Walk the shores of Ogliastra in Sardinia, an Italian island with crystal-clear waters and pink hillside flowers, and you鈥檒l see families eating fresh fish, people working the land and older couples strolling the hills.
You might also see an unusual number of centenarians. This area of Italy is one of three Sardinian provinces that make up a blue zone 鈥� a handful of regions in the world with a disproportionately high number of exceptionally older people. These areas are highly prized by researchers keen to uncover the genetic and lifestyle factors that influence longevity. But not everyone is convinced.
鈥淭he biggest secret of the blue zones is that they don鈥檛 exist,鈥� says at University College London. Newman recently threw a wrench into decades of claims that centenarians can be found congregated in five blue zones. He says the data behind these claims can鈥檛 be validated and appears riddled with mistakes 鈥� and sometimes outright fraud. Demographers who have spent their careers investigating blue zones, and others who have created profitable business ventures around these regions, are hitting back against the claims.
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The saga recently hit new lows. Relationships among the originators of the have disintegrated, and and recently reported that a leading voice in the venture 鈥� journalist , who wrote a 2005 that popularised the concept of blue zones 鈥� only included a location in the US to please his editor. However, Buettner has claimed he was misquoted on this point.
So, is there evidence that the lifestyles or genetics of people in blue zones really do extend their lifespans, or should the whole idea be ignored?
Preposterous claims about centenarians have a long history. In the , physician Alexander Leaf described populations in the Soviet Union, Ecuador and Pakistan that , despite poor sanitation and high infant mortality rates. Later checks of the data revealed that age misreporting was rife 鈥� people tended to exaggerate their ages to improve their social status or promote local tourism. In 1981, Leaf .
Then came physician at the University of Sassari in Italy, who, at a demography conference in 1999, presented evidence on unusual longevity in the province of Ogliastra in Sardinia, a relatively isolated Mediterranean island. Initially doubtful of Pes鈥檚 conclusions, at the Catholic University of Louvain and his colleagues . They sought official documents, cross-checked them with census information and birth, death and marriage records, then interviewed individual centenarians and their families. Pes and Poulain used a blue pen to mark on a map whenever they confirmed someone鈥檚 age. This led to a blue ring in which there were confirmed higher numbers of extreme ages. Sardinia was henceforth known as a .
Meanwhile, Buettner鈥檚 wildly popular story in National Geographic, detailed extreme longevity in Sardinia as well as in Okinawa, Japan, and Loma Linda, California. He teamed up with Pes, Poulain and other researchers and over time, the group identified other blue zones in the Nicoya Peninsula in Costa Rica, the Greek island of Ikaria, and the Caribbean island of Martinique. 鈥淭o be considered as a blue zone today, you need verifiable data to show that at least 1 in 50 people live to 100 in that area,鈥� says Poulain. Different researchers use different metrics, however, as some say the number may have to shift as the average age of a population changes with time.
Longevity secrets
There have been many studies that attempt to find reasons why these areas might encourage long life. In , Pes, Poulain and their colleagues noted that hotspots of longevity often appear in the island鈥檚 more isolated mountainous regions. There may be benefits to such isolation, they say, with low immigration and potential inbreeding creating a smaller gene pool that could potentially lead to the emergence of genetic traits that protect people from diseases associated with old age. Generally, a small gene pool is thought to produce lower genetic diversity that can lead to recessive genes causing reduced fitness or disease 鈥� the team didn鈥檛 study the idea that there may be benefits of such inbreeding.
Another study, published in 2019, suggests that people in the Sardinian blue zone were compared with people in other regions of the island. People with this variant showed a lower preference for high-fat foods. The variant is also associated with a more efficient immune system, and links have been found between . Other suggest that gene variants associated with better mitochondrial health might also contribute to longevity in blue zone regions. Poulain and his colleagues have studied several genetic markers but have not found clear differences in favour of blue zones. For example, research indicates that Ikarians are slightly more likely to have the ApoE2 gene that is protective against Alzheimer鈥檚 disease. However, supercentenarians 鈥� people 110 years or older 鈥� in Okinawa had a slightly increased likelihood of possessing a variant that makes them more likely to develop Alzheimer鈥檚.
