IBS diet: foods to eat and avoid

Diet and lifestyle changes for treatment of IBS

Before making any dietary changes, keep a food and symptom diary for a week. This can be a helpful way to identify foods that might trigger a response from your body. Make a note of everything you eat and drink for a week and record any symptoms you have. Try to include the approximate amount, as well as the time of day. IBS symptoms may not always be caused by what you eat so consider other factors that may be involved.

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Irritable bowel syndrome

IBS stands for irritable bowel syndrome, and it is a long-term chronic condition of the gut (bowel) that causes episodes of tummy (abdominal) cramps, bloating and either constipation or diarrhoea. IBS is a problem with how the bowel works.

by Dr Rachel Hudson, MRCGP

See also:

• What causes irritable bowel syndrome?

• What are the symptoms of irritable bowel syndrome?

• How to treat irritable bowel syndrome.

Step one - healthy eating and lifestyle changes

Making changes to your diet and lifestyle can help improve IBS symptoms. These changes include:

A healthy diet

This includes:

• Plenty of fruit and vegetables.

• Plenty of starchy carbohydrates. This type of food includes bread, rice, cereals, pasta, potatoes, chapattis and plantain.

• Some milk and dairy products (2-3 portions per day). If you are lactose intolerant include dairy alternatives such as soya, rice or oat milk and yoghurts that are enriched with calcium.

• Some protein foods like meat, fish, eggs and alternatives such as beans and pulses.

• Limited amounts of foods high in fats and sugars. Limit saturated fat that is found in animal products such as butter, ghee, cheese, meat, cakes, biscuits and pastries. Replace these with unsaturated fats found in vegetable oils such as sunflower, rapeseed and olive oil, avocados, nuts and seeds.

• Drink plenty - at least two litres of fluid per day, such as water or herbal teas.

See also the separate leaflets on Health eating and Mediterranean diet.

Lifestyle changes

• Have a regular meal pattern.

• Take time when eating meals.

• Try not to skip meals.

• Sit down to eat and chew food well.

• Try to avoid eating too late at night.

• Exercise regularly, such as walking, cycling, or swimming. If finding time is difficult, incorporate it into your day. For example - cycle to work, leave the train a stop early and walk, and use steps instead of lifts when possible.

De-stress

If you have a hectic lifestyle, stress and anxiety may also be causing IBS symptoms. There are many complex connections between the brain and the gut. Psychological factors, the nervous system, and muscle contractions in the gut all interact with each other, causing IBS symptoms. This is known as the brain-gut axis. Therefore, stress management can be effective in easing symptoms.

• Create time for relaxation.

• Make the most out of leisure time.

• Try relaxation therapies such as mindfulness.

• Exercise - try yoga or taking a walk.

• Get enough sleep.

• Seek support or counselling.

Step two - symptom-specific changes to the diet

Sometimes, a healthy balanced diet and lifestyle changes aren't enough to improve symptoms. It may be that more specific changes to the diet are needed. Many people report that what they eat affects their IBS symptoms. Therefore, altering what you eat can help to manage symptoms.

Reduce caffeine

Caffeine can stimulate activity in the colon, which may worsen symptoms of pain and diarrhoea. Limit tea and coffee to no more than three cups per day. Filter coffee contains higher amounts of caffeine (140 mg) compared to instant coffee (100 mg) and tea (75 mg). So, if filter coffee is included in your diet, you may want to limit this to two cups per day. There's also caffeine in cola and some other soft drinks - and in chocolate.

Limit alcohol and fizzy drinks

Fizzy drinks and alcohol can worsen symptoms of diarrhoea. Limit your intake of these drinks to improve symptoms. Aim to have at least two alcohol-free days a week and no more than two units each day.

A unit of alcohol is:

• One 25 ml shot of spirits.

• Half a pint of standard-strength lager/beer (3-4% alcohol by volume).

• One small 125 ml glass of wine (11% alcohol by volume).

