For many years cranberry juice (Vaccinium macrocarpon) has been used for prevention and treatment of urinary tract infection (UTI). The juice of the North American cranberry is used. The juice is very acidic.
Escherichia coli is the most common bacterial cause of urinary tract infection. Other causes are Proteus and Klebsiella species. Symptoms of UTI include “frequent and urgent urination, painful urination, cloudy urine and low back pain.”
One theory of the benefit of cranberry juice is that the acidification of the urine kills the bacteria. Previous research has not verified this as being the reason that cranberry juice works.
Lectins (short chain proteins) cause the adherence of bacteria to the bladder wall. Bacteria cannot grow and reproduce unless they adhere to the wall of the urinary tract. An unknown element of cranberry juice seems to prevent this adherence.
The author did a study in which some women received cranberry juice daily and some received a placebo daily. Differences were seen between the two groups within two months. The placebo group showed evidence of infection in 28% of the urine samples. The group treated with cranberry juice showed infection in 15% of the urine samples.
CONCLUSION: Cranberry juice caused a 53% reduction in urinary infections compared to women who drank an inactive substitute placebo