Despite international guidelines that suggest cutting caffeine to counter urinary incontinence, a new study finds that coffee or tea may not have much effect on the condition.
In a study of more than 14,000 Swedish twins, researchers found that drinking tea did not significantly increase the odds of having a leaky bladder. When age was taken into account, coffee drinkers had a somewhat decreased risk of the urinary disorder.
There have been plenty of studies about incontinence and caffeine, but the results have been inconsistent, according to lead author Giorgio Tettamanti, a doctoral student in epidemiology at the Karolinska Institute in Stockholm, Sweden.
"What we found is not really surprising, but it goes against current knowledge," Tettamanti told Reuters Health by email.
Doctors sometimes tell women with urinary incontinence to try reducing caffeine intake, said Nancy Nairi Maserejian, an epidemiologist at New England Research Institutes, Inc., in Watertown, Mass..
"It's actually part of the guidelines," Maserejian, who was not part of the study, told Reuters Health. Practice recommendations for doctors from the National Collaborating Center for Women's and Children's Health in the U.K. are used as international guidelines, she said.
But the new finding doesn't mean that women with leaky bladders should start downing lattes.
"I don't think we can make a blanket statement from this study," Maserejian said. "Moderation is key and women have to talk to their physicians and decide what works for them."
Tettamanti and co-workers ran an online survey of sets of female twins, asking about caffeine-consumption habits as well as urinary incontinence symptoms. In all age groups, slightly more than 900 of the women reported having at least one leaky bladder symptom.
Initially, the researchers found that about nine out of 100 coffee drinkers had urinary incontinence, compared to about six out of 100 non-coffee-drinkers.
However, when they adjusted their analysis to take into account other potential contributing factors -- including age, body mass index (a ratio of weight to height), smoking and whether the women had given birth - there was actually a decreased risk of incontinence, by about 22 percent, among coffee drinkers.
It turns out the coffee drinkers tended to be older and their age explained most of the original higher rate of incontinence, the report notes.
The researchers did not have sufficient information, though, to determine whether the seeming protective effect of coffee drinking came from the fact that women with incontinence might be avoiding coffee -- so women without incontinence would be more likely to be among the coffee drinkers.
Tettamanti's group did find a link between drinking tea and overactive bladder -- the sudden need to urinate, usually several times a day. Again, however, when they compared members of both identical and fraternal twin pairs, the association went away.
Comparing twins to each other allows researchers to tease apart inherent predispositions, like a family tendency to develop incontinence, from learned behaviors and other outside influences.
The study was published in the obstetrics and gynecology journal, BJOG.
In the U.S., between one and two out of 10 women report weekly bladder leakage, according to the Centers for Disease Control and Prevention.
Even though the current study didn't find an increased risk of urinary incontinence in people who drink coffee or tea, Tettamanti suggested that limiting these beverages may reduce total fluid intake and consequently how full the bladder becomes.
Drinking less fluid does not seem to help women avoid developing incontinence, another large study of women recently concluded (See Reuters Health story of March 11, 2011). Decreasing fluids can improve leaky bladder symptoms among women who are already incontinent, though, Tettamanti said.
"However, keep in mind that fluid restriction may cause troublesome constipation among elderly patients, and elderly subjects are more likely to experience urinary incontinence," he said.
More people have urinary incontinence as they get older, Maserejian agreed. "The bladder is muscle and the ability to hold the urine in weakens."
Genetic factors, childbearing, and greater body weight, especially around the waist, can also increase the risk of leaky bladder. Weight reduction can improve urinary incontinence, she said.
Women with incontinence should "ask about their specific situation and what their provider would suggest for them," Maserejian said.