According to the most recent report from the National Coffee Association of USA, 49 percent of coffee drinkers believe that coffee is healthy, and consumption of iced and frozen coffee and gourmet coffee is on the rise. One health concern related to coffee consumption is the potential effects of coffee and caffeine on urinary tract health and hydration levels. Research results are mixed in some areas, but the physiological effects of caffeine on the kidneys provide some insight into coffee's overall impact on urination.
Increased Volume and Frequency
Excessive caffeine intake can result in increased urination, according to MedlinePlus. This happens for several reasons. Caffeine causes dilation of blood vessels in the kidneys by blocking adenosine receptors and increasing the kidney filtration rate. Antidiuretic hormone (ADH) promotes reabsorption of water in the kidneys, and caffeine interferes with its production. Thus caffeine consumption reduces water reabsorption, increasing elimination of water in urine. Caffeine may also weaken some bladder muscles, creating the urge to urinate.
Possible Dehydration
Research is mixed about whether caffeine inherently causes dehydration. Some studies show that overall water loss can occur with higher levels of caffeine intake, and the American Heart Association warns that the increased urination due to consuming caffeine can lead to dehydration. This may be of particular concern for athletes who lose fluid through sweating as well. According to Peak Performance Sporting Excellence, dehydration results both from the increase in blood flowing through the kidneys for filtration and from a decrease in sodium reabsorption, which in turn leads to decreased water reabsorption. Other studies did not find a significant decrease in hydration following coffee consumption. In fact, MSNBC reports that moderate intake of caffeine does not produce dehydration. Athletes and individuals consuming high levels of caffeine should drink sufficient water to remain hydrated.
Related Effects
Both the acidity of coffee and its caffeine content can increase symptoms for individuals with interstitial cystitis (IC), a condition of chronic inflammation of the urinary tract, according to the Interstitial Cystitis Association. Such symptoms include increased urinary urgency and burning or pain while urinating. For some individuals problems occur even with decaffeinated coffee. Reduced-acid coffee allows some of them to drink coffee without aggravating the condition. In "Conquering Bladder and Prostate Problems," Dr. Jerry Blaivas notes that the caffeine in coffee may not only promote symptoms of IC but may also promote infection in the urinary tract.
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