Does Creatine Affect the Liver?

Creatine is predominantly marketed as a supplement to improve athletic performance and increase muscle mass. Clinical research studies are inconclusive about the efficacy and safety of creatine supplements; however, there are some indications that high-dosage or long-term use may result in damage to the liver or other serious side effects. Consult a qualified health care provider before taking creatine.

Creatine supplements are available as powders, liquids, capsules, energy bars and drink mixes.The safety of creatine has not been evaluated for children and teens and should not be taken by individuals under 19. An initial daily dose of 20 to 25 g is taken by athletes for about a week and then the dose is reduced to 2 to 5 g. Creatine supplements are also taken at a dose of 5 to 10 g daily to reduce cholesterol.

Creatine is an amino acid that is produced by the liver, kidneys and pancreas. Creatine is also obtained from dietary animal proteins, such as wild game, red meat and fish. After creatine is synthesized by a reaction in the liver it is transported to the muscles for storage, while the waste products of the reaction are excreted by the kidneys. During short-term, high-intensity exercise, creatine is converted into ATP, which is the energy source of the body.

Creatine supplements have not been shown to adversely affect the liver during short-term, low-dose usage. Additionally, a study in the "International Journal of Sport Nutrition and Exercise Metabolism" found that creatine supplements did not affect the livers of elite athletes even after long-term usage. However, creatine should not be used for more than six months as there is evidence that liver dysfunction or damage may occur. A study in the "American Journal of Physiology" found significant inflammatory lesions in the livers of mice that were given long-term creatine doses. Furthermore, taking supplements on a long-term basis may inhibit the liver's ability to synthesize creatine. More clinical research is necessary to conclusively establish the dosage limits and effects of creatine use.

Patients with liver disease are advised to avoid creatine supplements. Liver disease reduces natural creatine levels and taking creatine supplements may further inhibit the liver's ability to produce and process creatine. Kidney damage and other serious side effects may also occur if creatine supplements are not processed correctly due to impaired liver function.

Creatine should not be taken with anti-inflammatory drugs that are processed by the same liver enzymes, such as Motrin, Advil and Aleve. A singular study in the journal "Seminars in Liver Disease" described a case of profound jaundice and liver injury, which was linked to an athlete's long-term use of creatine combined with whey protein. A qualified health care provider should always be consulted before taking creatine or combining it with other supplements or medications.