Small Intestinal Bacterial Overgrowth (SIBO) is a condition characterized by an excessive amount of bacteria in the small intestine. This overgrowth can lead to a variety of uncomfortable gastrointestinal symptoms. Managing SIBO often involves dietary changes, and for those following a vegan diet, this can present unique challenges. This article aims to provide a comprehensive guide to navigating a vegan diet while effectively managing SIBO.
Understanding SIBO
SIBO, or Small Intestinal Bacterial Overgrowth, occurs when there is an imbalance of bacteria in the small intestine. The small intestine is responsible for absorbing nutrients. When bacteria from the large intestine migrate into the small intestine, they ferment food too early, leading to symptoms such as abdominal pain or discomfort, gas, belching, bloating, diarrhea, and sometimes constipation. In severe cases, it can lead to weight loss due to vitamin deficiencies.
Risk Factors for SIBO
Several factors can increase the risk of developing SIBO, including:
- Taking proton pump inhibitors or opioids
- Gastric surgery
- Nerve damage to the small intestine
- Failure of the ileocecal valve
Symptoms of SIBO
Left untreated, SIBO can cause a range of symptoms:
- Pain
- Diarrhea
- Malnutrition (due to the loss of the body’s main nutrients)
- In rare cases, a serious neurological condition called D-lactic acidosis can occur.
- SIBO can affect your stools, making them fatty or greasy, light, soft, and unusually foul-smelling.
The Challenge of a Vegan Diet with SIBO
For individuals diagnosed with SIBO, dietary adjustments are often necessary to manage symptoms and prevent recurrence after treatment. However, those following a vegan diet face additional challenges. Many common vegan staples are high in fiber and FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols), which can exacerbate SIBO symptoms.
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Common Vegan Foods That May Trigger SIBO Symptoms
- High-fiber foods: These are generally beneficial for gut health but can be problematic for SIBO sufferers as bacteria feed off fiber.
- Legumes: Beans and lentils, common protein sources in vegan diets, can cause bloating and gas due to their high fiber content and galactans.
- Certain vegetables: Cruciferous vegetables like broccoli, cabbage, and cauliflower, as well as those containing sulfur like garlic and onions, are known to produce gas.
- Sugar alcohols: Low-calorie sweeteners like mannitol and sorbitol can be fermented by gut bacteria, leading to digestive issues.
- FODMAPs: These difficult-to-digest carbs are fermented by gut bacteria in the colon.
The Role of Fiber in SIBO
Since the stomach bacteria that cause SIBO feed off of fiber, many people seek to consume less fiber. The notion that fiber should be avoided can conflict with tons of scientific data showing that a diet high in fiber can help reduce your risk of cancer, heart disease, and diabetes. Well, by eliminating fiber, you are reducing the food source for both the good and the harmful bacteria.
Dietary Strategies for Vegans with SIBO
Despite the challenges, it is possible to manage SIBO while maintaining a vegan diet. The key is to work with healthcare professionals and adopt a personalized approach.
Consulting Healthcare Professionals
Prior to incorporating any dietary changes to your treatment plan, discuss your options with your doctor. To benefit from an elimination diet, it’s important to work with a registered dietitian with training in SIBO conditions.
Elimination Diets
An elimination diet for SIBO may help you identify foods that bring on your digestive symptoms. However, an elimination diet is not a treatment for SIBO. Traditional treatment methods shouldn’t be ignored. Your doctor or a registered dietitian may suggest trying an elimination diet to find out if particular foods are contributing to your digestive symptoms.
To look for links between foods and SIBO symptoms, some people follow a short term elimination diet followed by careful gradual reintroduction of eliminated foods. The reintroduction of foods to the diet should be carefully guided by a registered dietitian who understands SIBO conditions. An elimination diet is a tool that can help you learn if certain foods are associated with your SIBO symptoms. However, it cannot replace other treatments prescribed to you to manage SIBO or other associated conditions.
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If you decide to try an elimination diet for SIBO, it’s important to plan it out with the help of a registered dietitian. They can help you build a list of foods to eliminate temporarily, and a plan for gradual reintroduction of foods.