Reduce intake of resistant starches

These are starches that are resistant to digestion in the gut (small intestine). Therefore, they reach the colon intact and are fermented by the germs (bacteria) in our gut. This produces gases and waste products, leading to symptoms of, bloating, wind and diarrhoea. People who have IBS react to smaller doses of resistant starches than those who don't have IBS. Reducing resistant starches may also improve symptoms of diarrhoea.

Avoid foods containing resistant starches

• Processed foods such as crisps, oven chips, supermarket pizza, biscuits and cakes, breakfast cereals.

• Foods that have been cooked and left out to cool - for example, cold potato/pasta salads.

• Ready meals.

• Partially baked bread - for example, garlic bread or pizza bases.

• Whole grains, pulses, sweetcorn, green banana and muesli that contains bran.

• Dried pasta - use fresh instead.

• Pastry.

• Savoury snacks.

Cook fresh food whenever possible and eat food that you've cooked straightaway. This will help to reduce intake of resistant starches.

Modify your fibre intake

Fibre can be a confusing subject for many of those affected by IBS. For some people, reducing high-fibre foods can help to improve symptoms. For others, increasing fibre can help symptoms improve, so it is very much dependent on the individual. Adjust how much fibre you eat according to personal symptoms. Use a food and symptom diary and monitor any changes.

It may help to clarify what exactly dietary fibre is and how it may affect symptoms. There are two types of fibre which work differently in the body. Generally, reducing insoluble fibre may help with symptoms but if an increase in fibre is necessary, this should be from soluble fibre.

Insoluble fibre
This type of fibre does not dissolve in water and is not readily broken down. This means it passes through the digestive system mostly intact. It absorbs water, adds bulk to stools (faeces) and allows waste to be passed through bowels more quickly. Reducing this type of fibre may help to improve symptoms of diarrhoea. Foods to reduce or avoid:

• Skin, pith and pips of vegetables such as - artichokes, brussels sprouts, asparagus, and fruits such as apples.

• Wheat and bran.

• Corn (maize).

• Nuts and whole grains.

Soluble fibre
This type of fibre dissolves in water and is broken down by the natural bacteria in the bowels. It softens stools and makes them larger. Increasing this type of fibre may help to improve symptoms of constipation. These foods include:

• Oats.

• Barley.

• Psyllium and ispaghula.

• Nuts and seeds.

• Fruit and vegetables.

• Beans and pulses.

Whole grains (for example, wholemeal bread, brown rice and wholewheat pasta) may also help with constipation. Although increasing fibre may help to improve symptoms, it may also generate gas and cause pain and bloating. Monitoring is important to help identify this and to adjust your fibre intake according to your symptoms.

If fibre intake is suddenly increased, this can cause symptoms of wind and bloating. Introduce high-fibre foods gradually to allow the gut to become used to the extra fibre. Introduce one new food over a two-to-three-day period and monitor any symptoms. For example, have porridge for breakfast on the first day, then add beans or extra vegetables to a casserole two days later. You could have an extra piece of fruit two to three days later.

Drink plenty of water

Fibre needs water, so aim to drink at least 8-10 cups of water a day or other fluids such as herbal teas or sugar-free squash. People with diarrhoea will need to make sure they are replacing these lost fluids. Drinking water will also help to improve constipation.

Include golden linseeds

Including these in the diet may improve symptoms of wind, bloating, constipation and diarrhoea. They are a source of insoluble and soluble fibre. They can be added to casseroles, stews, soups, porridge, cereals, yoghurts and desserts. Include one tablespoon each day.

Reduce fatty foods

Some people find that fatty foods are difficult to digest and can cause symptoms of diarrhoea. Therefore, reducing fat in the diet may help:

• Scale back on cakes, biscuits, chocolates and pastries.

• Cut down on fatty meat products such as sausages, pies and pasties.

