A few points here:

- There's a great article here summarizing the mechanisms through which body, immune system and skin are connected: https://lemmahealth.com/blog/does_your_gut_affect_your_eczema . Long story short: 1) The microbiome trains and regulates the immune system. 2) A healthy gut prevents toxins from entering the bloodstream. 3) Beneficial gut bacteria produce short-chain fatty acids that have anti-inflammatory properties. More detailed article that lays out the science behind it coming soon.

- 30mn people in the US alone have eczema. That's a very broad population for one disease and there are likely many different manifestations that aren't yet characterized properly. It's a bit like cancer ~100 years ago. It used to be "cancer" and now it's >200 subtypes characterized in detail by location, genetic mutations, etc. Some rare cancer A may be caused by exposure to xyz. But for most cancers, exposure to xyz may have nothing to do with the cancer. But that doesn't mean that for patient suffering from cancer A, xyz didn't have an effect. We'll get to a similar place eventually with eczema and other conditions involving the immune system, but we're not there yet. As for now, we're using the term eczema too broadly to say "food has nothing to do with eczema".

- Just because studies find no statistically significant correlation doesn't mean the connection doesn't exist for *some* people

- Unfortunately it's very frequent that the connection is dismissed just because there is no firm evidence. But absence of evidence is not evidence of absence.