We write a lot about longevity here at HuffPost UK; once you’ve written more than three articles on the topic, certain phrases and ideas bob up over and over like (fibre rich!) apples in the alleged fountain of youth.

Expert after expert says that good sleep, exercise, eating well, and socialising are all key to a longer, healthier life. Science has their backs on those.

But another cornerstone of longevity research – so-called “blue zones,” which include areas like Okinawa in Japan and Sardinia in Italy, and were identified by author Dan Buettner as being areas in which people are more likely to live to 100 – have been the subject of scientific debate.

In fact, speaking to New Scientist recently, Saul Newman at University College London said: “The biggest secret of the blue zones is that they don’t exist.”

So what’s going on with the supposed longevity hotspots, a 2005 National Geographic article about which has spurred decades of health advice?

Though the article that made “blue zones” big came out in 2005, the term was first used in 2004 in an article about the longevity of Sardinians by researcher Dr Michel Poulain (a co-founder of the blue zones company).

“The specific mechanism by which persons living in this territory were more likely to reach extreme longevity remains unknown but it is interesting to note that most of the ‘longevity hot spots’ identified in various regions of the world over the years have been located in mountainous geographical areas even if none of these longevity regions have been fully validated,” it reads.

Blue zones went “2005 viral” in National Geographic a year later, as Buettner linked similar findings to Okinawa and Loma Linda in California.

A 2019 study by the aforementioned Dr Newman, updated last year, suggested that “blue zones” were simply areas in which pension fraud may be more rife or record-keeping was poor, leading to incorrect age data.

That theory has been questioned by some experts and is itself incomplete; it didn’t debunk the recommendations Beuttner has made based on the “zones” either.

However it does highlight an issue with “blue zones” which more scientists are on board with; Buettner’s response, that the benefits of the “zones” themselves are “geographically defined,” doesn’t sit well with all experts.

Speaking to Science, Ross Brownson, an expert on evidence-based public health, said that Buettner’s ‘Power 9’ advice (including eating less red meat, reducing stress, and belonging to a community) are mostly “Good, safe messages that I don’t think many public health experts would argue with.”

But a paper published in 2024 suggests that those living in Okinawa, Japan, are no longer living longer than the rest of us; the same goes for Nicoya in Costa Rica.

Genes said to be linked to longevity that often appear in “blue zones” have had their real-life effects on lifespan questioned, too.

As Dr Nir Barzilai, director of the Institute for Aging Research at the Albert Einstein College of Medicine, told The New York Times: “Are the concepts of blue zones consistent with what we know about ageing? Absolutely.”

He added, however, that blue zones provide “An observation which is consistent with what we think we know about ageing. But it’s not a science.”

All of which is to say that while common sense health advice is always welcome, don’t stress if your healthy cooking or socialising takes place in rainy England rather than sun-soaked Sardinia, or if you’re more likely to take a drizzly stroll to the shops than you are to take a scenic walk on the beach.

Good health advice may be a little more universal than that.