A lactilose breath test can measure the likelihood of presence of bacterial overgrowth in the gut. To do the test, you should fast overnight before the test, and also take a low-fiber diet for 24 hours before the test. Lactilose is an indigestible sugar. Give several breath samples over a few hours. There should be a peak in hydrogen readings. If you have an increased gut transit time, the hydrogen will peak later. If you have an early hydrogen peak, it suggests that bacteria are breaking it down too early on in the cycle - an indicator of bacterial overgrowth. If you have low hydrogen output, chances are that you have a diarrhea problem.
Lots of methane in the gut is an indicator of constipation. Methane slows down the bowel movement process.
Fiber does not help in the process because it just provides more food for the bacteria. Beans and pulses are therefore not good foods to take in this case.
It's also recommended to allow your gut to rest for several hours between meals. Constant snacking doesn't allow adequate clearing time for the gut. Clearing time is also critical during sleep. Therefore, poor sleep contributes to poor digestion.
Diabetes and hypothyroidism also cause a slowing down of the digestion system.
Switch to a low-GI diet. Avoid fructose, corn syrup, sorbitol, xylitol, and dairy (lactose).
There is then reference to the FODMAPs diet. This involves a process of elimination of certain food types as explained on a FODMAP website:
Low FODMAP Diet*Dr Sue Shepherd developed the low FODMAP diet in 2001. She has proven, through her pioneering PhD research, that limiting dietary FODMAPs is an effective treatment for people with symptoms of IBS. The low FODMAP diet has been published in international medical journals and is now accepted and recommended as one of the most effective dietary therapies for IBS. Abstracts of these articles are available in our GP/Specialist Section.
FODMAPs are found in the foods we eat. FODMAPs is an acronym (abbreviation) referring to Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols*. These are complex names for a collection of molecules found in food, that can be poorly absorbed by some people. When the molecules are poorly absorbed in the small intestine of the digestive tract, these molecules then continue along their journey along the digestive tract, arriving at the large intestine, where they act as a food source to the bacteria that live there normally. The bacteria then digest/ferment these FODMAPs and can cause symptoms of Irritable Bowel Syndrome (IBS). Symptoms of Irritable Bowel Syndrome include abdominal bloating and distension, excess wind (flatulence), abdominal pain, nausea, changes in bowel habits (diarrhoea, constipation, or a combination of both), and other gastro-intestinal symptoms.