Centenarians and Blue Zones: Evidence and Caveats

What people mean by Blue Zones

A "Blue Zone" is a region reported to have an unusually high share of people who reach 100 (centenarians). The idea is popular in books, diets and media. This page looks at what the research behind it shows, including the serious criticism. It is information only. Evidence labels are explained in How We Label Evidence in Longevity Research.

How the term was defined

The term comes from demographic research. A 2004 study of Sardinia (the AKEA study) used validated centenarians to map a "Blue Zone" in the central-eastern, mountainous part of the island. In that zone, life expectancy was longer and the male-to-female ratio among centenarians was 1.35, compared with 2.43 in the rest of Sardinia. [1] The authors said the cause was unknown, and floated a genetic hypothesis: frequent marriages between relatives and low immigration may have narrowed the gene pool. They also noted that none of the longevity hot spots reported worldwide had been fully validated. [1]

A 2025 review in the American Journal of Lifestyle Medicine says four Blue Zones have been validated (Okinawa, Sardinia, Nicoya and Ikaria), with Martinique emerging as a fifth, and requires a longevity level at least 50% higher than the national average and strict age checks. [2] The review acknowledges criticism about data reliability, particularly the accuracy of centenarians' ages. [2] We did not check who funded or wrote it beyond what the abstract states.

Evidence that supports the records

In Okinawa, researchers checked the age of a subset (8%) of the centenarian population against documents and found reported ages matched documented ones. Their demographic tests suggested the registration system was reliable, so the high reported rate was considered valid. [3] Label: mixed (validation covered a subset, and it is about age, not about what causes long life).

The criticism

A preprint on bioRxiv by Saul Justin Newman argues that many extreme-age records reflect error or fraud. Key claims from its abstract: in the United States, introducing birth certificates by state was associated with a 69 to 82% fall in recorded supercentenarians (people 110 or older); only 18% of "exhaustively validated" supercentenarians had a birth certificate; and birthdates clustered on days divisible by five. [4] It also reports that the Sardinia, Okinawa and Ikaria zones corresponded to regions with low incomes, low literacy, high crime and short life expectancy relative to national averages, and concluded that fraud and error play a primary role in remarkable age records. [4]

How to weigh this: the page we read presents a preprint, and we did not find a peer-reviewed publication of it. The author wrote that the latest version added a long response to nine peer reviewers. [4] The authors declared no competing interest. [4] The criticism is a serious challenge to extreme-age records, while the Sardinia and Okinawa validation work (published in 2004 and 2008, before the preprint) addresses age accuracy for those places. Neither settles whether lifestyle explains long life. Label for the claim that "the Blue Zone lifestyle makes people live longer": insufficient evidence.

What is not shown

• Cause. The Sardinia authors said the mechanism remained unknown, with environment or genes both possible. [1]
• Diet and habits. The 2025 review lists diet, physical activity, social support and environment as core factors. [2] None of the sources we read tested a Blue Zone eating pattern in a randomized trial, so we do not give a "Blue Zone diet" as advice.
• Individual benefit. Group patterns in regions do not tell any one person what to do.