Stewart I agree with the general comments and would add one missing element due to travel and a recent visit to a nutritionist.
You mention that people like to promote the best diet based on regional health and longevity. However this is also a regionally developed diet over centuries and prior to the advent of cheap travel and work relocation.
Diets were heavily renationalised and the body adapted to them over 100's of years based on resources. Now with people rearing next generations in different locations you see problems. Chinese and India/West Indian diabetes rates are not only much higher but far easier to trip with western diets. This was from a food nutritionist I have been to see recently. They have a chart which appears to show the medication levels needed for the different genetic chains.
When they say which part of the world is healthiest and point out their diet it only works if the body is adapted for that diet making it a hollow in many ways?
The displacement effect is considerable.
