Cranberry Less Effective, Risky than Drug

AMSTERDAMA prescription drug may be more effective than cranberry capsules when it comes to preventing recurrent urinary tract infections (rUTIs), but the drug also increased antibiotic resistance, according to a new study published in the Archives of Internal Medicine (2011;171(14):1270-1278). A complementary commentary noted certain aspects of this study demonstrated why consumers may opt for a natural option over the prescription despite the better efficacy (Arch Intern Med. 2011;171[14]:1279-1280).

The antibiotic used in this study appeared to be more effective at preventing rUTIs than cranberry capsules, but the researchers noted achieving this result also seemed to increase the rate of antibiotic resistance. From clinical practice and during the recruitment phase of this study, we learned that many women are afraid of contracting drug-resistant bacteria using long-term antibiotic prophylaxis and preferred either no or nonantibiotic prophylaxis," they reported. In those women, cranberry prophylaxis may be a useful alternative despite its lower effectiveness."

The study examined 221 premenopausal women who had rUTIs (had reported at least three symptomatic UTIs in the previous year) and their use of either either trimethoprim-sulfamethoxazole (TMP-SMX, 480 mg at night, plus one placebo capsule twice daily) or cranberry capsules (as Cran-Max from Proprietary Nutritionals Inc., Kearny, NJ, 500 mg twice daily, plus one placebo tablet at night) for 12 months. Researchers assessed participants clinical status once a month (and for three months after stopping the study medication) via urine and feces samples and a questionnaire; participants also submitted urine samples when they experienced UTI-like symptoms.

At 12 months, the average number of clinical recurrences was 1.8 in the TMP-SMX group and 4.0 in the cranberry capsules group. Recurrence occurred, on average, after eight months in the drug group and after four months in the cranberry capsules group.

However, antibiotic resistance rates tripled in the pathogens found in patients in the TMP-SMX group; three months after the drug was discontinued, resistance rates returned to the levels they had been at when the study began. 

Of course, botanical dietary supplements are not intended to be used to treat, cure or prevent disease. Bill J. Gurley, Ph.D., from the University of Arkansas for Medical Sciences, Little Rock, noted this in an accompanying commentary, and added supplements such as cranberry capsules may not demonstrate optimal efficacy due to issues with poor water solubility and the type of metabolism that occurs.

Gurley noted, given that one month into the study, antibiotic resistance for Escherichia coli was higher than 85 percent in the TMP-SMX group, but less than 30 percent in the cranberry capsule group, such a marked reduction in antibiotic resistance certainly favors the therapeutic potential of cranberry as a natural UTI preventative." Further, Gurley pointed out that TMP-SMX showed superior efficacy to cranberry capsules, but that the low rate of bioavailability of bacteria-fighting chemicals in the dosage used of the latter may have affected the studys results. Because optimal doses have not been established for many botanicals, clinical efficacy trials have often yielded negative or inconclusive results." He added an ongoing dose-ranging study for cranberry may provide more information on this supplements effectiveness.

Holistic Pharmacist and author, Sherry Torkos, said, "Prevention of UTI with antibiotics is effective but undesirable due to side effects (most commonly diarrhea, upset stomach and yeast infection). In some cases, a potentially fatal superinfection with the bacteria Clostridium difficile can occur due to antibiotic use. Antimicrobial resistance is another concern. In fact, resistance to trimethoprim in bacteria causing UTIs has been steadily increasing in Northern European and American countries from 10 percent to 15 percent in the 1970s to about 24 percent in 2004."

Dean Mosca, president, Proprietary Nutritionals, said, Having not seen the study, or methodology used, it is difficult to comment with confidence about what may have impacted the outcome." He noted a previous study found Trimethoprim had only a limited advantage over Cran-Max in the prevention of rUTIs in older women and had more adverse effects (J Antimicrob Chemother. 2009 Feb;63(2):389-95).

The authors of that study reported, Our findings will allow older women with recurrent UTIs to weigh up with their clinicians the inherent attractions of a cheap, natural product like cranberry extract whose use does not carry the risk of antimicrobial resistance or super-infection with Clostridium difficile or fungi." In this study, 137 women with two or more antibiotic-treated UTIs in the previous 12 months were randomized to receive either 500 mg of cranberry extract or 100 mg of trimethoprim for 6 months. Thirty-nine of 137 participants (28 percent) had an antibiotic-treated UTI (25 in the cranberry group and 14 in the trimethoprim group); difference in proportions relative risk 1.616 (P=0.084). The time to first recurrence of UTI was not significantly different between the groups (P=0.100). The median time to recurrence of UTI was 84.5 days for the cranberry group and 91 days for the trimethoprim group (P=0.479).

Steve Siegel, vice president, Ecuadorian Rainforest LLC, added, The new Archives of Internal Medicine study is nothing new but further supports this amazing fruit. Cranberry products should be included in everyones diet, not just women. He pointed to a 2009 study that found consuming a reconstituted, unsweetened cranberry drink from extract reduced the risk of UTI by inhibiting pathogen adhesion while not detrimentally affecting urinary pH or vaginal microbiota (Can J Urol. 2009 Dec;16(6):4901-7).