Vegetarian diet may cut UTI risk

Adopting a vegetarian diet may reduce the risk of uncomplicated urinary tract infections (UTIs), a recent prospective study showed.

The study population comprised 9,724 individuals aged ≥20 years enrolled in the Tzu Chi Vegetarian Study (TCVS; comprising Buddhists from Taiwan) with no history of UTIs. A food frequency questionnaire was used to ascertain diet; a total of 3,257 and 6,467 participants identified as vegetarian and non-vegetarian, respectively (72.4 and 58.6 percent female, respectively). The participants were followed up for 10 years during which time there were 661 UTI incidents, 217 and 444 in vegetarians and non-vegetarians, respectively.

Compared with non-vegetarians, vegetarians in this study were older (mean 51.2 vs 50.1 years), were less likely to have smoked (10.8 percent vs 17.4 percent) or consumed alcohol (11.5 percent vs 16.5 percent), or have hypertension (15.7 percent vs 17.9 percent), diabetes (4.9 percent vs 7.2 percent), or hyperlipidaemia (2.4 percent vs 3.4 percent). They were also less likely to have conditions predisposing them to UTIs (hyperplasia or urinary tract tumour: 4.9 percent vs 7.0 percent; urolithiasis: 9.8 percent vs 11.5 percent; renal failure: 1.5 percent vs 2.1 percent). 

Vegetarians had a 16 percent reduced risk of UTIs compared with non-vegetarians (adjusted hazard ratio [adjHR], 0.84, 95 percent confidence interval [CI], 0.71–0.99; p=0.038). [Sci Rep 2020;10:906]

This reduced UTI risk in vegetarians was particularly notable in females (adjHR, 0.82, 95 percent CI, 0.69–0.99) and in never smokers (HR, 0.80, 95 percent CI, 0.67–0.95; p_interaction=0.029), as demonstrated in subgroup analysis.

The reduced UTI risk among vegetarians was specific to uncomplicated UTIs (adjHR, 0.81, 95 percent CI, 0.68–0.98), with no apparent impact in complicated UTIs (adjHR, 0.96, 95 percent CI, 0.67–1.37).

The association between a vegetarian diet and reduced risk of uncomplicated UTIs was independent of risk factors for UTI such as hypertension, diabetes, and hyperlipidaemia. “This suggests that the effect of vegetarian diet is not mediated through these related diseases,” noted the researchers.

Other factors associated with increased UTI risk were age (HR, 1.03; p<0.001), or having diabetes (HR, 1.57; p=0.001), urine retention (HR, 1.86; p=0.001), or renal failure (HR, 1.97; p<0.001). Men were at lower risk of UTI than women (HR, 0.29; p<0.001).

According to the researchers, recent studies have suggested that dissemination of extraintestinal pathogenic Escherichia coli, the strains that commonly cause UTIs and are similar to that found in meat, may occur via “food reservoirs and foodborne transmission.” [J Infect Dis 2005;191:1040-1049; Emerg Infect Dis 2010;16:88-95]

“As vegetarians avoid meat … we hypothesize[d] that a vegetarian diet may be associated with a lower risk of UTI,” they said.

Reasons cited for the reduced UTI risk were variance in gut and faecal microbiota between vegetarians and non-vegetarians and a greater consumption of plant-based phytochemical phenolics which may have antibacterial properties, said the researchers. However, the exact cause of the reduced risk remains to be determined.

The researchers pointed out that increasing antimicrobial resistance rates have led to challenges in antibiotic treatment of UTIs as well as the need for alternative treatment measures. “High phytochemical content in a healthy vegetarian diet may provide an alternative prophylaxis from and bactericidal effect against UTI,” they noted.