What Are SIBO and SIMO?
Small intestinal bacterial overgrowth, also known as SIBO, is one of the more common causes of digestive issues such as consistent/stubborn bloating, gas, diarrhea, constipation, and pain in the stomach or while passing stools. SIBO is the result of bacteria producing an excess of hydrogen or hydrogen sulfide gas. Small intestinal methanogen overgrowth, also known as IMO or SIMO is caused by archaea (a type of microorganism) producing an excess of methanogens or methane gas. SIBO and SIMO can be similar in their presentation, which is why proper diagnosis is critical for appropriate and effective treatment.
SYMPTOMS OF SIBO/SIMO:
Bloating (individuals often describe themselves as looking pregnant)
Nausea
Gas
Low appetite, constant feeling of fullness
Abdominal pain and cramping
Pain while passing stool
Diarrhea (more common with SIBO)
Constipation (more common with SIMO)
Food intolerances
Nutrient deficiencies/malabsorption of nutrients
Impaired GI motility
Inflammation
Damaged microvilli (gut lining)
Dysbiosis
Impaired digestive capacity
COMMON CAUSES OF SIBO/SIMO:
Hypochlorhydria (low stomach acid)
Dysbiosis
Insufficiency of digestive or pancreatic enzymes
Certain medications (especially antibiotics, immunosuppressants, and antacids)
GI motility issues
Impaired immune function
Surgery or anatomical issues
NUTRITIONAL INTERVENTIONS FOR SIBO/SIMO
A key component to effectively addressing SIBO and SIMO is making dietary changes to reduce the growth of additional bacteria and methanogens, which in turn helps reduce the uncomfortable symptoms that come with SIBO/SIMO. These diets should be followed for 2-6 months under guidance from your healthcare practitioner. Afterwards, foods will slowly be added back into the diet. Two common dietary strategies are the low FODMAP diets and low fermentation diets.
Low FODMAP Diet
FODMAPs are a group of short-chain carbohydrates (sugar molecules) that are not absorbed in the gut. As they move slowly through the small intestine they attract water and as they move into the large intestine they are fermented. This combination can lead to bloating, gas, pain and digestive distress and difficulties.
FODMAPs= Fermentable, Oligosaccharides, Disaccharides, Monosaccharides and Polyols
Oligosaccharides (fructans and Galacto-oligosaccharides) found in wheat, rye, onion, garlic, legumes, lentils, asparagus, banana, watermelon, cashews, pistachios.
Disaccharides (lactose) found in dairy products
Monosaccharides (fructose) found in honey, apples, grapes, peas, agave, high fructose corn syrup
Polyols (sorbitol and mannitol) found in avocado, corn, blackberries, cauliflower, and often used as artificial sweeteners in food products
This diet attempts to lower the ingestion of FODMAPs and in turn lower the symptoms associated with SIBO/SIMO.
This diet is more appropriate for more severe cases of SIBO, or cases that did not resolve from a low fermentation diet alone
Foods to AVOID on a Low FODMAP diet
Vegetables: artichokes, asparagus, beets (raw), cauliflower, celery, garlic, bell peppers (green okay in small quantities), ancho chili, jalapeno, chipotle chili, broccoli, broccolini, savoy cabbage, cauliflower, celery, corn, fennel (bulb), leek, lotus root, mushrooms, onion, scallions (white part), snow peas, snap peas, green peas, delicata squash, acorn squash, butternut squash, pumpkin, tomatoes (roma and cherry), shallot
Fermented Vegetables: kimchi, sauerkraut, pickles, all other fermented veggies
Soy: natto soy milk, tofu (silken)
Beans: all beans, lentils, hummus and chips/crackers that contain beans/bean flour
Fruit: apple, apricots, avocado (no more than ¼ per day) blackberries, currants, cherries, cranberries, fig, goji berry, guava, jackfruit, lychee, grapefruit, mango, nectarines, peaches, papaya, pears, persimmon, plums, pomegranate, watermelon, any canned and dried fruit
Grains: all gluten-containing grains including barley, rye, triticale, wheat (durum, farro, kamut, spelt), wheat products (bulgur, couscous, semolina)
Dairy: milk, buttermilk, condensed milk, yogurt
Drinks: coconut water, aloe juice, fruit juices, rum, fennel, chamomile and oolong tea, oat milk, coconut milk
Condiments: onion salt/powder, garlic salt/powder, any condiments that contain a significant amount of onion/garlic
Sweeteners: agave, artificial sweeteners (acesulfame-K, aspartame, saccharin, sucralose), erythritol, applesauce, high fructose corn syrup, honey, xylitol.
Other: carob, leather, molasses, processed food products made with gluten containing grains and corn
Low Fermentation Diet
This diet is far less complicated and restrictive in comparison to the low FODMAP diet
This diet attempts to lower the fermentation of foods in the gut as well as reducing sulfur rich foods which can often contribute to fueling SIBO/SIMO
Foods to AVOID on a Low Fermentation diet
Fermented Foods/Drinks: yogurt, kefir, sauerkraut, kimchi, fermented vegetables, miso
Legumes: lentils, beans, hummus, and bean dips
Cruciferous vegetables: cabbage, broccoli, cauliflower, brussels sprouts, kale
Sugar alcohols: xylitol, sorbitol, erythritol, maltitol, anything ending in “-ol” that is added to make something sweet
Refined sugars: cane sugar, white sugar, brown sugar, corn syrup
Highly processed foods and snacks
Gluten
Dairy (okay in moderation - ideal to avoid if possible)
TESTING OPTIONS TO CONFIRM THE PRESENCE OF SIBO/SIMO:
Breath Test (best way to determine SIBO/SIMO): To take this test you will drink a glucose or lactulose beverage and then take breath samples over a three hour period to determine whether you have elevated Methane, hydrogen, or hydrogen sulfide.
Comprehensive Stool Analysis: A comprehensive stool test looks at bacterial, viral and parasitic pathogens, fungus and yeast, and assesses the type and amount of opportunistic and beneficial bacteria , as well as markers for inflammation, immunity, and digestive capacity and health.
PREVENTING SIBO/SIMO RECURRENCE:
After 2-6 months of following a specialized diet, along with incorporating supplemental and lifestyle recommendations given to you by your medical provider, you should see an improvement and be feeling better. Once your medical provider has determined that your SIBO/SIMO has been eradicated it is paramount to then work on repopulating your microbiome and prioritizing gut health. We do know that it is possible for SIBO/SIMO to return, therefore it is important to put things into place to optimize gut health and prevent recurrence from rearing its ugly head.
Strategies to prevent recurrence include:
Eat a diverse nutrient dense diet rich in vitamins & minerals (enjoy a variety of colors, textures, and a combination of raw vs. cooked foods)
Avoiding fried foods, processed foods, & foods high in refined sugars and flours
Prioritize foods rich in prebiotics (legumes, lentils, grains, veggies)
Prioritize foods rich in probiotics (yogurt, kefir, sauerkraut, fermented veggies, miso, tempeh)
Eat slowly, mindfully, and remember to chew food well
Managing stress and incorporating stress reduction techniques into your day to day life
Reduce consumption of alcohol
Only utilize antibiotics when necessary and if needed, take with a double dose of probiotics both during and after the antibiotic course has ended, for at least an additional week to 10 days.
Stop or reduce smoking (cigarettes)
Prioritize sufficient sleep
Continue taking any supplements your healthcare practitioner may have recommended to optimize gut health
Address any underlying conditions that may be contributing to SIBO/SIMO