I think most people can handle most diets. I do think that there are influences from things like excess sugar, seed oil and highly processed foods. These are

I think most people can handle most diets. I do think that there are influences from things like excess sugar, seed oil and highly processed foods. These are things that are generally hard to study en-masse and take a lot of time. Observational studies are more difficult to get anything convincing from in general. Not to mention differences that take place over generations, like experienced in some cat feeding experiments. "Food" has changed so much in the past 150 years and more around 100 years ago then the history of man before it. Humans are also incredibly adaptive, and experience disease in different ways altogether.