In medicine, the hygiene hypothesis states that a lack of early childhood exposure to infectious agents, symbiotic microorganisms (e.g., gut flora or probiotics), and parasites increases susceptibility to allergic diseases by suppressing natural development of the immune system. Because of this we fail to induce a Th1 polarized response early in life so as we grow up we are more prone to developing Th2 induced disease. The rise of autoimmune diseases and acute lymphoblastic leukemia in young people in the developed world has also been linked to the hygiene hypothesis.
There is some evidence that autism may be caused by an immune disease; One publication speculated that the lack of early childhood exposure could be a cause of autism.
Read more about Hygiene Hypothesis: History, Mechanism of Action, Breadth of The Hypothesis, Supporting Evidence, Helminthic Therapy, Alternative Hypotheses
Famous quotes containing the word hypothesis:
“The hypothesis I wish to advance is that ... the language of morality is in ... grave disorder.... What we possess, if this is true, are the fragments of a conceptual scheme, parts of which now lack those contexts from which their significance derived. We possess indeed simulacra of morality, we continue to use many of the key expressions. But we have—very largely if not entirely—lost our comprehension, both theoretical and practical, of morality.”
—Alasdair Chalmers MacIntyre (b. 1929)