Understanding probiotics - so much more than a simple digestive aid.

What are they?

Probiotics are live bacteria, or microorganisms, found in the digestive tract which have been shown to benefit human health and contribute to a healthy microbiome.  The microbiome refers to the balance of different types of bacteria in the gut and a healthy microbiome contains plenty of beneficial strains (or probiotics).  Numerous studies show that a healthy microbiome can positively influence many aspects of human health, including digestion, mental health, and immunity. 

Probiotics are found in certain fermented foods like yoghurt, kimchi (fermented and spiced vegetables), kombucha (fermented tea), sauerkraut (fermented cabbage), kefir (fermented milk or water), tempeh and miso (fermented soya).  Probiotics may also be taken as a food supplement. 

Probiotics are also passed from mother to baby via the birth canal during childbirth and via breast milk.  The mother’s probiotic status is, therefore, an important consideration during pregnancy, given that her baby will also inherit the same microbiome.

There are a number of different probiotic strains, but the most studied strains with proven health benefits include Lactobacillus and Bifidobacterium varieties, as well as the yeast saccharomyces boulardii.

How do they work?

The health benefits of probiotics relate to the following mechanisms: -

1.        Improved integrity of the epithelial barrier

The epithelial barrier is a defence mechanism that helps to maintain the integrity of the gut and protect the rest of the body from bacteria, food antigens and other potentially toxic substances passing into the bloodstream and triggering an inflammatory response. Consumption of non-pathogenic bacteria can enhance this barrier function, and probiotic bacteria have been extensively studied for their involvement in the maintenance of this barrier.  It is not yet fully understood how probiotics achieve this, but Lactobacillus, in particular, has been found to achieve positive results.

1.        Increased adhesion to the intestinal mucosa

For humans to benefit from probiotics, adhesion to the intestinal mucosa is essential.  This adhesion enables modulation of the immune system and antagonism against pathogens. Various strains of Lactobacillus Acidophilus and Bifidobacterium have been shown in studies to have these adhesion properties.

1.        Inhibition of pathogen adhesion

Probiotics cause alterations in the intestinal mucins which prevent pathogens from binding to the intestinal barrier.  These beneficial bacteria are degraded into antimicrobial peptides, which lends anti-pathogenic properties to the host when under attack from pathogens.

1.        Competitive exclusion of pathogenic microorganisms

Studies show probiotics, particularly Lactobacilli and Bifidobacterium, can crowd out and exclude pathogenic microorganisms.

1.        Production of anti-microorganism substances

Probiotics are involved in the production of several anti-microbial substances including organic acids, Bacteriocins, health promoting fatty acids and de-conjugated bile acids, all of which work to eliminate pathogens.

1.        Modulation of the immune system

Probiotics have been well researched for their immunomodulating properties.  They can influence both the innate and adaptive immune systems and downregulate intestinal inflammation (Bermudez-Brito et al, 2012).  Around 80% of human immune system