How to get fiber when you have SIBO?

October 12, 2025 •

4 min read

According to estimates, up to 78% of people with Irritable Bowel Syndrome (IBS) may also have Small Intestinal Bacterial Overgrowth (SIBO), often struggling with gas, bloating, and abdominal pain. This makes understanding how to get fiber when you have SIBO a critical part of managing symptoms while supporting gut recovery and overall health.

Quick Summary

Managing fiber with SIBO requires focusing on low-fermentation sources and strategic intake to minimize symptoms. Gradual reintroduction of well-tolerated options, proper cooking methods, and a focus on specific low-FODMAP fibers can help support bowel function without feeding bacterial overgrowth.

Key Points

Prioritize Low-FODMAP Fibers: Focus on fibers from sources with low fermentable carbohydrates, such as oats, chia seeds, and cooked vegetables.
Introduce Fiber Gradually: Use a 'low and slow' approach when adding fiber back into your diet to avoid overwhelming the system and causing symptom flare-ups.
Choose Specific Supplements: Partially Hydrolyzed Guar Gum (PHGG) is a well-tolerated, low-fermentation supplement shown to enhance SIBO treatment outcomes.
Cook Your Vegetables: Thoroughly cooking vegetables breaks down fiber, making it easier to digest and less likely to be fermented by SIBO bacteria.
Support Motility with Timing: Spacing meals 3-4 hours apart allows the gut's natural cleansing waves to work effectively, preventing bacterial overgrowth.
Stay Hydrated: Always drink plenty of water when increasing fiber intake to prevent constipation and support proper digestive function.

Understanding the SIBO and Fiber Connection

For many, fiber is a cornerstone of digestive health, but for individuals with Small Intestinal Bacterial Overgrowth (SIBO), the relationship is more complex. SIBO involves an overgrowth of bacteria in the small intestine, and certain types of fiber—specifically highly fermentable carbohydrates known as FODMAPs—can act as a fuel source for these bacteria. This fermentation produces excess gas, leading to common SIBO symptoms like bloating, abdominal distension, and pain. The key is to select fiber sources that are less likely to ferment rapidly in the small intestine, providing benefits without exacerbating symptoms.

There are two main types of fiber to consider:

Soluble Fiber: This type dissolves in water to form a gel-like substance that can help regulate stool consistency. While some soluble fibers are highly fermentable (and thus high-FODMAP), others are low-fermentation and well-tolerated in moderate amounts.
Insoluble Fiber: Found in things like fruit skins, nuts, and whole grains, insoluble fiber adds bulk to stool and can help with constipation. Many insoluble fibers are also high in FODMAPs, requiring careful selection.

The Best Fiber Sources for SIBO

Navigating fiber with SIBO means prioritizing specific foods and supplements known to be low in fermentable carbohydrates. These options allow for the benefits of fiber without significantly feeding the bacterial overgrowth.

Low-FODMAP Foods

Oats: In appropriate portions, oats can be a source of gentle, low-FODMAP soluble fiber.
Flaxseeds (Ground): Rich in both soluble and insoluble fiber, ground flaxseeds can be tolerated well by many.
Chia Seeds: Similar to flaxseeds, these are excellent sources of soluble fiber in small servings.
Cooked Vegetables: Thoroughly cooking vegetables can break down their fiber content, making them easier to digest. Safe low-FODMAP examples include carrots, zucchini, and spinach.
Low-FODMAP Fruits: Berries, citrus fruits, and kiwi can provide fiber and nutrients with less risk of fermentation.

Strategic Supplements

Partially Hydrolyzed Guar Gum (PHGG): This soluble, low-fermentation fiber is often recommended for SIBO, particularly when combined with antibiotics like rifaximin. Research has shown it can increase eradication rates and improve symptoms without causing significant bloating. It may also support the Migrating Motor Complex (MMC), the gut's 'cleansing waves' that help prevent bacterial buildup.
Psyllium Husk: As a low-FODMAP soluble fiber, psyllium can be well-tolerated and is often used to manage both constipation and diarrhea in IBS and SIBO patients, though individual tolerance varies.

