Small intestinal bacterial overgrowth (SIBO) affects millions of Americans and can manifest in various uncomfortable digestive symptoms. The American College of Gastroenterology's (ACG) Clinical Guidelines for SIBO management suggest that dietary manipulation may be beneficial in managing SIBO. With a variety of diets available, understanding their principles and how they might affect your gut health is essential. This article explores common dietary approaches for managing microbial overgrowths like SIBO, intestinal methanogen overgrowth (IMO), and intestinal sulfide overproduction (ISO), with a special focus on the SIBO Bi-Phasic Diet (SIBO B-PD).
Disclaimer: There is no one-size-fits-all solution for managing medical conditions. Consult with your healthcare provider to assess your condition, investigate possible causes, and explore effective treatment and management approaches.
The Relationship Between Food and Microbial Overgrowths
Food nourishes not only you but also the trillions of microbes in your digestive tract. In a healthy gut, these microbes exist in appropriate quantities and break down fiber and carbohydrates into useful nutrients. Diet changes the fuel available to these microbes, affecting their population growth and potentially leading to dysbiosis-a harmful imbalance in the gut microbiome. Dysbiosis can create or aggravate symptoms like bloating, diarrhea, constipation, abdominal discomfort, and changes in bowel habits.
Common Dietary Approaches for Managing SIBO
Several dietary approaches are commonly used to manage SIBO, each with its own principles and goals.
Low FODMAP Diet
Developed by researchers at Monash University, the Low FODMAP diet is a popular choice for patients with SIBO, irritable bowel syndrome (IBS), and related conditions. The diet involves eliminating fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) to reduce fermentation and gas production in the intestines.
Read also: The Hoxsey Diet
How it works: By reducing FODMAP intake, the diet aims to minimize the fuel available for bacteria in the small intestine, thereby reducing symptoms.
Limitations: The Low FODMAP diet is usually recommended with other treatments like antibiotics and is not intended as a permanent solution. Long-term restriction of FODMAPs can negatively impact the gut microbiome, limiting its diversity and potentially leading to nutrient deficiencies.
Low Fermentation Eating (LFE)
Developed by Dr. Mark Pimentel and his team at Cedars-Sinai, Low Fermentation Eating (LFE) is a more sustainable dietary approach that addresses the limitations and nutritional concerns associated with indefinite adherence to the Low FODMAP Diet. LFE focuses on reducing fermentable foods while emphasizing consistent meal timing and limiting problematic foods to minimize bacterial overgrowth.
How it works: LFE reduces fermentable substrates for gut microbes and maximizes healthy spacing between meals. Spacing meals four to five hours apart allows the migrating motor complex (MMC) to sweep bacteria out of the small intestine between meals.
Elemental Diet
The Elemental Diet is a medical nutrition therapy used as a gut reset, particularly for those with severe or recurrent SIBO, IMO, or ISO. It is often recommended when antibiotics are ineffective or not well-tolerated.
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How it works: The Elemental Diet involves consuming a liquid-only formula with fully broken-down nutrients (amino acids, simple carbs, and fats) that are easily absorbed in the gut without fermentation. This deprives bacteria of their food source, starving out the bacterial overgrowth. Studies suggest a high success rate, with significant reductions in bacterial overgrowth after two to three weeks.
Limitations: Strict adherence to a specific liquid diet can be challenging due to taste, cost, lifestyle issues, and calorie restrictions.
Foods to Choose: The Elemental Diet formula.
SIBO Bi-Phasic Diet (SIBO B-PD)
The SIBO Biphasic Diet, developed by Dr. Nirala Jacobi, is a structured eating plan specifically for people diagnosed with SIBO. It is designed to limit foods that are more likely to ferment in the small intestine, such as certain fibers, legumes, and high-FODMAP fruits.
How it works: The diet is structured in two phases. Phase 1 restricts foods to minimize bloating, gas, and abdominal discomfort. Phase 2 gradually reintroduces foods, with adjustments based on individual tolerance and symptom response. By removing fermentable carbohydrates during phase 1, the diet reduces the fuel needed for bacterial overgrowth. Phase 2 broadens food categories by gradually reintroducing foods, with adjustments dependent on individual tolerance and symptom response.