Low-FODMAP Diet
One option is a diet low in FODMAPs, which are difficult-to-digest carbs that are fermented by gut bacteria in the colon. A low FODMAP diet should be done under the supervision of a registered dietitian or gastrointestinal specialist, since it is an extremely restrictive diet and persons following it need to make sure they are still eating adequately. You should work with a registered dietitian to create a diet plan that is appropriate for your individual symptoms and nutritional needs. If you decide to pursue an elimination diet, the foods you need to avoid will be specific to your personal diet plan. A registered dietitian can work with you to develop this plan.
In some cases, your doctor or dietitian may recommend temporarily eliminating a type of carbs called FODMAPs. Because many people with IBS also have SIBO, a low-FODMAP diet is sometimes suggested for people with SIBO. The main categories of FODMAPs include:
- Fructose, simple sugars commonly found in fruits and some vegetables, honey, and agave nectar
- Lactose, a sugar molecule in dairy products
- Fructans, a sugar compound found in gluten products, fruits, some vegetables, and prebiotics
- Galactans, a compound found in some legumes
- Polyols, sugar alcohols often used as low-calorie sweeteners
Foods that contain higher amounts of FODMAPs include:
- High-fructose corn syrup
- Agave nectar
- Honey
- Soda and soft drinks
- Garlic
- Onions
- Asparagus
- Butternut squash
- Cauliflower
- Artichokes
- Beans
- Apples
- Dried fruits
- Sausage
- Flavored yogurt
- Ice cream
- Sweetened cereals
- Barley
- Rye
- Grains
- Peas
- Mannitol
- Sorbitol
Everyone reacts to these foods differently. Even if some FODMAPs cause symptoms for you, other FODMAP-containing foods may not. A low-FODMAP diet is only one example of an elimination diet for SIBO. Remember, it’s best to take an individualized approach when planning a SIBO elimination diet. Although the low-FODMAP approach is popular, there is little evidence to show that a low-FODMAP diet can help with SIBO.
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Plus, restricting FODMAPs has been linked to potentially harmful changes in the types of bacteria growing in the gut. This effect was seen in people with IBS who followed a low-FODMAP diet for a prolonged period of time. People with SIBO already have an overabundance of unhealthy gut bacteria, so some researchers caution that a low-FODMAP diet may not always be beneficial.
If you’re avoiding FODMAPs during your elimination diet, the list of foods you should avoid can be restrictive. But there are still a number of foods you can enjoy while on this temporary diet. Some foods contain low amounts of FODMAPs in small servings but may be limited because larger servings would increase the FODMAPs. Some of the acceptable foods for a low-FODMAP diet include:
- Meat
- Fish
- Eggs
- Crackers, gluten-free
- Oatmeal
- Unsweetened cereal (made from low FODMAP grains)
- Spaghetti squash and summer squashes
- Broccoli (heads only, less than 3/4 cup)
- Leafy greens
- Carrots
- Rice or gluten-free noodles
- Olives
- Peanuts
- Potatoes
- Pumpkin
- Quinoa
- Seeds
- Some fruits (blueberries, grapes, oranges, and strawberries)
To help you plan meals and make the right food choices, your dietitian may recommend using a FODMAP app like the one created by Monash University or Fast FODMAP.
Focusing on SIBO-Friendly Vegan Protein Sources
The challenge for a vegetarian diagnosed with SIBO is obtaining adequate amounts of protein, since most sources of vegetarian protein are not in the green/safe zone (assuming you are following Dr. Siebecker’s guidelines).
- Peanuts: Peanuts (other nuts are ok in lower quantities; peanuts offer the highest quantity in the safe zone).
- White rice: If your body is able to tolerate white rice (not everyone with SIBO can), plain white rice and white rice noodles are another option.
- Canned green jackfruit: From everything I’ve researched, canned green jackfruit is fine for most SIBO people. Canned green jackfruit offers an acceptable “meaty vegetable” substitution in many recipes (I see it used most often for vegetarian and vegan pulled pork / carnitas / barbecue). It’s not super high in protein, but it’s a convenient addition to a vegetarian diet.
