Dear Dr. Rabin:
When I was in nursing school in 1998, I was part of a clinical trial on using cranberry juice to prevent urinary tract infections. I actually dropped out of the study because I couldn’t take the taste of the little vial of concentrate we had to drink twice a day. Almost 10 years later, I still fight an occasional UTI, but now I can stomach cranberry juice cocktail (at least for a few weeks at a time). My question is: I’d be much better about taking a cranberry supplement capsule every day if I would get the same protection, but would I?
-- Brenda, Athens GA 

I don’t blame you for dropping out of the trial; I would have done the same thing. The closest I can get to cranberry juice is toasting Carrie Bradshaw with a Cosmopolitan during re-runs of Sex and the City on Turner Broadcasting. Actually, that’s not completely true. Sometimes I order orange-cranberry muffins at Starbucks – but only because they contain Craisins. I’ll support any product that manages to combine dried fruit with mental illness (cranberries so crazy, they think they’re raisins!). Pure marketing genius; Samantha would approve.

As most women know, a urinary tract infection (UTI) is about as much fun as a heavily edited, family friendly re-run of a TV show about sex. Quite painful in fact, a UTI is caused by bacterial invasion of the normally sterile bladder or the urethra (urine’s exit route). The result is frequent, burning elimination of often-cloudy urine. These infections are most common in young females, the elderly, and anyone who requires a urinary catheter, such as those with spinal cord injuries. Though it is possible for an infection to originate in the bloodstream, most often the bacteria enter from the outside. The usual suspect, an E. coli escapee from the nearby gated community of the colon, somehow makes its way up the urethra. Unfortunately for women, their anatomy is designed with a much shorter urethra than men, making access by rogue bacteria that much easier.

Enter cranberry juice. Thought to be a Native American remedy, it has become ubiquitous as the method of choice for dodging the UTI. Among countless users, some 40% of those with spinal cord injuries requiring a urinary catheter use some form of cranberry juice to stave off infection. In projects like the one in which you briefly participated, most research has fully supported cranberry’s preventive use. In fact, some studies have shown a decrease nearly halving the number of new infections. To be clear, evidence suggests cranberry juice may prevent infections, but no studies indicate any effect in treating existing infections. Regarding cranberry supplement capsules, they have not yet been evaluated – all meaningful research tested the pucker-inducing juice. For now, at least, you’re stuck with nature’s bounty.

That bounty starts with a shrubby little plant with long vines and dark pink flowers that produces a mature, but still white, berry. If left on the vine another three weeks, the fruit develops the characteristic deep cranberry color we associate with bridesmaid dresses and acrylic sweaters. The berry’s unique ability to float lends itself to an unusual harvest method: the bed (or bog) is flooded with water so the crop can be corralled into one corner an easy roundup. Cranberry wranglers sell 95% of the herd for juice, canned sauce or craisins – only a small amount is sold fresh.

The fresh cranberry’s dreadful acidic taste gave rise to the initial theory of its apparent effectiveness in preventing UTIs. It was thought the fruit acidified the urine and kept bacteria from reproducing. Further research demonstrated that idea to be false; it now seems that certain compounds unique to the cranberry hinder bacteria from growing thin, hair-like appendages called fimbriae. In normal circumstances, this little fringe works like microbial Velcro, allowing bacteria to attach themselves to, among other things, the cells lining our urinary tract. Without them, the bacteria literally cannot get a foothold and are easily flushed out by normal urination. 

Cranberry juice cocktail is only about one quarter actual cranberry juice – the rest is essentially sugar and water. Because of its popularity, the cocktail has been used in most studies, and recommendations generally suggest two 8 oz. glasses per day. A pint, however, is a pretty hefty commitment to Ocean Spray, especially if you don’t like the taste. Alternatively, the company now sells a 100% juice product, reducing your obligation to a 2 oz. shot, twice a day. Funny, that’s just enough for a couple Cosmopolitans. You could ask, but I doubt the bartender will put it on your health savings account.