• Diet for IBS
• Exclusion diet
• Fibre and IBS
• Diet tips
• Fructose intolerance
• Lactose intolerance

There is no easy way to identify which food if any is causing the IBS symptoms

Introduction - general concepts

• Irritable bowel syndrome has no definable cause but there are clearly some triggers that aggravate the condition.
  
• The main triggers are:
  • Stressful life events.
  • Food triggers.
  • Gastroenteritis infections
• Altering the diet is always going to be the easiest approach to reducing these "triggers" but approaches towards reducing stress should also be explored.
  
• The majority of food triggers are best described as an intolerance rather than food allergy.
  
• Genuine food allergy as a cause of IBS is probably uncommon.
  • Food allergy causes rapid onset of itching, swelling of lips, tightness in throat and wheezing.
  • 90% of food-related allergic problems are caused by the following foods.
    • Milk, eggs, peanut, soy, other nuts, fish, shellfish.
• The mechanism by which foods aggravate IBS is unclear.
  • It probably involves events in the lumen of the bowel rather than any inflammatory or immune response of the bowel wall.
  • This means that the symptoms may be due to foods that were consumed over the past 1-3 days - not just the last meal.
  • "Intolerance" may occur for larger helpings of a particular food but not with smaller amounts. This is different from a genuine allergy where even small amounts can cause symptoms within a few hours.
  • Colonic fermentation is probably an important mechanism.
    • This depends on the type of bacteria in the colon AND,
    • the type of food AND,
    • The speed of transit through the colon.
  • Fermentation and gas production is increased in people with irritable bowel.
• For example the exclusion of wheat from the diet is a common recommendation (and often helpful).
  • This has nothing to do with the immune-based disease of coeliac disease(gluten-sensitive enteropathy).
  • The mechanism by which wheat aggravates IBS may be because of higher fermentation levels (gas production) in the colon with wheat compared with rice.
• The types of diets that have been developed for IBS come from extensive questionnaires rather than from any direct scientific study.
  • There is no easy shortcut to finding out what are the aggravating foods.
    • Skin prick tests and blood tests for allergy have proven to be disappointing.
  • The suggestions for "allowed" and "not allowed" (in the exclusion table are simply those foods that are prominent in dietary surveys of people with IBS.
  
  The strict approach is too have a very restricted diet for 2-4 weeks and then gradually add in foods one by one. This is called an exclusion diet. This is straightforward concept but difficult too achieve in practice. The underlying variability of IBS makes any improvement or deterioration difficult to interpret. These negative and discouraging comments shouldn’t detract from the main message.
• Food triggers are common.
• If identified, exclusion can make a long-term difference to quality of life with IBS.
• Food exclusion is always a more preferred option to taking prescribed medications for IBS and of course has no long term side-effects.

• The main risk from an exclusion diet is developing an inappropriately strict approach to food exclusions that may not necessarily to be required.
  • Potentially leading to weight loss!
  • To an unhealthy obsession with what can and can't be consumed.
  • Possibly heightened stress with regard to food choices.
• There are some foods that cause problems for most people with IBS but there are also unique issues for any individual.

• Useful websites

  
  National Institute of Health information on lactose intolerance
  http://www.niddk.nih.gov/ddiseases/a-z.asp
  
  www.coeliac.com.au
  This is an excellent website with many good dietary tips.
  
  Recommended recipe book
  
  "Irresistables for irritables" by Sue Shephard
  Available through Pathfinder Bookshop 0800 55 44 55
  

Exclusion diets can still be tasty!!

Exclusion diet

• The table below is a suggested list of allowed and not allowed foods in each major food group.
  
• This has been modified from an exclusion diet developed by the dieticians at the John Radcliffe Hospital, Oxford, England.
  
• If the strict exclusion diet approach sounds too difficult then simply scan through the suggested exclusion.
  • Pick out some foods that seem to be possible “triggers” in your case.
  • Remember it can take 2-4 weeks of exclusion before any clear trends emerge.

