Gut microbiota - host interactions now also brain-immune axis.

The 'gut-brain axis' is a fairly new term in the fairly new field of the gut microbiota. The gut microbiota, the collection of microorganisms residing in intestines of vertebrates, was shown to have major effects on host physiology. The field has seen a renaissance due to advances in deep-sequencing. Recently, there is an explosion of studies on the physiological and therapeutic potential of the gut microbiota. These microbes are considered to reside in symbiosis with their hosts, and are termed 'commensals', originated from Latin - 'at table together'. We provide the gut microbes nutrients and a living niche, and they in turn, provide us with essentially the same - nutrients derived from the food we eat, that we cannot digest, and essential functions for health and longevity. In the past few years it has been appreciated that gut microbes can even affect our brain, behavior, and neurological disorders, which we here review.