Read also: Weight Loss with Low-FODMAP
Considerations: Due to the complex nature of the SIBO Biphasic Diet, it is generally not recommended without the supervision and guidance of an appropriate healthcare provider.
Phases of the Bi-Phasic Diet
- Phase 1 (Restrictive Phase): Lasts 2-6 weeks, limiting the bacteria's food supply to reduce their population in the small intestine. This phase involves a low-FODMAP diet, avoiding or minimizing foods high in fermentable carbohydrates known to ferment in the gut and exacerbate symptoms. High-FODMAP foods include certain fruits, vegetables, grains, legumes, dairy products, sweeteners, and food additives. In addition to FODMAPs, the patient should avoid known trigger foods, even if they are low-FODMAP. This phase emphasizes eating smaller, frequent meals with adequate protein and healthy fat sources.
- Phase 2 (Reintroduction Phase): Starts after Phase 1 and lasts 4-6 weeks. The objective is to gradually reintroduce foods to expand the diet and identify individual dietary triggers. Introductions should be performed in a controlled, systematic manner. Each food is reintroduced one at a time, and the patient should keep a food-symptom diary to track symptoms to determine how each food affects their body.
- Maintenance Phase: Naturally progresses from Phase 2. The overall goal of the SIBO B-PD protocol is for the patient to create a sustainable, nutritious, and individualized dietary plan based on their tolerance levels.
Implementing the Bi-Phasic Diet Plan
- Preparation and Planning: Consult with a knowledgeable healthcare provider, such as a functional doctor or nutritionist specializing in SIBO, before starting the diet. They can assess your specific condition, recommend and order SIBO testing if needed to tailor the treatment plan to your particular needs, and guide you through the protocol. Familiarize yourself with low-FODMAP food options and create a meal plan for the restrictive phase. Shop before starting the elimination diet to stock up on the necessary ingredients and clear your kitchen of high-FODMAP and trigger foods.
- Emotional Preparation: Food and social eating are a means of community, connection, and happiness for many people. Emotional preparation for the diet and finding a support network in friends, family, or support groups can ease the emotional shock of the diet's restrictive phase.
SIBO B-PD Phase 1 Food Choices
- Protein: poultry, beef, lamb, pork, fish, eggs
- Non-Starchy Vegetables: leafy greens, zucchini, bell peppers, cucumbers, carrots, eggplant, and bok choy
- Healthy Fats: olive oil, coconut oil, avocado, and moderate amounts of nuts and seeds
- Fruits: lemon, lime, berries
- Fermented Foods (as tolerated): cultured vegetables, sauerkraut, kimchi
- Beverages: water, herbal teas, black coffee
Foods to Avoid or Minimize During Phase 1
- Vegetables: onion, garlic, artichokes, asparagus, cauliflower, broccoli, Brussels sprouts, cabbage, potatoes, mushrooms
- Fruits: apples, apricots, figs, mango, peach, pears, plums
- Legumes: beans, soy (tofu, tempeh), peas
- Dairy: milk, yogurt, cheese, ice cream
- Grains: wheat (bread, pasta, pastries, cereals), barley, rye
- Sweeteners: sorbitol, xylitol, mannitol, high-fructose corn syrup, agave
As patients begin implementing a low-FODMAP diet, they may experience die-off symptoms as the bacteria are cut off from their food supply. Staying well hydrated; eating smaller meals; chewing and swallowing food slowly and mindfully; keeping a journal to identify and avoid triggering foods; and engaging in stress-relieving activities can help manage uncomfortable digestive symptoms. Your doctor may also recommend digestive aids, such as digestive enzymes, digestive bitters, and carminative herbs, to provide additional symptomatic relief.
SIBO B-PD Phase 2
During Phase 2 of the SIBO B-PD, patients will systematically reintroduce higher-FODMAP foods into the diet. It is recommended to keep a diet-symptom journal during this process to help identify individual triggers, determine personal tolerances, and track progress. The patient should be instructed to introduce foods one at a time and to begin by reintroducing generally well-tolerated foods that are less likely to trigger SIBO symptoms. These often include lactose-free dairy, gluten-free grains, and small amounts of fruits and vegetables. The introductions will be spaced several days apart, allowing the patient to accurately monitor the body's response to each food. Start with a small portion of each reintroduced food, and gradually increase the portion sizes as tolerated. Remembering that this process is highly individualized, based on the patient's specific symptoms and sensitivities, is important. Staying in communication with their healthcare provider during this process can help patients to navigate the process effectively and guide them on specific foods that should be reintroduced or avoided based on needs and preferences.
