As scientists sequence DNA in microbiome samples, they are discovering new building blocks of life. About 30 percent of the genes in genomes sequenced in large-scale studies code for proteins that are new to science.
MICROBES IN HUMANS
Estimates of the number of nonhuman cells in our bodies range from 30 trillion to 400 trillion. The human body contains about 37 trillion human cells.
The gastrointestinal tract contains so many nerve cells that it is known as the “second brain.” Phrases such as “gut feeling,” “butterflies in the stomach” and “trust your gut” are thought to reflect the mind-gut connection.
In 1907, Élie Metchnikoff, a Nobel Prize-winning Russian microbiologist, suggested a connection between longevity and fermented milk. He proposed that lactic acid bacteria “could normalize bowel health and prolong life.” Medical researchers ignored his theories for most of the 20th century.
PREBIOTICS VS. PROBIOTICS
Online or in the health-food aisle at the grocery store, you can buy probiotics and prebiotics that claim to support digestive health. Probiotics are living microorganisms that have been shown to exert a beneficial impact. Prebiotics are compounds (such as dietary fiber) that may promote the growth of beneficial microbes.