What you describe is typical of a condition called irritable bowel syndrome or IBS.

It's also sometimes called irritable bowel disease or IBD, but be careful because IBD also stands for inflammatory bowel disease. This includes Crohn's disease and colitis, which are different to IBS.

No one knows the cause of IBS but symptoms include:

• Abdominal pain, bloating and wind
• Diarrhoea or constipation, or episodes of both
• Passing mucus when you open your bowels
• Nausea and vomiting
• Depression, anxiety and stress

Stress is only part of the story

Because the cause is unknown, emotional or psychological factors are often blamed. While these can make it worse, they aren't the cause. What research is starting to show is that people with IBS seem to have a colon (also called the large bowel) that is super-sensitive.

The whole length of the bowel is controlled by a nervous system, which carries signals back and forward between the gut and the brain. Some experts believe this 'enteric' nervous system is faulty in people with IBS.

In IBS, the bowel responds with powerful contractions or spasms to stimuli that wouldn't bother other people, for example, simply eating food. The fact that many women with IBS find it's particularly bad just before or during their period has led researchers to suggest that female hormones may play a part.

There isn't a cure for IBS, but you can identify your triggers.

Watch your diet

• Make a food diary. Try to work out how your diet relates to your symptoms, by comparing what you have eaten with bad attacks.
• The gut normally responds to food by contracting, and the strength of the response seems to be linked to the amount of fat in the meal. So try to cut down on the fat in your diet. Avoid fat-rich food, such as dairy food, ensure your milk is skimmed or semi-skimmed, and cook with minimal fat by baking or steaming food rather than frying or roasting.
• Avoid large meals as they can trigger spasms. Instead, eat small amounts more often.
• Be careful about lactose (the sugar in dairy products) because this may aggravate IBS.

As many as one in ten people in the UK - and more among those of African or Asian descent - has lactose intolerance, as they lack the enzyme necessary to digest lactose. Lactose from foods passes undigested to the large bowel, where it is fermented by the gut bacteria, resulting in cramps and gas production. Lactose intolerance can cause symptoms very similar to IBS.

Cut down on dairy products and see if your symptoms improve. You can also try supplements of lactase –the enzyme that digests lactose.

The importance of soluble fibre

Fibre can help to reduce IBS symptoms and prevent spasms. But be careful what type of fibre you eat and how much you consume because people can react very differently. In diarrhoea, fibre may firm up and slow down the passage of stools, but some people with IBS also get constipation and then fibre can bulk up and soften stools, making them easier to pass.

But fibre can aggravate both constipation and diarrhoea. Current thinking is that soluble fibre is probably most helpful for people with IBS. High levels of soluble fibre are found in vegetables, such as potatoes, and some fruits (apples and citrus), dried beans, oats and barley.

Insoluble fibre may also be helpful for constipation. Good sources include wheat bran, whole grains, cereals, seeds and the skins of many fruits and vegetables.

Fibre supplements may be worth a try, too. You may find an increase in gas and bloating at first, but this will soon calm down.

Tackle stress

Try to get as much sleep as you need, ensure there's a least one set period each week when you can have some time exclusively for yourself (ideally, you should do this at least once a day) and take up some relaxation therapies.

Get expert help

There are drugs that can help reduce spasms in IBS. Talk to your doctor or pharmacist, especially if things get really bad.

A couple of words of warning. Occasionally, chronic gastrointestinal infections can lead to symptoms such as yours, so it's important you see your doctor to confirm the diagnosis is IBS.

Second, if you pass blood when you open your bowels, get checked by your doctor as this isn't normal, even in IBS.

This article was last medically reviewed by Dr Trisha Macnair in March 2008