Only a century ago, people bought snake oil and other fraudulent remedies because of a lack of sufficient information about their effects. Today, we have the opposite problem – an internet full of science, pseudo-science, and self-proclaimed experts, all providing conflicting information about the health benefits of some supplement that, depending on who you believe, either makes people run faster and jump higher, or causes cancer in lab-rats (or possibly both).
Creatine continues to be one of the most frequently discussed and frequently misunderstood dietary supplements known to the internet. I am not an expert in dietary science, and so I have no business trying to contribute to the scientific debate about creatine. I am going to stick to what I’m good at: research. This post is an attempt to provide a layman’s summary of what we do and do not know about creatine as a dietary supplement. The end of this post will include a list of some of the main sources that I consulted, so you don’t need to take my word for anything written here.
What is creatine and how does it work in your body?
Independent of the supplements that you take, your body is constantly using dietary amino acids to produce creatine in the liver and kidneys. The creatine that your body produces circulates through your blood stream and plays an important role supplying energy to cells in your body, especially the cells that compose skeletal muscle and the brain. Without getting mired in the biochemistry, creatine (as creatine phosphate) is involved in, and used up during, the chemical reactions that power muscle contractions (during short, i.e. phosphagenic, efforts). The more creatine phosphate available, the more contractions are possible before the creatine is used up. NOTE: This is the primary and most well-understood mechanism through which creatine is associated with athletic activity and might improve athletic performance. There are other mechanisms that have more to do with muscle repair after exercise than with muscle contractions and power output during exercise, but these mechanisms are still under-supported by existing research.
How does creatine work as a supplement?
Creatine is just another dietary supplement. For example, if you want to have more vitamin C in your body to help your immune system, you can eat more oranges, or you can take a vitamin C supplement. At the molecular level, your body really doesn’t seem to know the difference between a chemical compound in food, versus the same chemical compound, isolated, in a pill. If you want to have more creatine in your body to help with short bouts of high-intensity exercise, you can eat more meat, or you can take a creatine supplement. All that creatine supplements do is provide additional sources of synthetic creatine (usually as creatine monohydrate) that your body can digest, break down, and use in the muscle-contractile processes described above. Just as your body breaks down protein supplements to use the amino acids to build and repair muscle tissue, your body breaks down creatine monohydrate to form creatine phosphate that can be stored in muscle tissue to power muscle contractions. The benefit of creatine supplements over creatine-rich foods is that you can consume a much higher amount of creatine and achieve much higher levels of creatine in your blood and muscle tissue using a supplement, than eating meat. The internet suggests that, roughly, 2 pounds of meat = 1 teaspoon of creatine monohydrate powder (See this site for a summary of the creatine content of foods).
What are the benefits of creatine supplementation?
There are a wide range of possible benefits of creatine supplementation, many of which go well beyond questions of improving athletic performance and recovery. The Mayo Clinic website has an excellent presentation of major hypothesized benefits of creatine, ranked according to the quality and quantity of the research supporting those hypotheses.
The most carefully tested and repeatedly affirmed claims about creatine all relate to exercise, and specifically to measurable increases in anaerobic work-capacity. All together, this research suggests that short and long-term creatine supplementation will improve performance in phosphagenic efforts, including sprinting and repetitive heavy lifting. For example, in one of the more recent and sophisticated studies on the topic, short-term (7 days) creatine supplementation measurably and significantly improved mean anaerobic power output (measured as the average amount of power produced during the course of 30 seconds of maximum effort on an exercise bike), but did not improve maximal power output (i.e. a one-rep max). There are now several studies all showing that creatine improves anerobic work-capacity by enabling athletes to either do more work in a fixed period of time, or to sustain a given intensity of work for a longer period of time. In terms of resistance training, this translates into the ability to do more reps per set without reaching failure, or the potential to do a set number of reps at a slightly higher percentage of 1 rep max (1RM) without failing.
It is currently unclear whether or not creatine improves maximal strength as in a 1RM effort. There are a few studies offering support for the idea that creatine improves 1RM, but just as many studies suggesting the contrary.
Creatine may also improve short and longer-term recovery, but it is still unclear exactly how would happen inside the body (i.e. what the mechanisms are). The more reliable studies that I have found all suggest that short-term creatine supplementation does not help with recovery in terms of reducing muscle damage, swelling, and soreness. It is possible that creatine does lead to faster recovery via faster muscle-repair. Since creatine supplementation is often associated with significant gains in lean muscle-mass (as compared with placebo groups), there is some support for the idea that creatine helps with processes of muscle (re)building.
