On The Shelf

Mickie Cathers

Creatine is a very popular sports supplement among athletes and individuals seeking to enhance muscle growth, performance, and strength. The supplement is also advertised as an aid in endurance and recovery. While research does show real benefits, creatine doesn’t quite live up to the hype.

Creatine is a naturally occurring amino acid found in our muscles, brain, liver, pancreas, and kidneys. Creatine is also found in protein-rich foods such as pork, beef, fish, shellfish, and cow, sheep, and goat milk.

Our body uses creatine to build proteins that are then stored in our muscles as phosphocreatine or creatine phosphate. Phosphocreatine aids in the creation of adenosine triphosphate (ATP), an energy source for muscle cells used during activity and exercise. The rate of ATP demand increases up to a thousandfold during intense exercise compared to rest. For example, high-intensity exercise, such as weightlifting, requires rapid access to a large amount of total ATP. Performance intensity drops if ATP isn’t available within a quick time frame, and creatine supplementation can improve the amount of ATP replenishment to the muscles to counteract attenuation and decreased energy.

Is there a benefit?

Since the 1970’s, studies on creatine have revealed beneficial effects on short-term physical performance such as weightlifting, sprinting, and jumping. However, scientific research on creatine has shown inconsistent evidence that creatine helps with endurance sports, and no benefit to performance in long-term activities such as swimming or even a track run as short as 2 to 5 minutes.

Clinical studies have shown creatine produced a small but significant increase in lean body mass aided by improved resistance training capacity and increased intramuscular fluid retention. Creatine causes muscles to attract and hold water, which may also help prevent dehydration and aid muscle cramping, recovery, and prevention of sports or exercise-related injuries. This water retention increases the size and weight of muscles only while taking creatine. Also, current evidence doesn’t show that creatine causes any structural changes in muscle fibers.

Beyond its favorable effects on muscle building and short-term physical performance by boosting ATP, creatine has also been studied in aging and sarcopenia, ischemic heart diseases, dyslipidemia, diabetes, cancer, osteoarthritis, fibromyalgia, and depression.

Creatine has been found to improve mitochondrial efficiency and reduce formation of reactive oxygen species in its metabolic role in synthesizing ATP. Creatine is also thought to slow the growth of tumors, prevent cardiac toxicity of chemotherapy compounds, and aid the immune system in fighting cancer.

There is some evidence creatine may aid in heart disease by lowering triglyceride and homocysteine levels as well as aid those with heart failure to exercise without fatigue. 

However, most research involves animal models and more human clinical trials are needed to confirm the beneficial effects of creatine supplementation beyond increased energy.

Dosage and availability

Creatine is available online and in health food and grocery stores as tablets, a powder to mix into drinks, energy bars, and drink mixes. Long-term observational and experimental studies have provided evidence that creatine supplementation up to 10 g per day is safe and does not impair renal function.

What to tell your patients

Generally considered safe, there is evidence that creatine can help build muscles and strength through short-lived increases in energy. As supplements are not regulated by FDA, caution patients to choose a trustworthy brand. Adverse effects of supplementation are uncommon and can include weight gain, anxiety, difficulty breathing, diarrhea, fatigue, fever, headache, kidney issues, nausea, vomiting, rash, or upset stomach. Creatine isn’t recommended for patients with diabetes, kidney disease, or liver disease. Advise pregnant or nursing patients and children under 18 years to avoid taking creatine. Creatine may affect blood glucose levels.  ■