Coffee, espresso, cola, tea, chai and most energy drinks contain caffeine. If you consume these beverages regularly, you might be concerned about the health effects of caffeine, especially if you have kidney disease. Fortunately, for most people, moderate use of caffeine produces no untoward effects, such as high creatinine levels.
Definitions
Caffeine is an alkaloid found in coffee, tea and other plants. The stimulating effects produced by this substance are well documented. Mayo Clinic reports that it "stimulates the central nervous system, alleviating fatigue, increasing wakefulness, and improving concentration and focus."
Creatinine is a waste product produced by the breakdown of creatine in muscle. High creatinine levels are a sign of kidney disease, because creatinine is normally quickly removed from the circulation by the kidneys. Large, muscular people have slightly higher normal creatinine levels than smaller, less muscular people. Normal creatinine levels for adult men are between 0.8 and 1.3 milligrams per deciliter. Normal creatinine levels for adult women are between 0.6 and 1.0 mg/dl.
Safety
As of 2011, no research in the U.S. Library of Medicine database shows a relationship between caffeine and high blood creatinine levels. The Mayo Clinic reports that 200 mg to 300 mg of caffeine per day, equivalent to two to four cups of coffee, is not harmful. Moreover, the U.S. FDA includes caffeine on its list of substances generally recognized as safe.
Research
A single paper published in the March 1999 "Journal of Cardiovascular Pharmacology" suggested that mice with high blood pressure showed a decline in renal function when fed water spiked with caffeine for 10 to 20 weeks. Although the article did not specifically mention elevated creatinine levels, the creatinine levels presumably rose because creatinine clearance declined and urine protein increased.
Kidney Disease
Kidney stones can be made from oxalate, struvite, uric acid and other substances. If you are prone to oxalate-type kidney stones, your doctor may tell you to avoid instant coffee because it is high in oxalate, a chemical compound. Likewise, if you have chronic kidney disease, your nephrologist might suggest that you avoid instant ice tea because it is high in phosphorus. These recommendations have nothing to do with the caffeine content of the beverage.
References
- Mayo Clinic; Caffeine: How much is too much?; November 2010
- Mayo Clinic; Caffeine Content for Coffee, Tea, Soda and More; November 2010
- "Journal of Cardiovascular Pharmacology"; Effects of Long-Term Caffeine Consumption on Renal Function in Spontaneously Hypertensive Heart Failure Prone Rats; S.P.Tofovic; March 1999
- National Kidney Foundation: Diet and Kidney Stones
- National Kidney Foundation: Phosphorus and Your CKD Diet
