Creatine or Glutamine as a Dietary Supplement

¶ … Dietary Supplement for Athletes or Bodybuilding

Creatine is a dietary supplement that has been popular for more than thirty years amongst athletes and bodybuilders (Feldman 1999: 45). Its alleged benefits include enhancing muscle-building and recovery. The use of dietary supplements, particularly amongst adolescents and young adult athletes has increased in popularity and may even be endorsed by coaches and parents. Creatine is not recommended for young athletes because of questions about the long-term safety of its use, but pressures to 'be the best' have increased as the margin between first-class and second-class athletes grows ever more razor-thin (Dunn et al. 2001).One study found that "62% of adolescent athletes believed supplements improve performance, with 50% consuming dietary supplements" (Dunn et al. 2001). In another study of attitudes of young athletes Dunn (et al. 2001) found widespread acceptance of the use of creatine and belief in its benefits, even amongst athletes who did not use other ergogenic aids.

Use of creatine is even more common in the elite ranks of athletes. Amongst NCAA athletes, according to LaBotz & Smith (1999) "forty-eight percent of men reported having used creatine as compared with 4% of women. With two exceptions, all men's teams had at least 30% of athletes who reported a history of creatine use" (LaBotz & Smith 1999). Creatine is also popular amongst recreational body builders, who often ingest it in over-the-counter supplements.

The greater popularity of creatine use amongst males is likely because creatine is mainly effective in anaerobic sports which require muscle-building (such as football and rugby), versus endurance activities. In fact, "creatine biosynthesis rates are highest under anabolic conditions in young vertebrates with a good food supply and optimal levels of blood insulin, somatotropin, thyroxin, and testosterone" (Feldman 1999: 46). But research indicates that creatine has no benefit for endurance sports like long-distance running. For sports which aesthetics are an issue, such as gymnastics and figure-skating, female athletes may be deterred by the weight gain which is one of the side effects of creatine (Feldman 199:46).

Creatine is produced naturally in the body. It is "an amino acid that in its phosphorylated form transfers phosphate to adenosine diphosphate (ADP) to maintain high levels of adenosine triphosphate (ATP) in muscle and thus provides energy for muscle activity" (Feldman 1999: 45). Creatine is transported to muscle and nerve and crosses the cell membrane via a specific creatine transporter…. half-pound of meat contains approximately 1 g creatine. It has been shown that during consumption of a creatine-free diet, the body can synthesize the necessary amount. Creatinine does not remain in muscle, but is distributed throughout body water and is rapidly excreted in the urine. There is no renal threshold for urinary excretion of creatinine" (Feldman 1999: 46). Creatine can be obtained through eating meat and fish but "dietary supplementation of creatine provides an inexpensive and efficient means of increasing dietary availability of creatine without excessive fat and/or protein intake" (Butford et al. 2007).

The International Society of Sports Nutrition takes the stand that "Creatine monohydrate is the most effective ergogenic nutritional supplement currently available to athletes in terms of increasing high-intensity exercise capacity and lean body mass during training" and states that the supplement is not only safe, but is recommended to prevent injury and manage medical conditions to enable exercise (Butford et al. 2007).

Research study reviews

The findings of research studies on the benefits of creatine are mixed. One very small study by Tarnopolsky & MacLennan (2000) found that benefits exist for both males and females. 12 males and 12 females were given creatine monohydrate "using a randomized, double-blind crossover design (7-week washout)…significant main effects of Cr treatment included: increased peak and relative peak anaerobic cycling power (3.7%; p

Once again, it should be noted that these gains were anaerobic in nature. A report by Butford (et al. 2007) published by the International Society of Sports Nutrition found that "weight gain associated with CM supplementation could be detrimental in sports such as running or swimming" although for other sports "the average gain in performance from these studies typically ranges between 10 to 15% depending on the variable of interest" (Butford et al. 2007). On average, the International Society of Sports Nutrition reported that body composition athletes supplementing with creatine gain twice as much lean muscle mass than those taking a placebo (Butford et al. 2007).

But not all studies have confirmed this notion. In another small study by Beck (2007) fifty-one men were assigned a creatine drink while others were given a placebo. Neither group showed marked improvement on two 30-second Wingate Anaerobic Tests for determination of peak power (PP) and mean power (MP), percent body fat (%fat) and fat-free mass (FFM), and on tests of external resistance strength and muscular endurance over a ten-week period. However, none of these men were trained athletes, which may indicate that some natural ability to build body mass must be present for the supplement to be effective.

"The recommended initial dose for athletes for 1 week ranges from 15 to 30 g/day taken orally in a variety of forms and in divided doses with food or glucose-containing beverages. After this period of 'loading' 2-5 gl day is required for maintenance" (LaBotz & Smith 1999). The degree of benefit will vary with the individual and the "amount of increase in muscle storage depends on the levels of creatine in the muscle prior to supplementation" (Butford et al. 2007). People with low natural stores (such as vegetarians or near-vegetarians) "are more likely to experience muscle storage increases of 20 -- 40%, whereas those with relatively high muscle stores may only increase stores by 10 -- 20%" (Butford et al. 2007). Combining creatine with protein has shown to improve efficacy in some studies, one of which found that "adding 93 g of carbohydrate to 5 g of CM increased total muscle creatine by 60%" (Butford et al. 2007).

However, once again, other studies of small, specific population conflict with this assertion. In a study of ten international caliber competitive swimmers before and after a loading regimen of either creatine alone (Cr) or combined creatine and carbohydrate (Cr + CHO), "all subjects swam faster after either dietary loading regimen (p < 0.01, both regimens); however, there was no difference in the extent of improvement of performance between groups" (Theodorou 2005).