Yeah, Gerson is dangerous, as are many woo treatments that dubs and other fundies flock to.
I periodically post about "alt med" on my cult prevention blog because wooism mirrors cults in so many ways. Dubs are ripe for it. It requires rejection of logic, facts, skepticism and science.
I personally was a victim of it. My jw parent rejected appropriate medical care for "alt med" and 1930s-style jw healing. Not only did the rejection of medical care severely endanger me--my condition was made worse by herbs.
I was also essentially required to enter an "alt med" training program so I could fund my pioneering. The training program consisted of 2 days in a fellow dub's living room, talking about macrobiotics, iridology, acupuncture, qi, herbs and other poppycock.
But it was all legit though because we had an anatomy book.