended for children or teens.

Adult

Loading dose in exercise performance (for adults ages 19 and older): Take 5g of creatine monohydrate, 4 times daily (20s total daily) for one week.

Maintenance dose in exercise performance (for adults ages 19 and older): Take 2 - 5g daily.

For cholesterol reduction (for adults ages 19 and older): Take 20 - 25g daily, for 5 days, followed by 5 - 10g daily thereafter.

Your body may absorb creatine better when you take it with carbohydrate foods (such as fruits, fruit juices, and starches). The doses mentioned have been tested frequently in athletes. However, it is not known whether these dosages have the same effects in non-athletes.

Precautions:

Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable health care provider.

Side effects of creatine include weight gain, muscle cramps, muscle strains and pulls, stomach upset, diarrhea, dizziness, high blood pressure, liver dysfunction, and kidney damage. Most studies have found no significant side effects at the doses used for up to six months.

Rhabdomyolysis (breakdown of skeletal muscle tissue) and acute kidney failure was reported in one case involving an athlete taking more than 10 grams daily of creatine for 6 weeks. People with kidney disease, high blood pressure, or liver disease should avoid creatine.

Taking creatine supplements may prevent the body from making its own natural stores, although the long-term effects are not known. The Food & Drug Administration recommends talking to your doctor before starting to take creatine.

There have been reports of contaminated creatine supplements. Be sure to buy products made by established companies with good reputations.

Possible Interactions:

If you are currently being treated with any of the following medications, you should not use creatine without first talking to your health care provider.

Non-steroidal anti-inflammatory drugs (NSAIDs) -- Creatine may increase the risk of damage if taken with these pain relievers, such as ibuprofen (Motrin, Advil) or naproxen (Aleve).

Caffeine -- Caffeine may inhibit the body's ability to use creatine. Taking creatine and caffeine may increase risk of dehydration. Using creatine, caffeine, and ephedra (a substance that has been banned in the U.S. but that was used in sports supplements) may increase the risk of stroke.

Diuretics (water pills) -- Taking creatine with diuretics may increase the risk of dehydration and kidney damage.

Cimetidine (Tagamet) -- Taking creatine while taking Tagamet may increase the risk of kidney damage.

Probenicid -- Taking creatine while taking probenecid (a drug used to treat gout) may increase the risk of kidney damage.

Alternative Names:

Phosphocreatine