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Buettner and Poulain disagree on the specific combination of factors that lead to the development of blue zone populations. Buettner has a list of , which include such populations taking part in more incidental activity in their daily lives such as walking or climbing stairs, eating a plant-based diet, drinking a moderate daily amount of alcohol 鈥� 鈥減referably Sardinian Cannonau wine,鈥� Buettner notes 鈥� and having a supportive community.
鈥淭he key insight is this: when it comes to longevity, there鈥檚 no short-term fix,鈥� says Buettner. 鈥淭he only things that work are things you鈥檙e going to do almost every day for decades. People in blue zones live a long time because they live in environments that govern their unconscious decisions 鈥� every day for a lifetime.鈥�
Most of the behaviours Buettner suggests 鈥� with the exception of drinking alcohol, which is now generally well accepted not to be beneficial even in small quantities 鈥� have evidence behind claims that they are beneficial. Incidental activity was shown in a , for instance, while veganism is often associated with markers of good health. However, while they may be healthy lifestyle choices, no one has yet convincingly proved that these are the secret behind the extreme ageing thought to occur in blue zones.
鈥淪ome researchers will tell you they know the secret of longevity,鈥� says Poulain. 鈥淲e don鈥檛. To progress, we need to work together; psychologists, environmentalists, exercise, nutrition, genetics researchers. There is no research on blue zone areas that puts all these disciplines together.鈥�
Despite this, Buettner has built a business empire on the concept, with several books, cookery courses and a documentary all based on the concept of emulating blue zone lifestyles.
All was relatively well until last year, when Newman, an interdisciplinary senior researcher, published a claiming the data on which blue zones are based is flawed. 鈥淲hat these researchers are doing is checking the consistency of documents. But when the documents are consistently wrong, errors are undetectable,鈥� says Newman. 鈥淭his happens all the time 鈥� when you have someone鈥檚 age written down incorrectly at some point in their life, the error gets carried over.鈥�
There are several ways in which these errors can occur, says Newman. Young boys have exaggerated their age to sign up to the army during wartime, for example. People forget their age when filling in forms, and some don鈥檛 report deaths to fraudulently claim state money. In 2012, for instance, worth of pension payments after discovering that 200,000 people who were claiming the money were either not entitled to it or dead.
Newman says that errors in reporting age, although rare at younger ages, increase exponentially over time. Consider a million 50-year-olds, into which 100 40-year-olds (let鈥檚 call them 鈥測oung liars鈥�) are accidentally included, an error rate of 0.01 per cent. As the cohort ages, the young liars are less than half as likely to die as the actual 50-year-olds, says Newman, because they are 10 years younger. He calculates that by age 85, more than half of this population would be young liars and by 100, the young liar errors would make up almost the entire population.
Newman analysed data from several national databases to show that regions with the highest number of centenarians were mainly in countries that had unreliable birth certificates, high levels of poverty, had previously had no centralised government or communist dictatorships, or those actively engaged in war or genocide. Puerto Rico came in second place, for example. The US territory has had such a problem with stolen or forged birth certificates that the entire certification system relaunched in 2010, invalidating any certificates issued before then.
The designated blue zones of Sardinia, Okinawa and Ikaria correspond to regions with low incomes, low literacy and a high crime rate 鈥� they also have a shorter life expectancy relative to their respective national averages, says Newman. 鈥淩elative poverty and short lifespan constitute unexpected predictors of centenarian status,鈥� he says. 鈥淗ow plausible is that? It鈥檚 astounding.鈥� In 2024, his work won him an , a satirical award presented by the humour magazine Annals of Improbable Research.
Several blue zone researchers signed a in 2024 rebutting Newman鈥檚 claims. In it, the researchers describe how they validate the ages of centenarians using civil status databases, handwritten records, genealogical reconstruction, interviews and cross-checking of data with siblings. They maintain that the exceptional longevity of the people in blue zones is well-documented, and call Newman鈥檚 paper ethically and academically irresponsible. 鈥淲e are deeply shocked that after nearly 25 years there is someone who disputes the existence of long-lived populations,鈥� Pes says.
Buettner rebuts Newman鈥檚 conclusions on several accounts. For instance, he points to the fact that, despite Newman鈥檚 claims that birth certificates in Costa Rica are unreliable, the United Nations has, since 1961, denoted the birth and death registration system there as free of error and 鈥渃omplete鈥�.
