Marie F. Steinmetz, MD, is board certified in family medicine. She has a special interest in management of fatigue and gastrointestinal problems.

Digestive troubles could signal a common, but often overlooked, condition called small intestine bacterial overgrowth, or SIBO.

The reason doctors often miss it is that the symptoms are very similar to irritable bowel syndrome or other diseases of the digestive tract:

  • You have bloating, and certain foods may make it worse;
  • Carbohydrates and fiber have a bad effect on your gut;
  • You may have diarrhea;
  • You may have certain foods you’re especially sensitive to.

SIBO has several causes, including slow digestion, immune problems, prior intestinal surgery and aging. Probably one of the most common causes is use of medications to decrease stomach acid.

Severe cases may resemble Crohn’s Disease and even cause inflammatory arthritis. Generally gas, bloating and carbohydrate intolerance are the most common complaints. Some patients may have diarrhea and loss of vitamins and protein.

A breath test is a common method doctors can use to diagnose SIBO and eliminate other possible conditions as a source of the symptoms. The doctor will give you a dose of a sugar such as lactulose or glucose. In patients with SIBO there is an early rise in methane or hydrogen gas when the bacteria in the small intestine break the sugar down. It is possible to have no rise in hydrogen production during the breath test if hydrogen is converted to methane, so it is important to check both methane and hydrogen when doing the test.

A small bowel biopsy can be beneficial in identifying inflammation associated with overgrowth and helps to exclude other causes of malabsorption, such as celiac disease. In the absence of gut inflammation, SIBO is often asymptomatic.

SIBO patients may have inflammation in the small bowel and colon because bacteria release chemicals that cause inflammation, so treatment with corticosteroids or aspirin may be needed.

The goal of treatment is not to eliminate all intestinal bacteria, because you need them to maintain normal gut function, normal immune function, and normal digestion of nutrients. Instead, your doctor is trying to control the growth rates so you have the needed level, not too much.

Treatment consists of treating the underlying disease, dietary manipulation, antibiotics and treatment of inflammation. Patients should eliminate any drugs that slow movement of food through the digestive systems. Also, cut down carbohydrates significantly, as they are the primary nutritional source for the bacteria.

Doctors can attack the bacteria directly with antibiotics. Rifaximin, a non-absorbable antibiotic, is often the treatment of choice but there are also other antibiotic choices. Some patients may require a longer course or repeated courses of therapy. Doctors should monitor patients carefully, and keep in mind that reactions to antibiotics can cause of the same symptoms SIBO does; patients who continue to experience nausea, for example, should not assume the treatment isn’t working.

Patients may need nutritional support with vitamins they are not absorbing because of the bacterial overgrowth. SIBO is especially likely to deplete vitamins K and B12.

1 Comment

  1. Sunita on December 19, 2017 at 1:14 pm

    Very helpful article. I have inflammation for a very long time and doctors didn’t believe when I explained my condition like tightness around neck, feet and all over body. One doctor said it in my head. I asked him if it’s in my head then why I feel tightness and bloating also sometimes. His answer was that I am over weight! I start getting worse with recurring sinus infection, ear infection, UTI, and of course my stomach was getting worse with constipation. Other doctor gave antibiotics for sinus infection several times for more than a year. I kept telling him that I feel it’s related to my stomach. I told them that it started after my colo-rectal cancer surgery and neck surgery when doctor put me on Prednisone to relieve my stiffness. But doctors don’t want to check the history and talk to my other doctors so they can design proper treatment. I am still suffering with stomach issues and sinus infections.

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