This is an excellent, three-part documentary,
described in this 2017 blog post, starring a famous New Zealand chef.
It recently turned up on Youtube, and I found it highly informative. He meets with various experts on diet, science, and the doctors who treat the victims.
My favorite part was a visit to a school which banned sodas and began teaching children to bring health lunches to school. Behavior improved, playing returned to the playground, and the children influenced their parents. These were Islanders who were eating traditionally prior to exposure to Western processed food. We might say, like the Southwestern Indigenous in North America, they have even less resistance to it than Europeans do.
Now, returning to more traditional eating is becoming a known strategy on all the populated continents, and populations are seeing a return to health.
We see so much sick and propped up health we don't have too many memories of hale and hearty seniors, maybe? These Islanders had healthy seniors to emulate and listen to.