The most common definition of probiotics is stating that probiotics are live
micro-organisms that have a positive effect on the host by improving the
balance of pathogenic to beneficial bacteria in the gut. The benefits of
probiotics are based on two main functions, stimulating the growth of
beneficial microflora and suppressing the growth of pathogenic bacteria. Where
a higher number of beneficial bacteria are present they are more likely to
out-compete the pathogens for both nutrients and adhesion sites on the gut
wall, a process known as competitive exclusion. Beneficial bacteria, such as
Lactobacillus, are also known to release short chain fatty acids, becteriocins
and hydrogen peroxide, which have antagonistic effects on pathogenic bacteria.
