Many people suffer from digestive system ailments. Among the most commonly diagnosed are intestinal diseases like Irritable Bowel Syndrome (IBS), Small Intestinal Bacterial Overgrowth (SIBO), and Intestinal Methanogen Overgrowth (IMO). Often, individuals live with these conditions for a long time without a diagnosis, which significantly worsens their quality of life. Untreated, they can lead to more severe consequences. In addition to seeing a doctor, treatment requires consultation with a dietitian. Diet has a significant impact on treating these types of disorders. Here, you'll learn what SIBO is and how to manage it.
First, I'd like to clarify a few important points. Many people associate bacteria with something bad. However, the human body lives in symbiosis with countless bacteria, primarily forming the gut microbiota. These bacteria carry out many processes essential for human life, such as producing serotonin, the so-called "happiness hormone." Disruptions in serotonin balance are directly linked to depression. In return, bacteria get a favorable living environment and readily available food. For example, fiber is not digested by the human body but serves as an ideal food for bacteria. Living in harmony with your gut microbiota is essential for health.
SIBO is a condition of the small intestine, also known as Small Intestinal Bacterial Overgrowth. The name is quite precise: it refers to the excessive growth of certain bacteria in the small intestine. Normally, the largest bacterial habitat in the human body is the colon. As long as bacteria remain in the colon, they are beneficial. Problems arise when they spread to the small intestine, which is relatively low in bacteria and has mechanisms to keep it that way. Overgrowth in the small intestine disrupts its function, causing symptoms known as SIBO. We'll discuss these symptoms shortly, but first, let's look at the protective mechanisms.
The human body creates an unfavorable environment for bacteria where they are not needed. Bacteria from the colon are blocked in several ways. First, they must overcome the physical barrier of the ileocecal valve, which separates the small intestine from the colon. Second, the peristaltic movements of the intestines help prevent bacterial overgrowth. Additionally, various secretions inhibit bacterial growth, including stomach acid, bile, pancreatic enzymes, and immunoglobulin A (IgA).
Despite these protective factors, SIBO can develop if one or more of these mechanisms are disrupted due to various reasons, including dietary habits, diseases, surgeries, or medications.
Daily habits significantly impact the development of SIBO. For example, eating too quickly can lead to larger food particles reaching the colon, where bacteria thrive and multiply. Overloading the digestive system at night disrupts intestinal peristalsis and cleansing during sleep, crucial for preventing SIBO.
The diet itself also matters. Beneficial bacteria prefer a plant-based diet, while improperly digested meat can feed harmful bacteria, leading to intestinal diseases.
Recognizing SIBO based on symptoms alone is challenging as they overlap with other digestive disorders. Symptoms vary depending on the type and amount of bacteria overgrown in the small intestine, influenced by diet. Common symptoms include bloating, fullness, constipation, excessive gas, poor fat digestion leading to fatty diarrhea, unexplained weight loss, and abdominal pain.
Diagnosing SIBO requires tests. The most accurate results come from analyzing a sample directly from the small intestine, a complex and invasive procedure. More commonly, a breath test is used. It measures hydrogen and methane levels in the breath, gases produced by intestinal bacteria. Elevated levels indicate bacterial overgrowth. Blood tests can complement this by showing reduced levels of fat-soluble vitamins, especially B12. Sometimes, radiological examinations like abdominal X-rays are used to diagnose anatomical abnormalities.
Treatment primarily involves antibiotics and a suitable diet. Effective antibiotics include tetracyclines, amoxicillin with clavulanic acid, metronidazole, and doxycycline. Antibiotics should be chosen based on the type of bacteria identified, ideally from an intestinal sample analysis. Nutritional deficiencies may require supplementation, and the diet should be low in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols). In severe cases, surgery may be necessary to correct anatomical abnormalities.
A SIBO diet should be low in FODMAPs, meaning it should avoid easily fermentable carbohydrates like lactose, fructose, fructans, and polyhydroxy alcohols (e.g., sorbitol, mannitol, xylitol, and maltitol).
Table 1: Foods Categorized by FODMAP Content
| Food Groups | Low FODMAP (Recommended) | High FODMAP (Not Recommended) |
|---|---|---|
| Fruits | Bananas, grapes, kiwi, mandarins, oranges, pineapples, grapefruits, lemons, berries | Avocados, apples, pears, watermelons, mangoes, peaches, cherries, plums, apricots, nectarines, dried fruits, canned fruits |
| Vegetables | Carrots, tomatoes, cucumbers, bell peppers, Chinese cabbage, bamboo shoots, celery, corn, eggplant, lettuce, pumpkin, zucchini, sweet potatoes, chives | Onions, lettuce, asparagus, artichokes, broccoli, cauliflower, patty pans, Brussels sprouts, lentils, green peas, leeks, beets, cabbage, mushrooms, fennel, garlic |
| Dairy | Cheese (Swiss, cheddar, parmesan, mozzarella), almond milk, rice milk, butter, peanut butter, margarine | Cottage cheese, soft cheeses (brie, ricotta), condensed milk, yogurt, buttermilk, milk (cow, sheep, goat), sour cream, whipped cream |
| Others | Meat (beef, chicken, canned tuna, fish, pork, seafood, turkey, deli meats), eggs, coffee, tea, olive oil, most spices and herbs, homemade broth, mustard, mayonnaise, balsamic vinegar, gluten-free bread | Wheat products, products containing sorbitol and other polyols (mannitol, xylitol, maltitol sweeteners), sweets |
Probiotics are a promising area of research for gastrointestinal disorders. Lactobacillus and Bifidobacterium strains have been the focus, showing that Bifidobacterium reduces hydrogen levels in breath tests but increases methane, which is associated with IMO. Current knowledge is insufficient to draw definitive conclusions, but probiotics remain a promising field for further research.
I hope this article has provided useful information about SIBO. In summary, it is a condition caused by bacterial overgrowth in the small intestine, challenging to distinguish from IMO or IBS based on symptoms alone. Causes can vary widely, and bacteria play essential roles in our bodies, performing vital functions. Diagnosing SIBO requires a doctor's visit and breath test or intestinal sample. Treatment involves antibiotics and a low-FODMAP diet. If you need guidance on nutrition and training, I am here to help. I guarantee professional service, tailoring diet and training plans to your preferences and capabilities.
