The Okinawa diet is mainly plant-based and heavily features vegetables and soy.
A skinny, purple sweet potato called beni imo accounts for 67% of older Okinawans' diets, Buettner said in an episode of his Netflix docuseries "Live to 100: Secrets of the Blue Zones."
The sweet potatoes are a source of healthy complex carbohydrates, are filled with fiber, and contain more antioxidants than blueberries, Buettner said. Okinawans also eat seaweed, which is filled with nutrients such as iodine and antioxidants, he said.
Soy, in the form of tofu and miso, is another staple. Insider's Hilary Brueck previously reported that Okinawan tofu contains more protein and healthy fat than other tofus because the soybeans are squeezed raw before boiling instead of after.