What is SIBO?
Small intestinal bacterial overgrowth (SIBO) is defined as an increase in the number and/or alteration in the type of bacteria in the upper gastrointestinal tract (small intestine). More simply, it is excessive bacteria in the small intestine, or small bowel. While bacteria are naturally present throughout the entire digestive tract, in a healthy gut, the small intestine has relatively low levels of bacteria and the colon (large intestine) has the highest concentrations.
As part of the digestive tract, the small intestine is the longest segment of the tract and houses where food and digestive juices mix and nutrients are absorbed into the bloodstream.
What Causes SIBO?
Given the complexity of the intestinal microbiome, any disbalance may lead to severe health consequences including SIBO. Generally speaking, the etiology of SIBO can be very complex and is often associated with disorders of protective antibacterial mechanisms, anatomical abnormalities, and/or motility disorders. There are several underlying conditions that are believed to contribute to SIBO which include:
- Achlorhydria/hypochlorhydria
- Aging Blind loop syndrome
- Metabolic disorders (e.g. diabetes)
- Pancreatitis Diabetes
- Pancreatic exocrine insufficiency
- Cystic fibrosis
- Immunodeficiency syndromes/Immune system disorders (e.g. HIV/AIDS)
- Small intestinal obstruction
- Diverticulosis Fistula
- Previous ileo-cecal resections
- Scleroderma Post-radiation enteropathy
- Small intestinal pseudo-obstruction
- Certain medications (e.g. immunosuppressants, PPIs, H2 blockers, narcotics)
- Abdominal surgery
- Celiac disease
- Rosacea
- Viral gastroenteritis
- Crohn’s disease
- Gastroparesis
- Nerve damage
- Cirrhosis
- Portal hypertension
- IBS
- Certain gastric bypass procedures
- Surgeries that cause strictures or adhesions
- Injury
- Intestinal lymphoma
- Parkinson’s disease
- Hypothyroidism
- Chronic condition that affects GI tract
Common Symptoms
- Nausea
- Bloating/distension
- Vomiting
- Diarrhea
- Malnutrition
- Weight loss
- Joint pain
- Body aches/fatigue
- Rash
- Pain
- Acne
- Eczema
- Asthma
- Depression
- Rosacea
- Fat malabsorption
- Nutrient deficiencies
- Arthritis
- Vitamin B12 deficiency symptoms
- Numbness or tingling in extremities
- Anemia
- Jaundice
- Cognitive function decline
- Memory loss
- Neurologic abnormalities: Confusion, Slurred speech, Memory loss
- Altered mental status (may complain of or appear to be drunk in the absence of ethanol intake
Left untreated, SIBO can cause serious health complications, including malnutrition. Malnutrition entails the poor absorption of essential nutrients and macronutrients (i.e. protein, carbohydrates, and fat), causing deficiencies related to iron, vitamin B12, fat-soluble vitamins (A, D, E, and K), and calcium. Vitamin B12 deficiency is of particular concern (especially in vegetarians/vegans and those who have inadequate stomach acid or take medications that suppress stomach acid, such as PPIs, H2 blockers, and other antacids. In vitamin B12 deficiency, it is crucial megaloblastic anemia is caught early as prolonged deficiency can lead to permanent nerve damage.
How is SIBO Diagnosed?
- History: A Complete medical history is taken including review medical history, review history of medications, assess risk factors, record symptoms, and explore diet.
- Testing | Breath Tests: Hydrogen and methane breath tests (using a solution containing lactulose, glucose, or xylose) measure the amount of gas produced by the bacteria in the small intestine and hydrogen and methane in the body. The way this works is that the only way the body produces these types of gases is through the output of bacteria.
Hydrogen and methane are exclusively produced by intestinal bacteria in the large intestine (in healthy individuals). In the presence of SIBO, hydrogen and methane are produced by intestinal bacteria in both the large and small intestine.
The hydrogen breath test is considered to be more accurate for the diagnosis of SIBO compared to the methane breath test. However, possible false results and difficulty in their interpretation may exist. Additionally, people with lactose intolerance who do not produce hydrogen would form methane after lactulose administration instead of hydrogen.
Hydrogen breath test entails a low-fiber, low-fermentable diet for 24-48 hours and an overnight fast prior to the test. After the fast, a baseline determination is made of how much gas the person is producing. A predetermined load of simple carbohydrates (dextrose or lactulose) is consumed. Samples are collected every 15-20 minutes for a total of 3-5 hours. As a result, the test measures how much hydrogen and methane has been produced by the bacteria.
