As I was growing up in my grandparent's household my grand dad became a food faddist. He took over 90 vitamins a day. Everything was diet with him. He read what I would consider nonsense literature about conspiracies with the American Medical Association, synthetic vitamins and other claptrap. But, he believed.
I've never had any trouble with sickness, allergies or diet-related maladies. Why?
I have a fortunate gene pool behind me.
Some people inherit sensitivity to their enviornments and others don't.
I think much of diet-related thinking is just like religion: just another thing to obsess about and believe in.
Grand dad came from the same gene pool. His mother, who ate like a rat, lived into her 90's without any special diet. He lived to 91.
What disturbs me about subjective assessment of eating and effect is the "testimonial" aspect of the literature. Somebody is always ranting about......THEM: the others who conspire to keep us sick and dependant.
If the paranoia could be scraped off and the exaggerated reactionary rhetoric peeled away you'd probably just find snake oil and common sense left over.
Don't eat too much of anything.
Avoid fatty foods.
Exercise.
Don't smoke.
Be moderate.
Anybody could live better with the above.
All the rest is probably a way of separating you from your sanity and your wallet.
Terry