Irritable bowel syndrome is an embarrassing illness. The symptoms are unpleasant: painful stomach cramps, bloating, diarrhoea and constipation.
In the worst cases it can be so debilitating as to prevent people from working.
Yet IBS affects one in five people -- many of whom are suffering in silence -- and is twice as common in men as in women.
I was 22 when I first started having problems with my digestion. I was living in the countryside in the southern Japanese island of Kyushu, where hardly anyone spoke English. As a consequence, I was lonely and stressed, and these feelings were compounded by trying to keep up a long-distance relationship with my boyfriend at the time, who was living back home.
My weekends were spent with friends in karaoke bars, and initially I just put down my IBS-related symptoms to too many nights on the beers and cocktails.
My diet had also changed. I had been vegetarian for six years, but in Japan I started to eat fish, as it would have been almost impossible to live there without it.
I was teaching English in junior high schools and began to drink a bottle of school milk every day with the students, as I thought I could do with the protein and calcium. This, I now know, was probably the worst thing I could have done.
I started to suffer from excruciating stomach cramps and my digestive system became more and more messed up.
Eventually, I took myself off to a hospital to find out what was wrong.
The doctor's sole piece of advice was to tell me to avoid drinking orange juice. As I had been caning a couple of cartons a week, I thought he had a point and immediately cut it out of my diet.
But my symptoms persisted, on or off, for the rest of my four-year stay in Japan.
On my way back to the UK, I paid a visit to my brother who was living in Arizona.
Seeing me looking painfully thin after I had experimented with cutting wheat and dairy out of my diet, he immediately sent me off to see a specialist who booked me in for a sigmoidoscopy -- a scary-sounding examination of the lower part of the large bowel.
It was actually a painless procedure and the doctor assured me he could see nothing that could point to cancer in the lower bowel.
IBS is one of those mystery ailments that affects a large proportion of the population but doesn't have an obvious cause. It is believed to be linked to stress, which would explain why I developed it in Japan, while certain foods are thought to be triggers, provoking bouts of the disease.
There is no cure for IBS, though the symptoms do often ease or even disappear. So, once I had a label for my condition, I experimented with ways of controlling it. I started out with colonic irrigation, which is recommended to flush out the bowel, but it is not for the faint-hearted.
At the same time, I cut out wheat, gluten, dairy, meat, alcohol and caffeine -- in fact almost all things that makes eating and drinking fun -- and also took a course of probiotic supplements to add healthy bacteria to my gut.