Understanding What Foods Not to Eat with SIBO?

October 4, 2025 •

4 min read

According to studies, a majority of individuals with Small Intestinal Bacterial Overgrowth (SIBO) experience symptom improvement by following a specialized diet that restricts fermentable carbohydrates. Understanding what foods not to eat with SIBO? is a critical step in managing the condition and alleviating uncomfortable digestive issues. Following a specific diet helps reduce the food source for overgrown bacteria, allowing the small intestine to heal.

Quick Summary

A SIBO diet restricts specific fermentable carbohydrates, known as FODMAPs, to reduce bacterial overgrowth and alleviate symptoms like bloating and gas. Key foods to avoid include high-FODMAP vegetables, fruits, legumes, certain dairy products, and grains. The goal is to limit the fuel supply for gut bacteria while ensuring proper nutrition through alternative choices.

Key Points

Avoid High-FODMAP Foods: The primary strategy for a SIBO diet is to reduce the intake of fermentable carbohydrates, known as FODMAPs.
Steer Clear of Specific Vegetables: Common culprits to avoid include garlic, onions, asparagus, and cauliflower due to high levels of fructans and polyols.
Limit Certain Fruits and Sugars: Restrict intake of high-fructose fruits like apples and pears, as well as sweeteners like honey and high-fructose corn syrup.
Reduce Lactose-Containing Dairy: Avoid milk, soft cheeses, and yogurt to prevent bacterial fermentation fueled by lactose.
Exclude Problematic Grains and Legumes: Foods like wheat, rye, barley, beans, and lentils are high in fermentable carbohydrates and should be limited.
Watch for Processed Foods and Sweeteners: Highly processed foods and artificial sweeteners (like sorbitol and xylitol) can worsen SIBO symptoms by feeding gut bacteria.

Understanding the Role of Diet in Managing SIBO

Small Intestinal Bacterial Overgrowth, or SIBO, is a condition where there is an excessive amount of bacteria in the small intestine, leading to a host of unpleasant symptoms like bloating, gas, abdominal pain, diarrhea, and constipation. Unlike the large intestine, which is home to trillions of bacteria, the small intestine should have a much lower bacterial count. When these bacteria migrate or overgrow, they feed on undigested carbohydrates, or fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs). This fermentation process produces gas, which causes the characteristic symptoms of SIBO.

The SIBO diet, most commonly the low-FODMAP diet, is designed to reduce the amount of these fermentable carbohydrates, thereby 'starving' the overgrown bacteria. It is generally not a long-term solution but a temporary therapeutic approach used alongside treatment, often guided by a healthcare professional or dietitian.

High-FODMAP Foods: The Primary Culprits

The cornerstone of a SIBO-friendly diet is the avoidance of high-FODMAP foods. These carbohydrates are poorly absorbed by the body, so they reach the small intestine largely intact, where they are then fermented by bacteria.

Fermentable Oligosaccharides

These carbohydrates, found in vegetables, grains, and legumes, are common triggers for SIBO symptoms. They include fructans and galacto-oligosaccharides (GOS). Key culprits to avoid are:

Garlic and Onions: These are among the most potent SIBO triggers due to their high fructan content and are found in countless prepared foods.
Legumes: Beans, lentils, and chickpeas contain high levels of oligosaccharides that can cause significant gas and bloating.
Certain Vegetables: Asparagus, artichokes, cauliflower, and mushrooms are rich in fructans and polyols that can exacerbate symptoms.
Wheat, Rye, and Barley: These grains contain high levels of fructans and, in the case of some individuals, gluten, which can increase intestinal inflammation.

Fermentable Disaccharides

This group primarily refers to lactose, the sugar found in milk and dairy products. Lactose can be difficult to digest for many individuals, even without SIBO, but it is especially problematic for those with bacterial overgrowth. When undigested lactose ferments, it fuels bacterial activity and creates excess gas.

Dairy Products to Avoid: Milk, soft cheeses (like ricotta), yogurt, ice cream, and custard should be limited or eliminated initially.
Lactose-Free Alternatives: Many individuals with SIBO tolerate lactose-free dairy or dairy alternatives, like almond or soy milk, better.

Fermentable Monosaccharides

Fructose, a simple sugar found in many fruits, honey, and high-fructose corn syrup, is poorly absorbed by some people and can contribute to SIBO symptoms.

High-Fructose Fruits: Apples, pears, mangoes, watermelon, and dried fruits are particularly high in fructose and should be avoided or limited during the elimination phase.
Sweeteners: Honey, agave nectar, and high-fructose corn syrup can also feed intestinal bacteria and should be avoided.

Polyols

These sugar alcohols, including sorbitol, mannitol, xylitol, and maltitol, are often used as sweeteners in sugar-free products and are poorly absorbed, leading to fermentation.

Foods with Polyols: Avoid sugar-free gums, mints, diet sodas, and certain fruits and vegetables like stone fruits, cauliflower, and mushrooms.

