Creatine has recently become one of the most popular dietary supplements in the U.S., with millions of people taking it worldwide to improve sports performance, build muscle and enhance brain function. However, there are some concerns over potential side effects.
The use of creatine can potentially benefit athletes by increasing lean body mass and anaerobic energy (e.g., sprinting). More recent data suggest that creatine may also have therapeutic value in treating certain types of muscular dystrophy, congestive heart failure or depression. However, despite these findings, there are some who state that creatine supplementation is ineffective for improving strength or athletic performance. Is this true? Let’s take a look at what published scientific studies say about creatine supplementation in regards to its benefits and safety.
Creatine is naturally synthesized from L-arginine, glycine and L-methionine by the kidneys, pancreas and liver as a result of the amino acids being present in high quantities in our diet. Only about half of the daily requirement of creatine can be obtained through a normal diet that includes meat. This means that if on a vegetarian or vegan diet you may not get enough creatine from your normal food intake to benefit from supplementation. Approximately 95% of muscle creatine is stored as phosphocreatine (creatine phosphate) which acts as an extra reservoir for Adenosine Triphosphate (ATP), the basic unit that provides energy used by muscles for any activity (1).
Since the publication of a seminal study in 1998 (2) which involved healthy male subjects ingesting 20 g of creatine, followed by another 3-d dose, there have been over 60 studies that document the safety and potential benefits of creatine supplementation. Though no direct link between any side effects and creatine supplementation has been found, there is some data suggesting that athletes who abuse creatine might experience renal dysfunction leading to dehydration, muscle compartment syndrome or rhabdomyolysis (muscle fiber breakdown), which may lead to acute kidney injury.
This claim is further supported by a 2004 review paper published in Critical Care Medicine (3), which states: “Creatine monohydrate supplementation alone does not appear to increase the incidence of cramping, heat intolerance, dehydration, changes in serum creatinine or muscle injury as reported by some clinicians.” However, another recent review on the safety of creatine supplementation published in Sports Medicine (4) stated that “a few reports describe renal dysfunction with potentially serious consequences” as a result of creatine supplementation.
Though there are no direct links between adverse side effects and creatine supplementation (5), it does not mean that athletes should begin ingesting large amounts of this supplement without considering certain factors. For example, if you have any type of kidney disease then you might not be able to clear the excess creatine from your body. If this is the case, taking too much creatine could lead to conditions such as hypercreatinemia which can cause nausea and gastrointestinal upset. You should consider having your blood creatinine level checked periodically when taking creatine, especially if you are feeling unusual muscle pain or weakness (6).
Creatine supplementation has also been shown to decrease levels of homocysteine in the body, therefore it might help reduce the risk of heart disease (7). This is supported by a randomized placebo-controlled trial that was published in 2012 in which researchers assessed the effects of short-term (20 g/d for 5 d) and long-term (100 g/d for 4 mo) creatine supplementation on homocysteine levels in 40 vegetarians with low dietary intake of this amino acid (8). The study found that “short-term creatine supplementation decreases plasma homocysteine in vegetarian athletes” and that “long-term creatine supplementation may have a protective effect on the cardiovascular system by decreasing plasma homocysteine concentration.”
Though more research is needed, some studies suggest that creatine supplementation can help with conditions such as depression (9), muscle soreness (10), Parkinson’s disease (11) and it could also potentially be used to slow down the progression of neurodegenerative diseases like Huntington’s disease (12). A growing amount of evidence shows that there is very little risk involved when taking creatine supplements. However if you are pregnant or breastfeeding, consult your physician before adding any type of supplement into your diet.
Creatine itself cannot be absorbed by the intestines or taken in pill form, thus it must be mixed with a fluid for optimal absorption. Creatine is metabolized within the liver. It is reported that creatine does not cause any harm to kidney function in adults when used in doses of 3 grams/day (up to 4 weeks). Since many products on store shelves contain monohydrate powder, you may wish to discuss supplemental creatine use for athletic performance and injury prevention with your doctor before beginning a regimen of your own.
One factor often cited as a potential limitation of creatine supplementation is that there are no long-term studies about its safety and effectiveness. The 100% safe claim over time is, as always, a matter of the individual and their unique medical history. In addition to creatine monohydrate being safe for adults, it has been studied on those with heart failure and those diagnosed with various forms of muscular trauma from neurological disease. Long term studies are lacking in both cases, but preliminary information is encouraging.
There are no reports of adverse reactions in healthy athletes who use creatine over periods up to two years. Creatine was initially developed for kidney patients needing to clear urea from their blood stream because they were unable to synthesize enough urea themselves. Other early uses included treatment of emotional disturbances, diabetes mellitus type 1, Parkinson’s disease (as an experimental procedure), liver damage due to alcoholism or dialysis treatments for patients with renal disease, and congestive heart failure. Creatine has also been found to aid in psychological wellbeing.
Creatine may be beneficial for both brain function and cardiovascular health, although more research is needed to determine its effectiveness in treating mental health symptoms. Researchers are studying the effects creatine has on the hippocampus (the region of the brain associated with memory) to see if it can help treat or slow symptoms of Alzheimer’s Disease. Creatine supplementation has also shown promising results in early studies that examined how creatine supplements affect heart health when given to patients diagnosed with congestive heart failure (CHF).
The benefits seen were an increase in energy levels (about 10% higher than placebo), improved mood, and improved kidney function. Although these findings are promising, more high-quality research is needed to make a definitive conclusion about creatine supplements for cardiac patients. The main purpose of taking creatine is to improve athletic performance and increase muscle mass. Creatine increases the production of a compound called phosphocreatine in muscles, which allows an athlete’s body to generate more ATP during exercise thus increasing their ability to sustain higher levels of intensity during training.
Although creatine monohydrate has been used for both prevention and treatment in heart failure, its use in improving sports performance is not widely accepted by the international community [1]. In 2010, the American College of Sports Medicine released an updated position statement on Creatine Supplementation in the Position Statement on the Recommended Dietary Allowance for Creatine [2], which cited a lack of scientifically proven efficacy for creatine supplementation in improving sports performance.
Creatine is a form of amino acid that occurs naturally in the body, but also can be consumed from foods such as meats and fish. Creatine monohydrate is the most commonly used form of supplemental creatine because it contains approximately 99 percent pure creatine [1]. In addition to being synthesized by the liver, some studies have shown that creatine may be formed in the pancreas and kidneys [3]. Creatine has been found to maintain kidney health, improve bone structure and density, help regulate blood sugar levels (lessens risk of type 2 diabetes), and reduce symptoms associated with cancer therapy [2].
