If you're reading this on the loo, you're probably a man. The anecdotal evidence (there's no other kind) suggests it's largely men who pile up magazines, dog-eared books and newspaper supplements next to their toilet. If you're in the habit of reading on the loo - or even take your tea and biscuits in with you, as some men have been known to - then you could be damaging your health.

Experts are warning that if you sit for too long on the loo, you're likely to strain too much, which, in severe cases, could literally turn your bowels inside out.

And it gets worse. Apparently sitting too long on the toilet is just one of the many things we Brits are doing wrong, lavatory-wise. The reason is simple: we revel in toilet humour, but most of us are reluctant to discuss poo-related issues. Surveys suggest that few of us would complain even to our partners about constipation, diarrhoea, bleeding or incontinence.

So where are we going wrong on the toilet?

One common set of misconceptions surrounds how often we should go. The belief that once a day is the norm is outdated, according to Professor Roger Grace, a specialist in colorectal surgery at New Cross Hospital in Wolverhampton. "The thought that you should open your bowels once a day is a hang-over from Victorian times," he says. "At school, matron would come round each day and give a tick to those who had opened their bowels and give syrup of figs to those who hadn't. People get very obsessed with their bowels, and there is no doubt that they are much happier if they do open them every day."

But this pressure can cause people to strain, provoking problems such as haemorrhoids, enlarged veins in the lower section of the rectum or anus, and fissures (cracks in the anal canal).

"We don't know exactly why haemorrhoids occur but if you strain they are likely to drop towards or outside the anus," says Grace.

The Digestive Disorders Foundation claims a normal bowel habit can range from three times a day to three times a week, but other experts disagree. Dr Gillian McKeith, a colonic irrigation proponent who runs a "cleansing" clinic in Hampstead, north London, believes twice a day is best. "Most people look stunned when I say that but they often suffer from headaches, tiredness and painful period pains because they are not going enough," she says.

"Many people are constipated without knowing it. They can go to the loo but they don't get it all out."

McKeith believes most bowel problems are caused by a bad diet, but she also blames a poor sitting position, pointing out that we are designed to squat down, not sit, when we go. "The modern toilet was designed by a plumber, not a doctor," she says. "It helps the bowels if you sit in a simulated squatting position. I know someone who puts their feet on the seat, but an alternative is to put your feet on a pile of Guardians, about 10-12 inches off the ground."

If waste is not ejected from the body, it can go toxic in the intestines and contribute to many illnesses, McKeith claims colonic irrigation can clear this residue out. "The bowel is like a dirty sink, full of old fat, dripping and lard, and eventually you have to call in the plumber," she says.

In Chinese medicine the bowel is said to be the emotional centre of the body. Edward Kiff, consultant colorectal surgeon at Manchester University Hospital, certainly believes emotional problems can impact on the bowel. "Just as people display stress by biting their finger nails, they can project their problems onto their bowels," he says. "They don't go or they are forever going, then they develop mechanical problems."

An example of a severe mechanical problem is a rectal prolapse where the rectum, the last section of the intestine between the colon and the anus, is turned inside out and can come out with a stool. Jeanne Vervialle, who runs the Colonic Irrigation Clinic in Kensington, west London, believes many of her patients hang on to their stools in the same way they hang on to their emotions. "The English have been taught to suppress their emotions and this is linked to their bowels," she says. "They are so intent on holding in their emotions that they hold on to their stools."

Vervialle claims to treat many women who are too inhibited to go to the loo when they need to. "If you don't listen to the call of nature when you need to, it gets impacted on the colon wall and can trap bacteria and release toxins into your body," she says.

"Young girls with new boyfriends or husbands, especially, are scared to go to the loo in case it smells, so they won't go in the house."

Experts do agree that many hang-ups can be traced back to childhood. Jenni Smith, a chartered educational psychologist, says: "Funny attitudes can emerge from parents being too overbearing, either not wanting any mess or not giving their child any boundaries at all and allowing them to pee all round the house. But it is such a natural thing for children to learn to do that parents should just relax and be very positive."

Controlling the bowels is not just a problem which children have to deal with. Researchers estimate 8% of adults, and 10-30% of women aged 15-64, suffer from incontinence. Yet only 25% of sufferers seek help. Kiff believes the social stigma attached to stains and smells makes the plight of sufferers much worse. Many are left house-bound.

He claims there is a lack of funds for research into bowel and bladder problems because people are too embarrassed to talk about it at all levels of society. "Moving your bowels is a very secretive thing to do, we go into a small room and lock and bolt the door," he says. "There is no vocabulary for it so people cannot talk about it.

"This is virtually the one area of human function left which we don't talk about. Eating food has become a social act, but letting that food out the other end is a total taboo."