If you have irritable bowel syndrome, too much or too little dietary fiber can affect symptoms. Most doctors recommend increasing dietary fiber intake to relieve symptoms, but some types of fiber may be better tolerated than others.
Irritable bowel syndrome (IBS) is a gastrointestinal disorder that researchers believe is caused by issues with how the brain and intestines work together.
IBS is typically characterized by a group of symptoms that occur together, which may include:
- diarrhea
- constipation
- gas
- bloating
- abdominal pain or cramping
The cause of IBS isn’t fully understood, and symptoms can vary from person to person.
If you have IBS, many doctors recommend increasing your dietary fiber intake to help relieve symptoms.
Dietary fiber is the part of plant foods that your body can’t digest or break down. There are two types of fiber, soluble and insoluble, and you may need to be cautious with how much of both you eat. Eating too much fiber might also affect your symptoms.
Let’s review the different types of dietary fiber and how to make sure you’re getting the right amount of it to relieve your IBS symptoms.
Fiber comes from plants and is an essential part of a healthy diet. It aids digestion by bulking up your stool.
Both soluble and insoluble fiber can be good options for IBS. But they act differently as they pass through your digestive system. Many foods contain both types.
In general, fiber is found in plant foods like:
- fruits
- vegetables
- legumes
- nuts
- grains
Soluble fiber and IBS
Soluble fiber gets its name because it dissolves in water. Once dissolved, it forms a gel-like consistency in the gut. It can be helpful for people with IBS-D (with diarrhea) and IBS-C (with constipation).
Soluble fiber can be found in beans, fruits, and oat products. The best sources of soluble fiber include:
- legumes like black beans, lentils, and peas
- vegetables like zucchini, pumpkin, Brussels sprouts, broccoli, carrots, and sweet potato
- fruits like apples, oranges, berries, and figs
- whole grains like brown rice, oats, and barley
Insoluble fiber and IBS
Insoluble fiber doesn’t dissolve in water. It helps bulk up the stool, which can keep it moving through your digestive system and prevent constipation.
Insoluble fiber may be recommended for people with IBS-C. But eating too much of it may lead to excess gas production that can cause bloating and abdominal pain.
Insoluble fiber can be found in whole grains, fruits, nuts, and seeds. The best sources of insoluble fiber include:
- whole grains like whole wheat flour and wheat bran
- nuts and seeds like almonds and flax seeds
- fruits like bananas and apples
- vegetables like cauliflower, green beans, and potatoes
Research suggests this type of fiber
Fiber can also be broken down into fermentable and unfermentable. Fermentable fiber is more easily and quickly broken down by gut bacteria than nonfermentable fiber.
As it’s digested, fermentable fiber, like pectin and fructo-oligosaccharides, produces gas and other byproducts that can cause issues in some people with IBS.
Fermentable fiber and IBS
Highly fermentable dietary fiber can lead to increased production of gas in the gut, causing bloating, abdominal pain, and flatulence.
In general, people with IBS will want to avoid foods high in fermentable fiber, also known as FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols).
Foods high in fermentable fiber include garlic, onion, beans, rye, and certain fruits and vegetables.
Nonfermentable fiber and IBS
Foods containing moderately or low fermentable fiber don’t cause an excess of gas in the gut and are typically well tolerated by people with IBS.
Foods like potatoes, brown rice, oats, and nuts such as almonds can provide soluble and nonfermentable fiber.
Doctors recommend increasing fiber intake by 22 to 34 grams (g) per day to help regulate your stools. But most adults in the United States and Canada consume an
- Females ages 50 years and under: 25 to 28 g per day
- Males ages 50 years and under: 31 to 34 g per day
- Females ages 51 years and older: 22 g per day
- Males ages 51 years and older: 28 g per day
If you’re not able to get enough fiber in your diet, supplements containing psyllium have also been shown to be an effective way to improve IBS symptoms. Psyllium comes from the seed of the plant called Plantago ovata. It contains soluble fiber that is nonfermentable.
Speak with a medical professional before taking any supplements.
If you do begin taking fiber supplements, start slowly, so your body can get used to them. Taking too much at once can lead to side effects, like gas and bloating. Be sure to increase your water intake if you take a fiber supplement, too.
Most people with IBS report that certain foods trigger or worsen their symptoms. On top of eating more fiber, your doctor may suggest that you follow a low FODMAP diet. FODMAP foods are difficult for your intestines to digest and often lead to increased bloating and diarrhea.
Additionally, your doctor may recommend an elimination diet to understand which foods trigger your symptoms.
Some people with IBS avoid gluten, a protein found in wheat, barley, and rye; or lactose, a sugar found in cow’s milk, but
Speak with a doctor if you’re experiencing IBS symptoms frequently, such as:
- bloating
- abdominal pain
- diarrhea
- constipation
If you’ve already received an IBS diagnosis, see your doctor if your symptoms don’t improve after making changes to your diet, such as adding more fiber. They may refer you to a dietitian specializing in IBS and other gastrointestinal disorders.
Treatment for IBS involves a combination of medications, dietary changes, and stress reduction. Here are answers to some frequently asked questions about diet and IBS.
What are the worst foods for IBS?
Avoiding certain trigger foods may help with your symptoms. These foods can vary from person to person, but common triggers include:
- dairy
- fried food
- high fat foods
- fizzy drinks
- alcohol
- caffeine
- processed foods
- foods containing insoluble fiber
What are the best foods for IBS?
The best foods for IBS are those rich in soluble fiber and low in FODMAPs, as well as those with healthy fats, and lean sources of protein. Examples include:
- lean meats
- leafy greens
- eggs
- fish
- nuts and seeds
- certain fruits and vegetables
What is the best fiber for IBS?
Not all types of fiber are beneficial for people with IBS. While there’s no one-size-fits-all approach, doctors generally
If you have IBS, work with a doctor or dietitian to get the right amount and type of fiber in your diet. You can get fiber from the foods you eat or as a supplement. Foods or supplements with soluble and low fermentable fiber will most likely offer the most benefits for managing your IBS symptoms.
Add foods with fiber to your diet a little at a time to avoid side effects like gas and bloating. Speak with your doctor if you don’t notice any improvement in your symptoms after adding more fiber to your diet.