Xu Yuanshu, aged 110, photographed with her two great-granddaughters in Chongqing's Jiangjin district on July 4. Yang Hua / for China Daily

Luo Meizhen, 127, is believed to be the oldest person in China. Luo lives in Hechi city, Bama Yao autonomous county in Guangxi Zhuang autonomous region. This photo was taken two years ago. Liang Shaoen / Xinhua

Huang Magan, 107, is one of 87 centenarians in Bama Yao autonomous county in the Guangxi Zhuang autonomous region, most of whom are able to care for themselves. Liang Shaoen / Xinhua

Zhang Yincheng, aged 104, from Chongqing's Jiangjin district, learns how to use a cellphone. Liu Lanbo / for China Daily

Local authorities are vying to be awarded the title 'Home of Longevity', report Xu Wei in Chongqing and He Dan in Beijing.

The quest for longevity is beyond race and time. Humankind has been searching for ways of lengthening the natural span for eons, but for a large number of centenarians across China, the extension of life appears to have been gained easily and even unintentionally.

At 110 years of age, Xu Yuanshu maintains her lifelong habit of making insoles for her family. Sitting on an old couch in a mud-brick dwelling, she can still thread a needle with ease and stitch the hard paper framework of the handmade insoles with minimal effort. She also regularly feeds the family's livestock and husks freshly harvested corn.

Xu's village, in the Jiangjin district of Southwest China's Chongqing, is still a remote place, connected to the outside world by a series of uneven mud roads that can be impassable in winter. Drinking water comes from local mountain springs.

The elderly woman is typical of the estimated 48,000 centenarians across China, 90 percent of whom live in secluded, rural areas and who enjoy a relatively low standard of living, according to Zhao Baohua, deputy president of the Gerontological Society of China.

"Our statistics show that the percentage of centenarians is higher in these less well-off areas. Many centenarians live a poor life, in purely economic terms, with badly furnished houses and few everyday necessities. However, it's important to realize that they live poor, but happy lives," he said.

In 2006, the Gerontological Society began identifying the counties and districts where people have markedly longer lives than the norm, and awarded the title "Home of Longevity in China" to those that meet its criteria.

One of the key qualifications is that at least seven out of every 100,000 residents must be centenarians, and that those aged 80 or older must account for at least 1.4 percent of the local population.

Meanwhile, average life-expectancy must be three years higher than the national average, which was 71.4 years when the campaign was launched, although that figure had risen to 74.83 years for both sexes by August of this year, according to National Bureau of Statistics census data.

By August, 28 counties and districts nationwide had been identified as homes of longevity, including Xu's district in Chongqing.

Zhao was involved in the certification of almost every one of the 40-plus counties and districts that applied for the coveted title. During his work, he noticed a number of similarities between location and the centenarians.

"While the degree of economic prosperity of an area could increase life expectancy, it was not directly related to the number of centenarians in that area," he said.

Simple, but longer life

The demographic ratio of centenarians of China is still far below that in the United States, which had 71,991 - the largest number anywhere in the world - as of December 2010, according to the US Census Bureau in March 2011. The population of the US was roughly 314.30 million at the start of this month. The US Census Bureau has predicted that the number of centenarians will rise to 601,000 by 2050.

Meanwhile in China, most of those aged 100 years or older are concentrated in a number of specific regions, according to Wang Wuyi, who conducts research into environment and health at the Chinese Academy of Sciences,

Zhao noted four factors that contributed to the longevity of Chinese centenarians: A positive mental state; good family relationships; sensible dietary habits; and an affinity for hard work.

He estimated that 90 percent of the "long life" areas are secluded, mountainous regions with poor infrastructure and scant contact with the outside world. Zhao believes that the centenarians' secluded lives have contributed greatly to their inner peace, "Some are illiterate and few realize the diversity of the world outside their own limited lives. I have visited a lot of them and many live in very poor housing. Despite that, they seem to be content with their lifestyles."

A harmonious family relationship also seems to play a part in promoting long life:

"If their (centenarians) sons or grandsons frequently aroused anger in them, it would be impossible for them to live so long," Zhao said.

Members of Xu's family said she "has a very good heart and is ready to share whatever she has with family members and neighbors".

Xu has lived in the same dwelling, halfway up a mountain densely covered by forests, for almost 50 years and has always maintained a positive mental attitude, according to her son, 75-year-old Fu Maobing. "She always says that life today is much better than before," he said.

Her diet is simple too, mainly comprising sweet potatoes and vegetables, although the old lady does have a particular fondness for white sugar.

However, not all centenarians maintain a healthy diet, according to Zhao. "Some eat very fatty pork at each meal. Some drink alcohol every day and others even smoke. However, they all eat regularly and no one overeats. Moreover, they are all extremely hard working." Even at an advanced age many continue long-established routines, such as working in the fields and performing household chores.

Zhao's observation was echoed by Zhang Tiemei, a deputy director of the Beijing Institute of Geriatric Medicine at Beijing Hospital and an expert in the study of diseases that afflict the elderly.

