Drinking tea and smoking heavily has been linked to urinary incontinence in women, research suggests.
Tea drinking is linked to incontinence
A study found smoking more than 20 cigarettes a day was linked to the complaint.
The common myth about urinary incontinence is that it only affects the elderly, but the condition affects one in 10 people.
Up to 25% of women and 5% of men aged 15 to 64 are affected.
Norwegian researchers surveyed almost 28,000 women aged over 20 in the Nord-Trøndelag area of the country between 1995 and 1997.
They wanted to see if smoking, obesity, physical activity and the drinking alcohol, coffee or tea were associated with urinary incontinence in women.
Over 6,870 were found to have some sort of urinary incontinence.
It can take the form of stress incontinence, where sneezing, laughing, coughing, or heavy
lifting can cause urine to leak or urge
incontinence, where there is a sudden need to urinate.
Those who currently or formerly smoked more than 20 cigarettes a day were found to be at a higher risk of incontinence.
The condition was also more prevalent in older women and those with a higher body mass index.
Studies are needed to investigate whether a reduction of number of cigarettes smoked or intake of tea will reduce incontinence symptoms
Dr Yngvild Hannestad, University of Bergen
Tea drinkers were at slightly higher risk for all types of incontinence.
Women who did more low-intensity physical activity were less likely to suffer incontinence, the study found.
High intensity physical activity and drinking alcohol or coffee had no effect on incontinence risk.
Writing in the British Journal of Obstetrics and Gynaecology, Dr Yngvild Hannestad and colleagues from the University of Bergen, who carried out the research, said: "This large study is the first to show a dose-response effect of smoking on incontinence in an unselected population and investigate the effect on the different types.
"Intervention studies are needed to investigate whether a reduction of number of cigarettes smoked or intake of tea will reduce incontinence symptoms.
"The relation between physical activity and incontinence should also be further explored."
A second study by researchers at the university, published in the New England Journal of Medicine, found women who give birth by Caesarean are far less likely to develop incontinence than those who had their children naturally.
But women who had had Caesareans were more likely to have problems than women who never had a
child, the study of 15,000 women found.