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Fiber is an essential nutrient that aids in gut health.

Fiber and IBS

Fiber is one of the main components of a healthy diet but too much can spell trouble for IBS. Therefore, consuming the right amount of fiber can be a challenge for people with this common digestive disorder. Here’s all you need to know about fiber and IBS, and how to manage this complex relationship.

What Is Fiber?

Fiber is one of the essential nutrients alongside protein, carbohydrates, fats, vitamins, and minerals. It plays a vital role in digestive health, especially for people with IBS:

  • Creates a feeling of fullness after eating
  • Influences the balance of healthy bacteria in the gut
  • Reduces cholesterol
  • Regulates blood sugar levels
  • Helps maintain a healthy body weight

Experts generally recommend a fiber intake of 20 grams to 35 grams each day. However, in IBS the question of how much fiber to eat becomes a little more complicated. Let’s take a closer look.

How Fiber Affects People With IBS

While most people benefit from increasing the amount of fiber in their diets, eating too much can actually worsen some IBS symptoms.

For example, excess fiber can aggravate problems like bloating, gas and abdominal pain. However, fiber can help to relieve other IBS symptoms, like constipation. Therefore, getting the balance right is not always straightforward.

Unfortunately, not everyone with IBS experiences the same digestive issues. This can make it difficult to predict whether fiber is going to help an individual or make matters worse. Furthermore, there are two types of fiber and they affect the body in very different ways.

Is Fiber Good or Bad for IBS?

People often wonder whether fiber is good or bad for IBS. To understand this, it is necessary to know about the different types of fiber and how they influence digestion. The two main types of dietary fiber are soluble and insoluble fiber.

Soluble Fiber:

  • Dissolves in water to form a gel-like substance
  • Ferments easily in the gut
  • Slows down digestion
  • Absorbs excess water and prevents diarrhea
  • May increase gas production

Most people with IBS will benefit from increasing their intake of soluble fiber. However, they must be cautious with insoluble fiber, as it is more likely to make certain symptoms worse.

That said, those who regularly suffer from constipation may find increasing both soluble and insoluble fiber helpful.

Some good sources of soluble fiber:

  • Fruit (apples, oranges, berries, etc.)
  • Root vegetables (carrots, parsnips, etc.)
  • Legumes (e.g. peas)
  • Oats
  • Barley
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Insoluble Fiber:

  • Does not dissolve in water
  • Does not ferment easily in the gut
  • Speeds up digestion
  • Has laxative effects to ease constipation
  • May cause bloating and worsen diarrhea

Insoluble fiber can be found in:

  • Cruciferous vegetables (cabbage, broccoli, brussels sprouts, etc.)
  • Leafy greens
  • Beans and pulses
  • Seeds (flax, chia, etc.)
  • Wholegrains (e.g. wheat or corn bran)

When Should People With IBS Eat Fiber?

As you can see, people with IBS need to be cautious about how much fiber they consume and which type. As a general rule, most people will benefit from eating a moderate amount of fiber each day. However, anyone suffering from frequent bowel movements or diarrhea should not eat too much fiber, as it could make matters worse.

On the other hand, people suffering from constipation might benefit from increasing their fiber intake slightly. The best way to do this is gradually, to avoid exacerbating IBS symptoms. It might be best to increase your fiber intake at one meal, then wait a few days to see how it affects you.

Sometimes it can take some trial and error to find the right balance of fiber in IBS. Try keeping a diary to log how eating more high-fiber foods impacts you and make adjustments as necessary.

Dietary Recommendations for Fiber and IBS

The general recommendation for fiber intake in adults is 20 grams to 35 grams daily. However, some people with IBS may need to reduce this amount.
Experts recommend focusing on soluble fiber and aiming to eat around 12 grams 30 grams each day. However, people with diarrhea-predominant IBS will probably require less fiber than those who tend to be constipated.

Some simple ways to add more fiber to your diet:

  • Eating high-fiber breakfast cereals, such as oatmeal
  • Adding a vegetable side dish or salad to meals
  • Snacking on fruit
  • Replacing processed grains, such as white rice, with wholegrain versions

Fiber Supplements

For people who cannot get enough fiber from their diets, supplements are also available. One option, which may be especially helpful for people with IBS, is psyllium. Sometimes it is known as ispaghula. It comes from the seeds of a plant called plantago ovata and is reported to have numerous benefits for health.

One key factor to consider is that fiber works best for digestion in the presence of water. Therefore, it is important to up your fluid intake at the same time as eating more fiber. Failing to do so could prevent the fiber from doing its job and might even make certain symptoms worse.

Side Effects of Fiber and IBS

When increasing fiber intake, people with IBS should be aware that it could cause some unwanted effects:

  • Increased bloating, gas, or abdominal pain
  • More frequent bowel movements
  • Worsening of diarrhea

Some people with IBS will find eating more fiber helpful, but for others it could make their symptoms worse. Therefore, it is essential to boost your fiber intake gradually and carefully monitor how your body responds.