Many believe coffee causes conditions such as sleeplessness, high blood pressure and diabetes. Along with these conditions, the Centers for Disease Control reported 4.5 million new cases of kidney disease in 2009 alone, and some researchers wondered if there was a connection with coffee consumption. Scientists now believe coffee may have some health benefits due to the antioxidants it contains, and it may not contribute to kidney disease after all.
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A review of 13 studies involving almost 800,000 adults investigated whether there were associations between coffee, tea, milk, soda or fruit and vegetable juice consumption and cancer of the kidneys. A follow-up of seven to 20 years across studies, published in the “International Journal of Cancer” in November 2007, found that people who consumed three or more 8 oz. cups of coffee per day were 16 percent less likely to develop kidney cancer than those who averaged less than a cup per day.
Glomeruler Filtration Rate
Glomerular filtration rate, or GFR, is the best test to measure your level of kidney function and determine if you have kidney disease and the staging of the disease. A higher GFR is associated with an increased risk for kidney disease. A study published in January 2010 in the “British Journal of Nutrition” found that habitual coffee consumption of one or more cups of coffee per day was associated with increased levels of GFR. The researchers weren’t able to definitively link coffee consumption to kidney disease, however, and recommended further research into these effects.
A kidney stone is a hard mass developed from crystals within your urinary tract that can be quite painful. Diet may play a contributing role in kidney stone development. Researchers at Harvard published results of a study in 1996 in the “American Journal of Epidemiology” that found for each daily 8-oz. serving of either caffeinated or decaffeinated coffee there was a 10 percent decrease in the risk for development kidney stones. A study in a 2004 issue of “The Journal of Urology” reported that caffeine may modestly increase risks of developing a specific type of stone called a calcium oxalate stone.
Polycystic Kidney Disease
Polycystic kidney disease, or PKD, is a common genetic disorder that can lead to high blood pressure, kidney failure and other diseases. A study on rats in the lab, published in the November 2001 issue of “American Journal of Kidney Diseases,” found that caffeine exacerbated high blood pressure in rats with PKD, with researchers recommending that if you have PKD you limit coffee consumption to four or fewer cups of caffeinated coffee per day.
Renal failure, when your kidneys stop working, may require dialysis or a kidney transplant. Researchers at the University of Pittsburgh School of Medicine evaluated the effects of long-term caffeine consumption on renal failure and published their results in 2002 in the “Kidney International Journal.” They found that caffeine fed to obese, diabetic rats exacerbated renal failure in the rats. This effect was potentially caused by increases in cholesterol levels and proteinuria, or excess amounts of protein in urine.