Irritable bowel syndrome diet: what to eat and what not to eat in IBS

Irritable bowel syndrome (IBS) is a gastrointestinal disorder that causes changes in the normal functioning of the intestines. It manifests as a group of symptoms that range from abdominal pain and abdominal cramps to bloating, constipation or diarrhoea, presence of mucus in stools, and gas.

IBS doesn’t have a known cause; however, a number of possible causes have been associated with this condition. These include problems with the gut flora (the microbes that live in the gut), reduced gut motility (the contracting and relaxing of gut muscles that pushes food forward), inflammation in the gastrointestinal tract, food allergies and intolerance.

Research has shown that certain nutrients can affect and improve all of these symptoms and thus provide relief from IBS. On the other hand, certain foods trigger gut problems and worsen IBS symptoms.

If you have IBS, chances are your doctor would suggest some dietary changes, along with medications, to manage the symptoms.

Read on to know which foods can trigger irritable bowel syndrome and what foods you can eat to get symptomatic relief.

Good foods for irritable bowel syndrome (IBS)
Special diet for IBS
- Gluten-free diet
- Low FODMAP diet for IBS
IBS elimination diet
Foods to avoid if you have IBS

Doctors for Irritable Bowel Syndrome Diet

Good foods for irritable bowel syndrome (IBS)

IBS is mostly managed through specific diets. Here are certain dietary additions that may further aid you in controlling IBS symptoms:

(Read more: How to improve digestion)

Benefits of water for IBS

There isn’t any scientific evidence to prove or disprove the benefits of water in IBS. However, water is responsible for maintaining the fluid and electrolyte balance of your body - which is often disturbed if you have diarrhoea associated with IBS.

Water also aids in easier movement of food through the intestines and easier passage of stools, especially when you are taking a fibre-rich diet. So, it is best to keep yourself hydrated. Make sure to drink at least eight to 10 glasses of water per day.

On the plus side, water will also flush out the waste and toxins from your body and help in overall improvement in health.

Soluble fibre for IBS

Fibre is a type of complex carbohydrate which is present in most fruits and vegetables. There are two types of fibres: insoluble and soluble. The human body is not equipped to digest fibres, so both types of fibres are fermented (by microbes) in our gut before passing out of the body.

Moderately fermented soluble fibre such as that obtained from psyllium husk (packaged examples include Isabgol) is considered to be good for IBS patients. According to a systemic review and meta-analysis published in the American Journal of Gastroenterology, soluble fibres can provide relief from IBS symptoms. The meta-analysis included 14 random control trials that had more than 900 patients in all.

The recommended daily intake of fibre is around 25 grams per day. If you have IBS, you can also take about two tablespoons of linseed (flaxseed) per day. Linseed supplementation has been found to show beneficial effects within six months of regular use.

(Read more: Home remedies for constipation)

Probiotics improve IBS symptoms

Probiotics are live microbes that can be taken from fermented food such as yoghurt (curd) or in the form of tablets or capsules. They are considered to be highly beneficial in correcting the gut microflora of IBS patients, thus, improving digestion and assimilation of nutrients. Probiotics also improve gut motility and reduce abdominal pain. However, not all probiotics work in the same way. Lactobacillus and Bifidobacterium are considered to be especially good for diarrhoea.

Probiotics may also contain yeasts like Saccharomyces. If you have an otherwise weakened immune system, taking chemotherapy or steroids, check in with your doctor before taking probiotics.

Special diet for IBS

Those who have IBS usually know what triggers their condition and start to cut those foods from their diet. Experts suggest that while a restrictive diet may help keep the symptoms in check, it may cause some nutritional deficiencies. So, it is important to make appropriate changes in your diet to ensure that you get all the essential nutrients.

Dietary intervention in IBS is so important that there are specialised diets recommended for this condition. Here are three diets that are suggested to be helpful for IBS patients:

Gluten-free diet

A lot of IBS patients consider gluten to be a trigger for their symptoms. However, there isn’t clear cut evidence on the effects of gluten on IBS. Gluten is a protein that is present in considerable amounts in wheat and some other grains. Those with non-celiac gluten sensitivity (NCGS) especially report relief from symptoms on cutting gluten out of their diet. A 2016 study found that a gluten-free diet does help in reducing IBS symptoms in NCGS patients within four weeks.

However, some scientists say that it may not be gluten but some other compounds present in wheat (short-chain fructans) that may be triggering IBS in people with NCGS.

Regardless, completely cutting gluten-rich cereals may lead to nutritional deficiency as gluten-rich foods also contain a lot of nutrients.

(You may also be interested in: Wheat allergy: types, symptoms, diagnosis, treatment)

Low FODMAP diet for IBS

FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols.

Monosaccharides are the simplest sugar molecules that can't be broken down further. Disaccharides contain two monosaccharides and oligosaccharides contain three to 10 monosaccharides.

These are a group of short-chain fermentable carbohydrates that should be avoided if you have IBS. Here is a list of low FODMAP foods that you can add to your diet:

Cereals: Any product made with wheat-free flour, oats, rice, corn.
Vegetables: Vegetables like potatoes, carrots, tomato, spring onion, parsnips, pumpkin, eggplant, spinach, cucumber and bell peppers.
Milk substitutes and dairy products: Almond milk or any lactose-free milk, butter, hard cheese like Parmesan and Brie.
Fruits: Fruits like banana, strawberry, lemon, orange, kiwi, grapes and blueberry.

