Research shows that patients often seek advice on dietary intervention in order to help their IBS symptoms . Understandably, patients want to know which foods to avoid and which are safe to eat.
For many patients a transition to a simple healthy eating pattern may be sufficient to reduce symptoms considerably.
Over the last few years considerable research has been focused on looking for more specific and effective dietary solutions for IBS, in particular the Low FODMAP Diet and the gluten free diet. Indeed, the Low FODMAP Diet is discussed for IBS in the NICE Guidance , NASPGHAN, Academy of Nutrition and Dietetics and in the British Dietetic Association IBS Guidance .
The low FODMAP diet
The Low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet was developed by a team from Monash University in Melbourne, Australia. The mechanisms by which these fermentable carbohydrates provoke gut symptoms are due to two underlying physiological processes: first, they are indigestible and subsequently fermented by the bacteria in the colon, which leads to gas production. The resulting gas can alter the gut environment and cause hypersensitivity in those who are susceptible to gut pain . Secondly, there is an osmotic effect whereby fermentable carbohydrates increase water delivery to the colon leading to altered bowel habit .
There have been three randomized controlled trials published showing a clear benefit of using the Low FODMAP diet [4,6,7] and this data, along with three prospective uncontrolled trials [8-10] and two further retrospective trials [11,12], has led to fermentable carbohydrate restriction becoming an important consideration in IBS treatment. Research indicates that patients using this diet report a marked improvement in symptoms, with up to 70% of patients reporting benefits .
Where are FODMAPs found?
|Fermentable carbohydrate||Type||Relevant foods|
|Oligosaccharides||Fructans, galacto-oligosaccharides||Wheat, barley, rye, onion, leek, white part of spring onion, garlic, shallots, artichokes, beetroot, fennel, peas, chicory, pistachio, cashews, legumes, lentils and chickpeas|
|Disaccharides||Lactose||Milk, custard, ice cream and yogurt|
|Monosaccharides||Free fructose (fructose in excess of glucose)||Apples, pears, mangoes, cherries, watermelon, asparagus, sugar snap peas, honey, high-fructose corn syrup|
|Polyols||Sorbitol, mannitol, maltitol, xylitol||Apples, pears, apricots, cherries, nectarines, peaches, plums, watermelon, mushrooms, cauliflower, sugar free chewing gum/mints/sweets|
A gluten-free diet for IBS
Research suggests that some patients with IBS (where celiac disease has been excluded) find symptom relief when following a gluten free diet [18-21]. The reasons behind this observation are debated among experts and may be related to the presence of non-celiac gluten sensitivity in a sub-group of IBS patients. It is also plausible that symptom improvement upon commencement of a gluten free diet is simply related to the concurrent reduction in the FODMAP content of the diet, namely a reduction in fructans found in wheat, barley and rye . When considering the use of a gluten free diet for the management of IBS it is vital to ensure celiac disease has been excluded prior to the removal of wheat and/or gluten from the diet.
Research showing the benefits of probiotics in the treatment of IBS is conflicting and may be hampered by the fact that the human gut can be populated by a wide-ranging composition of 1000-1150 different bacterial species  yet most probiotic supplements contain just a handful of species. Nevertheless, some probiotics have shown benefits and current NICE guidance  recommends that patients with IBS who choose to try probiotics should be advised to consume them for at least 4 weeks while monitoring the effect on IBS symptoms.
Pharmacological and alternative therapies
Pharmacological treatment options for the management of IBS should be based on symptom nature and severity. These may include antispasmodics, laxatives, anti-diarrheal agents, tri-clyclic antidepressants and selective serotonin reuptake inhibitors. Side effects from pharmacological therapies are common and symptom relief may be variable. Patients who do not respond to dietary or drug management of their symptoms may benefit from psychological interventions including hypnotherapy .
- Halpert A, Dalton CB, Palsson O, Morris C, Hu Y, Bangdiwala S, et al. What patients know about irritable bowel syndrome (IBS) and what they would like to know. National Survey on Patient Educational Needs in IBS and development and validation of the Patient Educational Needs Questionnaire (PEQ). Am J Gastroenterol. 2007;102(9):1972-82.
- National Institute for Health and Care Excellence. Irritable bowel syndrome in adults: diagnosis and management of irritable bowel syndrome in primary care. London: NICE; 2015.