Dietary Maintenance Considerations
After completing Phases 1 and 2 of the SIBO B-PD, adopting a long-term maintenance approach to manage SIBO symptoms, support gut health, and potentially help prevent a recurrence is essential. As patients continue to incorporate more diversity into their diet through food introductions, they will naturally transition into a balanced and varied diet that includes a wide range of whole foods. Emphasizing nutrient-dense and anti-inflammatory options, like whole fruits, vegetables, lean proteins, whole grains, and healthy fats, encourages whole-body wellness and healthy digestion. Individual tolerances can change over time, so it can be helpful to occasionally rechallenge previous trigger foods to reevaluate food sensitivities and continue to diversify the diet. Also, remember that how you eat is just as important as what you eat regarding digestive health and function. Practice mindful eating habits, such as chewing food thoroughly, eating slowly, and paying attention to hunger and satiety cues.
Certain lifestyle factors can contribute to SIBO recurrence. Getting adequate sleep, staying physically active, avoiding excessive alcohol consumption, and implementing stress management techniques can support gut function and help prevent SIBO recurrence.
Regular follow-up with a healthcare provider can also increase long-term success. Healthcare providers should continue to work with patients to address underlying medical conditions that may increase SIBO risk and recommend gut-supporting supplements that support a healthy microbiome balance and intact intestinal barrier.
Monitoring Progress and Seeking Professional Guidance While on the SIBO Bi-Phasic Diet
Managing SIBO and maintaining healthy gut function requires an individualized approach, and everyone's progress on the SIBO B-PD will vary. Working closely with a healthcare professional, registered dietician, or nutritionist specializing in SIBO throughout the process is important to help accurately monitor progress and make necessary adjustments to the treatment plan. Regular, subjective monitoring by the patient of their quality of life and digestive symptoms helps to gauge the effectiveness of the treatment protocol. Improvements in bloating, bowel regularity, abdominal pain, energy levels, mood, sleep quality, and ability to perform daily activities indicate that the treatment plan is working. In some cases, objective measurements with laboratory tests may be required or helpful to monitor patient progress. These often include:
- SIBO Breath Test: The SIBO breath test can monitor SIBO management progress and track changes in hydrogen, methane, and hydrogen sulfide gas levels.
- Comprehensive Stool Test: Other factors besides SIBO can contribute to digestive symptoms. A comprehensive stool test holistically assesses gut health by measuring markers that assess for inflammation, intestinal permeability, dysbiosis, intestinal infection, and maldigestion.
- Food Sensitivity Panel: Definitively identifying food sensitivities and intolerances through observation alone can sometimes be difficult. A food sensitivity panel measures a person's immunological response to specific food proteins to identify foods that should be removed or limited from the diet at any point during the SIBO B-PD protocol.
Carnivore Diet
The Carnivore Diet is an extreme elimination diet that removes all plant-based foods and focuses exclusively on animal-based products such as meat, fish, eggs, and some dairy. Although not created for people with SIBO or IBS, it has gained some popularity among people experimenting with ways to reduce bloating, gas, or other gut symptoms.
How it works: The idea is simple: if fermentable carbohydrates are the main fuel for gut microbes, removing them entirely should reduce fermentation and gas. With only animal proteins and fats on the menu, there’s less fuel left for bacteria or archaea to break down. Some anecdotal reports indicate symptom relief when adopting this approach.
Limitations: It lacks fiber and key nutrients and is not generally recommended as a first-line SIBO therapy. Medical guidance is strongly recommended when considering your nutritional choices, especially one that may adversely impact your overall health.
Anti-Inflammatory Diet
An Anti-Inflammatory Diet isn’t a single, rigid plan, but rather a way of eating that emphasizes foods believed to calm inflammation in the body. It sometimes resembles the Mediterranean diet, which highlights fruits, vegetables, olive oil, fish, legumes, and whole grains. Some people also try variations which remove gluten or dairy from their diets as well, since these have also been linked to inflammation and gut distress in some people.
