A few years ago, I traveled to Okinawa in Japan, Nicoya in Costa Rica, Ikaria in Greece, Loma Linda in California and Sardinia in Italy — all "Blue Zones," or homes to the longest-lived peopleto find out what centenarians ate to live to 100.  

I also asked dozens of the world's leading nutritionists and food scientists what we should eat to enjoy a long and healthy life, while also taking care of the environment.