The amount of caffeine that's typically found in two cups of coffee may contribute to urinary incontinence in men, according to a new study.
"It's something to consider. People who are having problems with urinary incontinence should modify their caffeine intake," said Dr Alayne Markland, the study's senior author, from the University of Alabama at Birmingham.
The report doesn't prove that caffeine causes bladder leakage, but the men in the study who consumed the most caffeine were more likely to have the problem than those who consumed the least.
Plenty of research has linked caffeine to incontinence among women. But little is known about whether there is a similar connection for men.
It's estimated that 85% of Americans consume caffeine regularly, both in beverages like coffee, tea and soft drinks, and in foods like candy, pastries and ice cream containing chocolate.
Estimates of urinary incontinence among US adult men range from 5% to 21%.
How the study was done
For the new study, Dr Markland's team used responses from about 4 000 men to the National Health and Nutritional Examination Surveys (NHANES) 2005-06 and 2007-08. The researchers looked at how many had urinary incontinence and how much caffeine they ate or drank, as well as how much water they took in from both foods and beverages.
Overall, the men consumed an average of 169 mg of caffeine every day. That's a little more than the typical 125 mg in a cup of coffee.
About 13% reported leaky bladder, but only 4.5% had a problem considered moderate or severe, i.e., more than a few drops of urine leakage during the course of a month.
After adjusting for the men's age and other risk factors, the researchers found that those who consumed at least 234 mg of caffeine every day were 72% more likely to have moderate to severe urinary incontinence than those who consumed the least caffeine.
What the study found
Men who consumed more than 392 mg of caffeine daily were more than twice as likely to be incontinent.
Total water intake, in contrast, was not linked to a man's risk of moderate to severe incontinence.
It's not just a matter of how much fluid a person takes in. Dr Markland said that some research in women suggests caffeine irritates the bladder, and she believes that may also underlie the association in men.
"Although we didn't prove that in the study, that condition has been documented in women and we may need further evaluation in men," she said.
Dr Bryan Voelzke, from the Department of Urology at the University of Washington Medical Center in Seattle, said the medications such as diuretics could also affect men's bladder control.
This study on its own is not enough to say caffeine is the source of urinary incontinence, according to Dr Voelzke.
"I think - if anything - it's a suggestion. I don't think it's a call for action to stop drinking coffee," he said.