Strategic Dietary Tips for Fiber with SIBO

In addition to choosing the right fiber sources, your approach to eating is crucial for minimizing symptoms.

Go Low and Slow: Start with a very small serving of a new fiber and gradually increase the amount over several weeks. This allows your gut time to adjust and helps you identify your personal tolerance level.
Stay Hydrated: Fiber needs plenty of water to function effectively. Dehydration with increased fiber can worsen constipation, so ensure you drink adequate fluids throughout the day.
Space Out Meals: The gut's MMC works best between meals to sweep out bacteria. Continuous snacking can inhibit this process. Allowing 3-4 hours between meals can help support proper gut motility.
Monitor Symptoms: Keep a food and symptom diary to track how your body responds to different fiber sources. This personalized data can be invaluable for tailoring your diet.

Comparison of Fiber Sources for SIBO


Fiber Source Type	SIBO Tolerance	Common Examples
Low-FODMAP Soluble Fiber	Generally well-tolerated. Ferments slowly and less likely to cause gas and bloating.	Oats, chia seeds, flaxseeds, PHGG, psyllium husk.
Low-FODMAP Vegetables (Cooked)	Often better tolerated than raw vegetables as cooking breaks down fibers.	Carrots, spinach, zucchini, parsnips, lettuce.
High-FODMAP Soluble Fiber	Can cause significant gas, bloating, and discomfort due to rapid fermentation.	Inulin, chicory root, onions, garlic, legumes (e.g., lentils, beans).
High-FODMAP Insoluble Fiber	Can increase gas and motility issues, depending on individual sensitivity.	Wheat bran, high-FODMAP fruits (e.g., apples, pears), cruciferous vegetables (e.g., broccoli, cauliflower).

Conclusion: Finding Your Fiber Balance

For those with SIBO, fiber is not a one-size-fits-all nutrient; the type and amount matter significantly. By strategically choosing low-FODMAP and low-fermentation options, individuals can support healthy bowel function and feed beneficial gut bacteria without worsening SIBO symptoms. The 'low and slow' reintroduction method, coupled with supportive habits like hydration and meal spacing, provides a safe pathway to reincorporating this essential nutrient. A personalized approach is always best, and consulting with a healthcare professional or a dietitian specializing in gut health is recommended to ensure your fiber strategy aligns with your specific needs and treatment plan. For further reading on the use of a specific fiber supplement in SIBO treatment, see this resource from thegutco.com.au.

Frequently Asked Questions

No, not all fiber is bad. The key distinction is between high-fermentation (high-FODMAP) fibers and low-fermentation (low-FODMAP) fibers. High-FODMAP fibers can worsen symptoms, while low-fermentation options can be well-tolerated and beneficial.

Partially Hydrolyzed Guar Gum (PHGG) is widely considered one of the best fiber supplements for SIBO. It is low-fermentation and has been clinically shown to improve treatment efficacy and symptoms like bloating.

Yes, in small and monitored amounts, oats are a low-FODMAP source of soluble fiber that can be tolerated by many people with SIBO. Start with a small serving and observe your symptoms.

Yes, cooking vegetables until they are tender helps break down the fiber content, making it less likely to be fermented and cause gas or bloating. This is a good strategy, especially for individuals with a sensitive gut.

Foods high in fermentable FODMAPs should be limited, such as onions, garlic, beans, apples, pears, and wheat bran. Read labels carefully to check for high-FODMAP fibers like inulin or chicory root.

A temporary reduction of fiber, especially fermentable types, can be beneficial during the initial treatment phase. However, long-term restriction can lead to nutritional deficiencies, so working with a dietitian to reintroduce fiber is crucial.

Individual tolerance varies, so it is recommended to introduce new fibers slowly and keep a food and symptom diary. This helps you track your body's specific responses and identify triggers.