I think the research is correct. He wrote "Natural Medicine" Herbs, found to be, beneficial to the body are sold in health food stores.
I never see a store selling Hemlock,Poison Oak or Magic Mushrooms, or Opium.
I think all things on this planet is natural. There is a difference between natural and processed or extracted herbs, vitamins and foods.
Pharmacy processes and extracts for the good.(pain relievers). Evil people process and extract for the bad.(Heroin,opium)
Dr.Clark gives instructions as to what to do once a day once a week or once a year.
I work with people who over did it with a herbal remedy and stayed on it for months,or a mushroom diet for months.
I think this research is helping people.