Is fibre good for you? Maybe - but wholegrain breads cause bloading and wind and aggravate symptoms for many people with IBS


Try the rice bread by Vogels

Dietary Fibre - the benefits and disadvantages

• Soluble fibre can help to lower cholesterol although the effect is relatively small.
  • If raised cholesterol is a significant problem then oatbran etc is not going to resolve the issue.
    • You may need cholesterol lowering drugs.
    • Low fat diet.
    • Weight loss.
    • Attention to other risk factors such as high blood pressure and stopping smoking.
• Soluble fibre is found in;
  • Oats.
  • Legumes (dried peas, beans, lentils).
  • Nuts.
  • Most fruits.
  • There is some fermentation by colonic bacteria. This may produce beneficial effects on the colon – such as the formation of special fatty acids (butyric acid) but also may form unpleasant wind.
• Insoluble fibre is more resistant to digestion and creates less wind.
  • It is more difficult to find dietary sources.
  • Fibre supplements such as Normacol are one option.
• Resistant starch is found in
  • Cereals, vegetables and fruit.
  • It can also form after cooling of cooked potatoes.
  • Maize flours (corn) contain lots of resistant starch.
  • Benefibre is a commercial product used for constipation but does cause extra wind.
• Too much fibre will cause excessive wind and abdominal bloating.
  • Some fibre types are more likely to cause wind.
    • Beans, lentils and nuts are particularly prone to aggravate wind.
    • Whole grain breads may cause wind. Brown rice is OK.
  • If you have irritable bowel syndrome increasing fibre intake may actually aggravate your symptoms.
    • There has been too much emphasis on increasing dietary fibre with IBS.
    • Many people (perhaps 2/3 rds) are actually worse with increased fibre.
  • There is no value in taking fibre if diarrhoea is the predominant problem.
  • If constipation is the main problem.
    • Then dietary fibre can be helpful because the fibre absorbs water and softens the bowel motions.
• Fibre supplements.
  • Available to purchase from the chemist.
  • These are based on natural plant extracts - physillium or isphagula.
  • Probably the best type is Normacol (insoluble fibre).
    • This tends to have less wind production.
    • This is less palatable than the dissolving forms of fibre (Metamucil and Mucilax) but may have an advantage.
    • Granules can be taken on cereal, mixed with yoghurt etc.
• It is proposed that dietary fibre may decrease the risk of diverticular disease and bowel cancer.
  • These are unproven concepts.

Coffee is a great drink - but probably the top offender for many people. Coffee causes urgency and frequency and also increases abdominal cramps


What is good to drink? Tea is better than coffee. Peppermint tea has some anti-spasm effects


Good vegetables are lettuce, spinach, green beans (sliced), pumpkin, carrot, avocado, tomato, zucchini.

Important aspects of the exclusion diet

• Fortunately these are much more readily available now (including rice flour, rice flakes, ground rice -used for puddings, crumble topping, biscuits).
• Gluten-free bread may not always be beneficial in IBS because the substitutes for wheat , barley and rye may still be wind-producing. The best carbohydrate source by far is rice.
  
• The other source is the health food shop particularly for other less common substitute cereals.
  • Arrowroot - resembles cornflower – can be used as thickener for gravies.
  • Buckwheat - useful for coating fish.
  • Carob flour - used to flavour drinks or biscuits - “chocolate” taste.
  • Sago - useful for puddings or as a thickener.
  • Quinoa - similar to rice.
• Some vegetables are particularly wind forming.
  • The cabbage family.
    • Cabbage, brussel sprouts, broccoli, cauliflower, asparagus.
    • Contain a sugar called rabbinose.
    • This is poorly absorbed and causes increased fermentation.
  • Onions and garlic are well known culprits.
  • Beans cause gas!
    • In particular baked beans.
    • Bean salads and lentils (split peas) can cause problems.
    • If soaking overnight discard water and use fresh water. (Sliced green beans are OK).
  • Resistant starch is wind-forming. It is found in
    • Cold cooked potatoes.
    • Reheated pasta.
    • Green bananas.
  • Other wind-forming foods are nuts and seeds.
    • Fennel, sunflower, poppy seeds.
    • Peanuts, almonds.
  • Sorbitol.
    • Found in some sweets, diabetic drinks and jams, should be avoided.

