Table 2.

SCFAs produced by probiotics and their beneficial effects

Short-chain fatty acids	Effect of SCFA	Producing Bacteria	Ref.
Lactic acids	Maintaining intestinal and immune homeostasis As a mediator in the microbiota–gut–brain axis crosstalk regulating pH, Increasing the absorption of calcium, iron, magnesium, Anti-inflammatory activity (inhibiting NFκB macrophages) Inhibit the development of pathogenic microorganisms competing for colonization sites	Lactic acid bacteria (LAB) Lactobacilli, Bifidobacteria, Enterococci, Streptococci, Eubacterium	[39, 45–48]
Acetic acid	Key factor in the metabolism of carbohydrates and fats and synthesis of cholesterol Maintaining intestinal and immune homeostasis	LAB, Acetic acid bacteria (AAB), Acetobacter spp.	[49, 50]
Propionic acid	Inhibition of gluconeogenesis and cholesterol synthesis in the liver Maintaining intestinal and immune homeostasis Antibacterial and anti-inflammatory effects against pathogens	LAB Propionic acid bacteria (PAB) Propionibacterium	[51, 52]
Butyric acid	Anti-inflammatory effect Main source of energy for intestinal epithelial cells Immunoregulatory effect on intestinal epithelial cells and other mucosal cell populations Stimulating the expression of the MUC2 gene in cell lines. Production of mucin inhibiting tumor development and inducing the process of apoptosis	LAB, Bacteroidetes, Firmicutes	[47, 53–57]