Are there harmful side-effects of creatine supplementation?
The short answer is that there are no consistent and confirmed negative side-effects. This doesn’t mean that there aren’t minor or person-specific side-effects.
There are lots of alleged negative side-effects of creatine supplementation, and most of them have either been strongly disproven, or continue to be disconfirmed by scientific studies. The most serious potential side-effect involves the possibility of liver and kidney damage. Several studies have specifically attempted to assess the affects of short- and long-term creatine supplementation on liver and kidney function, and most human studies do not find any consistent negative effects. One study on rats found some signs of renal distress in rats ingesting large concentrations of creatine.
The two confirmed problems with creatine are: 1) some supplement-makers do not adequately purify their product, resulting in toxins being taken in along with the creatine, and 2) some individuals may manifest allergic or asthmatic symptoms in response to creatine supplementation.
Will creatine make me “bulky” or make me retain additional water-weight?
If you’re worried about “looking bulky,” you’re probably not serious enough about physical training to appreciate the benefits of creatine supplementation. Don’t feel bad. Just go away, clean up your diet, and make new goals that are performance-based.
Increased water-retention is a legitimate concern if you are an athlete who competes in a sport that has weight-classes. Creatine supplementation is often (though not always) associated with gains in lean muscle mass in scientific studies. There is no consistent evidence to suggest that creatine, on its own, leads to additional water-retention or to significant gains in bodyweight independent of medium- to long-term increases in lean muscle mass. Even in well-designed, randomized control studies with subjects consuming very high doses of creatine for 5-7 days, there is typically little to no real change in the bodyweight of the subjects using creatine.
Is creatine appropriate for women?
There is no evidence to suggest that the female body handles creatine differently from the male body.
How do I take creatine?
Most studies that find measurable positive effects of short-term creatine supplementation involve a heavy dose of 20g per day for 5-7 days. Longer-term studies typically start with a 3-7 day loading dose at 20g per day, followed by a maintenance-dose of 5g per day for the duration of the study. The exact amount needed will vary with the individual, their diet, and with the demands of their training program. The 20g loading-dose and 5g maintenance-dose should probably be considered the upper-limit for creatine supplementation. In general, the body has an upper limit to the amount of any given nutrient that it can possibly utilize. Once you supplement beyond this upper limit, the surplus nutrients (for the most part) come out in your poop.
The most common form of creatine is creatine monohydrate. There are other forms of creatine that purport to be absorbed faster into the body or cause less water-retention. None of those claims have been substantiated through scientific testing. As a general rule, don’t believe anything that you read on a supplement label. Take the purest form of creatine monohydrate that you can afford in either capsule or micronized-powder form.
It is not clear whether or not it is prefereable to “cycle” creatine (i.e. taking breaks from creatine supplementation and then returning to it) or to continuously supplement with creatine.
Consuming a significant amount of carbohydrate (roughly 90g in study populations) may increase the amount of creatine that the body can absorb.
Creatine supplementation is beneficial. Long- and short-term creatine supplementation has benefits in terms of increased anaerobic work-capacity. Strength or sprint athletes engaging in high-volume training, especially hypertrophy-specific training, will probably benefit the most from creatine supplementation. Creatine supplementation may be less appropriate for a strength athlete whose training is emphasizing maximal single efforts.
There are no consistent, confirmed negative side-effects of short or long-term creatine supplementation.
Dosing is important. The most measurable positive effects of creatine have been achieved on populations taking 20g/day doses for 3-7 days, and then tapering to a 5g/day dose (if long-term supplementation is desired). Carbohydrates may help with absorption.
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Rosene J, Matthews T, Ryan C, Belmore K, Bergsten A, Blaisdell J, Gaylord J, Love R, Marrone M, Ward K, Wilson E. “Short and longer-term effects of creatine supplementation on exercise induced muscle damage.” J Sports Sci Med. 2009 Mar 1;8(1):89-96.
Souza WM, Heck TG, Wronski EC, Ulbrich AZ, Boff E. “Effects of creatine supplementation on biomarkers of hepatic and renal function in young trained rats.” Toxicol Mech Methods. 2013 Oct 4. [Epub ahead of print]
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