Ultimate Fiber Guide for IBS: Best Practices for Relief

Never did I anticipate that fiber would become such a sexy topic, but here we are, and I’m living for it! Fiber is having a major moment in the spotlight, and for good reason. It is an essential nutrient that plays a vital role in both digestive health, fueling a thriving gut microbiome, and long-term health outcomes.

However, if you have Irritable Bowel Syndrome (IBS) or another gastrointestinal condition, navigating which fiber to select, and how to consume it, can pose a challenge for you.

While fiber can help manage IBS symptoms for some, it can also exacerbate symptoms like gas, bloating, constipation, or diarrhea, for others. But you’re about to become a fiber pro, so that the next time you’re wandering the aisles of the pharmacy trying to make a selection on the best fiber options for you, you know exactly what to choose and why!

The key is to develop an understanding of the varying properties associated with fiber, and then apply that information to personalized your fiber plan. This guide will help you understand the different types of fiber, how to incorporate them into your diet safely, and best practices for achieving symptom relief.

What is Fiber and Why Is It Important?

Fiber is a type of carbohydrate found in plant-based foods. Unlike other carbs, fiber is not digested through mechanical or chemical digestion in the human body. Key word: human. Instead, it passes through the digestive system largely intact, providing several health benefits, including aiding digestion, promoting regular bowel movements, and feeding the beneficial bacteria in your gut. That’s right - we’ve actually made an alliance with the microbes in our gut to break down fibers for us, and in so doing, our beneficial microbes are nourished and also unlock more nutrition for us from the fibrous foods we eat.

Types of Fiber

Soluble fiber dissolves in water to form a gel-like substance in the gut. It slows down digestion and can help manage symptoms like diarrhea. It is found in rolled oats, apples, citrus fruits, carrots, peas, and beans, among others.

Insoluble fiber does not dissolve in water and instead adds bulk to stool. By adding bulk, it helps food pass more quickly through the stomach and intestines. It is found in whole grains, nuts, seeds, and the skins of fruits and vegetables.

Resistant starch is a type of fiber that resists digestion through the gastrointestinal tract and makes its way largely intact to the large bowel, where it can feed the gut microbiome. Because it provides nourishment to beneficial gut microbes, it's considered a prebiotic. It is found in under ripe bananas and to varying degrees in all forms of cooked and cooled starches, including potatoes, breads, rice, legumes, and whole grains.

But there’s more to the story. We no longer just describe fiber as soluble or insoluble - that is so 30 years ago! We now know that the specific characteristics of varying fibers make a huge difference on how your body reacts to them. Those properties include solubility, viscosity, and fermentability. If your goal is to derive fiber from your diet, then you will want to note that every fiber-containing food is derived from plants, and all of those foods involve some combination of these three characteristics. Understanding how your body responds to variations of fiber-containing foods is essential to training your fiber tolerance over time, diversifying your diet, and doing so without triggering your IBS.

How Does Fiber Impact IBS Symptoms?

Fiber can have both positive and negative effects on IBS symptoms depending on the type of IBS (IBS-D, IBS-C, or IBS-M) and the type of fiber consumed, as well as your individual gut motility, stool burden, and tolerance to fiber (which can be trained!).

For IBS-D (Diarrhea-predominant), soluble fiber can help by absorbing excess water in the bowel and forming a gel that slows down digestion. Avoid excessive insoluble fiber, which can exacerbate diarrhea.

For IBS-C (Constipation-predominant), insoluble fiber can help by adding bulk to the stool and promoting movement through the intestines. However, it’s important to introduce it gradually to avoid bloating and discomfort. Individuals with IBS-C may also benefit from some forms of soluble fiber as well, like ground flax and psyllium husk.

For IBS-M (Mixed), a balance of soluble and insoluble fiber may be beneficial, but when it doubt, stick with the tried-and-true fibers that have been studied extensively in the IBS population. Psyllium husk at a dose of 10 grams per day for 12 weeks has been shown to help improve bowel regularity for individuals with IBS. Careful monitoring of symptoms is essential to determine which dose and types of fiber your body tolerates best.

How to Increase Fiber With IBS

While the best approach to increasing fiber with IBS is personalized based on your individual tolerance thresholds, predominant symptom type, and digestive health goals, there are some general pointers that can help you get started on your own.

Start Low, Go Slow: Gradually increase your fiber intake to allow your gut to adjust. Start with small portions of fiber-rich foods and slowly increase the amount over several weeks.

Stay Hydrated: Drink plenty of water throughout the day to help fiber move smoothly through your digestive system. Aim for at least 8-10 cups of water per day.

Prioritize Soluble Fiber: If you're prone to IBS flare-ups, prioritize soluble fiber sources. These foods are generally easier on the digestive system and can help manage symptoms like diarrhea.

Be Mindful of FODMAPs: Some high-fiber foods are also high in FODMAPs, which can trigger IBS symptoms. Consider working with a dietitian to identify and limit high-FODMAP foods while still getting enough fiber.

Experiment with Resistant Starch: Resistant starch is a type of fiber that can be particularly beneficial for gut health. Start with small amounts of foods like green bananas or cooked and cooled potatoes and see how your body responds.

Consider Fiber Supplements: If you struggle to get enough fiber from food alone, consider a low-FODMAP fiber supplement like psyllium husk. This can help you increase your fiber intake without exacerbating IBS symptoms.

Managing fiber intake with IBS can be challenging, but with the right approach, it can also play a crucial role in strengthening your digestive foundations and finding symptom relief. By understanding the different types of fiber and their properties, gradually increasing your intake, and being mindful of your body's responses, you can find a balance that supports your gut health without triggering IBS symptoms.

If you're ready to take control of your IBS and nourish your gut with vibrant plant foods, download my free IBS Microbiome Reset Meal Plan or explore the Plant-Based IBS and SIBO Breakfast Book to get started on your own journey to radiant IBS relief!