Berry berry good

Nutrition Action Healthletter, June, 2005 by David Schardt

Cranberries or prevent urinary tract infection, blueberries to protect against Alzheimer's, strawberries to lower your blood pressure, black raspberries to ward off cancer. Sounds like you'll be running marathons at if you could just manage to eat a big bowl of berries every day. Perhaps.

While berries are packed with nutrients and f===, much of their "super foods" reputation comes from animal or test tube studies that may or may not translate into benefits for humans.

Here's the evidence for two berries one with solid human research and one that's not quite ready for prime time.

Cranberries

Want to avoid a urinary tract infection? Try cranberry juice. hat's what people have been doing for more than 100 years.

Yet four years ago, an international network of scientists known as the Cochrane Collaboration found that "the small number of poor quality trials gives no reliable evidence of the effectiveness of cranberry juice and other cranberry products." (1)

Not any more.

Cranberry Flip

"Quite a lot has happened in cranberry research since then, and the Cochrane group has revised their conclusions," says researcher Amy Howell of Rutgers University's Blueberry and Cranberry Research and Extension Center in Chatsworth, New Jersey. (The center is funded by the U.S. Department of Agriculture, the State of New Jersey, and cranberry-juice producer Ocean Spray.)

"New, better-designed clinical trials in Canada and Finland have confirmed the benefit of cranberries in preventing UTIs," Howell says.

In the Canadian study, 100 women who had at least two urinary tract infections during the past year were given either cranberry pills (the researchers were fuzzy on how much) or three cups of cranberry juice every day. During the next year, they were half as likely to suffer a UTI as 50 similar women who were given placebo drinks or pills. (2)

In the Finnish study, 50 young women who had previously been treated for a urinary tract infection were given about four tablespoons of a mixture of cranberry and lingonberry juice concentrate every day (lingonberries, which are in the cranberry family, are popular in Scandinavia). During the following six months, they were half as likely to suffer a UTI as 50 similar women who were given either nothing or a beverage with no juice concentrate. (3)

In clinical trials, "it's been pretty consistent that about SO percent of the people are helped by cranberry juice," concludes Howell.

That's why the Cochrane Collaboration now says that "cranberry juice may decrease the number of symptomatic UTIs over a 12 month period in women." (4)

Flushing Away E. coli

How can cranberries ward off urinary tract infections.)

"In about half the cases of UTIs, the E. coli responsible have special little hairy tips called P fimbria," says Howell. "The bacteria use their fimbria to attach themselves to the bladder so that they can multiply and cause an infection."

That's where cranberries--which contain a group of chemicals called proanthocyanidins---come in.

"The particular proanthocyanidins in cranberries can bind to the P fimbria of the E. coli and prevent the bacteria from adhering to the bladder wall," says Howell. "It kind of gums up the E. coli, so that they get flushed out in the urine instead of causing an infection."

And because cranberries remove, rather than kill, the infection-causing bacteria, "there's less of a chance for the E. coil to become resistant, as they have to some of the antibiotics commonly used to treat UTIs."

But once the bacteria stick to the bladder wall and start multiplying, cranberries can't help and it's time to bring on the antibiotics.

"There is no evidence that drinking or eating cranberry products can cure a UTI once the bacteria have caused an infection," says cranberry researcher Kalpana Gupta of Yale University.

"That's why it's important for women who have recurrent UTIs to keep taking cranberries even when they don't have an infection," says Howell.

Anything Goes

Does it matter how you get your cranberries? "We've found that almost any kind can prevent the bacteria from adhering," says Howell, "even the cranberry sauce from a Thanksgiving dinner."

Even so, "your best bet is to drink two glasses of a cranberry beverage, one in the morning and one before you go to bed." The second glass may prove to be important, says Howell, because preliminary studies show that cranberries' effects wear off after about 10 hours.

It's possible that less than a full glass twice a day would also work, but so far, no one has done a study to find the lowest effective dose.

What to drink? "One hundred percent cranberry juice is too astringent, and it's not necessary," says Howell. Cranberry juice cocktail, which is about 25 percent cranberry juice and 75 percent sugar water, "works just as well as cranberry juice sweetened with other fruit juices." Ditto for the new white cranberry juice beverages. (White cranberries are harvested before they develop their characteristic reddish color.)

Just keep in mind that an 8-ounce glass of cranberry juice or cocktail has around 140 calories. "Light" cranberry juice cocktails, which replace sugar with the safe artificial sweetener Splenda (sometimes also with acesulfame-potassium, which may not be safe), have only 40 calories a glass. "The light versions work just as well," says Howell.