Small intestinal bacterial overgrowth (SIBO) is a condition characterized by an excessive amount of bacteria in the small intestine. SIBO is a functional digestive disorder whose incidence has been acknowledged by several medical associations, such as the American Gastroenterological Association. It is estimated that between 14% and 40% of patients diagnosed with irritable bowel syndrome also have SIBO, highlighting the importance of accurate diagnosis to enable effective treatment plans. This overgrowth leads to gastrointestinal symptoms, primarily involving abdominal distension, diarrhea, constipation, flatulence, indigestion, belching, and changes in gastrointestinal transit. These symptoms are essentially due to the activity of gastrointestinal bacteria when they come into contact with fermentable carbohydrates in the diet. One specific type of SIBO is hydrogen SIBO, which occurs when bacterial overgrowth produces hydrogen.
Managing SIBO often involves dietary changes to reduce the amount of fuel available for bacterial fermentation. This article explores various dietary approaches for managing hydrogen SIBO, their mechanisms, and their role in overall gut health. It is vital to consult with healthcare providers to assess the condition, investigate possible causes, and explore which approaches to treatment and management will be most effective.
The Relationship Between Food and Microbial Overgrowths
Food nourishes not only the body but also the trillions of microbes in the digestive tract. In a healthy gut, these microbes exist in appropriate quantities and help the system break down fiber and carbohydrates into useful nutrients. What we eat changes the amount and type of fuel that’s available to these microbes, affecting their population growth and sometimes leading to dysbiosis-a harmful imbalance in our gut microbiome. These imbalances can create or aggravate symptoms such as bloating, diarrhea, constipation, abdominal discomfort, and disruptive changes in bowel habits.
With that in mind, let’s dive right in and explore some of the most well-known diets, with a special focus on how they could affect someone with SIBO.
Dietary Approaches for Managing Hydrogen SIBO
Low FODMAP Diet
The Low FODMAP diet, developed by researchers at Monash University, is a well-known dietary approach often tried by patients with SIBO, IBS (Irritable Bowel Syndrome), and other related conditions. "FODMAP" stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. FODMAPs are foods that you may have trouble digesting when you have SIBO.
Read also: Risks of the Hydrogen Sulfide Diet
The idea behind the Low FODMAP diet is straightforward: if you eliminate your intake of FODMAP carbs, you will reduce the amount of fermentation and gas production happening in your intestines, making symptoms more manageable. A low-FODMAP diet focuses on limiting or eliminating high-FODMAP foods, like beans, lentils, and wheat-based snacks. The idea is that avoiding high-FODMAP foods may slow bacterial overgrowth that happens when bacteria feed on these types of foods.
The Low-FODMAP diet is usually recommended in conjunction with other treatments like antibiotics, and it is not generally intended to be a permanent solution. Long-term restriction of FODMAPs can negatively impact the gut microbiome, limiting its diversity and effectiveness, while also leading to a potential for nutrient deficiencies.
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
Instead, you want to fill your plate with low-FODMAP foods, like proteins, vegetables, fruit, grains and dairy, as well as nuts and seeds, that are less likely to trigger a bacterial growth spurt. Some foods that are considered low-FODMAP include:
Read also: The Carnivore Diet for SIBO
- Fruits like grapes, oranges, and strawberries
- Vegetables like carrots, cucumbers, and tomatoes
- Nuts and seeds like walnuts and pumpkin seeds
- Dairy alternatives like almond milk and soy milk
- Protein options like eggs and plain, cooked meats, poultry, and seafood
- Gluten-free grains like quinoa and oats
After the initial elimination phase of about three to four weeks while you’re being treated for SIBO, you’ll then slowly reintroduce food from one high-FODMAP group at a time. Following a low-FODMAP diet long term isn’t recommended, as many of these highly fermentable foods feed your gut microbiome.
Low Fermentation Eating (LFE)
Due to the limitations and nutritional concerns associated with indefinite adherence to the Low-FODMAP Diet, renowned gastroenterologist Dr. Mark Pimentel and his team at Cedars-Sinai developed a more sustainable dietary approach: Low-Fermentation Eating (LFE). LFE focuses on reducing fermentable foods while emphasizing consistent meal timing and limiting problematic foods to minimize bacterial overgrowth.
LFE reduces fermentable substrates for gut microbes, while also focusing on maximizing healthy spacing between meals. Spacing meals four to five hours apart allows your Migrating Motor Complex (MMC) to more thoroughly and rhythmically sweep bacteria out of the small intestine between meals.
The low-fermentation diets have three distinct phases. For the first phase, high-FODMAP foods should be identified and restricted. FODMAP groups include excess fructose, lactose, fructans, galactans, and polyols.
