Irritable bowel syndrome (IBS) is the most common problem to affect the gut. Worldwide, one in nine people are affected at any one time, but at least one in three people experience symptoms at some time during their life. Irritable bowel syndrome and diet go hand in hand, and following the nutritional approaches and the IBS diet food list below, can significantly improve symptoms for at least four out of five people with IBS.
Symptoms of IBS
IBS is not just a problem of bowel function. It is now recognised as a disorder of gut-brain interaction, and new diagnostic guidelines – known as the Rome IV Criteria – have simplified the diagnosis of bowel disorders.
For doctors to diagnose Irritable Bowel Syndrome, you must have recurrent abdominal pain which occurs, on average, at least one day a week, and is associated with at least two of the following:
- opening the bowels
- a change in stool frequency
- a change in stool form (constipation, diarrhoea or both).
The different sub-types of irritable bowel syndrome are irritable bowel syndrome with:
- Predominant constipation (IBS-C)
- Predominant diarrhoea (IBS-D)
- Mixed bowel habits (IBS-M)
- Unclassified, where bowel habit is not predominantly one or the other (IBS-U).
According to a review of 80 studies, involving over 260,000 people worldwide, each of the IBS subtypes has a similar prevalence of around one quarter of all cases.
Irritable bowel syndrome isn’t a diagnosis you should make yourself, however. You should always seek medical advice if these symptoms occur and keep going back to your doctor if symptoms change or worsen or the diagnosis of other bowel problems may get delayed.
What else could it be?
The diagnosis of IBS is not always clear-cut, as there is no single diagnostic test to confirm its presence. Your doctor will consider other conditions with similar symptoms, such as functional constipation, functional diarrhoea, functional abdominal bloating/distension, inflammatory bowel disease (Crohn’s, ulcerative colitis), food sensitivities such as coeliac disease or lactose intolerance. They will also want to exclude cancer of the bowel, ovaries or other internal organs.
But while keeping these possibilities in mind, it’s also important to avoid unnecessary tests if you don’t have ‘red flag’ symptoms. Factors such as a family history of bowel or ovarian cancer, weight loss or blood in the motions should always be taken seriously and lower the threshold for investigation.
The new Rome IV guidelines also suggest that anyone who develops bowel symptoms for the first time over the age of 50 should be offered appropriate tests such as a screening colonoscopy, and careful follow-up. That follow-up is important – don’t be afraid to keep going back to your doctor if your symptoms persist, worsen or change and you feel something isn’t right.
The cause of IBS
The exact cause of IBS remains poorly understood, but appears to involve interactions between the brain and gut. Normally, the brain filters out all the sensations involved with gut contraction and moving solid wastes through the gut, so they do not reach conscious thought. With IBS, these sensations are brought to the forefront and increased sensitivity of pain or stretch receptors in the gut lining trigger discomfort.
Imbalances in bowel bacteria are also involved, and symptoms are often triggered by events that suppress levels of beneficial ‘probiotic’ bacteria, such as food poisoning, taking antibiotics, food intolerances, long-term stress or surgery. These factors may affect intestinal permeability and alter the balance of digestive bacteria.
Bacteria within the bowel secrete substances that affect gut permeability, plus gases which can cause distension and bloating. Bacteria also secreted chemicals that affect local immunity and which have indirect effects on the brain.
Serotonin is best known as a brain transmitter that regulates mood, but 90% of the body’s serotonin is actually made within the lining of the digestive tract. If the balance of gut bacteria changes, so can serotonin production. That’s why IBS is now considered a disturbance of brain-gut interactions, rather than a pure gut problem.
IBS and diet
Up to two-thirds of people with IBS benefit from avoiding foods that can trigger symptoms. Common culprits include wheat, gluten, lactose, yeast, excess sugar and artificial sweeteners. Following a diet that is low in fructose, lactose and other sugars, and sweeteners can help – this is known as a low FODMAP diet.
FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols. Basically, these are a group of fermentable (gas-producing) sugars and fibres.
Eating foods high in FODMAPs increases the volume of liquid and gas in the small intestine which can trigger IBS symptoms. But if you select foods that are low in FODMAPs symptoms such as pain, diarrhoea and bloating usually improve.
Researchers have found that following a low FODMAP diet helps three out of four people with IBS manage their symptoms of constipation, diarrhoea (or both), abdominal pain and distention, excessive flatulence, fatigue and mood swings.
While originally developed by researchers in Australia, the low FODMAP diet is now recognised in the UK within NICE guidelines for managing irritable bowel syndrome symptoms.
