Creatine is a very popular dietary supplement among athletes, for its effects on physical performance. Nearly 500 publications have been published on creatine, but misconceptions about its efficacy, safety and impact on renal health persist.
Is it responsible for kidney failure? Is the kidney overtaxed by its consumption? So, is creatine really dangerous for the kidneys? Not at all! Let's take a look at how creatine, which is naturally present in the body, affects kidney function, and what the creatinine level in the blood is used for.
Whether you're concerned about your health, or curious and attentive to your metabolism, you'll find your answers here. A word of warning: this article is not a substitute for advice from your doctor, especially for people with a history of kidney disease or metabolic disorders linked to theelimination of waste from the body.
Contents
Creatine and its metabolism
What is creatine?
Creatine is naturally present in the body, and in the form of creatine monohydrate, it makes a very interesting dietary supplement for athletes.
Basically, creatine is an endogenous substance derived from amino acids (arginine, glycine, methionine). It is manufactured by the kidney, liver and pancreas, but also comes from thediet, through animal proteins such as meat and fish.
In the body, creatine is found in the muscles, where it has an effect on physical capacity. In fact, the European Commission recognizes its benefits "in the case of successive series ofvery intense exercises of short duration "¹, but creatine's effects are even more numerous.
During intense exercise, creatine is converted into phosphocreatine (CrP) by the enzyme creatine kinase. This creatine phosphate instantly ensures the regeneration of adenosine triphosphate (ATP), our energy supplier.
However, its reserves are limited, so that after 4 to 10 seconds of intense, maximal effort, phosphocreatine is depleted. Supplementation therefore induces an increase in muscle reserves, hence the effect on short, intense efforts².
The role of the kidneys in creatine metabolism
Inside the muscle, part of the phosphocreatine becomes creatinine, while the other part reverts to creatine, which is then synthesized back into phosphocreatine.
On average, between 1.7% and 2.5% of total creatine is converted to creatinine in the muscle itself, and subsequently excreted in the urine, after passing into the plasma². Significant inter-individual differences exist, as the level of creatinine in the blood is proportional to the individual's muscle mass and dietary creatine intake.
Men and women will therefore have different rates, as will people on vegetarian or vegan diets.
Physical activity moderately increases creatinine concentration in urine, in healthy subjects.
To understand the close link between creatine and kidneys, you need to know that, in the absence of pathology, healthy kidneys filter creatinine³. If this were not the case, creatinine levels in the blood would rise. Moreover, creatinine levels are an indirect marker of renal function.
The risks of creatine on renal health
Myths and facts about creatine and kidneys
Creatine has been authorized for use in France since 2007, and it's perhaps its previous ban that further tarnishes its image.
The cry of alarm about creatine's alleged harmfulness to the kidneys originated with an article dating back to 1998. Pritchard and Kalra's study claimed that creatine had exacerbated pre-existing renal insufficiency in one patient, and led to the deaths of athletes taking creatine supplements.
In the first case, the patient already had a dysfunctional kidney disorder, and the protocol neglected certain important aspects. As for the deaths, an investigation proved that they were linked to severe dehydration.
During 20 years of research, numerous other in-depth studies were carried out, none of which provedcreatine's deleterious effect on renal function.
Creatine and kidney health in athletes
Among the studies carried out, some focused on :
- in the short term, on the order of a few days ;
- medium-term, over two months ;
- over five years.
Whether it's creatinine clearance, urea or albumin in urine, no harmful impact on kidney function has been proven².
However, during a course of treatment, it is possible to find high levels of creatine in the urine, even though only creatinine is supposed to be present.
This has given rise to a misconception.
That a cure would overload the kidneys, forcing them to excrete higher levels than normal. However, no temporary increase in creatine has shown any disturbance of the kidneys.
Around 60% of creatine intake is eliminated in the urine each day. Exogenous creatine supplementation therefore often remains high in relation to the levels taken up by the muscles.
Even if supplementation is not harmful to the kidneys, the scientific community agrees that before any treatment, the athlete should be assessed. The idea is to rule out even the slightest risk of kidney disease.
This check-up should be repeated by the doctor every three months during the course of treatment, to stop supplementation at the slightest detected anomaly.
Caution should always be exercised when ingesting any dietary supplement or medication. But no more so with creatine than with any other supplement.
In reality, the danger lies mainly in the intrinsic quality of creatine. Be careful, therefore, to consume only creatine whose production and control are certain.
Creatine Creapure®
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Our tips for successful creatine supplementation
Adjust dosage to recommendations
There's no point in taking more creatine than necessary, as the effects will not be increased tenfold, and this is where health risks can arise.
The recommendations are to mix 3 g of creatine with carbohydrates. It can also be added to a whey shaker containing carbohydrates or gainer for optimal absorption. This mix is particularly interesting after training, to take advantage of a possible anabolic window.
You can divide the 3g into 2 or 3 portions throughout the day if taking it causes intestinal problems. A loading dose (20g/day for 5 days, divided into 3 to 4 portions) is not compulsory, but will enable you to reach your desired muscle levels quickly and healthily.
As for the duration of the cure, we recommend 1 to 1.5 months, with breaks of equivalent length in between.
Taking creatine without risk
When supplemented, urinary creatine levels can increase by up to 90 times, making it easy to detect and monitor.
This "over-solicitation" of renal excretion has been little studied. So beware of jumping to hasty conclusions, which is why sportsmen and women are advised to undergo multi-year monitoring².
What's more, we recommend taking creatine from a source that is guaranteed to be risk-free. Those with the Creapure® label are currently recognized as the best creatines available.
Conclusion
If used sensibly in doses of 3 grams a day (or 20 g over a short 5-day period), creatine poses no toxic risk to kidney health in healthy individuals.
The severe renal symptoms mentioned in an old 1998 study appeared only in a very special case, in the presence of an already existing pathology. This study, and a partial understanding of the mechanism of renal function, led to the banning of creatine in France until 2007, and then to misconceptions since its authorization.
For athletes, creatine remains a safe supplement, especially if combined with good hydration, which plays a role in the elimination of metabolic waste.
Although the European Food Safety Authority (EFSA) considers creatine to be safe, regular monitoring and analysis are recommended, particularly for top athletes or those with high creatinine levels. The precautionary principle applies: if in doubt, consult a doctor to avoid any progression to a problematic stage. With a few good practices, creatine continues to support sporting performance in a safe way.
Find out more
Creatine remains one of the most studied and often misunderstood supplements. The question of creatine-related water retention frequently comes up, despite the fact that this is a natural intracellular phenomenon, often beneficial for performance.
Others worry about possible muscle loss after stopping, but the effects of stopping creatine are generally moderate and reversible.
More recently, research has highlighted creatine's potential role in the brain, notably in memory and concentration.
Finally, to maximize its effectiveness without risk, it is useful to understand when to take creatine monohydrate, depending on your type of training.
And for those seeking to optimize their physical transformation, Protéalpes offers specific dossiers on creatine for dry weight training and creatine for rapid mass gain.
