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.
Shortly after, back home, I registered with my GP. A colonoscopy revealed I didn't have the more serious Crohn's disease, and allergy tests showed I was mildly lactose intolerant. My milk habit had not been one of my greatest ideas.
IBS is not an illness as such. It is generally diagnosed when doctors can't find anything else wrong to explain the symptoms. Still, to have a diagnosis after five years of distress and hospital visits was a massive relief. It meant I could now work around trying to manage the problem.
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.
But I found it difficult to stick to the diet and soon got bored.
It was then that I had a bit of a breakthrough. My mum gave me Dr Gillian McKeith's You Are What You Eat book with its explanation of a "food separation diet". The TV presenter is not a medical doctor, but her regime has helped to turn my life around.
She advises those with a weak digestive system to avoid eating proteins and carbohydrates together as it makes them more difficult to digest.
And most important of all, she says, never eat fruit after a meal.
She also advises drinking warm water with lemon first thing in the morning instead of cold water and chewing food slowly.
The last is perhaps an obvious suggestion, but as I used to almost gobble my meals whole, it had an impact on my ability to digest.
Although I was only able to stick to food separation for a couple of weeks, my IBS symptoms gradually disappeared over the next six months.
Not everything can work for everyone. But I believe that by taking on board those suggestions that did me some good, and combining this with a balanced diet, packed with fresh vegetables, I have improved my well-being.
By taking the time to cleanse my system and give my body a break, I am now able to eat all those foods that I was advised to avoid.