What is SIBO?
SIBO is when there is an abnormally large amount of bacteria in the small intestine and the type of bacteria present there resembles the bacteria normally found in the large intestine.
Bacteria is littered throughout the entire gastrointestinal tract. Only a very small amount live in the small intestine in comparison to the large intestine (colon). The type of bacteria found in the small bowel are different to what's found in the colon.
What is the small intestine responsible for?
- digestion of food and absorption of nutrients;
- contains lymphoid cells which help regulate immune system function and prevent infection;
- houses beneficial bacteria that produce many nutrients such as short chain fatty acids (SCFA), vitamin K and folate;
- this beneficial bacteria protects against invasion from harmful bacteria and yeast after we eat or drink;
- this bacteria also maintains healthy muscular contractions in the small intestine which allow the passage of food and contents into the large intestine.
Small intestinal bacterial overgrowth (SIBO) is more common than we think. Up to 15% of people, free of symptoms have it and up to 80% of those with irritable bowel syndrome (IBS) are thought to have it.
How can SIBO affect us?
- SIBO can harm the structure and function of the small intestine;
- Damages cells that line the small bowel (mucosa) and reduce digestion of food and absorption of nutrients;
- Leads to leaky gut - mucosal damage weakens intestinal cell walls allowing undigested food and protein to pass through causing immune reactions. These immune reactions result in inflammation, allergies, sensitivities and autoimmunity;
- Causes nutritional deficiencies - especially of B12, protein and fat soluble vitamins A, D and E because bacteria like to gobble these up before our cells do;
- Burdens our detox pathways - bacteria produce ammonia that require detoxification.
Common symptoms and signs
- Abdominal pain
- Chronic diarrhoea (often seen in those with “Hydrogen gas”)
- Constipation (often seen with those “Methane gas”)
- Excess gas
- B12 deficiency
- Vitamin deficiencies
- Chronic fatigue and weakness
- Weight loss in severe cases
What causes SIBO?
To understand what causes SIBO, first we must understand how our body prevents it. Generally speaking SIBO may occur if more than one of these protective functions are compromised; the acidic environment of the small intestine (acid inhibits growth of bacteria), muscular bowel activity, antibodies in the intestinal fluid and function of the valve that allows movement of contents into the large intestine and prevents return of it back into the small bowel.
- Low stomach acid
- Stomach or small intestinal dysmotility (dysfunction of the muscular contractions that move contents through to the colon)
- Irritable bowel syndrome
- Inflammatory bowel disorders such as Celiac and Crohn's disease
- Bowel surgery
- Long standing or poorly controlled diabetes
- Recurrent antibiotic use
- Organ dysfunction - cirrhosis of the liver, pancreatitis, kidney failure, celiac disease
- Alcohol - alcohol damages intestinal walls and can cause leaky gut. It can also reduce muscular contractions in the small bowel and feed harmful bacteria, stimulating their growth.
Bold indicates the most common causes
SIBO is a complex condition and is NOT contagious.
How is SIBO diagnosed?
- Hydrogen/Methane breath testing is the most common method of testing. Your doctor or naturopath can refer you on.
- Poo test - I have found that certain signs in someone's poop test along with symptoms can strongly suggest the presence of SIBO such as disruption to short chain fatty acids and pancreatic enzyme production.
The three key principles of treatment are:
- address the cause;
- nutritional support;
- treat the overgrowth.
Common treatments include
- Antibiotics a course of antibiotics is often prescribed and at times cycled to prevent tolerance. Such as Rifaximin, Norfloxacin and Amoxicillin-clavulanate;
- Herbal antimicrobials - one study has shown that natural antimicrobials were more effective than antibiotic treatment. About 57% of those who did not get results with Rifaximin treatment got better results with herbal antimicrobials;
- Diet - a low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols) diet is generally prescribed. While this improves symptoms, it does not resolve the cause. More on diet below;
- Nutritional support - to correct and support weight loss and vitamin and mineral deficiencies such as B12, vitamin A, D and E;
- Sometimes compounds that improve muscular contraction are given if abnormalities of SI motility exist;
- Probiotic therapy - may help to reduce symptoms.
Why a low FODMAP is not the answer
FODMAP foods are fermentable carbohydrates that feed the good bacteria in the large intestine. While a low FODMAP diet reduces symptoms and makes you more comfortable by starving off bacteria in the small intestine, it does not get rid of the overgrowth.
In fact a low FODMAP diet long term can reduce the overall bacteria in the large intestine along with reduce the production of short chain fatty acids (SCFA), such as butyrate. Butyrate is essential for good health as it decreases inflammation in the colon and helps prevent the development of leaky gut.
Dr Mark Pimentel states that having well fed, happy SI bacteria is important if you want to remove SIBO. If you starve them, they are likely to “hide” and become more difficult to get rid of. Instead feeding the bacteria with a moderate amount of FODMAP foods, as much as can be tolerated is the key to a successful treatment. Consuming a prebiotic supplement along with antibiotic treatment has also been shown to improve the success rate by 63% and 87% if taken with antibiotics and guar gum.
Dietary treatment is highly personal because everyone responds differently. Some bloating and gas is to be expected but if symptoms are debilitating or causing pain then you may need to adjust the amount of FODMAP foods.
Other dietary and lifestyle considerations are to make sure that quality protein is consumed with every meal and that stress is minimised so that the immune system is not weakened while you detox and repair.
Unfortunately SIBO is a bugger to treat with a recurrence rate of almost 45% within a year of treatment. This just highlights that correcting the cause and drivers of SIBO is as important as treating the overgrowth and that more than one round of treatment may be needed to clear it.
There is still a lot to discover about treatment of SIBO so no doubt the current protocol will continue to change as new discoveries are made. In the meantime I suggest you get some support from a naturopath or GP if you suspect SIBO so that your treatment plan can be tailored and monitored to suit your individual needs.
I would love to hear of your experience with this so please feel free to leave a comment below.
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