鈥淭here鈥檚 an amazing circle of logic to all this when you鈥檙e checking the consistency of documents, even when it鈥檚 UN data,鈥� says Newman. 鈥淲hen documents are consistently wrong, errors are undetectable.鈥�
Poulain acknowledges the difficulties in age validation, having , but stands by his research. He says that he has personally visited 200 centenarians and validated their individual ages in multiple ways: 鈥淚 have the full conviction that they are really centenarian based on documenting their life.鈥�
, a demographer at the Max Planck Institute for Demographic Research, says it鈥檚 crucial to validate any claims with multiple methods. In her own work, using several statistical analyses of census data, she has shown that the number of self-declared centenarians in Brazil was almost 30 times higher than it should have been in 2000. But, she says, that doesn鈥檛 undercut all other claims of longevity.
鈥淭he peer-reviewed work of Michel Poulain has been done with great care,鈥� she says. 鈥淭he methodological part of his papers is full of details that allow the reader to follow all the steps performed and identify potential problems in the papers.鈥�
Meanwhile, more doubt was cast on the blue zone concept when , reported that Buettner had initially added Loma Linda in southern California to his list of blue zones because his editor at National Geographic wanted him to find 鈥淎merica鈥檚 blue zone鈥�. Science later quoted Buettner as saying he had 鈥渘ever bothered to delist it鈥�.
Buettner says this has been misreported. 鈥淎fter much research鈥� and using data from the Adventist Health Study showing that [members of the Seventh-day Adventists Church] were living seven years longer than their California counterparts鈥� I named Loma Linda a blue zone,鈥� he says. Buettner did not provide clarification on the rate of centenarians in Loma Linda after several requests. National Geographic pointed to the publicly available letter rebutting Newman鈥檚 paper in response to our requests for comment. Loma Linda still appears on the Blue Zones Project鈥檚 website, which Buettner sold in 2020 to Adventist Health, a non-profit based on the principles of Seventh-day Adventist traditions. The website states that 鈥渁 community of 9000 Adventists live in Loma Linda and live as much as a decade longer [than average].鈥�
Poulain and Buettner have since parted ways; Poulain now runs his own .
The future of Blue Zones
Many researchers 鈥� including Buettner and Poulain 鈥� suspect most, if not all, blue zones will disappear as their inhabitants increasingly take up Western diets and lifestyles linked to poorer health outcomes. 鈥淚 am quite sure that I will not discover a new blue zone and that the existing ones will dissipate,鈥� says Poulain. Buettner and Poulain both say Okinawa is no longer a blue zone, and that it can be argued that Ikaria and Nicoya are not far behind.
Newman says the decreasing numbers of centenarians in places like Okinawa support his claims of historically invalid data: 鈥淥kinawa was found to be a blue zone 20 years ago. What happened, did all the 80-years-olds suddenly give up a lifetime of healthy eating habits and go to McDonald鈥檚? It doesn鈥檛 make sense.鈥�
Ultimately, does it matter if blue zones are real? When asked whether the World Health Organization uses them to plan health policies, , head of ageing and health at the WHO says that blue zones appear to provide insights into lifestyles and environments that promote healthy ageing. Nevertheless, WHO鈥檚 global strategies don鈥檛 explicitly promote blue zones, nor have they focused on the veracity of blue zone research.
These regions are certainly a tourist draw 鈥� Poulain, who is against promoting blue zones to tourists, says authorities in Galicia, Spain, are eager for him to designate their region a blue zone because they know it improves tourism. 鈥淭hey have good data, but they don鈥檛 have enough centenarians to qualify,鈥� he says. 鈥淏ut still, they keep pushing me.鈥�
Regardless of the challenges of validating people鈥檚 ages, the blue zone concept has given people a concrete visual way of thinking about how lifestyle factors can all come together to promote good health, says at Harvard Medical School, who has previously worked as an advisor on blue zone initiatives. 鈥淧eople say, 鈥極h I get it now,鈥� and I think in some sense, that鈥檚 a great thing in terms of improving public health.鈥�
For readers looking to replicate the lives of supposed blue zone residents, I鈥檓 afraid it comes with no guarantee of living to 100. However, most of the advice that鈥檚 come out of studying these distinctive areas is sound, practical and eminently possible to recreate in your own community: cooking more plant-based foods, eating with and supporting family and friends, and avoiding a sedentary lifestyle. If you want to have a longer, healthier life, this is what you should be focusing on, regardless of whether blue zones exist.
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