JAMA:
Importance Bacteriuria plus pyuria is highly prevalent among older women living in nursing homes. Cranberry capsules are an understudied, nonantimicrobial prevention strategy used in this population.
Objective To test the effect of 2 oral cranberry capsules once a day on presence of bacteriuria plus pyuria among women residing in nursing homes.
Design, Setting, and Participants Double-blind, randomized, placebo-controlled efficacy trial with stratification by nursing home and involving 185 English-speaking women aged 65 years or older, with or without bacteriuria plus pyuria at baseline, residing in 21 nursing homes located within 50 miles (80 km) of New Haven, Connecticut (August 24, 2012-October 26, 2015).
Interventions Two oral cranberry capsules, each capsule containing 36 mg of the active ingredient proanthocyanidin (ie, 72 mg total, equivalent to 20 ounces of cranberry juice) vs placebo administered once a day in 92 treatment and 93 control group participants.
Main Outcomes and Measures Presence of bacteriuria (ie, at least 105 colony-forming units [CFUs] per milliliter of 1 or 2 microorganisms in urine culture) plus pyuria (ie, any number of white blood cells on urinalysis) assessed every 2 months over the 1-year study surveillance; any positive finding was considered to meet the primary outcome. Secondary outcomes were symptomatic urinary tract infection (UTI), all-cause death, all-cause hospitalization, all multidrug antibiotic–resistant organisms, antibiotics administered for suspected UTI, and total antimicrobial administration.
Whenever I’m answering the questions of friends, family, or people who I meet as to whether “this food” or “that food” works, and I inevitably tell them that there’s no evidence, a surprisingly large number will say, “But at least cranberry juice is good to prevent or treat urinary tract infections, right?”
This was a double-blind, placebo-controlled RCT of elderly women, both with and without pyuria (pus in your urine) at baseline, living in 21 nursing homes from 2012-2015. Half got two oral cranberry capsules each day, and half got good, old placebo. The main outcome of interest was bacteriuria (bacteria in the urine) plus pyuria, assessed every two months for a year. Secondary outcomes were full on urinary tract infections, death, hospitalizations, antibiotic use, and antibiotic-resistant organisms.
Adherence in this study was over 80%, which is pretty good. The adjusted analyses showed no differences in the main outcome of interest. There were also no significant differences in urinary tract infections, death, hospitalizations, antibiotics, and antibiotic-resistant organisms. None at all.
And this was in women who consumed cranberry capsules every day for a year. No one who asks me the question does that.
So the answer to “Cranberry juice is good to prevent or treat urinary tract infections, right?” is, “No.” Nothing works. Nothing.*
*The election is over soon, right?
