iThei mdcdaelcinfd o c elllllrllll citlhscor indigestible foods such as polysaccharides; synthesis of micronu-
trients and short-chain fatty acids; and absorption of trace elements.
The bacteria feed on fiber—poorly digested by all humans—by ferment-
ing it. During the fermentation process, short-chain fatty acids, lactate,
succinate, ethanol, hydrogen, and carbon dioxide gases are produced.
These beneficial bacteria attach to the intestinal tissue and colonize the
gastrointestinal tract. They compete with pathogenic bacteria for intes-
tinal attachment and nutrients, producing substances that kill foreign
bacteria and organisms.
This type of arrangement is called a symbiotic relationship and is one in
whichboth the host and bacteria thrive.
Having plenty of these good bacteria helps us metabolize complex
carbohydrates, maintain a proper intestinal barrier, and suppress in-
testinal inflammation.
The best-known beneficial bacteria are from the Lactobacillus and
Bifidobacterium species and are classified as gram-positive bacteria by
microbiologists.
Opportunistic Bacteria
Our intestines are also home to other types of bacteria known as oppor-
tunistic pathogens. They behave well when everything is balanced but
can be naughty when the opportunity arises. These bacteria may become
potential pathogens when we are vulnerable, such as in situations of a
compromised immune system, impaired digestion, intestinal permeabil-
ity, depletion of Lactobacillus or Bifidobacterium, and even when we ex-
perience psychological stress.