The low FODMAP diet
The following chart shows which foods are high or low in FODMAPs. Everyone is different, however, and some foods on the low FODMAP list you may not tolerate, and some on the high FODMAP list you may tolerate well.
The effect of FODMAPS is cumulative, so eating a lot of low FODMAP foods can add up and cause symptoms you would not normally experience, especially with fruits. It’s usually a good idea to limit yourself to one low FODMAP fruit per meal, and to ensure the fruit is ripe.
Similarly, limit yourself to one alcoholic drink per day as alcohol can irritate the gut to trigger symptoms.
If your symptoms are triggered by eating wheat, good alternatives include buckwheat (which despite its name is a gluten-free member of the rhubarb family), hempseed, brown rice, red rice, wild rice (a grass seed), corn, soy, amaranth, teff, quinoa, chia seeds, gram/chickpea flour, millet and tapioca.
I also advise avoiding caffeine and chewing gum which can make symptoms worse.
|Low FODMAP foods to try|
||Lactose free milks* like oat milk, rice milk, soy milk, almond milk, hemp milk
Butter, eggs, lactose-free yogurt
Cheddar, Feta, Mozzarella, Parmesan, Swiss cheese
*check all for additives
|Fruit||Banana, blueberries, clementine, coconut, cantaloupe, honeydew, grapes, guava (ripe), lemon, lime, kiwi, pawpaw/papaya, pineapple, raspberry, rhubarb, strawberries|
|Vegetables||Alfalfa, aubergine/eggplant, bamboo shoots, bean sprouts, bell peppers, bok choy, butternut squash, cabbage, carrots, celeriac, celery, courgette/zucchini, cucumber, green beans, endive, fennel, ginger, kale, lemon, lettuce, lime, mandarin, marrow, okra, olives, orange, passion fruit, parsnips, potato, pumpkin, radish, rocket, seaweed, spinach, swede, sweet potato, Swiss chard, tomatoes, turnip, water chestnuts, yam|
|Grains||Gluten and wheat free breads and cereals (check labels), buckwheat, corn, rice, quinoa, millet and pasta/bread made with them, arrowroot, psyllium, polenta, oats|
|Nuts and seeds
(10-15 max or 1-2 tbsp)
|Almonds, Brazils, chia and flaxseeds (linseed), chestnuts, hazelnuts, macadamias, peanuts, pecans, pine nuts, poppy seeds, pumpkin seeds, sesame seeds, sunflower seeds, walnuts|
|Meat||Fresh unprocessed meats (beef, chicken, duck, goose, lamb, pork, turkey), fish (white and oily), seafood (crab, lobster, mussels, prawns, shrimp etc), canned tuna|
|Sweeteners||Table sugar (sucrose), glucose, maple syrup, stevia|
|Alcohol||Most wines and beers, vodka, gin|
|Others||Most herbs and spices, cacao/cocoa powder, peppermint tea, quorn, vinegar,|
|High FODMAP foods to avoid|
|Dairy||Cows’ milk, sheep’s milk, goats’ milk; buttermilk, cream, custard, evaporated milk, ice cream, kefir, soft cheeses like cottage cheese, cream cheese, fromage frais, ricotta, mascarpone, yoghurt|
|Fruit||Apple, apricots, avocado, blackberries, black currants, cherries, dates, figs, goki berries, grapefruit, lychee, mango, nectarine, pear, peaches, pears, plums, pomegranate, prunes, raisins, sea buckthorn berries, sultanas, watermelon|
|Vegetables||Artichokes, asparagus, beetroot, broccoli, Brussels sprouts, cabbage, cauliflower, fennel, garlic, leek, mushroom, onions, pumpkin, shallots, spring onion, sugar snap peas (mangetout)|
|Legumes||Baked beans, broad (fava) beans, butter beans, chickpeas, haricot beans, kidney beans, lentils, lima beans, mung beans, soy beans (some soy milks), split peas|
|Grains||Rye, barley, bran cereals, wheat in large amounts (including bread, crackers, cookies, cous cous, pastries), inulin (chicory root)/FOS, muesli, spelt|
|Meat||Processed meats (eg chorizo, sausages, burgers etc)|
|Sweeteners||Agave, High Fructose Corn Syrup (HFCS), fructose, honey, sorbitol, maltitol, mannitol, xylitol (sugar-free sweets, gum, mints, cough drops, some medication)|
|Others||Chamomile, carob, dandelion teas, hummus, jams, tahini, teas (green, black, oolong, chai)|
High FODMAP ingredients are often hidden in foods, so it’s important to check ingredient labels.