Elemental Diet
The Elemental Diet isn’t a typical “diet”. Think of it as more of a medical nutrition therapy-a powerful gut reset-which can be especially useful for those with severe or recurrent SIBO. Since it aims to bring your gut back in balance using a heavily nutrition-focused approach, doctors sometimes recommend the Elemental Diet in cases where antibiotics aren’t effective or well-tolerated. The only proven diet for SIBO is the all-liquid elemental diet, which should only be embarked upon under a doctor’s supervision.
Read also: Phase 1 SIBO Diet
With the Elemental Diet, patients consume a liquid-only formula that provides fully broken-down nutrients (such as amino acids, simple carbs, and fats) in forms that are easily absorbed in the gut without requiring fermentation. By depriving bacteria of their food source, the diet essentially starves out your bacterial overgrowth while still providing essential nutrition.
Research shows that the elemental diet works. But it only works if you stay with it. That can be a challenge for reasons ranging from the way the formula tastes to being hungry, bored, or frustrated because you can’t participate in family or social events that center around food.
Studies show that the elemental diet has a high success rate, with some reports indicating that up to 80% of individuals experience a significant reduction in bacterial overgrowth after following the diet for two to three weeks. However, because it requires strict adherence to a specific liquid diet, it can be challenging for some people due to issues like taste, cost, lifestyle challenges, and calorie restrictions.
SIBO Biphasic Diet
The SIBO Biphasic Diet is a structured eating plan developed by Dr. Nirala Jacobi, ND, focused specifically on people diagnosed with SIBO. It’s a phased dietary protocol designed to limit foods that are more likely to ferment in the small intestine, such as certain fibers, legumes, and high-FODMAP fruits.
The “Biphasic” part of the name refers to the diet being structured into two phases. In the first phase, restricted foods are reduced or eliminated to help minimize bloating, gas, and abdominal discomfort. The phased design is intended to both address the symptoms in the short term and make the diet more sustainable over time. By removing fermentable carbohydrates during phase 1, the diet reduces the fuel needed for bacterial overgrowth. Phase 2 then broadens the Foods to Choose categories by gradually reintroducing foods, with adjustments dependent on individual tolerance and symptom response.
Because of the complex nature of the SIBO Biphasic Diet, it is generally not recommended without the supervision and guidance of an appropriate healthcare provider.
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.
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.
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.
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.
While anti-inflammatory diets have some similarities, their variations make it more difficult to make a definitive list of foods to avoid or choose, but some of the more common examples are provided below for reference. 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.
Additional Considerations
Probiotics and Prebiotics
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. Before making any changes to your diet or implementing new treatment, discuss the risks with your doctor or dietitian.
As for fructooligosaccharides and galactooligosaccharides, humans do not produce the enzymes required to hydrolyze them, so they are not absorbed and usually reach the colon, serving as prebiotics.
Nutritional Support
Correcting nutritional deficiencies is a crucial part of treating SIBO, particularly in people with severe weight loss. People with SIBO may need intramuscular injections of vitamin B-12, as well as oral vitamins, calcium, and iron supplements. Damage to the small intestine may cause you to lose the ability to digest milk sugar (lactose). In that case, it's important to avoid most lactose-containing products, or use lactase preparations that help digest milk sugar. Some affected people may tolerate yogurt because the bacteria used in the culturing process naturally break down lactose.
The SIBO Specific Diet
At this time we introduce the SIBO Specific Diet, created by Dr. Allison Siebecker, ND, which combines a specific carbohydrate diet (SCD) with low FODMAP foods. It’s based on the idea that we remove any foods that the SIBO bacteria could “ferment,” which is what typically causes SIBO symptoms. The bacterial is essentially starved, because they have nothing to feed on, which, paired with our herbal antimicrobials, means we’re both killing and starving them. The SIBO Specific diet is a therapeutic diet only and is not intended to be done long term.
Other Treatments
Antibiotics are the first line of treatment for SIBO. 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.
The Role of a Dietitian
Nutrition and diet therapy play a pivotal role in SIBO management, not only in alleviating symptoms but also in preventing relapses. This review will argue that dietitians can play a relevant role in the management of the disease by determining the most appropriate dietary therapy for SIBO. To do so, they must be familiar with the most recent and relevant information regarding the dietary management of SIBO. This familiarity will ensure that they can provide adequate and sufficient nutrition, avoid possible nutritional deficiencies, and prevent a worsening of the condition due to the implementation of inappropriate diets.
To benefit from an elimination diet, it’s important to work with a registered dietitian with training in SIBO conditions.