Some nutrients do not exist in food till they are created in the gut by non human genes

[www.ncbi.nlm.nih.gov]

The human gastrointestinal (GI) tract represents one of the largest interfaces (250–400 m2) between the host, environmental factors and antigens in the human body. In an average life time, around 60 tonnes of food pass through the human GI tract, along with an abundance of microorganisms from the environment which impose a huge threat on gut integrity [1]. The collection of bacteria, archaea and eukarya colonising the GI tract is termed the ‘gut microbiota’ and has co-evolved with the host over thousands of years to form an intricate and mutually beneficial relationship [2,3]. The number of microorganisms inhabiting the GI tract has been estimated to exceed 10 ^14 , which encompasses 10 times more bacterial cells than the number of human cells and over 100 times the amount of genomic content (microbiome) as the human genome [2,4].

The microbiota offers many benefits to the host, through a range of physiological functions such as strengthening gut integrity or shaping the intestinal epithelium [7], harvesting energy [8], protecting against pathogens [9] and regulating host immunity [10].

[www.ncbi.nlm.nih.gov]

Postbiotics include any substance released by or produced through the metabolic activity of the microorganism, which exerts a beneficial effect on the host, directly or indirectly.

The human body provides a stable, nutrient-rich environment for the inhabiting microorganisms, and in return, receives a number of benefits.