Creatine is a peptide created naturally in the body derived from three amino acids (methionine, glycine and arginine). It also exists as supplement and in meat as an external body source. Most of it is stored in the skeletal muscle and a small amount is in the brain, testes, and kidneys. Creatine is converted to phosphocreatine, which is the form in which a great part of creatine is stored in muscles. Have you heard about adenosine triphosphate or ATP? ATP is the “energy molecule” that transfers energy to the cell when it is needed. Well, phosphocreatine is a source of phosphate to create ATP in the muscle. Creatine supplements then increases the rate of phosphocreatine resynthesis during high-intensity exercise, enhancing muscle recovery and performance.
Creatine and phosphocreatine degrade to creatinine, which is exported to the blood and filtered by the kidney. Blood creatinine levels are used as a marker of kidney function. When it is above the normal levels, we considered it as a possible impaired renal function. On the other hand, we must consider that creatinine in blood is related to muscle mass, creatine intake by supplement or diet (meat).
Creatine is highly used in the USA by adolescent athletes and several review studies have showed no adverse effects. Specially, there is limited published evidence about creatine adversely affecting the kidney function. There are a few studies, that reported kidney damage in patients taking creatine supplements, but in these cases, there were some other factors related to these side effects, such as preexisting renal disease, ingestion of other supplements, inappropriate dosage of creatine ingested and the use of anabolic androgenic steroid use.
There have been other creatine side effects reported such as water retention with weight gain, muscle cramping, nausea, gastrointestinal upset, headaches with poor evidence.
There are also many questions regarding creatine use and its relation to hair loss, baldness, increase of body fat. For these and other questions related to creatine you can read the reports/articles listed in the references at the end of this article.
Creatine monohydrate supplement is the recommended form to be consumed, but many other formulations exist. These formulations include ethyl ester, nitrate, and phosphate, are usually more expensive, may contain impurities and may have no added the mentioned benefits.
Recommended dosage is 3-5 g/day over 28 days. Research states that loading doses of 20-25 g in four divided doses for 5 days is not necessary.
References:
R.Mawer. Everything You Need to Know About Creatine. Nutrition. May 18,2022.
J.Antonio, D.G Candow, T.N Ziegenfuss. Common questions and misconceptions about creatine supplementation: What does the scientific evidence really show? Journal of the International Society of Sports Nutrition 2021, 18,13.