- McKenzie YA, Alder A, Anderson W, Wills A, Goddard L, Gulia P, et al. British Dietetic Association evidence-based guidelines for the dietary management of irritable bowel syndrome in adults. J Hum Nutr Diet. 2012;25(3):260-74
- Ong DK MS, Barrett JS, Shepherd SJ, Irving PM, Biesiekierski JR, Smith S, Gibson PR, Muir JG,. Manipulation of dietary short chain carbohydrates alters the pattern of gas production and genesis of symptoms in irritable bowel syndrome. Journal of gastroenterology and hepatology. 2010;25(8):1366-73
- Murray K, Wilkinson-Smith V, Hoad C, Costigan C, Cox E, Lam C, et al. Differential effects of FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols) on small and large intestinal contents in healthy subjects shown by MRI. Am J Gastroenterol. 2014;109(1):110-9.
- Halmos EP, Power VA, Shepherd SJ, Gibson PR, Muir JG. A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology. 2014;146(1):67-75 e5.
- Staudacher HM, Lomer MC, Anderson JL, Barrett JS, Muir JG, Irving PM, et al. Fermentable carbohydrate restriction reduces luminal bifidobacteria and gastrointestinal symptoms in patients with irritable bowel syndrome. The Journal of nutrition. 2012;142(8):1510-8.
- de Roest RH, Dobbs BR, Chapman BA, Batman B, O'Brien LA, Leeper JA, et al. The low FODMAP diet improves gastrointestinal symptoms in patients with irritable bowel syndrome: a prospective study. Int J Clin Pract. 2013;67(9):895-903
- Mazzawi T, Hausken T, Gundersend D, El-Salhy M. Effects of dietary guidance on the symptoms, quality of life and habitual dietary intake of patients with irritiable bowel syndrome. Mol Med Rep. 2013;8:845-52.
- Wilder-Smith C, Materna A, Wermelinger C, Schuler J. Fructose and lactose intolerance and malabsoprtion testing: the relationship with symptoms in functional gastrointestinal disorders. Aliment Pharmacol Ther. 2013;37:1074-83.
- Gearry R, Irving PM, Barrett JS, Nathan DM, Shepherd SJ, Gibson PR. Reduction of dietary poorly absorbed short-chain carbohydrates (FODMAPs) improves abdominal symptoms in patients with inflammatory bowel disease - a pilot study. Journal of Crohns and Colitis. 2009;3(1):8-14
- Ostgaard H, Hausken T, Gundersend D, El-Salhy M. Diet and effects of diet management on quality of life and symptoms in patients with irritable bowel syndrome. Mol Med Rep. 2012;5:1382-90.
- Staudacher HM, Irving PM, Lomer MC, Whelan K. Mechanisms and efficacy of dietary FODMAP restriction in IBS. Nat Rev Gastroenterol Hepatol. 2014.
- Gibson PR, Shepherd SJ. Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. Journal of gastroenterology and hepatology. 2010;25(2):252-8.
- Shepherd SJ, Lomer MCE, Gibson PR, Rome Foundation Working Group: Short-chain carbohydrates and functional gastrointestinal disorders; Am J Gastroenterol; 2013, 108: 707-717
- Staudacher HM, Whelan K, Irving PM, Lomer MC. Comparison of symptom response following advice for a diet low in fermentable carbohydrates (FODMAPs) versus standard dietary advice in patients with irritable bowel syndrome. J Hum Nutr Diet. 2011;24(5):487-95.
- Gibson PR, Barrett JS, Muir JG. Functional bowel symptoms and diet. Intern Med J. 2013;43(10):1067-74.
- Biesiekierski JR, Newnham ED, Irving PM, Barrett JS, Haines M, Doecke JD, et al. Gluten causes gastrointestinal symptoms in subjects without celiac disease: a double-blind randomized placebo-controlled trial. Am J Gastroenterol. 2011;106(3):508-14; quiz 15.
- Biesiekierski JR, Muir JG, Gibson PR. Is gluten a cause of gastrointestinal symptoms in people without celiac disease? Current allergy and asthma reports. 2013;13(6):631-8.
- Vazquez-Roque MI, Camilleri M, Smyrk T, Murray JA, Marietta E, O'Neill J, et al. A controlled trial of gluten-free diet in patients with irritable bowel syndrome-diarrhea: effects on bowel frequency and intestinal function. Gastroenterology. 2013;144(5):903-11 e3
- Shahbazkhani B, Sadeghi A, Malekzadeh R et al. Non-Celiac Gluten Sensitivity Has Narrowed the Spectrum of Irritable Bowel Syndrome: A Double-Blind Randomized Placebo-Controlled Trial. Nutrients. 2015 7(6): 4542-4554.
- Biesiekierski JR, Peters SL, Newnham ED. No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates. Gastroenterology 2013. 145(2):320-8.
- Whelan K. Probiotics and prebiotics in the management of irritable bowel syndrome: a review of recent clinical trials and systematic reviews. Current opinion in clinical nutrition and metabolic care. 2011;14(6):581-7.