Sardinia in Italy, one of the "Blue Zones" identified by Michel Poulain and Buettner

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?

The term came into existence in 2004

Though the article........

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