Q. What is Creatine? A. Creatine is a nutrient normally found in the body, particularly in muscles. It is made from the combination of three amino acids. Creatine helps provide the energy to help our muscles move. It has been available as a supplement since the early 1990s. It usually comes as a white powder.

Creatine is also found in meat and fish, usually at a concentration of about 4 grams of creatine per kilogram. Most people ingest about one gram a day from foods. Vegetarians have a much lower intake of creatine that meat eaters. The human body is able to make about one gram of creatine a day.

Q. What benefits do supplements of creatine provide? A. The majority of those who take creatine find that their muscle size increases and many notice in improvement in strength. The increase in size may be due to a combination of water retention and increased protein synthesis. Creatine also increases oxygen uptake by muscle tissue and improves performance. Whatever the reason for the muscle bulking, the toned look often improves one's body image. Creatine has also been tested with positive results in those whose muscles have atrophied due to neuromuscular diseases.

Q. How soon will I notice results? A. Increased muscle mass often comes within a few days. After three or four days, many people report feeling more "pumped." Shirts may feel fitting tighter. When you look in the mirror you may be surprised at how quicker your muscles have become bigger. Results come much quicker if you start a weight lifting program in addition to taking creatine.

Q. What kind of drink can I use to mix the creatine with? A. Creatine powder is best mixed in fruit or vegetable juices although mixing it in milk is another option.

Q. What's the right dosage? A. Scientists are still trying to find the ideal dosage of creatine that works best. For non-athletes, particularly those who are interested in just toning their muscles and adding just a little more bulk, about 3 to 5 grams of creatine a day for a month is sufficient to provide results. This amount of creatine, often about a

Q. Can creatine be taken indefinitely? A. Until we learn more about the long-term effects of creatine on the body, I recommend you take a break after a month's use and then cycle your creatine use. For instance, you can take about 3 grams of creatine every other day or twice a week, just enough to maintain the gain in muscle size you had after the first month of use.

Q. What time of day is best to take the creatine? A. Anytime of the day is fine, but taking it around the time of a workout is a good option. Some get results even taking it at night before going to bed.

Q. Is there a decrease in muscle size after stopping creatine use? A. There is a gradual decline of muscle mass over days and weeks after stopping creatine, but gains return quickly when creatine is reinstated.

Q. Are there any specific concerns related to creatine supplementation for women? A. Generally the dose for women should be lower due to their smaller size. For women who just want to tone their body, 2 or 3 grams a day for a month should be sufficient.

Q. Does creatine help everyone increase their muscle size? A. Studies show that creatine supplementation results in increases in creatine present in muscles for some individuals but not others, suggesting that there are 'responders' and 'nonresponders'. The reason some people don't respond is not known at this time. Often, the increase in muscle creatine concentration among responders is greatest in individuals who have the lowest initial creatine levels, such as vegetarians.

Q. Does creatine improve performance in athletic events? A. Studies investigating the effects of creatine supplementation on short term, high intensity exercises have reported equivocal results, but, as a rule, a greater number of studies have reported benefits versus no effects. At this point, it is difficult to know for certain how much of role creatine supplementation plays in athletic performance. Creatine supplementation does not appear to aid endurance type exercises, such as long distance running or cycling.

Q. I have a teenage son who plays football. What is the earliest age you recommend that a person can begin taking creatine for athletic purposes? A. I am generally uncomfortable with teenagers relying on supplements for athletic gains. However, knowing that creatine is widely available, and opposing sports teams may be using it, I realize that a "just say no" policy is not going to be accepted by teenagers. I therefore take a moderate stand by condoning its use in teenagers for a specific period of time, such as one, two or three months during one sports season of the year, such as football. I prefer a person to be at least 16 years old before using creatine. Ingestion of 2 to 4 grams a day for a month followed by every other day use seems to be well-tolerated. This policy would probably be acceptable to all parties involved, including the teenagers, coaches, and parents. I also feel that the use of creatine may divert certain teenagers from relying on anabolic steroids.

Q. Are there side effects from creatine use? A. The most common side effect is loose stools, which can occur with as low a dose as 4 grams. High doses can lead to nausea, stomach upset, weakness, and dizziness. Many people are encouraged by the increase in muscle size that comes from creatine use and enthusiastically increase the weight and frequency of their workouts. If you overtrain, you can get muscle cramping or strained ligaments and tendons. The strained tendons occur because they have not had time to adjust to the increased intensity of the workouts. High doses, such as 20 grams, when use regularly for a few weeks can potentially cause kidney damage and place stress on the liver.

Summary Creatine is an effective nutrient to increasing muscle mass if used appropriately.

Ray Sahelian, M.D., is the author of Mind Boosters: A Guide to Natural Supplements That Enhance Your Mind, Memory, and Mood (St. Martins Press, 2000, $13.95). See his web site www.raysahelian.com for updates and FAQs.