Can Cranberries Contribute to Reduce the Incidence of Urinary Tract Infections?

Post on August 24, 2017 by André Broussard, D.C.

August 23, 2017

The Journal of Urology

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  • Urinary tract infections (UTIs) are common and result in considerable morbidity. While the ingestion of cranberry products has long been promoted to reduce the risk of UTIs, the effect of cranberry products on risk reduction remains controversial. This systematic review and meta-analysis evaluated the relationship between cranberry intake and reduction in the risk of urinary tract infection. Investigators found that the ingestion of cranberry products significantly reduced the risk of UTIs, and this effect was particularly pronounced among individuals with recurrent infections.
  • While cranberry products appear to significantly reduce the risk of UTIs, there remain key unanswered questions surrounding the optimal “dose” of cranberry necessary to achieve the desired effect in individual populations.– Matthew Resnick, MD

Primary Care

Written by David Rakel MD, FAAFP

Supplements to Prevent UTI

Cranberry

Previous meta-analyses on the benefits of cranberry for prevention of UTI have been equivocal. This one adds a significant amount of research extending the data set from 10 to 28 clinical trials. The results support cranberry with a weighted risk ratio of 0.6750 (95% CI, 0.5516–0.7965; P < .0001), a 33% reduction in frequency of UTI.

The active ingredient of cranberry is proanthocyanidin (PAC). These phenols inhibit the binding of E. coli to the bladder wall. It is important to realize that these work specifically on E. coli and recurring UTIs from other bacteria may not be prevented with cranberry. Unlike antibiotics, PACs have other health benefits that may reduce cardiovascular and diabetes risk.1,2

D-Mannose

Another promising supplement for preventing UTI is D-mannose. Although it is less researched than cranberry, there are some promising data. One study compared nitrofurantoin to 2 g of D-mannose in 200 mL of water for 6 months.3 D-mannose equaled the antibiotic in its ability to prevent UTI. It fools bacteria to bind to its surface instead of the bladder wall, and then cleans the urine as the sugar is cleared with urination. High doses can cause GI upset, but it does not appear to worsen blood sugar control in diabetes.
UTI Prevention

Dosing

Cranberry: 16 oz of unsweetened juice daily or 400 mg twice daily of cranberry extract. If you want to supplement with just PAC, the dose ranges from at least 36 mg (minimal effective dose) to a high dose of 270 mg daily.

D-mannose: 2 g dissolved in 200 mL water daily.

References

  1. Sun AY, Simonyi A, Sun GY. The “French Paradox” and beyond: neuroprotective effects of polyphenols. Free Radic Biol Med. 2002;32(4):314-318. http://www.sciencedirect.com/science/article/pii/S0891584901008036?via%3Dihub
  2. Holst C, Becker U, Jorgensen ME, Gronbaek M, Tolstrup JS. Alcohol drinking patterns and risk of diabetes: a cohort study of 70,551 men and women from the general Danish population [published online July 27, 2017]. Diabetologia. doi: 10.1007/s00125-017-4359-3. https://link.springer.com/article/10.1007%2Fs00125-017-4359-3
  3. Kranjcec B, Papes D, Altarac S. D-mannose powder for prophylaxis of recurrent urinary tract infections in women: a randomized clinical trial. World J Urol. 2014;32(1):79-84. https://link.springer.com/article/10.1007%2Fs00345-013-1091-6

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