So in general it's very hard to get good data on life expectancy on these fringe groups.
Then there's a question of how much access to health care should be needed? I was recently reading about a study that found when western diets entered a region health care costs go up. I was reading about it in Barons which is a financial publication. I imagine they are looking for investment opportunities. But, the observation is interesting. I'd link it if I could find it.
If you look at the US causes of death, a high percent of them are related to lifestyle. Like so many heart disease issues being linked to smoking or arterial blockages (and they've studied the causes of those). If a group doesn't have those lifestyle components they they have better health and longevity.