Diets and Irritable Bowel Syndrome (IBS)
Many people have some symptoms of Irritable Bowel Syndrome (IBS) which include abdominal pain, abdominal bloating, loose stools or diarrhoea but some patients have constipation and some alternate between diarrhoea and constipation.
The range in symptoms can make the diagnosis of IBS difficult and before dietary exclusions are used for any length of time, it is important to make sure the diagnosis is correct. The difficulty is there is no specific test for IBS but there are a number of safety tests that should be considered to make sure another condition is not the cause of the symptoms. If symptoms have persisted for longer than six weeks a blood count to exclude anaemia and a stool sample to exclude infections are recommended. In addition blood tests to exclude inflammation and coeliac disease are usually carried out.
For people over the age of 60 years whose bowels have become looser or more frequent habit changes for longer than six weeks it is a national recommendation (by NICE) that they should seek medical advice. Some of these patients may need to undergo a telescope examination of the lower bowel (colonoscopy) to make sure no other medical problems are present.
For patients with rectal bleeding, the age recommendation drops to 40 years and over when further investigations are also usually needed.
For younger patients further investigations are normally only necessary if the symptoms are unusual or persist despite treatments. One of the treatments considered is changes to the diet. A high fibre diet was popular in the 1980s and can be helpful for patients with colicky abdominal pain but can also make abdominal bloating worse.
Abdominal bloating
Abdominal bloating can be very severe with patients describing being six months pregnant! The amount of bloating tends to vary during the day and can be brought on by various foodstuffs. In addition to fibre, the commonest food to cause bloating are onions. Interestingly other similar foods such as leeks and garlic can cause the same symptoms, and this is most likely as they come from the same family of foods called alliums. Avoiding these types of food can often be helpful, but is difficult as they are involved in so many types of cooking.
Another type of food worth considering is wheat. Some patients have a specific intolerance of gluten and have positive tests for Coeliac disease. Other patients have symptoms brought on by wheat but can tolerate other types of gluten in rye or barley. There is also a group of patients, increasingly recognised, who do not have positive tests for Coeliac disease but find that gluten in their diets leads to abdominal symptoms and prefer to avoid gluten anyway.
Ensuring enough vitamins and minerals are included in the diet, however, is important and people often improve on a relatively bland diet of non-processed meat and vegetables that avoid wheat, insoluble fibre and other cereal crops. This has been termed a paleolithic diet (or paleo diet), but there does not seem to be one diet that suits everyone, and some people find that only certain foods trigger their symptoms. Losing weight unintentionally is of concern, and when abdominal symptoms have persisted, or occur with weight loss, then patients should seek medical advice.
British Medical Journal Article
A recent review article in the British Medical Journal (Sept 2012) discussed FODMAP diets which may be of benefit (FODMAP is an abbreviation for fermentable oligosaccharides, disaccharides, monosaccharides and polyols and means fermentable sugars). Diets high in these sugars are thought to increase fermentation and lead to bloating and diarrhoea.
FODMAP containing foods include apples, brussel sprouts, cabbage and some artificial sweetners and diets containing increased amounts of these types of foods were associated with increased symptoms in IBS. This article also discussed certain antibiotics such as the non-absorbable rifaximin which has been shown in randomized trials to reduce IBS symptoms but this antibiotics is not licensed for IBS treatment as yet in the UK. Probiotic studies were further mentioned but these have been concluded by NICE to offer no clinical benefit.
