Urinary tract infections, or UTIs, are caused by bacteria, most often Escheria coli. This is a very common infection, especially in women: Between 50 percent and 60 percent of women have a UTI at least once in their life, according to the University of Illinois at Urbana-Champaign. Cranberry juice is known to be useful in preventing UTIs.
Infection of the Urinary Tract
Cranberry juice is commonly used to prevent UTIs, which can affect the entire urinary tract, which includes the kidneys, ureter, bladder and urethra. The kidneys create urine by excreting certain substances and reabsorbing others, the ureter carries fluid from the kidneys to the bladder, the bladder holds urine and the urethra carries urine from the bladder to outside the body. E. coli from the vagina or the anal area is generally the bacterial source of the infection, which can reach the urinary tract and cause an infection through sex or wiping after using the bathroom.
History
Cranberry juice has been used as a preventative agent for UTIs for hundreds of years, notes the University of Maryland Medical Center, but only recently has the mechanism behind this natural food been closely investigated in the laboratory. Cranberries are indigenous to North America, and people that immigrated to the U.S. from England used these berries to treat many illnesses, including problems with digestion, loss of appetite, blood illnesses and scurvy. Although it is debatable that cranberry juice effectively treats the other ailments, the vitamin C content of cranberries means that they likely did cure scurvy, which is caused by a vitamin C deficiency.
Mechanism
Scientists first thought that cranberry juice prevented UTIs by increasing the acidity in urine, therefore preventing the bacteria from growing robustly in the urinary tract. However, the mechanism of prevention is actually mediated through its effect on the cells of the urinary tract: Cranberry juice prevents bacteria from adhering to the cells of the urinary tract. Drs. DR Schmidt and AE Sobota from Alliance City Hospital in Ohio published results from an interesting study in the Journal "Microbios" in 1988. These results showed that bacteria isolated from subjects with UTIs adhere tightly to the cells lining the urinary tract when tested in the lab. However, these bacteria did not adhere tightly to urinary tract cells obtained after subjects drank cranberry juice cocktail. Because the bacteria cannot grip onto the walls of the urethra or bladder, the putative mechanism is that the bacteria are flushed out of the system during urination. The University of Maryland Medical Center recommends 3 oz. of pure cranberry juice or 10 oz. of cranberry juice cocktail per day.
Nutritional Information
Hospitality and Dining Services of Harvard University publishes the nutritional facts of numerous foods, including cranberry juice cocktail. It reporst that 8 oz. of cranberry juice provides 140 calories; 34 g of total carbohydrates, including 33 g of sugars; and 100 percent of the percent daily value of vitamin C, but few other important nutrients. Cranberry juice is a great source of vitamin C both because cranberries naturally contain this vitamin but also because it is commonly fortified with extra vitamin C. Because one serving of cranberry juice contains about 11 percent of the daily value of carbohydrates, you might want to consider not drinking too much over the amount needed to prevent UTIs. The high amount of carbohydrates and calories could lead to unintended weight gain.
References
- University of Maryland Medical Center: Cranberry
- University of Illinois at Urbana-Champaign: Urinary Tract Infections in Women
- Harvard University Hospitality and Dining Service; Juice, Cranberry; March 2011
- "Microbios;" An examination of the anti-adherence activity of cranberry juice on urinary and nonurinary bacterial isolates; Schmidt DR and Sobota AE; 1988
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