Most mornings, as I set out for work from my apartment in western Tokyo, I spot my 85-year-old neighbour, Tsuneko Sasano, fussing over the vegetables she grows on a small plot next to her house. Although tiny and slightly stooped, she radiates the twinkle-eyed vigour of the senzen-ha, the pre-war generation.
Tsuneko-san washes, cooks, cleans and shops by herself, has never been in hospital and, apart from drinking a glass of tap water first thing each morning, can think of nothing to explain her longevity and health. Nor can Moju Sema, the owner of the local convenience store. At 84, he has the clear skin and head of black hair of someone 20 years younger. "You should have eaten more seaweed," he laughs, looking at my bald head.
Every neighbourhood in Japan, which has a larger share of people aged over 65 than any other country, boasts legions of these hardy pensioners. Japanese men can expect to live for more than 77 years, compared with about 73 for their Irish counterparts, and Japanese women have a life expectancy about five and a half years longer than the Irish average of 78.6. And Okinawans, who live on a string of islands in the extreme south of the country, top Japan's statistics. The average life span there is a whopping 86 years for women.
Researchers have trodden a well-worn path to the islands to try to find the secrets behind the statistics. Geriatrician Makoto Suzuki, Dr Bradley Willcox and his anthropologist brother, D. Craig Willcox, claim to have spent 25 years on the latest study, now a best-selling book called The Okinawa Program. They were curious not only about why Okinawans live longer than everyone else, but also why they are least likely to suffer from heart disease, stroke, cancer and dementia. The islanders, for example, have 80 per cent less breast cancer and prostate cancer than North Americans.
Perhaps the only surprising thing about the programme is that there are few surprises. Apart from a fondness for turmeric and a bitter melon called goya, Okinawans eat little that cannot be found in most Irish supermarkets - a basic diet that most older Japanese still stick to of fish, rice, vegetables tofu and soy. Most of the findings - that we should combine a low-fat, healthy diet with regular exercise, moderate drinking and a positive, easy-going approach to life, for example - have been accepted for years.
While acknowledging some genetic input, the book weighs heavily in favour of environmental factors and "lifestyle intervention" in explaining why Okinawans have gained more than 20 years in life expectancy over the past four decades. Islanders who move to other countries and abandon the local lifestyle and eating habits suffer from higher disease and mortality rates than those who stay.
There are a couple of surprises. Unlike the Irish, the average Okinawan listens to mum when she warns against being greedy. The authors claim that a practice called hara hachi bu (eating only until 80 per cent full) and a general cultural bias toward moderation are of profound importance.
"Limiting caloric intake is thought to limit production of DNA-damaging oxygen free radicals, which are generated mainly by metabolising (oxidising) food for energy. The more food we eat, the more free radicals we make".
The "psychospiritual outlook" of older Okinawans is also a key to their longevity. The islanders, particularly the women, have an adaptable, optimistic and stress-free approach to life, with a strong network of community support and a "deep spirituality". Many visit temples daily, in effect setting aside a portion of their day for meditation and contemplation. The authors also acknowledge the importance of a healthcare system that balances elements of both Western and Eastern medicine.
And the researchers found few women on the islands using oestrogen-replacement treatments. Most, apparently, sailed through menopause, a phenomenon they attribute to gentle exercise, avoiding smoking and a high intake of natural oestrogens, mainly from soy.
So, with relatively minor exceptions, there is little in the study you did not hear a thousand times when you were a child. The miracle elixir of life seems to be: never eat until you are full and, when you do eat, focus on a high-fibre diet, rich in fruit, vegetables and good fats; lay off the fags and booze; spend a couple of quiet minutes by yourself every day; and get some exercise. Make a start today. Walk to the pub.