One of the things that all the blue zones (populations with the highest longevity) have in common is that they consume diets high in unrefined carbs and low in animal products. There's multitudes of studies which link the consumption of animal products to a variety of illnesses.
I mean, sure, people are different to some degree but we're all the same species so generally we're all going to live optimally on a biologically appropriate diet. Some things work, some things don't. Eating chips and candy all day isn't going to work for anyone, for example.