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Controversy exists in the scientific community regarding Blue Zones and the methodology behind them. In 2024, Newman published a preprint questioning potential errors in the establishment of such regions, suggesting many reported centenarians may not be authentic [[70](javascript:;)]. His analysis found that after birth certificates became standard in 1900 in the USA, the number of verified supercentenarians declined, indicating possible age misreporting. In Greece, 70% of alleged centenarians were deceased. Newman also identified irregularities in birth records and noted that Blue Zones are often in remote, low-income areas with unreliable data. This phenomenon is not unprecedented [[44](javascript:;), [71](javascript:;)]; similar inconsistencies were identified in Vilcabamba, Ecuador, a region also considered to be a Blue Zone during the 20th century. It was determined that the population’s extreme longevity was due to exaggerated reported ages. Similar cases have been documented in Abkhazia (Caucasus) and the Hunza Valley in Pakistan, where the absence of reliable birth records also led to apparent cases of extreme longevity that were later invalidated [[44](javascript:;), [71](javascript:;), [72](javascript:;)].
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Summary
This paper is a scoping review of the scientific evidence behind “Blue Zones”: geographical areas claimed to have unusually high proportions of centenarians or exceptional longevity. The authors searched MEDLINE, EMBASE, PsycINFO, Web of Science and Scopus up to February 2025, following PRISMA-ScR guidance, and included peer-reviewed studies that identified or characterized naturally occurring Blue Zones. They excluded intentionally created “Blue Zone” projects and non-peer-reviewed/opinion material. The final review included 65 records after database searching and reference checking.
The review identifies ten regions that have been called Blue Zones or potential Blue Zones in the scientific literature:
| Classification in paper | Regions |
|---|---|
| Well-characterized Blue Zones | Ogliastra/Sardinia, Okinawa, Nicoya |
| Under investigation | Ikaria, Cilento, one unnamed municipality in the Netherlands, Martinique/Guadeloupe, Rugao |
| Excluded / insufficient evidence | Menorca, Loma Linda |
The key conclusion is that only three regions — Okinawa, Ogliastra and Nicoya — currently have strong enough demographic and epidemiological evidence to be considered well-characterized Blue Zones. Ikaria, despite its public reputation, is treated more cautiously because the authors find limited rigorous demographic validation. Loma Linda is particularly challenged: the review says there are no published longevity-indicator studies specific to Loma Linda, despite its frequent inclusion in popular Blue Zone accounts.
The factors repeatedly associated with longevity include traditional diet, physical activity, climate, geographical isolation, genetic factors, social cohesion and low smoking/alcohol patterns. However, the authors repeatedly stress that these are often correlational, incompletely studied, and sometimes based on small or non-replicated studies.
A major theme is that some Blue Zones may be losing their longevity advantage, especially Okinawa and Nicoya, possibly because of westernization, dietary change and cohort replacement. This makes Blue Zones not static “magic places” but historically contingent populations whose longevity patterns may fade.
What is novel or useful about the paper
The main novelty is not a new dataset, but a critical synthesis and classification of Blue Zone claims. Popular Blue Zone discussions often treat Sardinia, Okinawa, Nicoya, Ikaria and Loma Linda as a single accepted set. This paper separates them by evidential strength.
The paper’s most useful contribution is its three-tier classification:
- Well-characterized: official longevity indicators, verified data, multiple studies, sustained observation.
- Under investigation: suggestive data but incomplete validation.
- Excluded: insufficient or negative evidence.
That framework is helpful because it makes the term “Blue Zone” more scientifically testable. The paper emphasizes that a proper Blue Zone should require age verification, birth certificates, absence of registration error, comparison with adjacent areas, and clear geographic delimitation, rather than relying on reputation or lifestyle narratives.
A second novel aspect is the paper’s challenge to Loma Linda. The authors argue that Loma Linda’s inclusion rests largely on Dan Buettner’s popular account rather than local demographic evidence. That is important because Loma Linda is often used to support lifestyle prescriptions, particularly around Adventist vegetarianism, abstinence from alcohol, spirituality and moderate exercise.
A third useful contribution is that the paper explicitly addresses the controversy around centenarian validation, including the possibility of age misreporting, weak administrative records, and historical examples of exaggerated longevity claims. This is a necessary corrective to the often uncritical Blue Zones literature.
Critique
The paper is a valuable corrective to popular Blue Zone claims, but it has several limitations.
First, because it is a scoping review, it maps evidence rather than quantitatively evaluating effect sizes. It does not perform a meta-analysis, and the authors state that longevity metrics could not be pooled because different regions use different indicators and methods. This limits how directly one can compare Sardinia, Okinawa, Nicoya, Ikaria or other regions.
Second, the review depends heavily on whether studies used the term “Blue Zone” or framed a region as such. That risks missing extreme-longevity regions that have not adopted Blue Zone terminology. The authors acknowledge that many additional studies had to be found by manual reference searching, suggesting that database retrieval was imperfect.
Third, the classification is reasonable but still partly judgment-based. For example, Ikaria is downgraded to “under investigation” despite being widely accepted in public and some scientific literature. The authors’ reasoning is defensible — limited demographic validation — but the boundary between “well-characterized” and “under investigation” remains somewhat subjective.
Fourth, the review summarizes lifestyle factors such as diet, physical activity and social cohesion, but causal inference remains weak. Blue Zones are observational settings with many confounders: survivor bias, selective migration, historical poverty, low-calorie diets, physically demanding work, genetic drift, healthcare access, and reporting quality. The paper could have more sharply separated causes of longevity from features observed among long-lived survivors.
Fifth, the review could go further on socioeconomic paradoxes. Many Blue Zones are relatively low-income or historically isolated, which conflicts with the usual social gradient in health. The authors mention this, but it deserves deeper analysis: poverty may reduce processed-food intake and enforce physical activity, but it also worsens healthcare access and early-life conditions. That makes simple lifestyle prescriptions from Blue Zones risky.
Sixth, the title and abstract keywords appear odd: the listed keywords include “Epigenesis,” “DNA Methylation Aging,” “Biological Clocks,” and “Biomarkers,” but the review is primarily demographic and epidemiological, not an epigenetic-clock paper. That looks like a mismatch between content and indexing.
Bottom line
This is a useful, sceptical review. Its strongest message is that “Blue Zone” should not be treated as a branding category but as a demographic claim requiring verification. On that standard, the paper supports Ogliastra/Sardinia, Okinawa and Nicoya most strongly; treats Ikaria and several newer candidates as plausible but not fully validated; and argues that Loma Linda lacks sufficient direct scientific evidence as a Blue Zone.