Small Intestine Bacterial Overgrowth (SIBO): An Overview and More

Small intestinal bacteria overgrowth (SIBO) is an overgrowth of intestinal bacteria in the small intestine . SIBO can contribute to a wide variety of symptoms, from bloating to nutritional deficiencies, so getting a timely diagnosis is important. The disease can occur in adults and children at any age. However, this can be more common and problematic for older people .


There are several conditions that increase the risk of SIBO, including diabetes and Crohn 's disease. Experts suggest that SIBO may be quite common in the population, especially among people with digestive disorders, with an incidence of around 44% in women with irritable bowel syndrome (IBS) and 14% in men with IBS .

Symptoms of bacterial overgrowth in the small intestine

With SIBO, you may experience vague symptoms and it can be difficult to distinguish these effects from those associated with other common gastrointestinal (GI) problems. In fact, SIBO can make another GI condition worse, while other GI conditions can make SIBO worse, leading to a cycle of disease.

Common effects of SIBO include :

  • Swelling
  • Flatulence and gas
  • Abdominal pain
  • Swelling
  • Diarrhea, sometimes with urgency or contamination
  • Smelly stool
  • Constipation
  • Nausea
  • Weightloss
  • Fatigue

You may experience some or all of these symptoms, and they can come and go.


SIBO can interfere with the absorption of essential nutrients. The health consequences of malnutrition lead to subtle and vague symptoms such as fatigue, weight loss, and depression. You can also develop serious health problems, such as osteoporosis (brittle bones) and anemia (decreased function of red blood cells) .

Nutritional deficiencies associated with SIBO include:

  • Carbohydrates: An excess of bacteria in the small intestine can interfere with the absorption of carbohydrates. Sometimes people with SIBO avoid carbohydrates to prevent bloating and diarrhea. In general, a carbohydrate deficiency causes weight loss and low energy .
  • Protein – SIBO-induced changes in the small intestine interfere with proper protein absorption, leading to weight loss and decreased immune function.
  • Fat: SIBO lacks bile acids, which are responsible for the breakdown and absorption of fat. Fat malabsorption causes visible signs, including greasy, smelly, and floating stools. The health consequences include weight loss and fatigue .

Fat-soluble vitamins A, D, E, and K may not be absorbed properly if you have SIBO :

  • Vitamin A deficiency can cause vision problems and immunodeficiency.
  • Vitamin D deficiency causes osteoporosis and depression.
  • Vitamin E deficiency interferes with healing.
  • Vitamin K deficiency can cause easy bruising and bleeding.

Vitamin B12 deficiency can occur with SIBO because excess bacteria in the small intestine use up the vitamin itself, reducing its availability to your body. Vitamin B12 deficiency can lead to peripheral neuropathy , which causes pain in the fingers and toes. This vitamin deficiency also causes megaloblastic anemia (enlarged and dysfunctional red blood cells), leading to fatigue and irritability .

SIBO can cause iron deficiency , leading to microcytic anemia (small, dysfunctional red blood cells ) and a host of other health consequences, including fatigue .


The overgrowth of bacteria in SIBO is believed to be the result of changes in the acidity (pH shift) of the small intestine and decreased movement of the intestinal muscles .

  • Changes in pH facilitate the growth of bacteria from other areas of the small intestine and allow different types of bacteria to flourish.
  • Decreased intestinal motility keeps bacteria in the small intestine longer than usual, upsetting the normal balance of digestive enzymes .

Bacteria naturally found in the small intestine help break down and absorb nutrients and help prevent infection. The normal pattern of bacterial function is disturbed as a result of SIBO.

Bacterial overgrowth also leads to microscopic damage to the villi that line the walls of the small intestine , making it difficult for nutrients to be absorbed .

Several medical conditions can predispose you to SIBO . These diseases are usually diagnosed several years before SIBO and can alter the environment of the small intestine, setting the stage for the condition to develop.

The terms and conditions associated with SIBO include :

Keep in mind that you can develop SIBO even if you don't have one of the associated risk factors, and your healthcare provider may consider diagnostic testing if you have SIBO symptoms without an obvious predisposing cause.


There are three main ways to perform the SIBO test: breath test, analysis of small intestine samples, and antibiotic test. Each method has advantages and limitations, but direct sampling is considered the most efficient. trustworthy.

Breath test

The hydrogen breath test is a quick, non-invasive and safe diagnostic method. You drink the solution and after a few hours you analyze your breathing. The presence of hydrogen or methane indicates malabsorption.

However, this test is not considered highly reliable because there are other causes of malabsorption besides SIBO, and your diet and medications several weeks before the test can affect the results .

Jejunal aspiration

This is an invasive test that uses an endoscopy to collect a sample of fluid from the small intestine . Endoscopy is a test in which a thin tube with a camera is placed in the throat to visualize structures in the upper gastrointestinal tract; A biopsy or fluid sample may be taken during insertion of the endoscope.

The test can provide useful information on the bacterial composition of the small intestine, but there may be other causes of bacterial overgrowth, including infection.

Antibiotic test

Another method of diagnosis involves initiating antibiotic treatment for SIBO and assessing the response. This is usually a safe process, but you should tell your doctor right away if your symptoms get worse while taking antibiotics.

Watch out

If you have SIBO, you will need treatment for this condition. Treatment options include antibiotics to treat bacteria overgrowth, treat your underlying medical condition (such as pancreatitis or scleroderma), and nutritional supplements.

You may not need to use all of these methods, and your own treatment will be tailored to your symptoms and the effects you experience from the condition.

Keep in mind that SIBO can change over time, so it can take months or even years off your treatment. Be sure to discuss recurring symptoms with your healthcare provider so flare-ups can be treated quickly.


Various antibiotics can be used to reduce the number of bacteria in the small intestine. Xifaxan (rifaximin) is one of the most commonly prescribed antibiotics for SIBO. Your healthcare provider may choose a different antibiotic based on your jejunal sample or symptoms.

Handling basic conditions

If you have a medical problem that predisposes you to SIBO, treating the problem can reduce the overgrowth of bacteria in your small intestine.

Your treatment plan depends on several factors. For example, some diseases, such as Crohn's disease, can occur intermittently, while others, such as those that result from bowel surgery, are permanent.

Stop medication

While it is unclear whether medications used to treat heartburn promote SIBO, these medications can alter the pH of the gut. Some healthcare providers recommend stopping this treatment if you've been diagnosed with SIBO.

Nutritional supplements

If you have a gastrointestinal disorder that causes nutrient deficiencies, your healthcare provider can monitor your vitamin levels and prescribe supplements as needed. Since the nutritional deficiencies associated with SIBO are a consequence of malabsorption, you may need intravenous (IV) injections or supplements rather than oral tablets.

Diet modifications

Diet modifications may be useful as adjunctive therapy for the treatment of SIBO, for example, the use of the FODMAP (fermentable oligo, di, monosaccharides and polyols) diet. However, you should only stick to your diet after consulting your gastronomic doctor and dietitian.

For some people with this condition, symptoms get worse after eating certain foods, such as lactose or foods that contain fructose .

If you have a specific dietary intolerance, avoiding foods that aggravate your symptoms can help prevent irritation from SIBO.

You can identify food intolerances by using a food diary and tracking your symptoms.

Herbs have not been found to be effective in controlling SIBO and you should inform your doctor of any supplements you use because they can actually contribute to pH changes or bacterial overgrowth.

Get the word of drug information

SIBO is a condition that is increasingly recognized as a cause of gastrointestinal disorders and malnutrition. It may take some time to diagnose and plan treatment for SIBO, but you should feel more comfortable and energetic once your condition is properly managed.

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