By “nutritional therapy” I mean using additional, man-made, supplemental sources of vitamins, minerals, and other substances essential to bodily functioning to fix health problems. A more accurate term is orthomolecular therapy or medicine, but I didn’t come across that until recently.
I have altered my diet radically and frequently over the years — to avoid gluten, dairy, goitrogens, and histamine, among other things — and although it helped a great deal, it did not completely resolve my problems.
In my experience, and from what I have learned in my research, an illness that is due to a nutritional deficiency cannot be fixed with the amounts of nutrients found in food alone. Or not any time soon, anyway.