You mean this functional medicine? Or are you using the term in a different way?
> Functional medicine is a form of alternative medicine that encompasses a number of unproven and disproven methods and treatments.
> It has been described as pseudoscience,[5] quackery,[6] and at its essence a rebranding of complementary and alternative medicine.
Descriptions like the above which seek to attack and discredit any form of alternative medicine will always exist because mainstream medical practice first seeks to enrich corporations and only secondarily tries to help patients. (Not on an individual level, but structurally.)
I'd invite you to check out the YouTube channels or any of the books written by Dr. Mark Hyman or Dr. Gundry; the content they put out is incredible and has had a huge positive impact on my life.
The two people you mentioned seem to be regarded negatively by the scientific community.
Dr. Mark Hyman
> He was the editor-in-chief of, and is a contributing editor to, Alternative Therapies in Health and Medicine.
Looking at that journal it's definitely filled with crank nonsense.
And Dr. Gundry I assume is Steven Gundry, who is best known for false claims about lectins.
This doesn't constitute strong evidence and isn't how science works.