Other Food Groups to Consider Limiting

Highly Processed and Sugary Foods

Beyond high-FODMAPs, general dietary advice for SIBO includes reducing processed foods and excess sugar. Processed foods often contain a mix of fermentable ingredients, and sugar fuels the growth of harmful bacteria, throwing off the delicate gut flora balance. Examples include cookies, cakes, sweetened cereals, and fast food.

Excessive Alcohol and Caffeine

Alcohol, especially beer and wine, is fermented and can contribute to bacterial growth. Both alcohol and excessive caffeine can irritate the digestive tract and should be consumed in moderation or avoided.

Potential Issues with High Fiber Foods

While fiber is typically good for gut health, certain types of fiber can be problematic for some people with SIBO, particularly those with constipation-dominant SIBO (methane-dominant SIBO). Soluble fiber is generally better tolerated than insoluble fiber, but it is best to consult a dietitian to determine the right balance for your specific condition.

High-FODMAP vs. Low-FODMAP Foods for SIBO


High-FODMAP Foods (to Avoid)	Low-FODMAP Foods (Safe)
Vegetables: Garlic, Onions, Asparagus, Cauliflower, Mushrooms, Artichokes	Vegetables: Carrots, Cucumbers, Bell Peppers, Spinach, Zucchini, Lettuce
Fruits: Apples, Pears, Mangoes, Watermelon, Dried Fruits, Stone Fruits	Fruits: Oranges, Grapes, Strawberries, Blueberries (in moderation), Bananas (firm)
Grains: Wheat, Rye, Barley, Some Cereals	Grains: Oats, Quinoa, Rice, Buckwheat, Gluten-Free Breads
Dairy: Milk, Yogurt, Soft Cheeses, Ice Cream	Dairy: Lactose-free milk, Hard cheeses (cheddar, parmesan), Almond milk
Legumes: Beans, Lentils, Chickpeas	Legumes (in small amounts): Canned lentils (rinsed), Peanuts
Sweeteners: Honey, High-Fructose Corn Syrup, Agave, Sorbitol	Sweeteners: Stevia, Maple Syrup (small amounts), Table Sugar (small amounts)

Conclusion

Navigating a SIBO diet can feel restrictive, but focusing on what to avoid is a powerful strategy for symptom relief. The key takeaway is to reduce the intake of fermentable carbohydrates, primarily high-FODMAPs, which feed the bacterial overgrowth in the small intestine. This is not a permanent diet but a temporary therapeutic tool used in conjunction with other treatments. It is essential to work with a healthcare professional, such as a registered dietitian, to ensure you are receiving adequate nutrition while on a SIBO-specific diet and to properly manage the reintroduction phase. A personalized approach is critical, as individual triggers can vary, and a dietitian can help you identify them effectively. For more information on gut health and nutrition, consult authoritative sources like the AGA GI Patient Center.

AGA GI Patient Center

Frequently Asked Questions

Fermented foods, while generally beneficial for gut health, should be approached with caution during the elimination phase of a SIBO diet. The probiotics they contain can be helpful during recovery, but their fermentable nature can also exacerbate symptoms in some individuals. It's best to reintroduce them slowly and in consultation with a dietitian.

While gluten-containing grains (wheat, rye, barley) are high in fructans and should be avoided, simply switching to gluten-free alternatives is not a guaranteed solution. Many gluten-free processed foods can still be high in refined carbohydrates and starches that can feed SIBO bacteria. Focus on whole, naturally gluten-free grains like rice and quinoa instead.

No, the SIBO diet is not meant to be followed long-term. It is a temporary therapeutic diet designed to reduce bacterial overgrowth and alleviate symptoms. After an initial elimination phase, foods are slowly reintroduced to identify specific triggers and diversify the diet again. Long-term restriction is not recommended.

Yes, while the low-FODMAP diet is the most common, other variations exist, including the elemental diet and specific carbohydrate diets (SCD). An elemental diet, a liquid-only formula, is highly restrictive but can be very effective in severe cases. The best diet for you depends on your specific symptoms and should be determined with a healthcare provider.

A dietitian is crucial for managing a SIBO diet because they can create a personalized plan to ensure you get adequate nutrition while avoiding triggers. They help navigate the elimination and reintroduction phases safely, provide guidance on supplements like fiber, and prevent unnecessary long-term dietary restrictions.

Highly processed foods, such as fast food, cookies, and packaged snacks, often contain a high number of added sugars, inflammatory fats, and fermentable ingredients. These ingredients can fuel bacterial overgrowth, contribute to inflammation, and worsen overall gut health, making them a common trigger for SIBO symptoms.

The reintroduction phase typically follows a 2-4 week elimination period. Under a dietitian's guidance, you systematically add back high-FODMAP food groups one at a time to identify which specific foods and how much of them you can tolerate without symptoms. This helps create a more sustainable, personalized long-term diet.