It has been seen in observational studies that IBS patients start to experience symptomatic improvement within a week or two (three to four weeks at the max) of beginning the low FODMAP diet.

Some of the high FODMAP foods - or foods to avoid if you have IBS - include honey, apples, Cruciferae vegetables like cabbage, garlic, wheat and anything made from wheat like bread or pasta, legumes, pears, mangoes, watermelons, mushrooms. Avoid all these foods whenever possible.

Since it can be difficult to know all low FODMAP foods, it is best to talk to a dietician to get a low FODMAP diet plan for you.

IBS elimination diet

Elimination diets focus on restricting the intake of all the trigger foods one by one to manage the symptoms of the condition. An elimination diet for IBS generally starts with removing fibre, coffee, nuts and chocolate from the diet. You can gradually add more trigger foods to your list of things to avoid. The International Foundation for Gastrointestinal Disorders, US, explains a way to practice IBS elimination diet:

On a paper, write all of the possible foods you think are triggering your IBS symptoms.
Stop eating one of the listed foods for 12 weeks.
Make a note if you feel any improvement in symptoms.
Follow the same for all the foods on the list.
If you are not sure about your triggers, start with the four known triggers - fibre, coffee, nuts and chocolate.

Since insoluble fibre has a major effect on IBS, it is best to begin your IBS elimination diet with fibre.

Foods to avoid if you have IBS

There are a lot of foods that can worsen your IBS symptoms. These include:

Insoluble fibre: It is true that some types of fibre improve IBS symptoms. However, not all types of fibre are good for IBS patients. Insoluble fibres for one, decrease the transit time of food in intestines and may thus worsen IBS diarrhoea. Some foods rich in insoluble fibres are whole grains, wheat bran and nuts and seeds.
Fried and fatty food: Lab studies indicate that oily food or fats lead to retention of gas in your gut, leading to bloating and abdominal pain. For IBS patients, this leads to worsening of their existing symptoms.
A lot of IBS patients report fried and fatty food to be a trigger for their symptoms. But, there has been no clinical study to prove the negative effects of fatty foods on IBS. In fact, some studies show that polyunsaturated fatty acids (healthy fats like Omega 3 and 6) may decrease inflammation in the gut and thus may be effective against IBS.
If you have IBS, it is best to observe if your symptoms become worse after you have fatty foods. Try baking or grilling your food instead of frying it.
Some experts suggest that IBS patients should take 50 grams of fat per day, less than the daily recommended value of 65 grams in a 2000 calorie diet for a healthy adult. Fats should be between 20% and 35% of your total energy intake in a day (1 gram of fat gives you about 9 calories).
Spicy food: Spicy foods are a known trigger for IBS. Chilli peppers have a compound called capsaicin that binds to certain receptors in the intestines and hastens the transit of food in the gut. However, it also leads to pain and a burning sensation in the abdomen. In a study conducted in Iran, researchers found that people who consume a lot of spicy food are more likely to have IBS than those who don’t. The difference was more prevalent in women.
Though, some scientists say that this study can’t be used as confirmatory evidence since the population was Asian and had a higher average chilli consumption per week than those of European descent.
Additionally, an earlier study suggested that long-term consumption of red pepper (when consumed as enteric-coated pills which release the medicine in the gut) can actually help reduce IBS symptoms including bloating and stomach pain.
If spicy foods trigger your symptoms it is best to avoid them.
Dairy: Dairy products, especially milk, are yet another self-reported trigger for IBS. It is believed that lactose, a sugar found in dairy products, is the major culprit behind the negative effects of milk on IBS patients. Lactose intolerance is a fairly common condition that occurs when you lack a key enzyme - lactate dehydrogenase - that your body needs to break down lactose. If you have lactose intolerance, the microbes in your gut will break down lactose into small chain fatty acids, which would have the same effect on your gut as a fatty food.
However, lactase supplementation was not found to be helpful in an earlier double-blinded study. So, it can’t be said for sure that lactose is what triggers IBS symptoms. Instead, some other proteins in milk are hypothesised to be responsible for this effect.
Caffeine: While there is no study that says for sure that caffeine might trigger IBS symptoms, it is proven that caffeine-containing foods, especially coffee may have a laxative effect and thus stimulate diarrhoea. Caffeine-containing drinks like colas are also considered to be bad for IBS patients more so since they also contain gas.
Generally, 400mg of caffeine per day is considered to be safe for adults. This is roughly equal to four (240mL) cups of coffee, eight (240mL) cups of tea or three to four energy drinks.
However, it is best to notice your triggers and talk to your doctor to know how much caffeine is too much as per your condition.
Alcohol: Alcohol is considered a trigger for IBS symptoms. It is said that alcohol causes dehydration and may worsen constipation in IBS patients. However, there isn’t any firm evidence to support any of the claims. In an observational study done at the University of Washington, US, scientists found that alcohol only affects IBS symptoms in binge drinkers, that is, those who take more than four drinks a day. Those who take a moderate amount of alcohol (less than three drinks per day) do not get affected at all. Beer is generally thought to worsen the symptoms of IBS.
Nonetheless, more studies are needed to find out the association between alcohol and IBS.
If you have IBS, try the following:
- Limit your alcohol intake to one drink per day for women or two drinks per day for men (interestingly, this is also the maximum permitted limit of alcohol intake for avoiding liver disease).
- Have at least two alcohol-free days in a week.