Foods to Avoid When You Have Bacterial Overgrowth (SIBO)

November 16, 2025 •

4 min read

According to the Mayo Clinic, Small Intestinal Bacterial Overgrowth (SIBO) occurs when there is an abnormal increase in the overall bacterial population in the small intestine, leading to a variety of uncomfortable digestive symptoms. To help manage this condition, knowing what foods you should avoid when you have bacterial overgrowth is a key strategy for reducing symptoms and supporting gut healing.

Quick Summary

This guide details which foods to limit or eliminate to help manage symptoms associated with bacterial overgrowth, including high-FODMAP foods, sugars, and alcohol. Effective dietary changes can help reduce fermentation and discomfort.

Key Points

Restrict High-FODMAPs: Limit Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols found in foods like onions, garlic, beans, dairy, and certain fruits.
Cut Back on Sugar: Reduce intake of refined sugars, honey, high-fructose corn syrup, and sugar alcohols, which feed bacterial overgrowth.
Be Mindful of Fiber: Temporarily reduce high-fiber foods like some whole grains and cruciferous vegetables, as they can cause increased fermentation in some individuals.
Avoid Alcohol: Steer clear of alcohol, especially sugary drinks like beer and sweet wines, which can promote bacterial growth and irritate the gut.
Personalize Your Diet: Use a temporary elimination diet, like a low-FODMAP plan, under professional guidance to identify your specific food triggers.
Focus on Low-Fermentation Foods: Prioritize easily digestible proteins, low-FODMAP vegetables, and healthy fats while healing your gut.

Understanding Small Intestinal Bacterial Overgrowth (SIBO)

Small Intestinal Bacterial Overgrowth, or SIBO, is a condition where excessive bacteria, and often the wrong type, colonize the small intestine. Unlike the large intestine, which naturally has a high bacterial concentration, the small intestine should have a relatively low count. When this balance is disrupted, the bacteria ferment undigested carbohydrates, releasing gases that cause the hallmark symptoms of SIBO: bloating, gas, abdominal pain, and diarrhea. The dietary approach for SIBO focuses on reducing the fermentable carbohydrates that feed this overgrowth, thereby starving the problematic bacteria and alleviating symptoms.

High-FODMAP Foods: The Primary Culprits

FODMAPs are a group of short-chain carbohydrates that are poorly absorbed by the small intestine and are a primary food source for gut bacteria. The acronym stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. Limiting these foods is a central component of managing SIBO symptoms, and a low-FODMAP diet is often recommended for a temporary period under a doctor or dietitian's supervision.

Oligosaccharides: Found in wheat, rye, onions, garlic, and legumes like beans and lentils. These can be major triggers for fermentation.
Disaccharides: Lactose, the sugar in dairy products like milk, yogurt, and ice cream, is a common fermentable disaccharide. Lactose-free alternatives or hard cheeses (which are lower in lactose) may be better tolerated.
Monosaccharides: Fructose, a simple sugar found in fruits, honey, and high-fructose corn syrup, can exacerbate symptoms. Apples, pears, and mangoes are particularly high in fructose.
Polyols: These are sugar alcohols like sorbitol, mannitol, and xylitol, often used as artificial sweeteners in diet foods and chewing gum. They are poorly absorbed and provide ample food for bacteria.

Sugars and Artificial Sweeteners

Bacteria thrive on sugars and many types of sweeteners, using them as a fuel source. A diet high in added sugars, syrups, and artificial sweeteners can contribute to the dysbiosis seen in SIBO.

Refined and Added Sugars: Table sugar (sucrose), honey, agave nectar, and high-fructose corn syrup directly feed the overgrowth. Reducing your intake can be highly beneficial.
Sugar Alcohols: Found in many sugar-free products, sugar alcohols like sorbitol and xylitol are poorly absorbed and can cause significant gas and bloating.

High-Fiber Foods (with a nuance)

While fiber is typically promoted for digestive health, some high-fiber foods can be problematic for individuals with SIBO. The bacteria in the small intestine ferment certain types of fiber, which can worsen symptoms. The impact of fiber varies widely among individuals, and a dietitian can help determine personal tolerance levels.

