Do cranberries prevent burny pees?

There has been popular support for cranberries helping with urinary tract infections for a very long time.  But the research findings have been uneven. There has therefore been a wish for studies which would settle the question for once and for all. The abstract of the latest study is below.

It is undoubtedly a well-conducted study and a contemporaneous review has used it as something of a final nail in the coffin of clinical use of cranberry juice.

I wish to prise that nail out of the coffin, in part because I have personally found cranberry juice to be very efficacious. It doesn't happen often but, if I get a twinge of UTI, I rapidly belt a couple of mouthfuls of supermarket cranberry juice into me and the problem disappears.

So why is my experience different from what we read in the report below?  Several reasons.  For a start, I am not a sick and elderly woman living in a Connecticut nursing home.  More importantly, however, I take the juice as a cure, not as a preventive.  Its effects could wear off if you take it all the time.  Cranberries may not be able to prevent UTI but they could cure it.

I am also concerned that most of the studies administer the stuff in capsule form rather than as a drink. As a much-published academic researcher myself, I know exactly why they do that.  It enables standardization and replicability.  But what if the scientific precautions damage the effect?  What if capsules are not a good way of delivering the power of the cranberry?  To put it in academic terms, what if the finding is an artifact of the experimental method? What if capsules have processed all the goodness out of the cranberries? Health researchers are loud and frequent in condemning processed food generally, so how come cranberry capsules get a pass?

So it is my conclusion that most of the studies, including the one below, have been incautious despite themselves and have not examined the question adequately.  Drink up your cranberry juice!


Effect of Cranberry Capsules on Bacteriuria Plus Pyuria Among Older Women in Nursing Homes: A Randomized Clinical Trial

Manisha Juthani-Mehta et al.

Abstract

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.

Results  Of the 185 randomized study participants (mean age, 86.4 years [SD, 8.2], 90.3% white, 31.4% with bacteriuria plus pyuria at baseline), 147 completed the study. Overall adherence was 80.1%. Unadjusted results showed the presence of bacteriuria plus pyuria in 25.5% (95% CI, 18.6%-33.9%) of the treatment group and in 29.5% (95% CI, 22.2%-37.9%) of the control group. The adjusted generalized estimating equations model that accounted for missing data and covariates showed no significant difference in the presence of bacteriuria plus pyuria between the treatment group vs the control group (29.1% vs 29.0%; OR, 1.01; 95% CI, 0.61-1.66; P = .98). There were no significant differences in number of symptomatic UTIs (10 episodes in the treatment group vs 12 in the control group), rates of death (17 vs 16 deaths; 20.4 vs 19.1 deaths/100 person-years; rate ratio [RR], 1.07; 95% CI, 0.54-2.12), hospitalization (33 vs 50 admissions; 39.7 vs 59.6 hospitalizations/100 person-years; RR, 0.67; 95% CI, 0.32-1.40), bacteriuria associated with multidrug-resistant gram-negative bacilli (9 vs 24 episodes; 10.8 vs 28.6 episodes/100 person-years; RR, 0.38; 95% CI, 0.10-1.46), antibiotics administered for suspected UTIs (692 vs 909 antibiotic days; 8.3 vs 10.8 antibiotic days/person-year; RR, 0.77; 95% CI, 0.44-1.33), or total antimicrobial utilization (1415 vs 1883 antimicrobial days; 17.0 vs 22.4 antimicrobial days/person-year; RR, 0.76; 95% CI, 0.46-1.25).

Conclusions and Relevance:  Among older women residing in nursing homes, administration of cranberry capsules vs placebo resulted in no significant difference in presence of bacteriuria plus pyuria over 1 year.

JAMA. Published online October 27, 2016. doi:10.1001/jama.2016.16141