In the book "The Blue Zones Solution: Eating and Living Like the World's Healthiest People," author Dan Buettner reveals what the people around the world who live the longest are more likely to eat. One of the keys to longevity?

A plant-based diet, says Buettner and colleague Gianni Pes, a senior researcher at the University of Sassari, Italy. They share the foods that make up the regular diet of the people of Sardinia, Italy, one of the "Blue Zones" -- areas around the world where people are more likely to live to 100.