What Carbs Should I Avoid with SIBO?

January 9, 2026 •

4 min read

It is estimated that over 15% of Americans are affected by Small Intestinal Bacterial Overgrowth (SIBO), a condition where excess bacteria in the small intestine ferment undigested food, especially carbohydrates. The fermentation process produces gas, leading to a host of uncomfortable symptoms like bloating, abdominal pain, and indigestion. Managing SIBO often involves dietary changes, particularly avoiding certain carbohydrates that fuel bacterial overgrowth.

Quick Summary

This article details specific carbohydrates that should be avoided by individuals with SIBO to minimize bacterial fermentation and alleviate symptoms. It highlights high-FODMAP foods, including certain fruits, vegetables, grains, and sweeteners, which can exacerbate digestive distress due to poor absorption in the small intestine.

Key Points

High-FODMAP Carbohydrates: Avoid fermentable carbohydrates like fructans (wheat, garlic, onions), lactose (milk), excess fructose (apples, honey), and polyols (sweeteners, cauliflower) that fuel bacterial overgrowth.
Resistant Starch Caution: Temporarily limit resistant starches (like those in cooked and cooled potatoes, legumes) during the initial SIBO treatment phase, as they can worsen symptoms for some individuals.
Start an Elimination Diet: Utilize a temporary elimination diet, such as the low-FODMAP diet, for 2-6 weeks to reduce bacterial fermentation and calm symptoms.
Focus on Low-FODMAP Replacements: Consume well-tolerated carbohydrates like white rice, quinoa, and smaller portions of gluten-free oats instead of high-FODMAP grains.
Seek Professional Guidance: Work with a registered dietitian to navigate the diet and reintroduction phases effectively, ensuring a nutritionally complete and sustainable plan.
Customize Your Diet: Recognize that individual tolerance varies. Use the elimination and reintroduction process to pinpoint your specific trigger foods rather than restricting your diet long-term.

Understanding Fermentable Carbohydrates and SIBO

For those with Small Intestinal Bacterial Overgrowth (SIBO), managing symptoms often hinges on reducing the intake of fermentable carbohydrates. The low-FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) diet is a common approach used to accomplish this, as these specific carbs are poorly absorbed in the small intestine and provide a food source for the overgrown bacteria. When these unabsorbed carbohydrates reach the bacteria, they are fermented, leading to the production of hydrogen and methane gas, which causes bloating, abdominal pain, and other digestive issues.

Not all carbohydrates are equally problematic. The key distinction lies in how they are digested. Simple carbohydrates with high fructose content, lactose from dairy, and complex carbohydrates with high fructan and galactan content are often the primary culprits. In addition, many high-fiber foods, especially those with soluble fiber and certain resistant starches, can also be problematic in the initial stages of a SIBO diet because they also ferment in the gut.

High-FODMAP Carbohydrates to Avoid

When following a SIBO-friendly diet, the focus is on temporarily eliminating or significantly reducing the consumption of carbohydrates that are poorly digested. This primarily means targeting high-FODMAP foods. Here's a breakdown of the specific types of carbohydrates to avoid:

Fructose: A simple sugar found in many fruits and sweeteners. When consumed in excess of glucose, it can be poorly absorbed and act as fuel for small intestine bacteria.
- Examples: Apples, pears, watermelon, dried fruits, honey, high-fructose corn syrup, and agave nectar.
Lactose: A disaccharide sugar found in milk and other dairy products. Many individuals with SIBO have trouble digesting it, especially as they get older, which fuels bacterial growth and fermentation.
- Examples: Cow's milk, ice cream, yogurt, soft cheeses, and flavored dairy products.
Fructans: Oligosaccharides made of fructose chains. They are highly fermentable and are common in many grains and vegetables.
- Examples: Wheat, rye, barley, garlic, onions, asparagus, artichokes, and inulin.
Galactans: Oligosaccharides found primarily in legumes. They are not well-absorbed and ferment rapidly, causing significant gas and bloating.
- Examples: Beans, lentils, chickpeas, and peas.
Polyols: Sugar alcohols such as mannitol and sorbitol. Often used as artificial sweeteners, they can trigger symptoms by drawing water into the intestine and fermenting.
- Examples: Cauliflower, mushrooms, stone fruits, and diet products.

The Role of Resistant Starch and Fiber

Resistant starches and certain types of fiber also play a critical role in a SIBO diet, though their management differs. Resistant starches are carbohydrates that resist digestion in the small intestine and are fermented by bacteria in the large intestine. While this is beneficial for long-term gut health, it can exacerbate symptoms in the initial phases of SIBO treatment. Many people with active SIBO symptoms need to avoid high levels of resistant starches temporarily to reduce bacterial overgrowth. High-fiber foods, particularly those with soluble fiber like inulin, also act as prebiotics and can fuel bacterial growth in the small intestine, leading to increased gas and bloating. A cautious, gradual reintroduction of these beneficial fibers is often recommended under professional guidance.

