SIBO (bowel disorder): everything there is to know!

What is SIBO? 

SIBO (Small Intestinal Bacterial Overgrowth) is a condition that is defined by an increase in the number of bacteria and/or a change in the types of bacteria present in the small intestine. This leads to a range of intestinal symptoms.

For the majority of patients, SIBO is not caused by just one type of bacteria but by an overgrowth of different types of bacteria that can normally be found in the colon. More rarely, SIBO can also result from an increase in the number of bacteria considered normal in the small intestine.

The so-called good, beneficial bacteria are an essential part of the small intestine. They play an important role in food digestion and the absorption of nutrients. They help protect our bodies from bad bacteria (pathogenic bacteria) and ingested yeast.

These bacteria help the human body to absorb and produce nutrients: short-chain fatty acids. They are also involved in the synthesis of vitamins such as folate or vitamin K.

The human body has several mechanisms that help prevent bacterial imbalance in the small intestine:

• When food is ingested, stomach acids destroy bad bacteria and prevent them from passing through the intestines,
• Digestive motricity allows a proper cleaning of the intestinal tract,
  
• The ileocecal valve prevents retrograde transport of bacteria,
  
• Immunoglobulin A, present in the intestinal tract, maintains immunity.
  

Bacterial balance is therefore very important in keeping us healthy.

SIBO is a still poorly understood digestive disorder, which combines digestive symptoms with a disturbance in the intestinal flora. The number of people who suffer from it remains unknown to this day. Various studies suggest that between 6 and 15% of the healthy population suffer from SIBO, and about 80% of patients with irritable bowel syndrome (IBS) are thought to have it.

What are the symptoms of SIBO? 

Bacteria commonly found in SIBO include :

• Streptococcus sp,
  
• Bacteroides sp,
  
• Escherichia coli,
  
• Staphylococcus sp,
  
• Klebsiella sp,
  
• and Lactobacillus.
  

These bacteria, present in excessive quantities, reduce the absorption capacity of the intestinal cells and consume nutrients, especially carbohydrates and vitamin B12. This results in malabsorption of carbohydrates and certain nutrient and vitamin deficiencies. In addition, these bacteria, which also act on bile salts by altering them, prevent the formation of micelles leading to lipid malabsorption. Finally, severe SIBO leads to damage to the intestinal mucosa.

The main symptoms of SIBO are :

• Deficiencies in nutrients and fat-soluble vitamins (such as vitamin A and vitamin D),
  
• Abdominal discomfort (pain and spasms),
  
• Gastroesophageal reflux,
  
• Diarrhea of varying degrees or constipation, or alternating diarrhea and constipation,
  
• Steatorrhea, an abnormally high amount of fat in the stool,
  
• Excessive bloating and flatulence (due to the fermentation of bacteria that stagnate in the small intestine).
  

These various digestive symptoms are frequently associated with difficulties in concentration, chronic fatigue (even depression) and, in some cases, weight loss.

How can SIBO be diagnosed? 

There are several methods for diagnosing SIBO:

• By a breath test which measures the concentration of hydrogen, methane and hydrogen sulphide exhaled after ingestion of complex sugars (lactulose and glucose). This test lasts 3 hours with a measurement every 20 minutes. However, not all hospitals are equipped to perform this test, mainly those with a gastroenterology department coupled with a digestive disease center.
  
• By direct examination of the fluid contained in the small intestine. This involves performing an endoscopy.
  

How can SIBO be treated?

Patients with SIBO must be treated with antibiotics. Because of the polymicrobial nature of the gut flora, broad-spectrum antibiotics are needed to cover all aerobic (oxygen demanding) and anaerobic (difficult to live with or unable to multiply in the presence of oxygen) bacteria.

Thus, the treatment plan is usually based on the use of one or two of the following antibiotics for 10 to 14 days:

• Amoxicillin/clavulanic acid 500 mg 3 times/day; 
  
• Cephalexin 250 mg 4 times/day; 
  
• Trimethoprim/sulfamethoxazole 160 mg/800 mg twice/day; 
  
• Metronidazole 250 to 500 mg 3 or 4 times/day; 
  
• Rifaximin 550 mg 3 times/day.
  

Treatment may be cyclical or modified if symptoms tend to recur.

What diet should patients with SIBO follow?

The low FODMAP diet recommended for irritable bowel syndrome is also recommended for SIBO.

FODMAPs are carbohydrates that can be fermented. By avoiding them, it is more difficult for bad bacteria to grow in the small intestine. However, the low FODMAP diet is not suitable for all SIBO patients, such as those who are on antibiotics.

Do not hesitate to talk to your doctor before choosing any specific diet plan.

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