Patients with urinary tract infections (UTIs) or benign prostatic hyperplasia (BPH) often ask health care providers about using complementary and alternative medicine (CAM) to relieve symptoms or prevent recurrences. There are many reasons that CAM therapies may appeal to these patients—for example, if they are concerned about the side effects or costs of prescription medicines; worried about antibiotic resistance (in the case of UTI); concerned about the potential effects of more invasive treatments on sexual function or continence (in the case of BPH); or seeking "natural" approaches to treating these conditions.
Urinary Tract Infections
UTIs occur at all ages and in both genders, although the incidence is 50 times higher in women. Up to one-third of women have at least one recurrence after their first episode. In men, UTIs are uncommon before age 50 and often are caused by an underlying disorder, such as a urinary or kidney stone or an enlarged prostate. UTIs in older adults may be caused by a condition such as incontinence or incomplete emptying of the bladder.
UTIs are the second most common bacterial infection after respiratory infections. In 2000 in the United States, about 11 million outpatient visits, 1.7 million emergency room visits, 367,000 hospitalizations, and $3.5 billion in health care expenditures were attributed to UTIs in adults. E. coli is most often the cause, but other microorganisms may also play a role.
Cranberry
The natural product that is most used for UTI, and on which there is the most evidence, is cranberry (Vaccinium macrocarpon). In a 2007 national survey on Americans' use of CAM, among those who used natural products, cranberry was used by 6 percent (which translates to about 1.6 million people).
The mechanism of action of cranberry is not fully understood, but basic research has yielded findings that may explain its potential benefit in UTIs, such as the suggestions that:
- Proanthocyanidins unique to cranberry inhibit the ability of bacteria to adhere to the surface membrane of host cells in the urinary tract
- Cranberry has anti-inflammatory and antioxidant activity.
An early theory, that cranberry inhibits bacteria replication through acidifying the urine, has been largely discredited.
Proanthocyanidins are molecules that help create intense color in fruits and vegetables and are thought to have antioxidant properties.
Snapshots of the Evidence
Practice Guidelines
The American College of Obstetricians and Gynecologists (ACOG) released an evidence-based clinical practice guideline in 2008 on uncomplicated acute bacterial cystitis in nonpregnant women. Among ACOG's recommendations are to use antibiotics both as first-line therapy and for prophylactic or intermittent treatment. ACOG notes that drinking cranberry juice has been shown to decrease recurrence of symptomatic UTIs, although the optimal length of treatment and concentration of juice still need to be determined.
Systematic Reviews/Meta-Analyses
Two systematic reviews/meta-analyses on cranberry from the Cochrane Collaboration concluded the following:
- A 2008 review on cranberry to prevent recurrent UTIs (updated from 2004) included 10 randomized or quasi-randomized clinical trials. Most (7) studied cranberry in the form of juice, and 4 studied tablets (1,049 participants in total). The review found "some evidence" that cranberry juice may decrease the number of symptomatic UTIs over a 12-month period compared with placebo/control, especially in women with recurrent UTIs. Applicability to other groups was less certain. The review noted uncertainty as to what the optimum dosage or form is for cranberry therapy; a lack of standardization in available cranberry products; a lack of clarity as to whether juice and capsules/tablets are bioequivalent; and high drop-out rates.
- A 2009 review on cranberry to treat UTIs concluded that there is no good-quality evidence on this question.