Elevated levels of hydrogen in the breath indicate improper digestion (large amounts of hydrogen may be produced if malabsorption is present). Additionally, the test measures methane production. Elevated levels indicate overgrowth of methane-producing bacteria that consume hydrogen and produce methane as a by-product.
Treatment Options
- Antibiotics | removing bacteria: SIBO is often initially treated with antibiotics (e.g. Rifaximin, metronidazole, neomycin, tetracycline, or a combination). Antibiotic treatment helps to remove poor bacteria from the gut but also removes beneficial bacteria necessary for digestive function. In the presence of SIBO caused by blind loop syndrome, long-term antibiotics may be required. However, even with antibiotic treatment, SIBO has been found to have a high recurrence (~45%) rate as antibiotics are not the only form of intervention needed when treating SIBO.
- Herbal therapy | alternative treatment: Alternatives have proven to be as effective as three courses of antibiotic therapy and include the use of herbal therapy (i.e. oregano oil, berberine extract, wormwood oil, lemon balm, and Indian barberry root extract).
- Diet | management with nutrition: Diet plays a significant role in the management of symptoms. Following the 5R protocol with an experienced healthcare professional may be part of an effective treatment plan. Also, by reducing the load of fermentable carbohydrates (FODMAPs) through an elimination diet, symptom relief and healing may occur. FODMAPs – also known as Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols – are carbohydrates found in foods that are poorly absorbed in the small intestine. Since these carbohydrates are poorly absorbed, they arrive to the colon still intact and they are fermented by bacteria, resulting in gas. FODMAPs also have an osmotic effect, which means they draw water into the digestive tract. These actions in the gut can cause symptoms of diarrhea, constipation, gas, bloating and/or cramping for some individuals.
The 5R protocol includes the following:
- Remove | Stressors & Irritants
- Remove microbes via antimicrobial herbs or antibiotic treatment (e.g. Rifaximin, Metronidazole, Neomycin, or Tetracycline).
- Avoid snacking between meals.
- Eliminate fermentable carbohydrates (FODMAPs) and artificial sweeteners (e.g. Splenda)
- Replace | Digestion Facilitators
- Replace hydrochloric acid if low (can help to balance pH and prevent overgrowth of bacteria in the upper GI tract).
- Consider use of digestive enzymes or digestive bitters
- Support gut motility with artichoke and ginger or supplements.
- Address nutrient deficiencies (e.g. B12)
- If malabsorption (steatorrhea) is present, lipase enzymes and use MCT oil may help to prevent weight loss and support energy production (Note: MCT oil does not require bile acids for digestion and absorption).
- Repopulate | Probiotics & Prebiotics
Probiotic use in SIBO treatment is controversial because lactobacilli have been cultured in duodenal aspirates and adding to the bacterial load may exacerbate symptoms. Alternative to bacteria-based probiotics is spore-based probiotics (e.g. Bacillus) that go right to the colon where it starts conferring health benefits and doesn’t increase bacterial growth in small bowel.
- Repair | Intestinal Wall
- Replenish deficient vitamins and minerals
- Vitamin A Omega-3 fatty acids (cold water fish, flax seeds, etc.)
- L-glutamine
- Bovine colostrum
- Zinc carnosine
- Bone broth
- Rebalance| Stress Management & Lifestyle
- Eat at regular intervals every 4-5 hours
- Gradually re-introduce foods and assess tolerance
- Acupuncture 2-3x/week (support and stimulate peristalsis/gut motility)
- Yoga/deep breathing/meditation (stimulates vagus nerve and promotes healthy parasympathetic nervous signaling)
SIBO can cause unpleasant gut symptoms and may affect the quality of life of individuals. Management of SIBO includes identifying the root cause of SIBO (hydrogen or methane production bacteria), using antibiotics or antimicrobial herbs. following low FODMA diet, correcting nutrients deficiency, supporting gut motility and digestion, and managing stress.
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References
- Adike A, DiBaise JK. Small Intestinal Bacterial Overgrowth: Nutritional Implications, Diagnosis, and Management. Gastroenterol Clin North Am. 2018 Mar;47(1):193-208. doi: 10.1016/j.gtc.2017.09.008.
- Chedid V, Dhalla S, Clarke JO, Roland BC, Dunbar KB, Koh J, Justino E, Tomakin E, Mullin GE. Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth. Glob Adv Health Med. 2014 May;3(3):16-24. doi: 10.7453/gahmj.
- Patel SM, Young MC. The Identification and Management of Small Intestinal Bacterial Overgrowth: A Functional Medicine Approach. Phys Med Rehabil Clin N Am. 2022 Aug;33(3):587-603. doi: 10.1016/j.pmr.2022.04.003.