Okinawans over the age of 65 enjoy the world’s highest life expectancy: Men are expected to live to about 84, while women are expected to live to almost age 90. They suffer only a fraction of diseases that kill Americans: a fifth the rate of cardiovascular disease, a fifth the rate of breast and prostate cancer, and less than half the rate of dementia seen among similarly aged Americans.
Before 1940, the vast majority of the calories consumed — more than 60 percent — came from one food: the imo, or Okinawan sweet potato. A purple or yellow variety related to our orange sweet potato, the imo came here from the Americas about 400 years ago and took well to Okinawan soils. This sweet potato — high in flavonoids, vitamin C, fiber, carotenoids, and slow-burning carbohydrates — is one of the healthiest foods on the planet.