For years, it was something in the olive oil. Scientists, puzzled by the lengthy lifespans of Mediterranean communities, pointed to the condiment as a key ingredient in the elixir of life.
Then there was Japan, whose lengthy spell at the top of global longevity rankings was put down to its citizens' low-fat diet and love of raw fish.
Now, with South Koreans storming to the top of the table, the question is: is there something in the kimchi?
The east Asian nation this week stole global headlines and the crown for longest lifespans after a study from Imperial College London found that, by 2030, its citizens are set to live longer than anyone else. Girls born in South Korea 13 years from now can expect to live on average to the ripe age of 91. South Korean males — typically more partial to a drink and a smoke — will have to settle for 84, ahead of men anywhere else in the world.
These developments underscore the country's remarkable transformation over the past 70 years from an impoverished war-torn nation to a leader in technology, business — and now lifespan. As recently as the mid-1980s, life expectancy for South Korean women was less than 75, while men could not expect to make 65.
So what is the secret? On this, there is some consensus: investments in medical care, a health-conscious culture and a hearty diet underpinned by the ubiquitous presence of fermented vegetables, most notably kimchi.
Foodies around the world now integrate the pickled vegetables — typically cabbage — into their fare. But kimchi has long been a staple of Korean dining, immediately recognisable by its pungent odour and red appearance — the colour a result of an ample smothering of gochujang, a pepper-based condiment. It is made by fermenting vegetables with probiotic lactic acid bacteria and a host of other ingredients, including garlic and ginger.
The result is a dish rich in vitamins A and B and with abundant lactobacilli, the beneficial bacteria found in yoghurt, and in a healthy gut. For researchers, the benefits are manifold — from fighting cancer and lowering cholesterol to improving mental health and skin care.
But fermented vegetables have been an integral part of the country's cuisine for centuries. In fact, one could argue their role in bolstering national longevity has been countered in recent decades by the onward march of the fried-chicken outlet.
Following the country's financial crisis in the late 1990s, these cheap, cheerful, unhealthy eateries sprang up in their thousands to cater to the salaryman on a shoestring. Today, there are an estimated 60,000.
But the nation has a cultural obsession with feeling its own pulse. Many South Koreans will readily confess to suffering from "health anxiety", visiting a doctor for the slightest of symptoms. One study last year found that only 35 per cent of Koreans believe they are in good health, the lowest in the OECD, the Paris-based club of mostly rich nations.
And the phenomenon is underscored by TV shows offering medical advice, the number of which regulators deemed "incalculable". The health benefits of all this hypochondria are clear. The Imperial study lauds South Korea's efforts to check hypertension, obesity and chronic diseases.
These advances, however, were only made possible by the government's longstanding commitment to universal healthcare. Under the system, the vast majority of citizens pay a national health insurance premium deducted from their paycheck.
Patients over 40 have a free medical check-up every two years, and the cost of visiting a doctor is drastically reduced — an incentive that has increased early detection of disease."It's basically the opposite of what we're doing in the west," said the lead researcher in the life expectancy study. Food for thought.