Considering Elemental Diets
When antibiotics alone do not help, the elemental diet is the only diet proven to treat SIBO. It is a predigested liquid diet prescribed by a doctor. The only proven diet for SIBO is the all-liquid elemental diet, which should only be embarked upon under a doctor’s supervision. In some cases, your doctor may also prescribe a liquid diet called an elemental diet. An elemental diet temporarily replaces all foods and beverages with a nutrient drink that’s easy for your body to absorb. This diet must be carried out with a doctor’s supervision. No other diet is proven to treat SIBO.
General Dietary Recommendations
According to the American College of Gastroenterology, most diets proposed for SIBO reduce your intake of foods that are fermented by gut bacteria. These may include:
- High fiber foods
- Sugar alcohols, a type of low calorie sweetener
- Sucralose, a zero calorie artificial sweetener
- Inulin and other prebiotics
Addressing Nutritional Deficiencies
When you have to restrict a lot of foods for SIBO, as well as restrict foods for veganism, it can be very easy to become deficient in specific vitamins and minerals. Not to mention, vegans are notorious for developing a Vitamin B12 deficiency. If this is you, consider consuming more nuts and seeds, and higher protein pseudo-grains like quinoa.
The Importance of Gut Motility
The other major cause of SIBO is a breakdown in gut motility. We rely on our gut to function properly for the digestion of food. Any backup can cause a variety of symptoms, such as bloating and diarrhea. We should complete the digestion of food approximately 90 minutes after eating. Some people develop migrating motor complexes (MMC). With gut motility not working correctly, it allows room for SIBO to set in.
Medical Treatments for SIBO
Antibiotics are the primary treatment for SIBO. These medications get rid of the bacteria that’s overgrowing in the small intestine. Antibiotics are the first line of treatment for SIBO.
Probiotics
Probiotic supplements are often claimed to benefit digestive health. Some studies suggest that probiotics may limit bacterial overgrowth, lower scores on the hydrogen breath test, and reduce abdominal pain with SIBO. However, a 2021 systematic review concluded that large, high-quality studies are needed to understand the effects of probiotics on SIBO. Some experts believe probiotics could make SIBO worse.
Additional Considerations
SIBO and IBS
Because many people with IBS also have SIBO, a low-FODMAP diet is sometimes suggested for people with SIBO. SIBO is now known to be a leading cause of IBS.
Addressing Underlying Issues
For some people, successfully treating the bacterial overgrowth does not eliminate digestive symptoms. If your symptoms continue after treating SIBO, you may have another digestive condition that requires treatment or management. For example, lactose intolerance can cause symptoms similar to SIBO, such as bloating, gas, and diarrhea. If a food intolerance is causing digestive symptoms, you may need to make changes to your diet. These changes should be guided by your doctor or a registered dietitian.
In other cases, treating SIBO provides temporary relief, but not a long-term solution. In about 44% of cases, SIBO symptoms come back within 9 months after the first treatment.
Hammett reminds sufferers that even whilst employing treatments, finding the root cause of their SIBO is vital.
What is SIBO poop like?
SIBO can affect your stools, making them fatty or greasy, light, soft, and unusually foul-smelling. This is an indication you should see a doctor and be tested for this condition.
Testing for SIBO
Find a clinical practice that specializes in gastroenterology. Speak to a specialist about getting a hydrogen breath test (also known as the Lactulose Breath Test). Breath testing looks at the three-hour activity of different microbes throughout your gut biome. It accomplishes this feat by studying some of the byproducts different types of bacteria leave in their wake. The main objective of a Lactulose Breath Test is to measure the amount of hydrogen and methane gas emissions throughout the digestive tract. Based on these numbers, your doctor can determine if there’s an overgrowth of bacteria within.
Is avocado OK for SIBO?
Avocados were once thought to be rich in sorbitol, a type of sugar that is limited in the low FODMAP diet. However, recent research has discovered that this early finding was in error and avocados are actually far lower in FODMAPs than once thought. Nevertheless, further research is needed.
Are eggs OK to eat with SIBO?
Eggs are a nutritious, low-FODMAP food that are safe to eat if you have SIBO.