"The reasons for longevity are very complicated, and current studies have yet to fully uncover them all," Zhang noted. "But those who are long-lived do share common features, including a positive mental state and a lower than normal intake of calories," she said.

Genetic makeup

Regional longevity is the favored research topic of Yang Ze, also a deputy director at the BIGM at Beijing Hospital. Since 1997, Yang has focused on two counties in the Guangxi Zhuang autonomous region, working on the premise that the centenarians' genetic makeup could be a key factor in their longevity.

Yang's research has centered on the Bama Yao autonomous county, which has long had a reputation for producing the world's longest-lived residents. Even Time magazine commented on it in a 2003 feature, claiming that it was one of the world's top five areas for longevity.

In April, the county - population 250,000 - had 81 centenarians and 712 residents aged between 90 and 99, according to the local publicity bureau, and the ratio of centenarians is higher than in any other county or district in China.

According to Yang's research, about half of the centenarians in Bama have a family history of longevity. "The gene pool is important. Our study shows about half of the centenarians in Bama inherited their longevity from their parents, or have siblings who are also long-lived," he noted.

While studying the genes of local residents, Yang noticed that one - Apolipoprotein E - was prominent among local centenarians. The gene could be helping local oldsters to combat ailments associated with aging, such as senile dementia and cardiovascular disease, according to Yang.

A separate study in the region's Yongfu county in Guilin city, also led Yang to a similar conclusion: "It's all to do with natural selection. In the poorer areas, people who could live with hunger and were immune to certain diseases survived and, over time, their genes were passed down generation by generation," he noted.

Natural conditions

The physical landscape can also have a positive effect on life span. Most of the areas of marked longevity identified by the Gerontological Society are located in South China, mainly along rivers or on the coast. By contrast, few areas in Northeast or Northwest China can boast a large number of centenarians.

"There must be an adequate supply of water and it must not be polluted," said Zhao, commenting on the factors that lead to extended life. "There must be a low rate of endemic disease and a low risk of other disease," he added.

Meanwhile, the air in heavily forested regions is likely to include a large number of negative ions, which are known to "capture" airborne pollutants, a factor that could lead to a lower incidence of pulmonary and cardiovascular illnesses.

Most areas where residents live measurably longer lives are at altitudes lower than 1,500 meters and are in temperate or subtropical climatic zones, said Wang Wuyi.

Meanwhile, the composition of dietary minerals in the soil could be another contributory factor. An analysis of the composition of the soil, water and food sources in Bama, allied with a study of the hair of residents, provided more clues for Yang. The soil has a slightly higher amount of manganese and zinc than usual, but also contains a relatively lower level of copper and chromium. "A higher amount of manganese and zinc is good for the blood, while a lower level of copper and chromium is good for the heart," he noted.

A similar study, conducted by Wang Wuyi in Guangxi's Yongfu county and Chongqing's Jiangjin district, found a high amount of selenium in the soil and water. While selenium salt is toxic in large volumes, trace amounts are believed to help in combating cancer.

Official supervision

The search to identify China's "Homes of Longevity" was part of an attempt to regulate the use of the title, according to Zhao. "Before we started the certification process, some local authorities had already awarded themselves the title and we felt there was a need for official supervision," he said.

In addition to the counties and districts that have been officially awarded the title, many more have applied for it.

Zhao pointed out that being awarded the title may produce a range of profitable industries - including social welfare, foodstuffs, tourism and real estate - all of which might motivate local authorities to apply to become a "Home of Longevity".

"A bag of rice might be only worth three yuan (50 US cents), but if it is produced at a home of longevity, it might suddenly be worth 30 yuan," he said. "For many of these secluded places, the title could help them alleviate poverty."

In Bama, tourism brought revenue of 406 million yuan during the first five months of this year as the county received more than 643,000 visitors. Meanwhile, the title has made it a hot vacation destination for seniors nationwide, boosting the local real estate industry in the process.

Future days?

While there have been economic benefits, it remains to be seen how the centenarians' health will be affected. In recent years, Yang has monitored rises in blood pressure, blood fats and sugars among the centenarians of Bama, meaning that the risk of cardiovascular disease is higher than before.

"Many centenarians have moved to urban areas with their sons or grandsons. Some have changed their eating habits, and many like to eat fatty pork because they have lost their teeth," said Yang, who added that, although it will take time to assess the impact of these changes, they could be seen as an early warning sign.

Yang has now decided to move his research from Bama to Yongfu county:

"The changing environment is making research difficult. There are too many variables that could potentially influence the longevity of the residents," he said. "It is a totally different world in Bama, compared with 1997, when I first arrived. At that time, many people still went around barefoot and buffalos plowed the fields. Now everything is different. The simplicity and tranquility of rural life are being lost and the real estate industry is quickly transforming the county into an urban jungle."

"Ecology is like a natural resource - once exhausted, it will never come back," he said.

Huang Feifei in Nanning contributed to the story.

Contact the reporters at xuwei@chinadaily.com.cn and hedan@chinadaily.com.cn

(China Daily 09/06/2012 page6)