Small intestinal bacterial overgrowth (SIBO) refers to a condition, in which abnormally large numbers of bacteria (at least 100,000 bacteria per ml of fluid) are present in the small intestine and the types of bacteria in the small intestine resemble more the bacteria of the colon than the small intestine. This overgrowth also causes damage and inflammation to the gut wall.

Cause of SIBO

The gastrointestinal tract is a continuous muscular tube through which digesting food is transported on its way to the colon. The co-ordinated activity of the muscles of the stomach and small intestine propels the food from the stomach, through the small intestine, and into the colon. Even when there is no food in the small intestine, muscular activity sweeps through the small intestine from the stomach to the colon.

The muscular activity that sweeps through the small intestine is important for the digestion of food, but it also is important because it sweeps bacteria out of the small intestine and thereby limits the numbers of bacteria in the small intestine. Anything that interferes with the progression of normal muscular activity (the waves) through the small intestine can result in SIBO by allowing the bacteria to stay longer and multiply in the small intestine. The lack of muscular activity also may allow bacteria to spread backwards from the colon and into the small intestine, which is why types of bacteria normally found only in the colon, are found in the small intestine.

Symptoms of SIBO

Symptoms may include:

  • Abdominal pain – When bacteria digest food in the intestine, they produce gas. The gas can accumulate in the abdomen giving rise to abdominal bloating or distension. Distension can cause abdominal pain. The increased amounts of gas are passed as flatus
  • Gas – Reduced digestion or absorption by the small intestine allows increased amounts of sugar and carbohydrate to reach the colon, where greater amounts of gas are produced. When bacteria digest food in the intestine, they produce gas.
  • Bloating – When bacteria digest food in the intestine, they produce gas. The gas can accumulate in the abdomen giving rise to abdominal bloating or distension. Distension can cause abdominal pain. The increased amounts of gas are passed as flatus
  • Diarrhoea – The bacteria also convert food into substances that are irritating or toxic to the cells of the inner lining of the small intestine and colon. These irritating substances produce diarrhoea by causing secretion of water into the intestine
  • Constipation – Some patients with SIBO have constipation rather than diarrhoea. There is some evidence that the bacterial production of methane causes constipation
  • Weight loss – When the bacterial overgrowth is severe, the bacteria may cause malabsorption of food and deficiencies of vitamins and minerals may develop, leading to weight loss
  • Aches – mostly in joints
  • Fatigue – sleep can be impaired; and a lack of good nutrition caused by malabsorption can result in constant tiredness

How can we help

Hydrogen and Methane Breath test

Breath testing measures the hydrogen and methane gas produced by the bacterial fermentation of special types of sugars which are not absorbable by humans, only by bacteria.  The gases produced diffuse into the blood, and then into the lungs, for expiration. Hydrogen and Methane are only produced by bacteria, not by humans. The gas is measured over a 2-3 hour period (the typical small intestinal transit time) and compared to the starting level.

There are 3 main treatment options

  • Antibiotics- prescribed by a GP. However, post treatment it is not uncommon to develop rebound
  • A combination of herbal products such as oregano and golden seed. Grapefruit seed can also be used, but sometimes this can be poorly tolerated by clients.
  • Specific Carbohydrate Diet. this is often done with (2) as it starves the bacteria and can take much longer than the antibiotic treatment plan. The length of time on the plan will depend on the severity of symptoms and varies from client to client.