Eating a vegetarian diet has been linked with a lower risk of having a urinary tract infection. But there are caveats to the study that mean the results are still unclear.
The infections are usually caused by bacteria from faeces entering the urinary tract. Chicken and pork are a major reservoir of Escherichia coli, a bacteria that commonly causes UTIs. So Chin-Lon Lin at Tzu Chi University in Taiwan and his colleagues looked at whether vegetarians would have a lower risk of UTIs than people who eat meat.
“We know vegetarians have a different flora in the gut. We tried to see if the infection [rate] of the urinary tract of the vegetarians was statistically significantly lower than the meat eaters. And we prove that it is,” says Lin.
The study looked at 9724 people in Taiwan over 10 years and found that vegetarians were 16 per cent less likely to have a UTI than their meat-eating counterparts.
But when the researchers analysed the diets of men and women separately, they found the protective effect of a vegetarian diet was present in women but not in men. UTIs are more common in women because of the shorter length of the female urinary tract.
Lin says vegetarians may have a lower risk of UTIs because they have a lower risk of exposure to E.coli. It is also possible that the high fibre content in their diet helps vegetarians to avoid constipation and so reduces the risk of E.coli growing in their gut, he says.
The research shows diet is a “very significant element” in preventing UTIs, says Lin, though he adds the group in the study may not reflect the general population. For example, the study participants were all Buddhists based in Taiwan, who were required to quit alcohol and smoking. About a third of the participants gave up meat to protect the environment and animals.
There are several other reasons the study may have overstated the link between a vegetarian diet and a lower risk of UTIs, says Amee Manges at the University of British Columbia in Canada.
The study only looked at diet once, at the outset, so meat eaters may have become vegetarian later and vice versa, says Manges. People under 20 and those who previously had a UTI weren’t included, which could have meant many younger women – whose age affects their risk of having a UTI – were removed too. And while the researchers tried to adjust for some factors, they didn’t account for pregnancy, which is a major risk factor for UTIs.
“I am glad they did the study, but the results are likely an overestimate for this relationship,” says Manges.