Mechanisms of Action of Probiotics
Probiotics are live microorganisms that provide health benefits to the host when ingested in adequate amounts. The strains most frequently used as probiotics include lactic acid bacteria and bifidobacteria.
Antimicrobial Effects of Probiotics
- Modify microflora to suppress pathogens.
- Secrete antibacterial substances. Probiotic bacteria produce a variety of substances that are inhibitory to both gram-positive and gram-negative bacteria. These include organic acids, hydrogen peroxide and bacteriocins. These compounds may reduce not only the number of viable pathogenic organisms but may also affect bacterial metabolism and toxin production. This occurs through reduction of luminal pH through the production of volatile short-chain fatty acids, mainly acetates, propionates and butyrates. And of course, through production of lactic acid (Bifidobacterium, Lactobacillus, Streptococcus), leading to a reduction in colonic pH.
- Compete with pathogens to prevent their adhesion to the intestine.
- Compete for nutrients necessary for pathogen survival
- Antitoxin effect
Effect of Probiotics on the Intestinal Epithelium
- Promote tight contact between epithelial cells forming a functional barrier.
- Reducing the secretory and inflammatory consequences of bacterial infection.
- Enhancing the production of defensive molecules such as mucins.
Immune Effects of Probiotics
- Probiotics acting as vehicles to deliver anti-inflammatory molecules to the Intestine.
- Enhance signalling in host cells to reduce inflammatory response.
- Switch in immune response to reduce allergy.
- Reduce the production of inflammatory substances.