Can Vitamin C Be Used to Prevent Urinary Tract Infections

As seen in Consultant Connection March 2012 Issue
By: Kyle Steinmetz ONU Pharm D Candidate 2012

The urinary tract is one of the most common sites of bacterial infections in humans. Numerous bacterial organisms may be the cause of urinary tract infections, but the most common pathogen is E. coli, which is responsible for roughly 80% of cases of UTI. A variety of antibiotics are used for the prevention and treatment of urinary tract infections, and a growing concern is the increasing
resistance of UTI pathogens to conventional antimicrobial agents. Because of this, the use of drugs other than conventional antibiotics for prophylaxis and treatment of UTIs is desired, and the search for such treatments is ongoing.

One such agent proposed to be useful in preventing urinary tract infections is vitamin C. Also known as ascorbic acid, vitamin C is an antioxidant with a number of proposed health benefi ts, including treatment and prevention of the common cold, hypertension, coronary heart disease, gout, and cancer. The recommended dietary allowance of the vitamin is 75 milligrams per day in women and 90 milligrams per day in men. High-dose vitamin C, at one to two grams per day, is commonly used for disease treatment and prevention. When the vitamin has been used in even higher daily doses, several types of adverse effects have been reported, including diarrhea, hyperglycemia, hemolysis, and renal failure.

Vitamin C is thought to have an effect in UTIs by acidifying the urine. The urine contains nitrates, both obtained from the diet and produced naturally by the body. Bacteria with nitrate reductase activity, such as E. coli, convert these nitrates to nitrites. At an acidic pH, the nitrites are then converted to various nitrogen oxides which are toxic to bacteria. Therefore, urine acidifi ed
by vitamin C may be deadly to many of the bacteria that cause urinary infections, including E.coli.
Although vitamin C has long been suggested as a supplement to prevent UTIs, there have been relatively few studies looking at its effectiveness. The studies that do exist found that decreasing the pH of urine to a level of 5.5 or lower effectively kills E. coli bacteria. However, at the doses used in the trials, between two and four grams per day, the vitamin C was not found to effectively lower the pH to this level of acidity, and therefore was not effective in killing the bacteria. The research on this topic does not support the use of high-dose vitamin C for the prevention of urinary tract infections.
Further studies could be done to determine whether even higher doses of the vitamin may be useful for UTIs, but the risk of adverse effects at such doses may be greater than the potential benefits.

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