Some Grains: Whole grains like wheat and rye are high in fructans, a type of fermentable carbohydrate. Some SIBO protocols recommend temporarily limiting these to help with symptom management.
Cruciferous Vegetables: Vegetables like broccoli, cauliflower, and Brussels sprouts contain fibers that can be gas-producing. For some, these can worsen bloating and discomfort.

A Comparison of Foods to Avoid vs. Safer Alternatives

To better understand what to eliminate and what to replace it with, this table provides a helpful comparison for managing your diet during bacterial overgrowth treatment.


Food Category	Foods to Avoid	Safer Alternatives
Dairy	Cow's milk, ice cream, soft cheeses, flavored yogurt	Lactose-free milk, hard cheeses (like cheddar), almond or oat milk
Grains	Wheat, rye, barley, many cereals, bread	Gluten-free grains like rice, quinoa, oats (limit portions)
Legumes	Beans, lentils, chickpeas, soy beans	Smaller portions of canned beans (with liquid rinsed off), or avoid entirely
Fruits	Apples, pears, cherries, peaches, watermelon, mangoes	Bananas (ripe ones are high FODMAP, unripe are lower), berries, citrus fruits
Vegetables	Garlic, onions, asparagus, cauliflower, artichokes, mushrooms	Leafy greens (spinach, kale), carrots, zucchini, tomatoes, cucumbers
Sweeteners	High-fructose corn syrup, honey, agave nectar, sugar alcohols	Small amounts of maple syrup, Stevia, or other non-fermentable sweeteners
Drinks	Soda, fruit juice, sweet wine, beer, sugary cocktails	Water, unsweetened tea, clear broths

Alcohol and Other Irritants

Alcohol can directly feed bacteria and disrupt gut motility, making it generally recommended to avoid during active SIBO treatment. Sugary and fermented alcoholic drinks like beer and sweet wines are particularly problematic. Other irritants to consider include fried and processed foods, which can be hard to digest and put extra strain on the gut.

Navigating an Elimination Diet

To identify specific triggers, a temporary elimination diet, such as the low-FODMAP diet, is often used. Under the guidance of a registered dietitian, individuals temporarily restrict high-fermentable foods and then slowly reintroduce them to monitor for symptom return. This helps personalize dietary needs, as tolerance varies widely from person to person. An elimination diet is a tool for management, not a cure, and should be part of a broader treatment plan with medical supervision.

Conclusion: Personalizing Your Approach

Knowing what foods to avoid when you have bacterial overgrowth is a critical step towards managing your symptoms. By reducing your intake of fermentable carbohydrates like high-FODMAP foods, added sugars, and alcohol, you can help starve the problematic bacteria and alleviate discomfort. However, since individual triggers differ, working with a healthcare professional or registered dietitian is highly recommended to create a personalized elimination and reintroduction plan. This ensures you maintain a balanced diet while giving your digestive system the rest it needs to heal. By carefully listening to your body's responses, you can make informed dietary choices that support your journey toward better gut health. For further information and detailed food lists, resources like the Cleveland Clinic offer extensive guidance on managing SIBO through diet.

Frequently Asked Questions

The low-FODMAP diet is a temporary eating plan that reduces the intake of fermentable carbohydrates that can feed bacteria in the small intestine. Following it helps reduce fermentation, gas production, and associated symptoms like bloating and pain.

It is often recommended to avoid most dairy products, as they contain lactose, a fermentable sugar. However, some hard cheeses and lactose-free dairy alternatives may be tolerated in small amounts.

Yes, sugar is bad for SIBO because it is the primary fuel source for the bacterial overgrowth. This includes refined sugars, honey, and high-fructose corn syrup, which should be avoided during treatment.

High-fructose fruits like apples, pears, cherries, and watermelon should be avoided. Safer alternatives often include berries, citrus fruits, and smaller portions of less-fermentable options.

Avoid high-FODMAP vegetables such as garlic, onions, asparagus, cauliflower, and artichokes, as these can increase fermentation and gas. Many leafy greens, carrots, and zucchini are generally better tolerated.

Grains like wheat and rye contain fructans, a type of fermentable carbohydrate, which can cause issues for some SIBO patients. Alternatives like rice, quinoa, and oats are often better tolerated in moderation.

A SIBO diet, particularly the restrictive phase, is usually temporary, lasting around 4-6 weeks under medical supervision. The goal is to gradually reintroduce tolerated foods to support a balanced gut microbiome long-term.