Comment by 323

Citation? I think there might be a bit of "telephone game" happening here. The current science shows that avoiding allergens increases the risk of developing allergies. The hypothesis for how that happens is that if an infant's first exposure to an allergen is on their skin (e.g., peanut oil), then their body may classify it as invasive and develop anti-bodies to attack it. If they are first introduced to an allergen as food, then their body classifies it as food. By avoiding feeding allergens to infants, you increase the time window for their bodies to be exposed through the skin and classify it as invasive. I could certainly see this idea transmuting through word of mouth into the "first world is too clean" idea in your comment, but that's pretty far off.

Anecdotally, this is insufficient to explain the evidence.

I have approximately no allergies but was exposed to a very diverse and not sterile environment from early on, with other siblings being similar. I have two brothers close to my age that did have significant and in some case deadly allergies, who were born and raised in the same environment.

Among my siblings, it is a completely mixed bag of sensitivity. Some were highly sensitive to many things, others were sensitive to almost nothing. If mere exposure to non-sterile environments was sufficient then we should all have had similar sensitivity to allergens but the variance in fact was quite high.

It is a current theory. It is far from being the current theory, and IMO a woefully insufficient one. I'm not a clean freak by any means and still developed a couple dozen food allergies as an adult. Ultimately the immune system is hopelessly complex and this will likely take decades more for us just to arrive at the right theory.

But this is kind of strange, as for example in France, you definitely don't see the same level of allergies as in the US.