Monday, October 29, 2018

Professor Kenji Shibuya of Tokyo University published a paper two years ago which suggested three reasons for Japanese longevity. "First, Japanese people give attention to hygiene in all aspects of their daily life," he wrote. "This attitude might partly be attributable to a complex interaction of culture, education, climate, environment and the Shinto tradition of purifying the body and mind before meeting others.

Second, they are health conscious.

In Japan regular check-ups are the norm. Mass screening is provided for everyone at school and work or in the community by local government authorities. Third, Japanese food has a balanced nutritional benefit and the diet of the population has improved in tandem with economic development."

Could there also be a genetic component? We often talk informally about old age running in families and there is scientific back-up for the notion. A common scientific theory is that about a third of human lifespan may be heritable.

Researchers are particularly interested in this in Okinawa, the chain of subtropical islands in an arc between Japan and Taiwan whose residents enjoy the highest life expectancy on the planet. When population researchers started looking at centenarians and other elderly islanders in 1975 they found an unusual number of them to be in extraordinarily healthy shape. They were lean, youthful looking, energetic and had remarkably low rates of heart disease and cancer.

"It's an everyday occurrence in Okinawa to find energetic greatgrandparents living in their own homes, tending their own gardens and at weekends being visited by grandchildren who in the West would qualify for pensions," according to John Robbins, author of Still Healthy At 100. "The word 'retirement' does not exist in the traditional Okinawan dialect."

THE Okinawa Centenarian Study was the first research group to identify human longevity genes when it published a study showing that centenarians on the islands have genetic polymorphisms that place them at lower risk for inflammatory and autoimmune diseases. It also found siblings of Okinawan centenarians were more likely to live longer.

"Does this mean that Okinawan longevity is all genetic? Not at all," says the group's website. "We believe the Okinawans have both genetic and non-genetic longevity advantages - the best combination. The Okinawan traditional way of life - the dietary habits, the physical activity, the psychological and social aspects - all play an important role in Okinawan longevity."

Back in Kyoto on the mainland the late Jiroemon Kimura put his long life down to waking early, eating small amounts (his favourite breakfast was rice porridge and miso soup), reading the newspaper and watching parliamentary debates on TV. But genetics may also have played a part: four of his siblings lived beyond 90 and his youngest brother reached 100.

Meanwhile his successor as the world's oldest person - Misao Okawa, from Japan's third city Osaka - is a spring chicken at 115.



late, record breaker, Jiroemon Kimura

This week saw the death of the world's oldest person and the oldest man in recorded history. It may not be a surprise that 116-year-old Jiroemon Kimura was Japanese. He too reportedly helped his son on the family farm until the age of 90.

For most of the past 25 years Japanese women have enjoyed the longest life expectancy in the world, peaking at an average of 86.3 years in 2010. That compares with 82.3 years for women in the UK. The figure slipped back to 85.9 years in 2011, putting the country behind Hong Kong for the first time, which experts attributed to the loss of life in the tsunami of March 2011.

Even though Japanese men have a lower life expectancy (currently 79.4 years compared with 78.2 years for British men), the country has proportionally far more longer-lived people of both genders than we do. Japan, which has twice the population of Britain, has four times more people aged 100 or more than us (about 51,000 of them according to the health ministry in Tokyo).

The secret of that longevity is a traditional diet of fish, rice and simmered vegetables, easy access to healthcare and a comparatively high standard of living in old age.

"But on balance and compared to the rest of the world an extraordinary number of Japanese live a very healthy lifestyle in large part because of what they eat," says Moriyama, pointing out that retail giant Wal-Mart invested in Japanese supermarket chain Seiyu so it could learn Japan's secrets of food distribution and freshness. Staples of the national diet include tofu, a curd made from soya beans that is free from cholesterol, low in calories and very high in protein; shiitake mushrooms, which have been used in Chinese medicine for thousands of years and have been shown to boost the immune system and lower cholesterol; and seaweed, which contains a compound that helps burn fatty tissue.

Moriyama says there is far too much salt in the Japanese diet, in foods such as salted dried fish, pickled vegetables and soy sauce. Japanese men also smoke at an alarmingly high rate (about one in three compared with one in five British men) and alcohol-related ailments are also high. But obesity is the lowest in the developing world because of a culture of small portions - there is a Japanese saying "eat until you're only 80 per cent full".

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