When cutting out foods, it’s important to avoid nutritional deficiencies, and a good multivitamin and mineral supplement is essential.
Click here to read my review of the best multivitamin supplements.
How effective is the low FODMAP diet?
A study in the UK involving 82 people with irritable bowel syndrome compared the effects of a low FODMAP diet against a standard English diet for 9 months. More people following the low FODMAP approach reported symptoms improvements (86% versus 54%) with significant reductions in bloating, abdominal pain and flatulence, although only sixty-four percent strictly stuck to the low FODMAP diet during the whole study period.
In a randomised trial involving 41 people with irritable bowel syndrome, 68% of those following a low FODMAP diet for one month reported improvements in symptoms, compared to 23% of those following their usual diet.
Another study, involving 90 people with IBS showed that following a low FODMAP diet for almost 16 months significantly improved abdominal pain, bloating, flatulence and diarrhoea. Overall, 72% were happy with their symptoms. Those with fructose (fruit sugar) intolerance (identified using hydrogen breath tests) gained greater symptom benefits than those with normal breath testing.
Many people find the diet most successful if they are advised by a trained healthcare professional. Ask your GP or Gastroenterologist to refer you to a Registered Dietician trained in the FODMAP approach.
When a low FODMAP diet doesn’t work
Overall, a low FODMAP diet effectively reduces symptoms in three out of four people with irritable bowel syndrome. That means it is ineffective for one in four. If you don’t respond, despite sticking to the diet properly, you are likely to have visceral hypersensitivity or enhanced gut-brain communication.
Antispasmodic treatments may help, such as Buscopan (hyoscine) or peppermint oil.
Some people benefit from taking psyllium fibre supplements, which absorb water to reduce both diarrhoea and help overcome constipation.
Start with a low dose and slowly build up.
Always take fibre supplements with plenty of water to prevent bloating.
Another important approach is to take a mineral gel which absorbs toxins within the bowel – including those secreted by some bacteria – to help reduce diarrhoea in those with diarrhoea-predominant IBS.There are two main forms:
- Silicol gel, which contains a natural colloidal solution of silicic acid, which also helps to improve the strength and quality of hair, skin and nails.
- Enterosgel, containing a mineral polymer, which is licensed to treat diarrhoea, including diarrhoea-predominant IBS.
IBS and probiotics
Probiotic digestive bacteria that suppress the growth of less desirable, gas-forming bacteria, and have beneficial effects on immune function.
Research involving 186 people with irritable bowel syndrome has shown that taking a daily dose of a multi-strain, non-dairy, probiotic drink (Symprove) produced significantly greater improvements in pain, constipation and diarrhoea than an identical placebo, with improvements starting within four weeks and continuing throughout the 12 week trial.
Compared with placebo, the total IBS symptom severity score (IBS SSS) reduced by 35 points.
The IBS pain score reduced by 19 points, bloating reduced by 4.6 points, bowel habit improved by 10.4 points, and quality of life improved.
Improvements continued throughout the 12 weeks, presumably because it takes this long to reset the brain-gut interactions involved in generating IBS symptoms.
The four probiotic strains present in Symprove are: Lactobacillus rhamnosus, Lactobacillus plantarum, Lactobacillus acidophilus NCIMB 30175 and Enterococcus faecium NCIMB 30176. These are suspended in a water-based solution containing barley extracts (gluten and dairy-free) to provide the bacteria with nourishment.
Symprove is available as one bottle, or as the full 12 week program. Keep refrigerated.
VSL#3 is a powder formulation of 8 different strains of probiotic bacteria: Lactobacillus acidophilus DSM 24735, Lactobacillus plantarum DSM 24730, Lactobacillus paracasei DSM 24733, Lactobacillus delbrueckii bulgaricus DSM 24737, Bifidobacterium longum DSM 24736, Bifidobacterium breve DSM 24732, Bifidobacterium infantis DSM 24731, Streptococcus thermophilus DSM 24731.
Dietary approaches are effective
The symptoms of irritable bowel syndrome fluctuate and the average duration varies between 5 and 13 years.
Identifying the foods that trigger your symptoms, and avoiding them, will help to bring symptoms under control. Symptoms will improve over time so that, for example, symptoms are rarely seen in people aged 70 and over.
What dietary approaches have you found helpful? Please share your experiences via the comments box below.
Image credits: shutterstock; pixabay