What is the recommended dosage and safety protocol for a generally healthy individual using creatine (creatine monohydrate) for athletic performance enhancement, considering potential interactions with pre-existing kidney or liver disease?

Creatine Supplementation for Athletic Performance

Recommended Dosing Protocol

For generally healthy individuals seeking athletic performance enhancement, creatine monohydrate should be initiated with a loading phase of 20 g/day divided into four equal doses for 5-7 days, followed by a maintenance dose of 3-5 g/day. 1

Loading Phase

• 20 g/day divided into 4 equal doses (5 g each) for 5-7 days 1
• Concurrent consumption with approximately 50 g of mixed protein and carbohydrate enhances muscle creatine uptake via insulin stimulation 1
• Expect a 1-2 kg body mass increase during this phase due to intracellular water retention 1

Maintenance Phase

• 3-5 g/day as a single dose for the duration of supplementation 1
• Alternative lower-dose approach: 2-5 g/day for 28 days avoids the associated body mass increase 1
• Approximately 4-6 weeks are required following cessation for muscle creatine levels to return to baseline 1

Performance Benefits

Creatine improves high-intensity repeated sprint performance and enhances training capacity for muscle strength, power, and lean body mass. 1

• Increases muscle creatine stores, enhancing phosphocreatine resynthesis 1
• Most effective for short-duration, high-intensity activities rather than endurance sports 2, 3
• May also support brain function 1

Safety Profile in Healthy Individuals

No negative health effects occur following appropriate protocols in healthy individuals without pre-existing kidney or liver disease. 1

Short and Long-Term Safety

• Studies ranging from 5 days to 5 years with doses of 5-30 g/day showed no significant effects on kidney function indices including glomerular filtration rate in healthy athletes 4
• Most common adverse effect is transient water retention during early supplementation 5
• Anecdotal reports of muscle cramps and gastrointestinal complaints have limited incidence and are not necessarily linked to creatine itself 6

Critical Contraindications and Precautions

Creatine supplementation should NOT be used by individuals with pre-existing kidney disease or those with potential risk factors for renal dysfunction. 4, 6

Absolute Contraindications

• Pre-existing kidney disease of any stage 4, 6
• Diabetes mellitus (risk factor for renal dysfunction) 6
• Hypertension (risk factor for renal dysfunction) 6
• Reduced glomerular filtration rate 6

Monitoring Requirements

• If renal dysfunction develops during supplementation, immediately discontinue creatine 7
• While pre-supplementation kidney function testing appears unnecessary in normal healthy subjects, it might be considered for safety reasons in those with borderline risk factors 6

Liver Disease Considerations

Cases of liver complications have been reported when creatine is combined with other supplements or taken at higher than recommended doses for several months. 5

• Avoid exceeding recommended doses (>5 g/day maintenance) 5
• Do not combine with other supplements that may stress hepatic function 5
• Individuals with pre-existing liver disease should avoid creatine supplementation due to lack of safety data in this population 5

Product Quality Concerns

Commercially marketed creatine products do not meet pharmaceutical quality control standards, raising concerns about impurities or inaccurate dosing. 2

• Creatine monohydrate is the most extensively studied form; other forms such as creatine ethyl ester have not shown added benefits 5
• Choose reputable manufacturers with third-party testing when possible 2