General tips

• Lunches are a particular problem especially if eating on the run.
  • Many people feel bloated after lunch.
  • I advice against a sandwich or filled roll as the bread can be a problem.
  • Rice is good – sushi or leftover fried rice or rice crackers can be tried.
  • No carbohydrate at all may be best - try tuna with lettuce salad or soups.
• If diarrhoea is a major problem.
  • Coffee should be stopped completely.
    • This has a profound stimulant effect on the colon causing looseness, urgency and abdominal cramps.
    • Decaffeinated coffee does not appear to be much better.
    • Tea is OK but herbal tea or water is best.
    • There may be some withdrawal headaches during the following 2 weeks after stopping coffee.
  • Alcohol should be avoided.
    • Wine may be the worst culprit but all alcohol may cause a tendency to diarrhoea.
  • Spicy foods may cause diarrhoea.
• Some sugar substitutes in diet foods may cause problems (sorbitol and xylitol).
  • Sorbitol is found naturally in fruits.
    • Including apples, pears, peaches, prunes.
  • Xylitol or sorbitol is present in diet chewing gums and diet sweets.
    • Also in regular sweets, low calorie ice-cream, diet yoghurt.
  • There are many different sugar alcohols.
    • All of which can cause GI symptoms because of poor absorption.
    • Isomalt, lactilol, maltilol, mannitol, lactalol.

Fruits is a mixed blessing!! Clearly there are some health benefits to fresh fruit but can be aggravating for people with IBS. Surprisingly canned fruit and cooked fuit is OK

Fructose malabsorption

• Some people are not able to handle excess amounts of fructose.
  • A degree of fructose intolerance may be found in 1/3 rd of people.
    • This is only a problem if larger amounts of fructose are ingested.
  • Fructose is becoming a popular food sweetener for a variety of manufactured foods.
    • e.g in muesli bars.
    • It can be made cheaply from corn syrup.
  • Fresh fruits are obviously a healthy food item but unfortunately in excess may aggravate IBS.
  • Surprisingly many people with IBS can tolerate canned fruit – e.g. peaches, pears or cooked fruit (apples) – but not fresh fruit.
• Food to avoid if fructose intolerance is suspected.
  • High fructose fruits - pears, cherries, grapes, apples.
    • Low fructose fruits are berries, avocado, rhubarb.
  • Honey.
  • Onions, artichokes, wheat.
  • Food additives / sweetener.
    • Check food labels carefully.
    • May state high fructose corn syrup (HFCS).
  • Carbonated drinks - Coke,Sprite etc.
  • Corn syrup - common additive in muesli bars and other snack foods, many processed and canned foods.

Lactose Intolerance (benefit of a dairy-free diet)

• Dairy products contain the milk sugar lactose.
  • Some people are unable to digest lactose because they lack the enzyme lactase which splits the lactose into in parts (galactose and glucose).
  • Lactose is also added to many commercial foods e.g salad dressings, bread, cereals.
• Lactose that is not digested enters the colon and is fermented by the action of bacteria in colon. This produces;
  • Wind (bloating and flatulence).
  • Loose bowel motions.
  • Abdominal cramps as a result of the distension from increased gas production.
• A lack of the lactase enzyme.
  • Is more common in Asian, African and Middle Eastern populations.
  • Temporary lactose intolerance is common after a gastroenteritis illness.
• Lactose intolerance is not the same as having irritable bowel syndrome.
  • But may be an aggravating factor for some people with IBS.
  • The contribution of lactose intolerance to IBS in general is debated and may vary from country to country.
• The association of symptoms with dairy food intake may not be obvious and there will need to be a one-month trial of dairy food exclusion to see if there is any improvement.
  
• There are tests available for testing the level of lactase enzyme activity.
  • The most accurate test is a hydrogen breath test.
    • This requires the collection of a sample of exhaled air every 30mins over a 3-hr period after having ingesting a large amount of lactose.
    • Some symptoms may be caused by the lactose load if there is a genuine intolerance.
  • The other method is to take a biopsy sample from the small bowel (duodenum) at the time of a gastroscopy.
    • In practice this has proved to be less accurate.
• Usually I favour the pragmatic approach of trying a dairy-free diet rather than trying to prove a problem with lack of lactase enzyme.
  • In general it is usually the lactose levels in dairy foods that determines intolerance.
  • BUT there are probably other parts of dairy products that can also cause symptoms.
• General tips for reducing lactose in the diet.
  • Soft cheese has much more lactose than hard cheese.
  • Lactose levels in yoghurt are generally low.
    • They are often tolerated when other dairy foods give symptoms.
  • The presence of acidophilus and lactobacillus in natural yoghurt may ease some bowel symptoms.
  • Milk - as drinks or on cereal;
    • This is the source most likely to be giving the highest lactose load.
    • Use soya-based or rice-based milk on cereal.
  • Calcium intake.
    • Can be maintained by taking yoghurt.
    • OR by using soy milk enriched with calcium (So Good).
  • Some UHT milks have the lactose levels reduced.
  • Lactose-free ice-cream is also available.