The following article looks at the harmful effects of excessive hygiene and while it’s clearly directly relevant to America’s hand-sanitizing cleanliness-obsessed culture, the fear of germs is itself symptomatic of a wider culture of fear.

In our hunger to feel safe we have lost an understanding of the healthiness of insecurity and the pathology of safety. A society that craves constant safety can never grow up. It ends up becoming literally and metaphorically allergic to life.

Sedeer at Inspiring Science writes: Since moving to Finland, I’ve become accustomed to asking guests whether they have any allergies before I prepare dinner. I grew up in the developing world where allergies and asthma seem to be much less common than they are here; in fact, various studies have found higher rates of allergy and autoimmune conditions in developed than developing countries. One explanation for this is the “hygiene hypothesis,” which proposes that excessive hygiene early in life can affect the development of the immune system and result in allergic conditions and autoimmune diseases in later life. In a recent study appearing in Science, a team of scientists in Germany and the United States present evidence supporting the hygiene hypothesis and the importance of an early challenge to the immune system.

The researchers tested this idea in mice, which are commonly used as a model system to study the human immune response; they compared the immune systems and responses of germ-free (GF) mice, which were completely free of any microorganisms, and specific pathogen-free (SPF) mice, which had normal gut microbiota but were free of pathogens. The researchers measured the level of invariant Natural Killer T (iNKT) cells, which are an important part of the immune system, and found that the germ-free mice had more iNKT cells in their colon and lungs than their SPF counterparts. In addition to playing a vital role in our immune response, iNKT cells have also been implicated in several autoimmune conditions; the GF mice were more susceptible to induction of asthma and colitis (an autoimmune bowel inflammation), perhaps due to the increased quantity of iNKT cells. Although allowing the adult germ-free mice to be recolonized by microbes didn’t reduce their iNKT levels or their susceptibility to asthma or colitis, recolonization of pregnant GF mice just before delivery did lead to normal iNKT levels and reduced susceptibility in their offspring. Simply having microbiota wasn’t enough; the microbes had to be present at the right developmental stage in order to properly regulate the immune response. [Continue reading…]