Nutrition Diet: What Foods are the Worst for SIBO?

October 11, 2025 •

3 min read

With up to 80% of IBS patients also experiencing SIBO, understanding what foods are the worst for SIBO is a critical step toward symptom relief. For individuals with bacterial overgrowth in the small intestine, certain foods can act as fuel for bacteria, leading to gas, bloating, and digestive distress.

Quick Summary

Certain carbohydrates and processed ingredients can worsen SIBO symptoms by feeding excess bacteria in the small intestine. Key culprits include high-FODMAP foods, excess sugar, alcohol, and fibrous vegetables.

Key Points

High-FODMAP Foods: Fermentable carbohydrates found in certain fruits, vegetables, grains, and legumes are a primary fuel source for overgrown bacteria in SIBO.
Excess Sugars and Sweeteners: High levels of refined sugars and sugar alcohols feed bacteria and can cause excessive gas production, worsening symptoms.
Lactose-Containing Dairy: Dairy products with lactose, a disaccharide, are often poorly digested and fermented by intestinal bacteria in people with SIBO.
Alcohol and Carbonated Beverages: These can irritate the sensitive gut lining, further fuel bacterial overgrowth, and add extra gas to the digestive system.
Ultra-Processed and Fried Foods: Packed with unhealthy fats, additives, and high sugar content, these foods contribute to gut inflammation and exacerbate symptoms.
Individualization is Key: The list of trigger foods varies greatly among individuals, so a personalized elimination and reintroduction approach is essential for identifying specific culprits.

Small Intestinal Bacterial Overgrowth (SIBO) is a condition marked by an abnormal increase in bacteria in the small intestine. This overgrowth can disrupt digestion and lead to a range of uncomfortable symptoms, including bloating, gas, abdominal pain, diarrhea, and constipation. While treatment often involves antibiotics, dietary changes play a crucial role in managing symptoms and preventing recurrence by limiting the foods that fuel bacterial growth. Certain food categories are particularly problematic for SIBO and are often restricted in therapeutic diets like the Low-FODMAP diet.

The Role of Fermentable Carbohydrates (FODMAPs)

FODMAP is an acronym for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. These short-chain carbohydrates are poorly absorbed in the small intestine and are fermented by overgrown bacteria in individuals with SIBO, leading to gas production, bloating, and abdominal discomfort.

High-FODMAP Fruits, Vegetables, and Legumes

Many fruits high in fructose or sorbitol, vegetables containing fructans and mannitol, and legumes with oligosaccharides can aggravate SIBO symptoms. Examples of these problematic foods include:

Fruits: Apples, pears, cherries, peaches, mangoes, watermelon, and dried fruits.
Vegetables: Garlic, onions, leeks, asparagus, artichokes, cauliflower, mushrooms, and Brussels sprouts.
Legumes: Various beans, lentils, chickpeas, and soybeans.

Refined and Artificial Sweeteners

Sugars and certain sweeteners are primary food sources for bacteria. Refined sugars like granulated sugar and honey fuel bacterial overgrowth, while sugar alcohols such as xylitol and sorbitol can cause laxative effects. Some research also suggests artificial sweeteners may alter the gut microbiome.

Dairy Products and Lactose

Dairy products containing lactose, a fermentable disaccharide, are often poorly tolerated by those with SIBO. This can be due to poor lactose absorption or a secondary lactose intolerance where the bacteria interfere with lactase enzyme production. Examples include milk, yogurt, and soft cheeses. Hard cheeses and lactose-free dairy may be better options.

Grains with High Fructan and Gluten Content

Grains high in fructans or gluten, such as wheat, rye, and barley, can contribute to SIBO symptoms. Other high-FODMAP grains like amaranth may also be problematic.

Alcohol and Carbonated Drinks

Alcohol can irritate the gut lining and disrupt digestion, while carbonated beverages add gas, worsening symptoms in those with SIBO. This includes beer, wine, soda, and sparkling water.

Processed and Fried Foods

Ultra-processed foods often contain added sugars, unhealthy fats, and preservatives that can exacerbate gut inflammation and SIBO symptoms. This category includes fast food, sweets, processed meats, and pre-packaged meals.

Navigating the SIBO Diet with an Elimination Phase

A healthcare professional or registered dietitian may recommend a temporary elimination diet, like the low-FODMAP diet, to identify individual triggers. This involves removing high-FODMAP foods for a short period and then gradually reintroducing them to pinpoint specific problem foods.

Comparison of High vs. Low-FODMAP Foods for SIBO


Food Category	High-FODMAP (to avoid)	Low-FODMAP (often tolerated)
Vegetables	Onions, garlic, cauliflower, mushrooms, asparagus	Carrots, spinach, cucumber, bell peppers, eggplant, potatoes
Fruits	Apples, pears, mangoes, watermelon, cherries	Oranges, grapes, strawberries, blueberries, kiwi
Grains	Wheat-based bread, rye, barley, couscous	Rice, oats, quinoa, gluten-free bread
Dairy	Cow's milk, ice cream, yogurt, soft cheeses	Lactose-free milk, hard cheeses, almond milk
Legumes	Beans (most types), lentils, chickpeas	Limited amounts of canned lentils or chickpeas
Sweeteners	High-fructose corn syrup, honey, agave, sugar alcohols	Table sugar (in moderation), maple syrup, stevia, monk fruit

Conclusion: Personalized Nutrition for SIBO

While certain foods are generally problematic for SIBO due to their fermentable carbohydrate content, finding relief is a personal journey. Long-term restrictive diets can be detrimental, so identifying individual triggers through a structured process with a healthcare professional is key. By limiting trigger foods and focusing on tolerated ones, symptoms can be managed and gut health improved. The Monash University FODMAP Diet App offers further guidance on FODMAPs.

How to get help with a SIBO diet

Working with a qualified nutritionist or registered dietitian is highly recommended to create a personalized diet plan. They can guide you through elimination and reintroduction phases while ensuring adequate nutrition.

Frequently Asked Questions

SIBO, or Small Intestinal Bacterial Overgrowth, is a digestive disorder where there is an excessive amount of bacteria in the small intestine, leading to symptoms like bloating, pain, and gas.

FODMAPs are fermentable carbohydrates that are poorly absorbed and provide an easy food source for the overgrown bacteria in the small intestine. This bacterial feast produces gas, which causes bloating and discomfort.

Yes, but you may need to choose carefully. Products high in lactose, like milk and soft cheeses, are often poorly tolerated. Many people with SIBO can consume hard cheeses, lactose-free milk, or plant-based alternatives like almond milk.

For those with SIBO, these vegetables can be problematic because they contain fermentable carbohydrates like fructans and raffinose. Cooking can sometimes make them easier to tolerate, but many find they must be limited during the elimination phase.

No. While high-fructan grains like wheat and rye should be avoided, low-FODMAP, gluten-free grains like rice, quinoa, and oats are often well-tolerated in moderate portions.

It is generally recommended to avoid alcohol, as it can irritate the gut lining, fuel bacteria, and slow gut motility, which can worsen SIBO symptoms.

The most effective method is a guided elimination diet, such as the low-FODMAP diet. Working with a registered dietitian is crucial for a safe and effective reintroduction process to pinpoint your personal triggers.