Creatine, or methylguanidino acetic acid, is a naturally occurring compound found in abundance in skeletal muscle. Available in some meats (4.5 g/kg in beef, 5 g/kg in pork) and fish (10 g/kg in herring, 4.5 g/kg in salmon), creatine is essential for energy transmission and storage.

Less than 100 percent of dietary creatine is absorbed by the small intestine, and intensive exercise quickly uses up the body’s stores. Creatine supplements have been available for some time. They’re widely used among athletes for studied ergogenic effects. In addition, recent research suggests that creatine may be useful for muscle-depleting illnesses like amyotrophic lateral sclerosis (ALS) and Huntington’s disease.

What Creatine Does

Creatine concentrates mostly in the large (skeletal) muscles, where it is involved in producing energy and moderating muscle fatigue. An adult of average weight (about 155 pounds) stores approximately 120,000 mg of creatine and uses approximately 2,000 mg every day.

Muscle stores of creatine appear to decrease dramatically during the first few seconds of exercise, especially activities that require a maximal effort or energy burst like sprinting, kickboxing, or heavy weightlifting. As muscles use creatine for energy, this substance is then changed into a metabolic waste product known as creatinine, which is filtered into the urine by the kidneys.

Formation in the Body

The amino acids glycine, arginine, and methionine are the body’s building blocks of creatine, which is transported to the heart, brain, and muscles. Ninety-five percent of bodily stores remain in skeletal muscle, while excess creatine is lost in the urine.

Why Supplement?

Because creatine increases recovery and slows the likelihood of fatigue, supplements allow you to work out longer, increasing both endurance and strength. Longer workouts can result in greater lean muscle mass.

While there’s still some controversy regarding how much creatine to use and when to take it, science supports a logical approach to timing. Workouts deplete creatine stores, so they can be replenished post-workout via supplementation. Forms other than monohydrate are available but have not been extensively studied.

How Much Creatine?

The recommended serving size of a creatine monohydrate product should be around 3 to 5 g (3,000 to 5,000 mg). One dose at that level per day should be more than adequate to meet your needs.

Creatine is best used in combination with a nutritionally balanced diet. Do not take this supplement with fruit juice, though, as this combination produces creatinine, which is difficult for the kidneys to process.

As always, do your homework and read the published literature before using any supplement. Also consult your healthcare practitioner or sports medicine physician to determine if creatine monohydrate is right for you.

A Bad Rap?

Inaccurate media reports have portrayed creatine as an anabolic steroid, steroid precursor, or gateway to steroid use. But creatine monohydrate is one of the best scientifically studied dietary supplements. There are hundreds of research studies to its credit, including nearly 70 clinical trials over the past 10 years, most showing a positive ergonomic benefit.

This supplement, however, is not recommended with certain drugs: cimetidine (Tagamet), nonsteroidal anti-inflammatories like ibuprofen, and/or diuretics.

Another Type of Creatine

The heart enzyme, creatine kinase, is a marker for a myocardial infarction or heart attack. When a patient comes to the emergency room with chest pain, levels of this enzyme are measured.