Are the Blue Zones real? What the demographic data actually shows

The map, and what it is worth

You have seen the map. Five circles drawn on five parts of the world, each one supposedly home to people who live extraordinarily long lives. Okinawa in Japan. Sardinia in Italy. Nicoya in Costa Rica. Ikaria in Greece. Loma Linda in California.

The story attached to that map is worth a great deal of money. It has sold books, branded food, retreats, certification programmes and municipal consulting contracts. The promise is simple and irresistible: these people found something, and if you eat what they eat, you get what they have.

Here is the part that rarely travels with the map.

In 2024, the Ig Nobel prize for demography went to a researcher for showing that the data underneath it does not hold up. Saul Newman, a demographer at UCL, had spent years looking at where extreme old age is actually reported, and the pattern he found was not the one the story requires.

Take Okinawa, the most cited of the five, and the origin of the sweet potato and vegetable story that most longevity cookbooks are built on.

According to the Japanese government's own national nutrition data, Okinawans eat the fewest vegetables in Japan and have the highest body mass index in Japan.

Read that twice. The prefecture sold to the world as the vegetable-eating longevity capital is, by its own country's measurements, the least vegetable-eating prefecture in that country.

Where extreme old age is actually reported

If diet and lifestyle produced extreme longevity, you would expect the places with the most hundred-year-olds to be the places with the best health, the best food, the best medicine and the best records.

Newman's analysis found close to the opposite. The strongest predictors of a region reporting very high rates of extreme old age were:

• High poverty.
• The absence of birth certificates.
• Fewer ninety-year-olds, which is the number you would expect to rise, not fall, in a genuinely long-lived population.

That last one is the tell, and it is worth sitting with. A population that genuinely produces many hundred-year-olds must first produce a great many ninety-year-olds. When the hundreds go up while the nineties go down, something is wrong with the counting rather than remarkable about the living.

He also found people recorded as living centenarians who were, on inspection, alive in government records and dead in reality. One man who held a world record for age had three different birthdays in three different documents.

None of this means nobody reaches a hundred. People do. It means the clusters, the circles on the map, the thing an entire industry is built on, are substantially an artefact of bad paperwork and the quiet pressure to keep a pension arriving.

When the same work moved on to United Nations late-life data, the places that came out as having the most extreme longevity were Monaco, Malawi, Kenya, Western Sahara and Puerto Rico. That is not a list of dietary paradises. It is a list of places with very different record-keeping systems.

Why the story survives anyway

A reasonable question: if the data is this shaky, why does the story keep selling?

Because it is a very good story, and because of what it lets you buy.

It has a hero and a secret. A remote village, an old person still tending a garden, a food you had not heard of. That narrative shape sells. A meta-analysis does not.

It converts into products. You cannot sell a person "there is no shortcut". You can sell them olive oil, a cookbook, a subscription, a tour.

Nobody checks the register. Verifying an age claim means finding a birth record from the 1910s in a place that may never have kept one. That is slow, unglamorous work with no product at the end of it. Almost nobody does it. Newman did, and got an Ig Nobel for the trouble.

And it flatters us. The story implies that death is a solvable problem and that the solution is a shopping list. That is a comforting thing to believe, and comfort has always been the easiest thing in the world to sell.

So what is actually left?

Quite a lot, and this is the part worth staying for. The evidence for a handful of ordinary things is genuinely strong, considerably stronger than most people realise, and it has been sitting there in plain sight while the interesting story took all the attention.

Start with the largest number, because it is not on your plate at all.

Researchers followed 70,913 men and women, measuring two things: cardiorespiratory fitness, meaning how well the heart and lungs deliver oxygen under load, and grip strength, a simple and startlingly informative proxy for whole-body muscle strength. Comparing the highest group to the lowest:

• 47 percent lower hazard of death from any cause for those highest in both fitness and grip strength.
• 69 percent lower hazard of cardiovascular death for the same group.
• Taken separately, high fitness alone carried a hazard ratio of 0.65, and high grip strength alone 0.79.
• For cancer mortality the association did not reach significance, and the honest thing is to say so rather than round it into the headline.

The authors' conclusion is the part to keep: improving both, rather than either one alone, appears to be the most effective strategy. Not cardio instead of strength. Not strength instead of cardio. Both.

Now put that beside the diet numbers. The best-evidenced dietary changes sit in the range of 10 to 30 percent differences in risk. Being in the top group for both fitness and strength sits at 47 percent, and at 69 percent for cardiovascular death.

These are different studies measuring different things, and none of it is a randomised trial. This is observational work, and reverse causation is a genuine worry: early illness makes people weaker and less fit before it kills them. That limitation applies to the figure above exactly as it applies to every dietary claim you have ever read, including the ones in this article.

But the direction is not subtle, and it is the opposite of what is being sold. The supplement aisle is downstream of a claim about food. The claim about food is downstream of a map that does not survive its own paperwork. And the thing with the largest number attached to it cannot be bought at all.

How to read the next claim

You will meet another version of this story next week. A few questions make short work of most of them:

• Who counted, and could they have been wrong? Extreme claims about age, in particular, rest entirely on documents that may not exist.
• Is there a product at the end of the sentence? Not disqualifying, but it tells you which way the pressure runs.
• Does the population make sense? More hundred-year-olds should mean more ninety-year-olds. When the shape of the pyramid is wrong, the counting is wrong.
• Observational or randomised? Almost all nutrition evidence is observational. That does not make it worthless. It makes confident causal language a warning sign.
• What is the size of the effect? "Associated with lower risk" is not a number. If nobody will give you a number, there may not be much of one.

None of this is cynicism. The unglamorous answers are real: enough protein, enough fibre, less ultra-processed food, and a body that is loaded regularly enough to keep the muscle it has. The reason you have heard less about them is not that they are weakly evidenced. It is that nobody can sell you a tour of them.

The goal is not a longer life. The number of years is largely not in your hands. The condition you are in during those years is much more in your hands than you have been led to believe, and it is a better thing to aim at anyway.

This article is the opening of Still Able.