Japan – 83.3

Cited by some researchers as the healthiest people on the planet, the Japanese enjoy an average lifespan of 83.3 years. Japan has been studied by scientists across the world for having the highest per capita number of centenarians (people living to over 100 years old) at 34.85 per 100,000. The highest proportion of these centenarians are on the island of Okinawa: the highest consumer of seaweed in the world. Maybe we have something to learn from the green stuff.