2013 Public Lecture
Beating the bloat: the FODMAP diet and Irritable Bowel Syndrome
Central Clinical School held its annual public lecture for 2013 on 30 October, on one of the most common complaints in our community, irritable bowel syndrome (IBS), and how diet can be used to control the symptoms.
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Professor Peter Gibson is an internationally renowned expert in the field. He presents on the problem of IBS and gut symptoms in general and about the world-wide fascination with dietary cures. He describes the controversy surrounding wheat intolerance, the most current research and outline the new dietary approach, the low FODMAP diet, that is changing the way doctors and dietitians help people with IBS to manage their problem.
This event was part of Melbourne Knowledge Week 28 October - 3 November 2013, proudly presented by the City of Melbourne. For more information visit: melbourne.vic.gov.au/knowledge.
About our speaker
Professor Peter Gibson is Head of the Gastroenterology Department in the Central Clinical School and The Alfred. Professor Gibson is a Gastroenterologist who has long-standing, active clinical and research interests in inflammatory bowel disease, coeliac disease and functional gastrointestinal disorders like irritable bowel syndrome. Together with Dr Jane Muir, he leads a program of research into diet and how it can be used to treat or prevent chronic intestinal illnesses. This research involves translating ideas and basic research from their laboratory to clinical medical and dietetic practice, including the implementation of new therapeutic programs across the community. An example has been the low FODMAP diet that has changed the face of medical and dietetic practice of people with IBS. He is an Editor on the American Journal of Gastroenterology and the Journal of Gastroenterology and Hepatology.
About irritable bowel syndrome, FODMAPs and gluten
A high proportion of the population suffer gut symptoms such as boating, discomfort, pain and change in bowel habits on an occasional and intermittent basis. If the symptoms are occurring frequently (e.g., for more than three months in one year), this group of symptoms are referred to as irritable bowel syndrome (IBS) when another cause for them such as coeliac or Crohn’s disease is not present. While IBS is not associated with increased risk of death or nasty complications, its significance to the community cannot be underplayed – it affects about 10-15% and is the second most common cause of absence from school or work.
Frequently, wheat is considered the ‘enemy’. About 20% of the Australian population is now avoiding wheat and many are following a gluten-free diet. Reasons for this are not clear but, in the vast majority, it is not for coeliac disease, but rather it is to improve bloating or just because gluten is ‘bad for you’. There is little doubt that wheat can trigger bloating and other symptoms in many, but what is controversial is which component(s) of wheat is/are responsible. The two parts of wheat most implicated are proteins, comprising mostly but not exclusively gluten, and carbohydrates, comprising digestible and easily absorbed components (sugars and starches) and indigestible components (fibre and FODMAPs). The major controversy at present is whether it is the gluten or the FODMAPs that are the major trigger of symptoms.
FODMAPs are found in a wide variety of foods, not only in wheat products. They are sugars and short-chains of sugars that are poorly absorbed in the small bowel. They drag more water in to the bowel and are fermented by the abundant bacteria in the large bowel, generating odourless gases (hydrogen, carbon dioxide and methane). The sum effect of these actions is to distend the bowel which, if the bowel’s nervous system is sensitively tuned (as in people with IBS), may cause bloating, pain and change in bowel habits. Hence, FODMAPs might trigger symptoms of IBS and reduction of their intake in the diet might then reduce those symptoms. There is now a wealth of studies that have confirmed that the Monash University low FODMAP diet does lead to marked improvement in gut symptoms in three out of four people taught the diet.
Gluten is the major protein in wheat. About 1% of Australians have an immune reaction to a part of the gluten and this damages the small bowel lining. This is a well-defined condition, coeliac disease, and it responds well to a gluten-free diet. However, the real controversy is whether gluten causes trouble in those who do not have celiac disease, an entity that has been termed ‘non-coeliac gluten intolerance’ (NCGS). Recent scientifically rigorous studies from our group have not been able to confirm that such an entity indeed is present, although there is some evidence that gluten might contribute to some of the symptoms.
Thus, what the science tells us is that wheat can trigger symptoms, that it is the FODMAP content that causes most of the problem, and that gluten cannot currently be blamed as a major player in generating those problems.
The design of the low FODMAP diet has been based on scientific knowledge of food composition (defined in our own laboratories) and gut physiology. High quality and up-to-date information is available to all (in the form of the Monash University Low FODMAP diet app). However, it is a diet that is effective for IBS symptoms but not a diet to be extended to everyone ‘for good health’. FODMAPs have potentially beneficial effects for our bowel and body alike, and the longer term effects of restricting FODMAPs is currently under scrutiny.
Our current recommendation is that those who have had a very good response to the low FODMAP diet de-restrict their diet gradually to find what level of FODMAP intake they can tolerate. In fact, many do not need the strict diet in the longer term, but can remain well with few symptoms with only some restriction (such as avoiding onions, consuming only small quantities of wheat-flour-based products).
For more about the low FODMAP diet, see http://www.med.monash.edu/cecs/gastro/fodmap/.