The world’s “blue zones”, which are home to an unusually high number of centenarians, keep changing every few years, according to a new study that may unravel the secret to long life.
These blue zones – Italy’s Sardinia, Japan’s Okinawa, Costa Rica’s Nicoya, Greece’s Ikaria – count among their inhabitants a disproportionately large number of people living into very old age, especially past 90.
Many researchers are sceptical about whether the popularity of these regions as longevity hubs may be due to data collection errors, fraud or poor recordkeeping.
So better age verification in these areas is very important, especially as scientists attempt to learn about factors that help people live longer.
The new study, published in The Gerontologist, confirms the authenticity of blue zones, saying their status as longevity hot spots is based on the “painstaking cross-checking of records” that often go back more than a century.
The study confirms – based on multiple independent documentary sources like civil birth and death records, church archives, genealogical reconstruction, electoral and military registries, and in-person interviews – that these places are indeed home to disproportionately large numbers of nonagenarians and centenarians.
“Extraordinary claims about longevity demand extraordinary evidence,” study author Steven Austad, director of the American Federation for Aging Research, noted. “What we show in this paper is that the original blue zones meet – and often exceed – the strict validation criteria used worldwide to confirm exceptional human longevity.”
Researchers observed that blue zones weren’t permanent, with old ones disappearing over time and new ones emerging elsewhere.
In Okinawa and parts of Nicoya, for instance, immigration, modernisation and lifestyle changes appear to be weakening the once exceptional longevity patterns.
New blue zone candidates are emerging elsewhere in the world, underscoring the need for continuous validation to find health interventions for lifespan extension.
“The fact that blue zones can appear and disappear actually strengthens their scientific value,” Dr Austad said.
“It allows researchers to study how social, cultural, and lifestyle factors influence healthy aging over time.”
In effect, researchers say, these places are among the most valuable “natural laboratories” for understanding healthy aging.
“A common theme of these four classic blue zones is isolation,” the research points out, noting that Sardinia, Ikaria, Okinawa occupy all or a part of an island, while Nicoya lies on a peninsula that until recently was difficult to access.
“Isolation makes possible cultural, and possibly genetic, uniqueness,” researchers say. “Other than isolation there’s little geographic, climatic, or ecological similarity among the blue zones.”
They hope to study emerging blue zones in China’s Rugao and the Caribbean island of Martinique to get a better understanding.
“At a time when populations around the world are aging rapidly, it is essential that public discussion and promising interventions be grounded in sound science,” said National Geographic fellow Dan Buettner, who popularised the concept of blue zones but was not involved with the study.
“Blue zones continue to offer real, validated insights into how we can all live healthier, longer.”