Meta analysis showed that cranberry juice could prevent urinary tract infection

According to a meta analysis published in the archives of internal medicine on July 9, cranberry products have the effect of preventing urinary tract infection (Arch Intern Med 2012; 172 (13): 988-996) A 2008 Cochrane analysis of cranberry and UTI related literature showed that cranberry juice helped prevent symptomatic UTI with a risk ratio (RR) of 0.66 After that, some new research evidence appeared, prompting Dr Chih hung Wang and his colleagues from the Department of emergency medicine of Taiwan National University in Taipei to conduct a new meta analysis They reviewed a number of randomized controlled trials that compared cranberry products with placebo or control substances and measured the incidence of UTI, with a total of 13 such studies, including nine parallel group studies and four cross-over trials Ten of the studies were conducted in North America and three in Europe The total number of subjects was 1616 However, most studies did not fully report the randomization process, and the rate of lost visits was high (0% ~ 48%) There were also significant differences in the form, dose, and content of proanthocyanidins in cranberry products measured in these studies Nine studies used cranberry juice, four used capsules or tablets, and the daily dose range was 0.4-194.4g Three randomized controlled trials were excluded from the quantitative analysis, and the results of 1494 subjects were summarized (794 were treated with cranberry and 700 as controls) Preliminary analysis showed that the protective effect of cranberry was not statistically significant, but the results were highly heterogeneous One of the 10 studies was an important source of heterogeneity When this "outlier" study was excluded, the heterogeneity was significantly reduced, and the RR of the result was 0.62, suggesting that cranberry products had significant effect in preventing UTI This result is very close to the previous Cochrane analysis Inclusion of more recent studies allowed researchers to assess the effect of cranberry products on some subgroups of patients Subgroup analysis showed that cranberry juice may be more beneficial than tablet or capsule Subjects who drank cranberry juice may have better hydration In addition, the researchers believe that cranberry juice may contain a hitherto unknown substance that can play a superimposed or synergistic protective role, while other products do not contain this substance Another subgroup analysis suggests that frequent use may be more effective than taking one or two times a day Because some previous in vitro studies reported that "after drinking cranberry juice, the anti adhesion activity of E.coli flagella can last for about 8 hours, and it should be more effective if taken more than twice a day" The researchers concluded that cranberry products may have the effect of UTI prevention, and cranberry juice is more effective than tablets and capsules, and the preventive effect is better when taken more than twice a day.