How could any bacteria cause a bladder infection without just getting flushed away—literally? Bladder infections may make sense if we’re not drinking enough or if we leave behind a stagnant pool because we can’t empty completely (as in men with enlarged prostates). However, in most people there should be a constant flow of water. The way bladder infection-causing E. coli hold on is that they evolved finger-like projections (fimbrae) they can use to stick to the walls of the bladder so they don’t get washed away.
Almost 30 years ago, it was demonstrated that if you drip cranberry juice on E. coli, their fimbrae aren’t able to stick as well. Grape juice doesn’t work, nor does orange or apple juice. Even white cranberry juice made from unripened berries doesn’t work, suggesting that it’s one of the red phytonutrients that’s the active ingredient. For more on these natural plant compounds, see Phytochemicals: The Nutrition Facts Missing From the Label and for those doubting the power of plants, Power Plants.
Even if it works in a petri dish, though, we don’t pee cranberry juice. How do we know that the anti-adherence phytonutrients are even absorbed through the gut and make it into the bladder? Subsequent studies have shown that if you drip the urine of someone who drank cranberry juice onto E. coli, they don’t stick as well either. Now we’re getting somewhere. If you check out my 4-min video Can Cranberry Juice Treat Bladder Infections?, you can see the stickiness of strains of E. coli wading in urine from someone drinking water, and the stickiness in the urine of someone drinking cranberry juice. Within hours of consumption there’s a drop in E. coli adherence that appears to last throughout much of the day. So might cranberries really help prevent bladder infections?
The best way to prevent infections is to not get infected in the first place, which may involve the avoidance of chicken so you’re not constantly re-infecting yourself (see my last video Avoiding Chicken to Avoid Bladder Infections).
If that doesn’t work, however—if your gut remains stubbornly colonized with these bad bladder bugs—various tested cranberry products appear to reduce the recurrence of bladder infections by about 35 percent. Not as effective as antibiotics, but cranberry juice doesn’t foster antibiotic resistance and has fewer side effects.
There’s no good evidence to suggest cranberries are an effective treatment, though, which makes sense. Cranberries prevent the initial adherence, but that occurs at the start of the infection. When the infection is present and already stuck, there’s no clinical data to suggest that cranberries are effective in the treatment of urinary tract infections, meaning it doesn’t work better than placebo—but placebos work! For example, ibuprofen seems to work just as well as antibiotics for the treatment of uncomplicated urinary tract infections.
Some people really do need antibiotics—pregnant women, children, men, those with kidney infections, and systemic symptoms like nausea and vomiting. For most healthy women, though, bladder infections just go away on their own without antibiotics. Women who drink cranberry juice and have their symptoms disappear may falsely attribute their recovery to the juice. However, when it comes to most UTIs, nothing works–as in nothing, a sugar pill, actually works!
I discuss the controversy around doctors giving placebos in The Lie That Heals: Should Doctors Give Placebos?
How can you consume cranberries palatably? Check out my recipe for Pink Juice with Green Foam.
If cranberries are so good at keeping bacteria from sticking to the wall of the bladder, what about keeping bacteria from sticking to other places like our teeth? I touch on that in my video Childhood Tea Drinking May Increase Fluorosis Risk.
-Michael Greger, M.D.
Image credit: ztephen / Flickr
In research I profiled in my video Which Fruit Fights Cancer Better?, cranberries were found to suppress the growth of human liver cancer cells in vitro. Other studies have found similar effects against human breast, colon, brain tumor, oral, and ovarian cancer cells. In my 4-min video Cranberries versus Cancer I profile the latest looking at prostate cancer cell growth.
The United States has the highest rate of prostate cancer in the world, so let’s try a native American fruit! Researchers started out with about 50,000 human prostate cancer cells in a petri dish and if you do nothing, within a day you’re closer to 100,000, then 200,000 and then nearly 400,000 within 72 hours. But by adding just a tiny amount of cranberries, that exponential cancer growth can be blocked.
The reason they tested such tiny concentrations is that we only absorb a small fraction of the cranberry phytonutrients we eat into our bloodstream. Still, cranberries are cheap. If drug companies and supplement manufacturers are going to capitalize on this they needed to find cranberry’s active ingredient.
In my video Cranberries versus Cancer I show a graph with some of the various phytonutrients in cranberries. Different fractions were tested against various types of cancer to find the magic bullet. Various fractions of phytonutrients inhibited colon cancer cell proliferation about 15 percent, but nothing compared to the total extract of the whole fruit. There seems to be additive or synergistic anti-proliferative effects resulting from the combination of the various components compared to individual purified phytochemicals. So it’s always better to eat the whole fruit.
How do you do that with cranberries, though? Although five percent of cranberries are sold fresh, the vast majority are consumed as processed products. To get the same amount of anthocyanin phytonutrients in a cup of fresh or frozen cranberries, you’d have to drink 16 cups of cranberry juice cocktail, eat seven cups of dried cranberries, or 26 cans of cranberry sauce!
The problem is that raw cranberries are so tart that folks may opt for the 7 cups of dried. In a taste test survey, consumers said they wouldn’t mind eating dried cranberries every day, but the preference for raw cranberries sloped down toward maybe once a year. The problem is dried cranberries tend to come sweetened. Raw cranberries don’t affect your blood sugar, but sweetened dried cranberries do—even the low sugar varieties.
What about cranberry “juice”? Cranberry cocktail is usually only about a quarter cranberry juice. The ruby red phytonutrients in cranberries and pure cranberry juice are powerful antioxidants, increasing the antioxidant capacity of our bloodstream within hours of consumption. But the high fructose corn syrup acts as a pro-oxidant, even with added vitamin C, canceling out some of the cranberry benefit. So how do you get the upsides without the down? Check out my Pink Juice with Green Foam video, where I offer a recipe for making no added sugar whole fruit cranberry cocktail.
And for another reason to avoid high fructose corn syrup: Mercury in Corn Syrup?
More on nutrient synergy in:
- Fighting Inflammation With Food Synergy
- Garden Variety Anti-Inflammation
- New Mineral Absorption Enhancers Found
- Apples and Oranges: Dietary Diversity
- Constructing a Cognitive Portfolio
-Michael Greger, M.D.
Image credit: Muffet / Flickr