What Is Small Intestinal Bacterial Overgrowth (SIBO)?

Severely underdiagnosed and misunderstood, small intestinal bacterial overgrowth (SIBO) can significantly affect gut health. The small intestine normally contains low levels of friendly bacteria, such as lactobacillus, essential for the digestive process. But, sometimes, the small intestine gets an excess invasion of bacteria from the large intestine. SIBO occurs when there are more than 100,000 bacteria per milliliter of fluid in the small intestine.1 That’s 10 times the normal: Generally, there are fewer than 10,000 organisms per milliliter present in the small intestine.

Apart from the number of organisms present, the type of microbial flora also matters in SIBO. For example, gram-negative coliform bacteria, like the Klebsiella species, can produce toxins that damage the mucosa, thus leading to malabsorption of nutrients from food.2

When one has SIBO, the good bacteria in the gut turns harmful: It starts producing enzymes, toxins,

and intestinal gases like carbon dioxide, hydrogen, and methane. These toxins and gases can cause extreme discomfort, disrupt digestion, and even damage the small intestine if left untreated. The excess bacteria not only uses up the nutrients required for the rest of the body to run properly, but also interferes with nutrient absorption and damages the intestinal lining. The result: malnourishment and anemia.3

Symptoms Of SIBO

People with SIBO may not initially show any symptoms, which can make it harder to control once the condition worsens. When it does, a range of symptoms will likely appear, including:

  • Weight loss
  • Malnutrition
  • Anemia
  • Chronic diarrhea
  • Abdominal pain and cramps4

Causes Of SIBO

SIBO is attributed to a number of underlying conditions that can trigger bacterial overgrowth:

  • Diseases that interfere with the movement of food in the intestine, including diabetes and scleroderma
  • Immune deficiencies like HIV and primary immunodeficiency (PID)
  • Celiac disease, which disturbs gut motility
  • Irritable
    bowel syndrome and Crohn’s disease (aka inflammatory bowel disease)
  • Surgical complications that lead to blockages or obstructions in the small intestine5

Treating SIBO

SIBO is usually diagnosed using breath testing (to check the exhaled gas produced by the bacterial metabolism), fecal culture, and, in some cases, a biopsy of the small intestine.

The goal of SIBO treatment is three-pronged:

  • To correct the underlying trigger
  • To treat the overgrowth of bacteria
  • To provide nutritional support

Conditions impacting digestion, like diabetes, Crohn’s disease, and IBS, must be under control to suppress the initial trigger. In some cases, a low-carbohydrate diet is helpful. People with celiac disease, typically need to go on a strict gluten-free diet.

The bacterial overgrowth is usually treated with antibiotics like amoxicillin/clavulanate, ciprofloxacin, and doxycycline.6

People who are severely dehydrated or malnourished will need to be hospitalized for a

few days and will be given intravenous food supplements and electrolytes.7

Complications Of SIBO

While SIBO is not a life-threatening condition, the resultant complications can often become serious, especially for those who are asymptomatic. If undiagnosed and untreated, SIBO can lead to complications like:

  • Dehydration and consequent loss of consciousness
  • Non-alcoholic liver disease, which causes scarring of the liver (fibrosis) and ultimate liver failure. In a study by Riordan et al., 40 of the 70 subjects with liver disease also had SIBO.8
  • Osteopenia or osteoporosis. Since the condition leads to malabsorption of essential nutrients, people with SIBO often end up with severe calcium and vitamin D deficiencies. Consequently, osteopenia and osteoporosis can cause stress fractures.9

If diagnosed and treated early, SIBO can be controlled and

cured. If you suffer from repeated episodes of diarrhea or gastric symptoms like pain and bloating, do not ignore them. Consult a physician, who can run a range of tests to check if you have bacterial overgrowth in your small intestine. Early intervention is often the best way to tackle SIBO.