Cranberries found to reduce UTIs

Women, who are more vulnerable than men, also have other options to stave off these types of infections

Q: I've recently had two urinary-tract infections, both of which went away with antibiotics. My mother gets them, too, and she suggested that I drink cranberry juice daily to prevent future problems. My husband says this is just an old wives' tale. Is there any evidence that cranberry juice might help?

A: Urinary-tract infections (UTIs) are common in women of all ages. They can affect any part of the urinary tract, but most occur in the bladder, causing frequent, urgent and painful urination. Other symptoms may include blood in the urine and lower-abdominal pressure or pain. Less often, the kidneys become infected, causing back pain, nausea, vomiting and high fever.

Most UTIs are caused by bacteria called Escherichia coli, or E. coli, which is abundant in human feces. E. coli can travel from the anus to the urethra when you move your bowels or have sexual intercourse. After gaining a foothold in the urethra, the bacteria can move up the urinary tract to the bladder or kidneys. Some strains of E. coli are particularly likely to cause infections because they are able to stick to the cells that line the urinary tract.

Women are more vulnerable to UTIs than men because a woman's urethra is close to the vagina and anus. It's also shorter than a man's, allowing bacteria easier access to the bladder. Women are much more likely than men to experience recurrent UTIs, that is, three or more in one year.

As you've experienced, antibiotics are effective for treating UTIs. They also can help prevent recurrences.

In some cases, a doctor may prescribe antibiotics daily, after intercourse (if that seems to be the source of infections) or for a day or two when symptoms first appear. If necessary, Bactrim, the most widely prescribed drug for UTIs, can be taken safely for several years to prevent infections.

Even so, many women don't like to take antibiotics because they can cause allergies, diarrhea, nausea and yeast infections of the vagina or mouth. Another risk is the creation of antibiotic-resistant bacteria, a danger clinicians try to avoid by using the lowest effective dose.

Cranberry juice has been used for years to treat and prevent UTIs. Some may question the practice, but scientific studies point to its effectiveness.

In January, researchers with the highly respected Cochrane Collaboration, experts who identify and evaluate studies of health care interventions, published a report saying that evidence supports daily consumption of cranberry products to reduce the likelihood of UTIs.

The Cochrane reviewers searched medical databases and clinical-trial registries and consulted cranberry- industry sources to find studies that lasted at least one month and that compared cranberry juice, capsules and tablets with a placebo or water for the prevention of UTIs.

They identified 10 studies involving a total of 1,049 participants that met their criteria.

Results showed that over a 12-month period, cranberry products reduced the overall incidence of UTIs by 35 percent. They appeared to be most effective in women with recurrent symptomatic UTIs, cutting the annual rate of new infections by 39 percent.

What makes the little red berries so special?

They contain several compounds that could confer health benefits, including salicylic acid, the active ingredient in aspirin. They also contain plant chemicals call polyphenols, which have antioxidant properties.

No one knows exactly how these compounds prevent infections, but in laboratory tests, cranberry extracts have been shown to hamper the ability of E. coli to stick to the cells that line the urinary tract.

If you want to give cranberries a shot, drink one or two glasses of 100 percent juice a day. But keep in mind that cranberry juice is fairly high in calories, about 130 to 140 calories for an 8-ounce serving. The same amount of orange juice has about 100 to 110 calories. Also, some people don't like the tart taste of 100 percent juice, which can make it hard to stomach "cranberry therapy" over the long term.

Fortunately, there are many other things you can do to help stave off UTIs. Be sure to drink plenty of water to increase urine output. Don't resist the urge to urinate; go when you need to. Take showers instead of baths. Urinate before and after sexual intercourse.

If you continue to have problems, talk with your doctor about antibiotic therapy. He or she might also recommend a urologic evaluation in case there's an underlying cause, such as a kidney stone or anatomic abnormality.

By taking some preventive steps, your annoying, painful infections may become little more than a distant memory.

The Harvard Medical School Adviser is researched and written by the faculty and staff of Harvard Medical School. Visit www.health.harvard.edu/adviser.