The Nub of it:
The old friends hypothesis is a further refinement of the hygiene hypothesis. T regulator cells can only become fully effective if they are stimulated by exposure to several particular varieties of microorganisms and parasites. These consist of pathogens that present only low levels of pathogenicity, and which have coexisted universally with human beings throughout our evolutionary history—that is, at least until recent times, as the development of hygienic practices and effective medical care have diminished or eliminated such traditional fauna from the populace. For example, proper development of T regulator cells in individuals may depend on exposure to organisms such as lactobacilli, various mycobacteria, and, albeit unpalatable, certain harmless helminths. The T regulatory cells learn to respond to harmless or beneficial invaders by damping down the aggressive reaction of the helper T cells and other immune system components to the antigens presented by the harmless symbiotes. As a result, a properly developed immune system is unlikely to aggressively attack harmless allergens or self cells. In this light, not only a virulent environment but also a sterile environment are both detrimental to optimal immune system development.
Recent research has demonstrated even more remarkable beneficial effects for sufferers of multiple sclerosis[6] and Crohn’s Disease[7] The reasoning is that our immune systems evolved under constant assault from a variety of parasites, most of which have to modulate our immune response to succeed. That is, they have to down regulate the response that would otherwise attack them. Evolving with a down-regulated immune system means that in the absence of those down-regulating parasites our immune systems often attack our own tissues, leading to asthma, hay fever, IBD, colitis, Crohn’s, multiple sclerosis and perhaps other autoimmune diseases. Hence the increase in autoimmune diseases in the relatively clean and sterile industrialized world.
By the way thread, you can get the good stuff mentioned in post 107 by eating yogurt with those bacteria mentioned above in the culture.
I think it is important to have lots of exposure to fresh air and dirt and eat yogurt and kefir.
btw a helminth is a parasitic worm :)