Small Intestinal Bacterial Overgrowth (SIBO) occurs when an excessive number of bacteria colonize the small intestine. These bacteria consume and ferment undigested food particles, especially carbohydrates, leading to uncomfortable symptoms. A SIBO “flare-up” is an acute, severe exacerbation, often presenting as intense bloating, abdominal pain, and changes in bowel movements. During this acute phase, immediate dietary modification is the most direct way to reduce the bacteria’s fuel supply, helping to calm the digestive tract and achieve symptom relief.
Immediate Dietary Restrictions
The primary goal during a flare is to eliminate highly fermentable carbohydrates that feed the bacteria. These compounds, known as FODMAPs (Fermentable Oligo-, Di-, Mono-saccharides, and Polyols), are quickly metabolized, producing the gas that causes severe bloating and pain. Immediate removal of high-FODMAP offenders is necessary to reduce fermentation.
Foods like onions, garlic, wheat products, apples, pears, and honey should be avoided due to their high concentration of fructans and fructose. Polyols found in sugar-free gums and vegetables like cauliflower and mushrooms can also trigger symptoms and must be eliminated. Concentrated sugars, including high-fructose corn syrup, provide a readily available energy source for bacteria and should be strictly avoided.
High-fiber foods, especially insoluble fiber, must be restricted because they are mechanically irritating to a sensitive gut lining. This includes raw vegetables, whole grains, and legumes. Alcohol, even in small amounts, can irritate the mucosal lining and trigger a flare.
Safe and Gentle Foods for Acute Relief
Focus on foods easily absorbed high up in the small intestine to ensure less residue reaches the bacteria. Low-fat, easily digestible protein sources are recommended, such as plain baked or steamed white fish, poultry breast, and eggs. These foods contain minimal carbohydrates and do not contribute to bacterial fermentation.
Low-residue carbohydrates are the safest choice for energy, including plain white rice or well-cooked, peeled root vegetables like carrots and parsnips. Cooking and peeling breaks down problematic fiber, making them gentler on the digestive system. Small portions of low-FODMAP fruits, such as peeled kiwi, cantaloupe, or strawberries, can provide vitamins without excessive fructose.
Healthy fats should be sourced from easily assimilated forms, such as olive oil, coconut oil, or ghee, which contain medium-chain triglycerides (MCTs). MCTs are absorbed quickly and efficiently, reducing the likelihood of undigested fat causing irritation in the lower small intestine.
Preparation Methods to Aid Digestion
Food preparation significantly impacts how easily the small intestine can process a meal during a flare-up. Thoroughly cooking vegetables until very soft (steaming, boiling, or stewing) helps predigest the cellular structure and soften fiber. This minimizes digestive effort and reduces the residue available for bacterial consumption.
Peeling all fruits and vegetables is important, as the skins contain insoluble fiber that can be irritating. Creating pureed foods, like simple vegetable soups or smooth cooked porridges, ensures contents are quickly assimilated.
Meals should be kept small to avoid overwhelming the gut, and individuals should focus on eating slowly and chewing thoroughly. Avoiding frying and heavy seasonings is advisable, as added fat and spices can increase the digestive load and potentially irritate the inflamed gut lining.
Hydration and Electrolyte Management
Maintaining proper fluid balance is important during a SIBO flare, as diarrhea can lead to rapid dehydration and loss of essential minerals. Plain, still water is the simplest form of hydration, helping to flush the system without irritants. Low-sugar electrolyte solutions are highly beneficial for replenishing lost sodium and potassium, especially after diarrhea.
Fat-skimmed bone broth provides readily available minerals and gelatin, which can be soothing to the gut lining. Ensure the broth is completely de-fatted to prevent digestive upset.
Herbal teas, such as peppermint or ginger, may help calm the digestive tract and reduce nausea or cramping. Carbonated and sugary drinks must be avoided, as the bubbles and high sugar content introduce gas and fermentable carbohydrates, worsening acute symptoms.