Some types of tea can cause bladder irritation that may play a role in increased susceptibility to urinary tract infection. Bladder infection itself is caused by bacteria---usually E. coli---that take up residence in the bladder and then multiply. For this reason, tea itself can't directly cause infection, but its bladder-irritating properties may contribute to the inflammation that makes infection more likely.
Caffeine and the Bladder
There are many different types of tea available on grocery store shelves, including herbal teas and blends marketed to treat specific complaints like PMS and anxiety. Most caffeinated varieties have the potential to cause irritation in the urinary tract. These include black, green, white and oolong tea blends. These contain antioxidants and other healthy compounds and need not be avoided entirely, but should be limited to decrease harmful effects caused by excessive caffeine intake.
Caffeine is a known bladder irritant. It causes inflammation in the urinary tract, which can make it easier for bacteria to attach to bladder walls due to improper immune response. In other words, while the immune system should be attacking the bacteria, it's attacking the bladder itself in the form of inflammation, allowing the bacteria to escape unharmed and multiply in the bladder.
Tea as a Diuretic
The caffeine in tea is considered a diuretic, meaning it increases urine output. The downside is that bacteria present in small amounts can more easily multiply when the urine is highly concentrated and not enough water is available to dilute the urine.
Tea, coffee and other caffeinated beverages increase the frequency of urination as well, which may further irritate an already-inflamed urinary tract due to repeated wiping and passing of small amounts of highly concentrated urine.
Owing to its diuretic properties, caffeinated tea is capable of causing dehydration. Urinary infections are much less likely to occur when you're well hydrated as pure water is needed to flush bacteria out of the bladder and urethra. To avoid caffeine-induced dehydration, replace caffeinated beverages with plain water or herbal tea, and drink 473ml of water each day.
Other Contributing Factors
Tea and other caffeinated substances are more likely to lead to bladder infection if other contributing factors are present. Diet, hygiene and immune function all play a role in the occurrence of bladder infections.
To avoid urinary tract irritation, don't use harsh soaps and deodorants on the genital area, and always wash and urinate immediately after sex. Drink 454gr of water each day, and avoid excess sugar and caffeine intake. Consuming 100 per cent cranberry juice may help prevent bladder infection for some women. According to RenalandUrologyNews.com, cranberry juice is as effective as the antibiotic trimethoprim in preventing recurrent UTIs in older women.
If you suffer from repeated urinary tract infections, your immune system may not be functioning at its peak. Eating a balanced diet and supplementing with a daily multivitamin can aid in optimal immune function, as can some herbs like astragalus and Siberian ginseng.