(Small Intestine Bacterial Overgrowth)

What is SIBO?
SIBO is a condition where the small intestine – for whatever reason – has an overgrowth of bacteria or yeast, or both. It really should be called Small Intestine Microbial Overgrowth.

Often these patients have been labeled as “Irritable Bowel Syndrome”. In a meta-analysis of major IBS studies, 50 to 70% of IBS patients had SIBO when they went back through the data. Dr.’s Pimental and Hall (Cedar St Sinai) found SIBO as an underlying cause of 78% of their IBS patients.

SIBO has only been on the radar since about 2006/2007.

How does one get SIBO?
SIBO can have many causes.
The leading trigger for SIBO is food poisoning. Further secondary triggers include:
1. Bacteria or yeast may have migrated up from the large intestine.
2. Low Hydrochloric acid production, thus there’s not enough acidity and it allows bugs to grow.
3. SIBO may also be a result of routine antacid use and so the pH has changed and allows overgrowth.
4. It could be from chronic constipation and/or slow peristalsis as in gastroparesis (diabetes or neurological damage), or bile insufficiency which can slow transit time.
5. Resection or incompetence of the ileocecal valve between the small and large intestine.
6. Suppressed immunity which allows overgrowth of bugs – think stress, steroids or other immune suppressing drugs.
7. Intestinal strictures which can result in a diminished flow; allows for buildup and stagnation. This is common in Crohn’s disease.
8. Heavy metal toxicity.

What are the symptoms of SIBO?
Symptoms of SIBO are similar to that of Irritable Bowel Syndrome, such as intestinal gas, bloating, distention, discomfort, diarrhea, constipation, abdominal pain, steatorrhea (when BM’s float because fat is malabsorbed), and weight loss (due to malabsorption). Fatigue and lethargy are common complaints.

Symptoms vary due to the amount and type of microbes. SIBO can mimic Celiac disease. Certain carbohydrates and whole wheat products make it worse since the fibers are fermented in the distal small intestine so patients may notice they can eat white bread or some white rice but not whole wheat bread or brown rice.

What are the complications of SIBO?
Nutrient malabsorption occurs as a result of “overcrowded” working conditions and no one is getting their chores done. The bacteria also produce “toxins” and these toxins damage and inflame the small intestine further. Additionally, the bacteria “eat” the vitamin B12 so it is often sub-optimal or frankly deficient in the patient. Complications:
• Macrocytic anemia (B12 deficiency).
• Microcytic anemia (iron deficiency).
• Osteopenia or osteoporosis as minerals & Vitamin D are malabsorbed.
• Osteomalacia (softening of new bone formed due to defective mineralization of Phosphorus, Mg, and Ca). Osteomalacia manifests as achy bones and muscle weakness.
• Night blindness as fat soluble vitamin A is malabsorbed.
• Low protein stores/protein losing bowel disease.

How is SIBO diagnosed?
• Jejunal aspirate; which is invasive, costly, and has low accuracy according to Dr. Gerald Mullen, Johns Hopkins Gastroenterologist.
• A breath test measuring hydrogen and methane production. It is important to test for methane in addition to hydrogen since the treatments are different. Recently a test for sulfur producing bacteria has also become available.
• A urine test measuring by products of the bacteria, which end up in the blood stream and then the urine can diagnosis dysbiosis (large bowel bacteria abnormalities) but not SIBO. Stool testing can also detect increased methanogenic bacteria and dysbiosis indicating further evaluation for SIBO.

How is SIBO treated?
1. Anti-microbials can be herbal or conventional antibiotics to kill the bacteria. An elemental diet is a third treatment option. This involves consuming a commercial product mixed in water and consuming only this for 14 days. This results in removing all food from bacteria in the GI tract for 2 weeks while providing all essential nutrients in their elemental form for the patient.
2. A special diet is started after anti-microbial treatment to avoid foods which would result in regrowth of bacteria. I start patients on the SIBO Specific Diet developed by Dr. Allison Siebecker. This diet has combined the low FODMAPS diet and SCD diet. This is quite a restrictive diet and once SIBO has be eradicated, patients should expand their diet by gradually transitioning to a low FODMAP diet. It’s a bit of trial and error since the bacteria that overgrow aren’t 100% the same in every patient. It’s all about removing the “fuel” that feeds the bacteria or yeast (or both), and allows them to ferment (and thus result in bloating, gas, distention, pain, etc.)
3. Herbals or pharmaceutical pro-kinetics are used to re-establish the Migrating Motor Complex (MMC). This is what is commonly known as “stomach growling” when hungry. SIBO patients rarely if ever notice this and frequently state they are usually not hungry. The MMC is a propulsive action of the small bowel which occurs ONLY WHEN THE STOMACH IS EMPTY flushing undigested food, liquid and bacteria into the colon. This action sends the fiber/food to the bacteria which belong in the colon to keep them healthy. This is one of the reasons people with SIBO have dysbiosis.

How long does treatment take?
Antimicrobial treatment duration depends on what treatment is used and the level of gas noted on the SIBO test. The DIET needs to be continued for months until a Migrating Motor Complex has been restored and this varies for each patient. SIBO quickly returns if sugar or other fuels are introduced into the diet too early. After eradication of SIBO it’s paramount the GI tract be re-populated with good flora via prebiotic foods, probiotics, cultured foods, and nutrients to heal and seal the damaged intestinal lining. The lining takes time to repair the damage. Expect 6 months to a year minimum – up to 2 years to really be back to a full tolerance of a wide variety of foods.

What are FODMAPs and how do they affect SIBO?
FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. Simply put, these are the “fuel” for the bugs which have over populated. They are small chain fermentable carbohydrates. The bacteria feed off of these quickly fermented carbohydrates and malabsorbed sugars, resulting in bloating, gas, and pain. In order to follow a low FODMAP diet, one must free their diet of foods high in Oligosaccharides (fructans, galactans), Disaccharides (lactose), Monosaccharides (fructose), and Polyols (sugar alcohols like xylitol, maltitol, etc).

What is the Specific Carbohydrate Diet (SCD)?
This diet was born out of work by Elaine Gottschall and it eliminates di-saccharides as a remedy for IBS and IBD (Crohns, Ulcerative colitis), and Celiac disease that doesn’t fully resolve with the removal of gluten.