Blue Zones: what research establishes and what it does not prove

Where does the term come from?

Demographers Michel Poulain, Anne Herm and Gianni Pes define a Blue Zone as a limited region where the population shares a common lifestyle and environment, and whose exceptional longevity has been accurately verified. Their 2013 paper compares four areas: Ogliastra in Sardinia, Okinawa in Japan, the Nicoya peninsula in Costa Rica and the island of Ikaria in Greece. It confirms the exceptional male longevity of the Sardinian zone and notes that these populations are geographically or historically isolated, on islands and in mountains, and have kept a traditional lifestyle with intense physical activity.

Why the verification step matters

The definition rests on four conditions, and the last one is the demanding one. Saying that a region has many very old residents is easy; showing it requires documents that confirm each person's age. That is why the demographers' definition insists on longevity that has been accurately verified, and why a later review had to separate the regions with solid data from those with thin or inconclusive data.¹²

Seen this way, a Blue Zone is a research finding that depends on the quality of age records, not a label that a region earns by reputation. The 2025 review illustrates the point: it found regions with more centenarians than their neighbours, but it also found regions where the data were inconclusive, a region with fewer centenarians, and one with no studies at all.²

What did the 2025 review find?

A scoping review published in 2025 by Candal-Pedreira and colleagues included 65 publications on ten regions. It concludes that some areas have more centenarians than neighbouring areas, that three of them are well established as Blue Zones, and that others still need investigation or lack sufficient evidence.

Three publications, three different jobs

A scoping review maps what has been published on a topic; it describes the evidence base rather than weighing every study against a standard. That is useful here, because it tells the reader which regions have been studied and which have not, but it does not by itself show why any region has more very old residents. The 2022 review is the one that asks about causes, and it concludes that the causal role of diet should be proven.

Does diet explain the longevity?

That is not established. The review by Pes, Dore, Tsofliou and Poulain (Maturitas, 2022) covers Okinawa, Ikaria, mountain Sardinia and Nicoya. According to its abstract, it is too often taken for granted that being documented in a long-lived population is enough to make diet a cause: that causal role should be proven. The authors add that this diet is assumed to be homogeneous and stable over time, while some evidence suggests the opposite. They ask whether it is a model of eating for everyone, or a set of evolving food patterns specific to a few communities.

Why diet gets so much attention

According to the 2022 review, eating habits hold a prominent place among the features described for these populations because, unlike many others, they are easily quantifiable and can be applied on a larger scale.³ That convenience is also a risk: a feature that is easy to measure and to copy can be mistaken for the explanation. The authors also note that the longevity of these regions is a relatively recent phenomenon, investigated mostly since the start of this century, and that the diets themselves may have changed over time.

The review frames the open question in two alternatives: either these diets are an example of healthy eating valid for anyone, or they are a set of evolving food patterns that have offered benefits to a few specific communities in recent decades. The abstract does not choose between them, and neither does this page.

What can be taken from it

• A few regions really do have more centenarians than their neighbours, once ages are verified.
• Many factors are associated: diet, physical activity, climate, genetics, geographical isolation.
• No food, no single habit and no product has been shown to be responsible for the longevity of these regions.
• Products and diets sold under the Blue Zones name do not rest on this research.

A short checklist for claims about Blue Zones

• Does the claim name the region and the study it relies on?
• Does it separate what is associated with longevity from what causes it?
• Does it mention that some regions have well-characterised data and others do not?
• Does it avoid presenting a single food, habit or product as the explanation?
• Does it say that the pattern may not carry over to other places?

If the answer to several of these questions is no, treat the claim with caution. Remember also that a review is a snapshot: the 2025 scoping review searched the literature up to February 2025, and new studies can change which regions count as well characterised. For related reading, see social connection and ageing, healthy life expectancy and walking and longevity. The group is collected in healthy ageing research, and every topic is listed in the Chutex guides.

What cannot be claimed

• That copying a Blue Zone lifestyle would produce the same results elsewhere.
• That all five commonly cited Blue Zones are validated: the 2025 review found no studies on Loma Linda.
• That diet is the cause: it is a hypothesis still to be proven.
• The reviews' abstracts were read for this page, not their full text.

Frequently asked questions