How it works: The theory here is that reducing chronic inflammation can help soothe the gut environment and improve overall health. While these diets don’t target microbial overgrowth directly, they may decrease gut irritation, improve nutrient intake, and support a broader approach to digestive wellness.
Limitations: While anti-inflammatory diets have some similarities, their variations make it more difficult to make a definitive list of foods to avoid or choose. It should be noted that some of the foods encouraged for anti-inflammatory diets may be at odds with the more focused list of foods you would follow when adhering to a SIBO-specific diet like Low Fermentation Eating.
Understanding Carbohydrate Intolerance in SIBO
Carbohydrates are a primary food source for bacteria. When bacteria consume carbohydrates, they produce gases as a byproduct of fermentation, triggering symptoms like bloating and abdominal discomfort. SIBO diets reduce carbohydrate intake to help manage these symptoms.
Which Carbohydrate Foods Cause Symptoms Varies Greatly Per Person
In SIBO, what is and isn't tolerated varies greatly per person. One person’s most aggravating food can be the next person’s best tolerated food. By reducing carbohydrates overall, SIBO diets greatly help symptoms, but can't account for this level of individuality across all SIBO patients. Thus customizing a SIBO diet by experimentation to find one’s individual food tolerances is recommended for the best success - both in reducing symptoms and increasing nutrition (so as not to avoid foods that are actually tolerated). While opinions vary, my opinion is that if a food is known to be tolerated (does not cause or worsen symptoms), it does not need to be avoided, even if a SIBO diet says to avoid it.
Carbohydrate foods include vegetables, fruits, beans, nuts, seeds, and grains.
The Bi-Phasic Diet Controversy
The Bi-Phasic Diet is considered controversial for several reasons:
- Misleading: It can be perceived as a standalone treatment, which is inaccurate.
- Risk of Nutrient Deficiency: The restrictive nature of the diet can lead to nutrient deficiencies if not carefully managed.
- Opportunity for Disordered Eating: The strict elimination of foods can increase the risk of developing an obsessive or disordered relationship with food.
- Socially Isolating: Following a strict elimination diet long-term can be challenging and isolating, making it difficult to participate in social events involving food.
Addressing SIBO Holistically
A healthy approach to treating SIBO involves several steps:
- Identify and Address Root Causes: Determine the underlying reasons for SIBO development.
- Eliminate: Reduce bacterial overgrowth through a combination of diet, lifestyle changes, and antimicrobials/antibiotics.
- Repair: Focus on repairing the intestinal lining and restoring gut health.
- Sustain: Implement long-term strategies to prevent SIBO recurrence.
Foods Often Avoided on SIBO Diets
While specific food lists vary depending on the chosen diet, some foods are commonly avoided due to their high FODMAP content or potential to exacerbate symptoms. These include:
- Vegetables: Asparagus, artichokes, garlic, onions, cauliflower, broccoli, Brussels sprouts, cabbage, mushrooms.
- Fruits: Apples, apricots, cherries, mangoes, peaches, pears, plums, watermelon.
- Legumes: Beans, lentils, chickpeas.
- Dairy: Milk, yogurt, cheese, ice cream.
- Grains: Wheat, rye, barley.
- Sweeteners: High-fructose corn syrup, honey, agave, artificial sweeteners.
- Other: Processed foods, alcohol.
Foods Often Allowed on SIBO Diets
Again, depending on the specific diet and individual tolerance, some foods are generally well-tolerated. Examples include:
- Proteins: Meat, fish, chicken, eggs.
- Non-Starchy Vegetables: Leafy greens, zucchini, bell peppers, cucumbers, carrots, eggplant.
- Healthy Fats: Olive oil, coconut oil, avocado.
- Fruits (in moderation): Berries, lemons, limes.
Lifestyle Changes to Consider
In addition to dietary changes, lifestyle factors can significantly impact gut health and SIBO management:
- Stress Management: Chronic stress can negatively affect gut function. Practice relaxation techniques like meditation, yoga, or deep breathing exercises.
- Sleep Hygiene: Aim for 7-8 hours of quality sleep per night to support gut health.
- Regular Exercise: Physical activity can improve gut motility and reduce inflammation.
- Mindful Eating: Pay attention to hunger and fullness cues, chew food thoroughly, and eat slowly.