I went to Holtorf in California maybe 8 years ago. I wouldn't recommend it. I had gone for hypothyroidism and to look for a better approach than just being given pills, wanted to find a root cause, etc. I was hoping Holtorf was that.
However, I was just given a high dose of T3 (didn't work). There wasn't intensive investigation or anything like that. Doctors rotate through there pretty often - my first one left the clinic and I got another - seemed like that happened a lot.
A couple years later, through a true functional practitioner, I found out I was intolerant of gluten, grains, dairy, fixed my gut as best I could, worked on my liver, etc. None of this was explored at Holtorf. My functional practitioner actually told me several of his clients were from Holtorf and they were suing the group for making their condition worse. I wish I could have gone to the real functional guy first and maybe saved my body a little.
At Holtorf they also advertised Botox and fillers so you could get that done while working on your chronic disease!
Also, MEAction decided not to put Holtorf on their list of providers as they have heard that there were issues with patients there (OMF stated they heard this too).