cranberry juice for preventing urinary tract infections (UTI)

Last edited 11/2018 and last reviewed 01/2023

Lee Y-L et al (1) undertook a short study to investigate the effects of cranberry juice on the growth of bacteria in broth culture:

• seven strains of bacteria were tested
• all seven strains were cultured in broth and broth plus cranberry juice
• growth of all seven strains was reduced by cranberry juice - the broth/cranberry juice culture medium stopped the growth completely of five bacterial strains - these included Escherichia coli, Staphylococcus aureus and Proteus mirabilis

This study does bring some credibility to the anecdotal evidence that cranberry juice can be used in the treatment of urinary tract infections. However it does not prove that cranberry juice is an effective treatment for urinary tract infections.

There is, however, some evidence that a daily 'dose' of cranberry juice may reduce the risk of recurrent urinary tract infection. A 12-month study (open, randomised, controlled) was undertaken involving 150 women with proven E. coli infection(2). Women were allocated to three groups - either daily cranberry-ligonberry juice concentrate (CLJC); lactobacillus drink five days per week; control. This study revealed that, at 6 months, recurrence of UTI rate was 16% in the CLJC group, 39% in the lactobacillus group and 36% in the control group (p=0.048).

More recent reviews also concluded that (3,4,5):

• there is limited evidence suggests that cranberry products can help to prevent the recurrence of urinary tract infections (UTIs) in women at risk of developing such infections - effectiveness for other groups is less certain (4)
  • the optimal dosage regimen for cranberry and how this compares with prophylactic antibacterial therapy have not been established
    • not clear what is the optimum dosage or method of administration (e.g. juice, tablets or capsules)
  • no convincing published evidence to support the use of cranberry in treating people with current UTIs (3)
• cranberry-containing products are associated with protective effect against developing UTIs (5)

NICE guidance with respect to cranberry products in UTIs (6)

• NICE recognised that cranberry products are used widely and discussed the very low quality evidence showing some benefit for reducing the risk of UTIs, specifically in nonpregnant women, and children and young people
  
  
  • taking account of the limitations of the evidence, and the need to minimise antimicrobial resistance, the committee agreed that some women who are not pregnant and some children and young people under 16 may wish to try cranberry products as a self-care treatment
    • however, due to safety concerns with delayed treatment, particularly in children and young people, the committee agreed that cranberry products should only be considered in this population following advice from a paediatric specialist
      
      
• NICE recognised that there was some evidence to suggest that cranberry juice was not significantly better than placebo in non-pregnant women, while cranberry capsules showed a significant benefit
  • however, due to significant limitations in the evidence the committee was not able to recommend a specific cranberry product
    
    
• NICE discussed the sugar content of cranberry products, and based on their experience, agreed that people should be advised to take account of their daily sugar intake if using cranberry products.

Reference:

• (1) Lee Y-L, Thrupp L, Cesario T (2000). Does cranberry juice have antibacterial activity? (research letter). JAMA; 283:1691.
• (2) Kontiokari et al (2001). Randomised trial of cranberry - ligonberry juice and Lactobacillus GG drink for the prevention of urinary tract infections in women. BMJ; 322:1571-3
• (3) Drug and Therapeutics Bulletin 2005; 43 (3):17-19.
• (4) Jepson R, Craig J. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2008 Jan 23;(1):CD001321
• (5) Wang CH et al. Cranberry-containing products for prevention of urinary tract infections in susceptible populations: a systematic review and meta-analysis of randomized controlled trials. Arch Intern Med. 2012 Jul 9;172(13):988-96.
• (6) NICE (October 2018). Urinary tract infection (recurrent): antimicrobial prescribing