Microbiome, fermented food and lacobacilli.
Humans possess two protective layers of biodiversity, and the microbiome has been proposed as an important actor of COVID-1915. The environment (outer layer) affects our lifestyle, shaping the microbiome (inner layer). 16Many fermented foods contain living microorganisms and modulate the intestinal microbiome. 2,17-20
The composition of microbiomes varies in different regions of the world. 21 Urbanization in western countries was associated with changes in the gut microbiome and with intestinal diversity reduction. 3,5,22-24 Westernized food in Japan led to changes in the microbiome and in insulin resistance.25 The gut microbiome of westernized urban Saudis had a lower biodiversity than that of the traditional Bedouin population.26 Fast food consumption was characterised by reduced Lactobacilli in the microbiome. 27
The links between gut microbiome, inflammation, obesity and insulin resistance are being observed but further large studies are needed for a definite conclusion. 28-30
Some COVID-19 patients have intestinal microbial dysbiosis31 with decreased probiotics such as Lactobacillus  and Bifidobacterium 32. Many bacteria are involved in the fermentation of vegetables but most traditional foods with live bacteria in the low-death rate countries are based on LAB fermentation. 33-37 Lactobacilli are among the most common microorganisms found in milk and milk products38-40.