SIBO Testing

SIBO is the acronym for “small intestinal bacterial overgrowth,” defined as excessive bacteria in the small intestine. Bacterium naturally occurs throughout the digestive tract in a healthy system. The small intestine has relatively low levels of bacteria compared to the large intestine. When bacteria invades and takes over the small intestine it can lead to poor nutrient absorption.

Symptoms are very similar to other gastrointestinal disorders and include nausea, diarrhoea, bloating, etc.

There are many theories as to what is the potential cause of SIBO is but none of them had been clearly proven. Some theories talk about aging, diabetes, diverticulosis and other background conditions.

Diagnosis of SIBO is done by measuring the transit time, from the mouth to the small intestine, of 50 grams of Glucose (diluted in a glass of water). The transit time is measured by a series of breath tests over a course of 1 hour (1 breath every 15 minutes), using a hydrogen sensitive breath analyser.

If SIBO is diagnosed it is most often treated with antibiotics.

What is the preparation for the SIBO test?

For the SIBO test to be valid, it is important that you follow these instructions concerning medications, supplements, and diet prior to the test.

  • No antibiotics for 4 weeks before your test
  • No probiotics for two weeks before your test (e.g. acidophilus or bifidobacteria powders or capsules).
  • Allow at least 1 week after a colonoscopy procedure before breath test appointment.
  • Take all your usual medications including the oral contraceptive pill and antidepressants.
  • Unless absolutely necessary, we prefer you not to take vitamins, minerals, laxatives, anti-laxative, yakult and fish oil capsules on the day before and the day of your test.
  • Follow the diet on the back of this information sheet for 24 hours before each test.
  • Fast from 8pm the night before each test. You may drink water but nothing else.

What are the diet instructions for the SIBO test?

On the day before each test please only have foods and drinks from the list below.


Water (unflavoured, non fizzy)

Coffee (instant, plunger, espresso are all fine), no coffee substitutes such as Caro

Tea (normal, herbal, or green tea)

Lactose free milk (e.g. Liddells long life milk in the supermarket), rice milk

Alcohol (maximum per day of 250mls wine or 60mls spirits or 200ml beer)

Cereals, crackers and breads

(Please do not eat in excess quantities).

Corn flakes, rice bubbles, corn products, plain rice cakes, gluten free bread.


(Please do not eat in excess quantities).

Any type of rice, corn, maize, buckwheat, amaranth, quinoa, millet


Plain, fresh or tinned fish, plain meat such as beef, lamb, venison, pork, chicken, ham

Fruit and vegetables

Mandarins, green kiwifruit, strawberries, oranges, rock melon (only 1 palm full of fruit per 2 hours)

Sweet corn, green beans, potatoes (peeled), pumpkin, carrots, courgette, tomatoes, lettuce, spinach, silverbeet.


Eggs, white or brown sugar, barley sugars, boysenberry, raspberry or strawberry jam, marmalade, vegemite, jelly, oil, margarine, butter, peanut butter, nuts, seeds.


(chewing gum or mints.).

Many packaged or canned foods have sauces, spices, onion flavouring, artificial sweeteners, soy products etc. which you cannot have because they interfere with the test. If food or drink is not on the list, please do not eat it the day before your test.

Fast from 8pm the night before your test.

After 8pm the night before your test:

  • You can drink small amounts of water.
  • Do not smoke on the morning of the test.
  • Clean your teeth with toothpaste and rinse your mouth well with water.
  • Do not use mouthwash.
  • Do not use perfume, aftershave, body lotions or scented moisturiser or makeup, deodorant is ok.
  • Do not wear clothing that has been washed in fabric softener.
  • Do not wash your hair with highly scented shampoo or condition.

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