I’ve just come across this excellent article in the current issue of PNAS – by science writer Megan Scudellari. The article is liberally sprinkled with quotes from the doyen of the so-called “old friends” hypothesis, Graham Rook of University College, London, and his colleague from the London School of Hygiene and Tropical Medicine, Sally Bloomfield. Both argue that the term “hygiene hypothesis” is an historical anachronism and a misnomer because it is widely taken to mean that the key to later immune health requires a slackening in standards of hygiene, and that an obsession with hygiene and antimicrobial cleaning products is to blame for the current epidemics of allergic and autoimmune diseases. Although none of this will come as much of a surprise to members of the evmed community this is a very readable and well researched piece which seeks to replace the literal interpretation of the hygiene hypothesis with the understanding that it is the dysbiosis of the gut microbiome that is to blame for the poor regulation of our immune systems. Rook is quoted and saying: “We know an awful lot now about why our immune system’s regulation is not in terribly good shape, and it’s got absolutely nothing to do with hygiene,” while Bloomfield weighs in with: “I’ve even seen things in the media saying we shouldn’t wash our hands. What the hell are they talking about?” Well worth a read.