SIBO – a possible cause of IBS?

Our intestinal tract is long – approximately 25 feet in total! The initial 20 feet is the small intestine. The final 5 feet comprises the large intestine (the colon).

A huge population of bacteria live within the digestive tract – the vast majority of these reside in the large intestine where they play a vital role in stool formation, nutrient synthesis and immunity. 50% of the mass of a bowel movement is actually bacteria! Only a small proportion of these bacteria live in the small intestine.  The small intestine needs to be fairly sterile as this is where digestion of food and absorption of nutrients takes place. Too many bacteria in the small intestine would interfere with this process.

However, things do not always go according to plan! It is possible to develop a condition called Small Intestinal Bacterial Overgrowth (SIBO) in which bacteria from the colon migrate into the small intestine and cause all sorts of problems.

Common symptoms of SIBO

  • Diarrhoea, constipation, or a combination of both.
  • Bloating – some of my SIBO clients report feeling 6 months pregnant by the end of the day. Bloating is usually better by the next morning, but worsens during the day.
  • Fasting alleviates symptoms.
  • Antibiotics may temporarily alleviate symptoms, though they usually return within a few days/weeks.
  • Blood tests may reveal low iron or ferritin with no obvious cause.
  • Symptoms of SIBO tend to be quite inconsistent and random with some better days and some bad days – this can leave people very confused as to the underlying cause of their issues.

You may notice that the symptoms of SIBO are very similar to those of IBS – various studies have shown that SIBO may actually be the underlying cause of IBS in many patients.

Possible causes of SIBO

  • It is common to develop SIBO after a gut infection or “traveller’s diarrhoea”.
  • Proton Pump Inhibitors (medication to reduce stomach acid) can over time increase the risk of developing SIBO as they lead to poor digestion of food and so give the bacteria in the intestines an easy meal!
  • Anything that slows or interferes with the Migrating Motor Complex (MMC) may lead to SIBO. The MMC is the contraction of intestinal muscles a few hours after a meal to sweep any debris through the intestinal tract. Certain medications can affect the MMC. Eating too frequently means the MMC is not activated. Certain medical conditions such as diabetes can adversely affect the MMC.
  • Celiac disease is linked with SIBO.
  • Hypothyroidism slows down intestinal movement which increases the risk of SIBO.
  • Adhesions or scar tissue on the intestine, perhaps following surgery, may have an impact on intestinal motility, and therefore SIBO.

Testing for SIBO

An excellent method of testing for the presence of SIBO is a Hydrogen/Methane Breath Test. Intestinal bacteria ferment food and produce these two gases which are then absorbed into the blood stream, taken to the lungs and expelled in the breath.

In controlled conditions a drink containing the sugar lactulose is consumed and breath samples are taken every 20 mins for 3 hours. This is to ascertain whether there are bacteria living within the small intestine. In a healthy individual with no SIBO these gases should only be detected when the lactulose solution reaches the large intestine – this takes approx 2 hours. However I have seen many breath tests when the gases start to rise within the fist 1hr – this is a good indication of SIBO. The test costs approx £120.

Strategy for SIBO

Diet is the first step in addressing SIBO. Foods which actively and easily feed a bacterial overgrowth need to be reduced or eliminated. I have found a low FODMAP diet to be very useful for a period of time.

FODMAPs are found in various carbohydrate foods and they can be poorly absorbed by some people. Lactose is a FODMAP. Onions, garlic and leeks are high in FODMAPs. Wheat, beans and lentils are also a source, as are various other fruits and vegetables. All of these foods are generally thought of as healthy. So I often see clients with IBS, who have cut out junk foods and are eating a really good diet, but their symptoms have continued to deteriorate. This can be a sign of SIBO.

A FODMAP diet may also need to be combined with a low carbohydrate diet – focusing on cutting down on starchy grains and vegetables which also have a tendency to feed a bacterial overgrowth. This is not always necessary – it really depends on the particular case.

Once in place, it is usually necessary to accompany the diet with appropriate anti-bacterial supplements for a few weeks to eliminate the bacterial overgrowth. Antibiotics are also an option if you can find a doctor who is familiar with the recommended SIBO protocol.

A programme to rebuild defences, strengthen and improve movement in the intestinal tract is then recommended to ensure that the SIBO does not return. There may well be additional underlying issues that also need to be addressed to meet this end point. The diet should over time be expanded again to include some of the healthy and gut supportive foods that may have been previously eliminated.

Get in touch for more information

So, in conclusion, SIBO is not an easy thing to deal with. However for IBS symptoms which match those listed above, I always consider it as a possible underling cause.

Please get in touch with me if you would like more information or if you wish to book an appointment to see if SIBO may be an issue for you.

In addition to Breath Testing and diet/supplement advice, I also include Kinesiology muscle testing as part of my sessions – this can be very helpful in assessing any potential bacterial overgrowth and helping to guide the strategy to deal with it.