What happens when Japanese people start eating a Western diet? Could it mean that their famed long life span starts to decline?
It certainly could. It could even mean that the people of these islands become less Japanese.
I don't mean to say that in a nationalistic sense — in the way that oddities such as Tokyo Gov. Shintaro Ishihara might argue there is something intrinsically patriotic about consuming miso soup and natto (fermented beans). Of course, food is closely linked with national culture, and in Japan it may be even more closely linked than in most countries.