Highlights

  • Researchers argue that exceptional-longevity regions, including purported Blue Zones, should be evaluated with transparent demographic data and independently verified age records rather than anecdotal reports alone.
  • More rigorous validation would strengthen efforts to identify which social, environmental, behavioral, and biological factors, if any, truly contribute to longer, healthier lives.

As published in Aging and Disease, researchers from the University of Santiago de Compostela in Spain argue that there is no standardized framework for defining geographical regions with a notably high prevalence of people over 100, often called Blue Zones. This gap limits the identification of new longevity hotspots and makes it difficult to confirm whether those already identified persist over time.

“We contend that extreme longevity areas exist in at least some regions of the world and that their rigorous characterization should be both scientifically warranted and methodologically feasible,” say the authors in their publication.

More Information on Blue Zones

With a high concentration of people who live over the age of 100, Blue Zones are often associated with favorable health outcomes in older ages. The idea of the Blue Zone is used to explore whether shared features of place, lifestyle, and social life might contribute to longer, healthier lives. Some researchers warn, though, that the Blue Zone concept should be treated as a research hypothesis, rather than proof that any single Blue Zone lifestyle causes exceptional longevity.

Along these lines, the concept originated in demographic work in Sardinia, Italy, where researchers identified and marked villages with exceptional longevity in blue on a map. It was popularized in later studies and associated with five widely cited locations:

  • Sardinia, Italy
  • Okinawa, Japan
  • Ikaria, Greece
  • Nicoya Peninsula, Costa Rica
  • Loma Linda, California, United States

Accordingly, these places have been described as having more people over the age of 100 (centenarians) than expected compared to other populations. Sometimes, researchers have observed that aged individuals in these regions have lower burdens of chronic age-related diseases later in life. However, the central question is not merely why individual people in these regions appear to live longer, but why clusters of exceptional survival might occur in particular populations or communities.

Spanish Researchers Contend That We Need a Standardized Framework to Verify the Occurrence and Persistence of Blue Zones

To address a lack of standardization in the identification and confirmation of the persistence of Blue Zones, Spanish researchers call for a transparent and repeatable way to identify these geographical areas. Their approach centers on five linked elements:

  1. Use a clear operational definition—A region should not be labeled a Blue Zone simply because it has many older residents or a high life expectancy. Rather, the designation should be based on a defined, comparable population-level measure of exceptional survival.
  2. Base estimates on groups of people that share the same birth year—To reach a defined, comparable population-level measure of exceptional survival, researchers should use the Extreme Longevity Index calculation. This calculation should be done as follows: (the number of people born in a certain year from a specific region that survive to a predefined exceptional age / the number of births in the same year). This calculation helps avoid misleading comparisons based on the current number of centenarians in a given region, which can be distorted by differences in migration patterns. For example, people with exceptional longevity may be more inclined to move to certain areas.
  3. Set statistical thresholds for exceptional longevity—The framework should distinguish an apparently high longevity rate from a truly unusual one using transparent statistical criteria and suitable reference populations for comparison. In practice, this means comparing an area’s survival pattern with expected values at broader geographical levels, rather than relying on raw counts or informal assessments.
  4. Require accurate, auditable data—Claims should be supported by reliable birth and death records, validated ages, and publicly transparent assessment methods of births, deaths, and ages. Strong age verification is especially important because even small errors in age reporting can substantially inflate apparent centenarian prevalence.
  5. Test persistence through time—An area should be reassessed across successive groups born in years spanning timeframes of a few decades. A genuine Blue Zone should show a consistent excess of exceptional survival over time, such as over the course of decades, rather than only appearing in a group born in a certain year due to chance variations, migrations, or historical circumstances.

Why This Matters

The proposed framework separates two key questions related to Blue Zones:

  1. Occurrence—Is exceptional longevity demonstrably higher than expected in this place?
  2. Persistence—Does the excess of exceptionally long-lived individuals remain evident when the same metric is applied to groups born in later years?

Only after a geographical location meets both of these criteria, the authors argue, should it be treated as a robust setting for investigating the environmental, social, behavioral, genetic, and healthcare-related characteristics that may contribute to exceptional longevity. This would make comparisons among established and newly proposed Blue Zones more credible and reproducible.