I don't think you can prove that assertion. The personal physician to the King of Olde would not know about Germ Theory, nor about the importance of basic hygie

I don't think you can prove that assertion. The personal physician to the King of Olde would not know about Germ Theory, nor about the importance of basic hygiene and cleanliness. A modern poor person at least has a chance to learn about such things, and there is a significant number of people who provide medical care for free to those in need.