Comparison of High vs. Low-Carb SIBO Diets

Different dietary approaches exist for SIBO management, with the low-FODMAP diet being the most common, but other methods like the Specific Carbohydrate Diet (SCD) also play a role. The table below offers a comparison of common dietary considerations.


Carbohydrate Group	High-FODMAP Example	Low-FODMAP Alternative
Grains	Wheat, Rye, Barley, High-fiber cereal	White rice, Quinoa, Gluten-free oatmeal (small amounts)
Dairy	Cow's milk, Soft cheeses, Ice cream	Lactose-free milk, Hard cheeses (like Parmesan), Almond milk
Fruits	Apples, Pears, Watermelon, Cherries	Grapes, Oranges, Strawberries, Blueberries, Ripe bananas (small)
Vegetables	Onions, Garlic, Cauliflower, Artichokes	Carrots, Spinach, Cucumber, Zucchini, Bell peppers
Legumes	Beans, Lentils, Chickpeas	No specific alternatives, typically avoided initially
Sweeteners	Honey, High-fructose corn syrup, Sorbitol	Maple syrup (small amounts), Sucrose (small amounts)

The Importance of an Individualized Approach

While general guidelines exist, every individual's response to SIBO-triggering carbs is unique. The goal of a SIBO diet, especially one following a low-FODMAP framework, is not to permanently restrict food but to systematically identify personal triggers. A typical approach involves an elimination phase (2-6 weeks) where high-FODMAPs are avoided, followed by a reintroduction phase where foods are tested one by one to determine tolerance levels. Working with a registered dietitian or gastroenterologist is highly recommended for creating and navigating this personalized plan safely. Long-term, overly restrictive diets can lead to nutritional deficiencies and may even negatively impact the gut microbiome. The ultimate objective is to return to the broadest possible diet that minimizes symptoms while promoting long-term gut health. For more detailed information on SIBO and its treatment options, including the use of elimination diets, see the Healthline resource.

Conclusion

Effectively managing SIBO requires a focused approach to the carbohydrates in your diet. Avoiding high-FODMAP foods—specifically those rich in fructose, lactose, fructans, galactans, and polyols—can significantly reduce bacterial fermentation and ease symptoms like bloating and pain. Initially, it may also be necessary to limit fermentable fibers and resistant starches. The key is to follow a structured elimination and reintroduction plan, preferably with professional guidance, to identify your personal triggers and build a sustainable, nourishing diet. This temporary restriction is a tool to restore balance, not a long-term solution, and should eventually be expanded to reintroduce beneficial foods as tolerated.

Frequently Asked Questions

FODMAPs are short-chain carbohydrates (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) that are poorly absorbed in the small intestine. For individuals with SIBO, these carbs can become a food source for overgrown bacteria, leading to fermentation and symptoms like bloating, gas, and pain.

No, you should not avoid all carbohydrates. The goal is to limit specific fermentable carbohydrates (high-FODMAPs) that feed the bacteria. Low-FODMAP carbs like plain white rice, quinoa, and some fruits and vegetables in controlled portions are generally tolerated well.

The goal of a SIBO diet is not permanent restriction. After an initial elimination phase, a structured reintroduction phase helps you identify which specific FODMAPs you can tolerate and in what amounts. Many people find they can eventually reintroduce some previously restricted foods without symptoms.

Some high-fiber foods, particularly those with soluble fibers like inulin, can act as prebiotics and feed gut bacteria, including the overgrowth in the small intestine. While fiber is important for long-term gut health, it's often introduced slowly during SIBO recovery after initial symptom management.

Resistant starches ferment in the large intestine, which is beneficial for overall gut health. However, in the initial stages of SIBO treatment, they can worsen symptoms for some individuals due to excessive fermentation. They are typically reintroduced gradually after the overgrowth is under control.

Honey, high-fructose corn syrup, and excessive simple sugars are high in fructose, a monosaccharide that is often poorly absorbed and can be a significant food source for SIBO bacteria. They should be avoided or severely limited, especially during the elimination phase.

The low-FODMAP diet is a management tool for SIBO symptoms, not a cure. It helps to starve the overgrown bacteria and reduce symptoms but does not address the underlying cause of SIBO. A complete treatment plan often involves antibiotics or other interventions under a doctor's supervision.