One has to wonder which diseases Betz is talking about. Vaccines and clean drinking water have done more than just about any other factors to lower the death rate of many diseases that have plagued mankind for as long as we have been on the Earth. Environmental radiation has yet to be shows as a cause of cancer, as it is at such low levels that its effects are difficult to measure. Areas of the US with high background radiation do not have higher cancer rates as one would expect. Nature is not the nice and friendly all-loving force it is often portrayed as being.
Nature is full of toxins and diseases that are very dangerous and destructive.
Cooking food kills germs. Chemicals are not the magic fountain of goodness either, don't get me wrong. Many chemicals such as DDT have been found to be harmful to humans and the environment. Chemicals that are to be added to food should and do have to pass many scientific tests to make sure that they are safe. I would like to see clinical tests of diets such as the Hallelujah diet to find out if there is any validity to the claims.