What are the Blue Zones and how much truth is there to them?

Five regions in the world were given the name 'Blue Zone': Ogliastra in Sardinia, Okinawa in Japan, Nicoya in Costa Rica, the Greek island of Ikaria, and the Seventh-day Adventist community in Loma Linda, California. The best documentation of an above-average share of centenarians exists for Ogliastra, Okinawa, and Nicoya. For other regions sometimes mentioned, such as Menorca and Rugao, the evidence is insufficient or absent.

The data underpinning the Blue Zone claims are not without controversy. Critical scientists point out that in regions with unreliable or incomplete civil registries, the advanced ages reported for residents may rest on administrative errors or fraudulent documentation. Broader methodological objections exist as well: the studies show selection bias in the choice of populations, there is insufficient control for confounding variables, and there are indications of commercial influence by food and pharmaceutical companies. The Blue Zone hypothesis is therefore not well supported scientifically as a causal model.

That the dietary pattern in these regions is plant-based and rich in polyphenols is reasonably well documented, but the fact that a population lives to an old age and also follows a particular diet does not prove that the diet is the cause of that longevity. Moreover, the diets across the different Blue Zones are not homogeneous and change over time. Polyphenols, plant-derived compounds that are abundantly present in this type of diet, do show indications in laboratory and human research that they can slow biological ageing mechanisms, but direct causality at the population level has not yet been demonstrated.

The strongest and most directly applicable evidence from Blue Zone research concerns physical activity. Regular walking and other low-intensity movement, of the kind that is naturally embedded in the daily lives of Blue Zone residents, reduces the risk of cardiovascular disease, type 2 diabetes, cognitive decline, and dementia, and improves sleep and mental well-being. Dose-response relationships have been established for cardiovascular outcomes. Thirty minutes of brisk walking per day, five days a week, is already sufficient to demonstrably lower risks.

Beyond diet and exercise, analyses of Blue Zones and comparable long-lived regions such as Cilento in Italy point to a broader combination: exposure to biodiverse, relatively low-pollution environments, strong social networks, and psychological resilience. Chronic exposure to environmental pollution and endocrine-disrupting substances demonstrably accelerates cellular ageing, and the absence of such exposure in Blue Zones is seen as a protective factor, although this is difficult to disentangle from all other environmental influences. The gut microbiome appears in this research as a possible intermediary between environmental influences and immune-metabolic health, but that is an early field of investigation with as yet limited direct evidence in humans.