[jessriedel]

> IBD presents all over the world and I'm guessing predates the microplastics phenomena.

IBD occurs in many parts of the world, but it is a disease of modernity. It is highly correlated with GDP. In particular, Chron’s and UC are basically absent among hunter gatherers and in very poor countries. (And researchers have good reasons to think this is not a measurement error.)

[nojs]

I would imagine the prevalence of microplastics in developing countries is just as high (or higher) though. So the GDP argument isn’t particularly supportive of a microplastics explanation.

[jessriedel]

Personally I doubt think it's just as high. But in any case, I'm not arguing for microplastics in particular as an explanation, just against the suggestion that IBD is some timeless human invariant that couldn't be attributed to peculiarities of the modern environment. (I find the hygiene-hypothesis-like explanations a little more compelling, although I don't have strong beliefs.) If the commenter wants to argue against microplastics as a cause, he needs to make claims like the one you made.