Re: keto and gut health. Mine has never been better. Here's another viewpoint that posits that our gut bacteria are really out for themselves.
Hyperlipid: Search results for Fiaf
Re: D3 supplementation. I've read similar arguments, but the weight of evidence is not supportive of his thesis. See the Vitamin D Council website articles and links. I am happy to discuss this at length, but I hate typing, lol! You can pm me if you want to skype! My own n=1 is that sun exposure was insufficient for MY optimal health. Inflammatory conditions and autoimmune can benefit from therapeutic doses of D3.
In any case, living in Ireland you are almost definitely D3 deficient, unless you holiday in warmer climes for a couple of months a year. Most of my nutrition clients are UK-based and ALL of them have tested as severely deficient. All of them have reported great health benefits after a few months of supplementation.