A blue zone is a region in the world where people are claimed to have exceptional longevity beyond the age of 100 due to a lifestyle combining physical activity, low stress, rich social interactions, a predominantly plant-based diet, and low disease incidence. The name blue zones derived simply during the original survey by scientists, who "used a blue pen on a map to mark the villages with long-lived population." Suggested blue zones include Okinawa Prefecture in Japan, Nuoro Province in Sardinia, Italy, the Nicoya Peninsula in Costa Rica, and Icaria, Greece. Based on an absence of scientific evidence, the concept of blue zones is commonly challenged as unproven. Subsequent research contradicted initial claims, such as Okinawa, which experienced substantial decline in life expectancy during the 21st century, and Nicoya, where people born after 1930 did not have exceptional longevity compared to the broader national population.