• Use lower-fat dairy products - for example, low-fat yoghurt, cottage cheese, semi-skimmed milk.

• Choose tomato-based sauces rather than creamy sauces - although some tomato sauces can be oily so check the label.

• Use small amounts of cheese - a matchbox size is a portion. Stronger-flavoured cheeses may help you to use less.

• Take care when using dressings and sauces such as mayonnaise and salad cream. Use small amounts and try the reduced-fat versions.

• Cut off visible fat from meat and choose leaner cuts of meat.

• Use minimal oil/butter when cooking - use an oil spray, or measure using one teaspoon of oil per person, per meal.

• Try different cooking methods such as steaming, boiling, microwaving, grilling and poaching rather than frying.

Reduce fructose

High fructose levels can cause diarrhoea in some people. Sometimes fructose is not well absorbed - it can draw water from the body into the bowel, which gives you watery poo (osmotic diarrhoea). If fructose is not well absorbed, it is fermented in the colon and gases are produced. This causes wind and bloating in some people with IBS.

Try limiting fruit intake to no more than three portions each day. Only have one small glass (150 ml) of fruit juice per day. Having more vegetables will help to meet the recommendation of at least five portions of fruit and vegetables a day. A portion is about 80 g, or what might fit in the palm of your hand. A portion of dried fruit is about one tablespoon.

It might be useful to limit honey, which contains fructose. Sometimes high-fructose corn syrup or corn syrup solids are added to processed foods, so try avoiding or limiting these. Check the labels for these ingredients.

Avoid sorbitol

Sorbitol is poorly absorbed and has a laxative effect when it enters the colon, so this can cause symptoms of bloating and diarrhoea. People with IBS may be sensitive to smaller amounts of sorbitol.

Sorbitol is found in artificial sweetener, low-sugar sweets, drinks, mints and gum and often found in diabetic or slimming products. Also check the labels of these products for mannitol and xylitol, which have a similar effect.

Try probiotics

Probiotics may be useful in improving symptoms of IBS, although they do not work for everybody. Probiotics can help to balance our gut bacteria. The 'good' bacteria in probiotics compete with 'bad' bacteria for space in the gut. This means that there are fewer 'bad' bacteria, making it a healthier gut environment. This can help with digestion and to improve symptoms of wind, bloating and diarrhoea.

There are a number of probiotic products available, including yoghurts, drinks and supplements such as tablets, capsules or sachets.

Probiotics need to be taken in the recommended dose every day for at least four weeks. Monitoring symptoms can help to identify any benefit. Other brands contain different mixtures of bacteria, so trying a different product may help if there is no success with one particular brand.

Step three - elimination diets

Some people find that even after making these dietary changes, their symptoms are still not improving. Avoiding single foods or following elimination diets might have some benefit for people with IBS. Such dietary choices should only be followed with the guidance of a doctor or dietitian.

Food intolerance

Some people with IBS may have a food intolerance. Food intolerances can be singled out by following a diet that excludes suspected foods.

If you think particular foods are causing symptoms, a dietician may advise you to exclude these foods for a while. This is to monitor whether symptoms improve when these foods are taken out of the diet. After this time period (usually 2-4 weeks) the foods are gradually re-introduced to see if symptoms come back.

Common intolerances include:

• Lactose - found in milk and dairy products.

• Wheat - found in bread, cereals and pasta.

• Caffeine - found in tea, coffee or cola.

The low FODMAP diet

There is a growing body of evidence that the low FODMAP diet is effective in improving symptoms of IBS. FODMAP stands for:

• Fermentable

• Oligo

• Di

• Monosaccharides

• And

• Polyols

These are a group of short-chain carbohydrates that are not very well absorbed in the gut. These carbohydrates are easily fermented and cause more fluid to enter the large bowel, leading to gas, bloating and diarrhoea. Reducing the total amount of these fermentable sugars may improve IBS symptoms. The low FODMAP diet should only be tried with the assistance of a dietitian.