In the pre-industry world the health challenges didn't change much from century to century. Now the rate at which chemicals are approved to enter the environment and food supply is much faster than their effects can be studied so even a sincere doctor would struggle to keep up with his patients' symptoms (see rates of diabetes, autism, specific cancers, etc.) I don't think big Med and big Ag necessarily meet in smoky rooms to gloat but industries clearly know how to influence each other for profit.
The modern West does seem uniquely bad about ignoring diet. Classical Greece, India, China, and other places were more holistic. The part that upsets me is when a friend says something like "i'll start eating right after I shake this depression/anxiety/lethargy"--they can't see the chicken & egg because daily junk is so normalized.
Lots of: urban hiking, cycling, sprinting
Lots of: fresh meat, seafood, eggs, organs, tubers, starch fruits, vegetables, meat fat, dairy fat, oil fruits
Some: cured meat, dairy protein, sweet fruits, rice, pulses, tree nuts, oil seeds
Minimal: soy, refined proteins, sugar, liquid carbohydrate, grains, refined oils, peanuts