You should take Hippocrates in context. During his time, it was common to speak in certain ways to increase the strength or fluidity of your message. One such way is to use a backward analogy.
When H says "Let your food be your medicine" he is not literally talking about food having medicinal properties. In context, he is metaphorically saying "let medicine be your food", better understood "let the art of medicine be your intellectual food", feed the mind (which is a common theme in much of what Hippocrates said). Philosphers during H's time were focused on feeding the mind, because thats what distinguished them from the average (and highly uneduated) population.
"Unfortunately I don't think the wall between modern medicine and natural medicine will ever come down. And that's because modern medicine is quackery pure and simple."
Statements like that are what keep the wall up. Remember, many in modern medicine would say the same thing about natural. The reason the wall is not coming down is because of people on both sides absolutely disreguarding anything the other side says. Now, I will agree, there is a lot of fraud in medicine, but it comes from both sides. There is validity in both views or they would not be around. Its only by finding the similarites and unity are we going to get a better system, not by pulling apart.