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Declining longevity advantage and low birthweight in Okinawa
Abstract
The prefecture of Okinawa is known for the longevity of its population, for 30 years it had the longest life expectancy of all prefectures in Japan. However this advantage was lost in 2000 and male longevity is now ranked 26th among the 47 prefectures of Japan. The aim of this study was to explore whether the recent decline in Okinawan life expectancy advantage is due to the cohort effect of low birthweight infants becoming middle- and older- aged Okinawans. This is an observational study using existing demographic and health statistics. Data on life expectancy, mortality and low birthweight rates were obtained from the Okinawan Prefectural Department of Health and Welfare and the Japanese Ministry of Health, Labour and Welfare. In the year 2000 the longevity advantage of Okinawan males over the Japanese mainland was lost and the relative life expectancy of females declines. The mortality ratio for heart disease has reversed showing a cohort effect, with younger Okinawans having higher death rates than those living in the rest of Japan. The low birthweight rate for Okinawa is 20% greater than mainland Japan. As the post World War cohort of low birthweight infants reaches middle age, the longevity advantage of Okinawans has been lost. The loss of the longevity advantage of Okinawa over the rest of Japan may be due to the increase in non-communicable disease in the post war cohort that has experienced a higher low birthweight rate.
... For almost 30 years (prior to 2000), Okinawa had the longest life expectancy of all prefectures in Japan. Since then, life expectancy of Okinawans declined due to factors that include the increasing Westernization of the lifestyle [3][4][5]. Prevalence data of centenarians in the Okinawa archipelago with its 1.3 million inhabitants are variable, but estimates from the Okinawa International University in Ginowan, Okinawa, suggest approximately 50 centenarians per 100,000 persons [6], amounting to about 650 centenarians in Okinawa. This is about 4-5 times the average for most Western countries [6]. ...
... This is about 4-5 times the average for most Western countries [6]. The longevity of Okinawans has been linked to various conditions, including the local cuisine-the "Okinawa diet" [5]. ...
... In the past years, several reports have focused on Okinawan longevity and its causes [3][4][5][7][8][9]. In addition, researchers (above all from the University of the Ryukyus, Okinawa) have been interested in characterization of a particular plant, namely shell ginger (Alpinia zerumbet (Pers.) ...
The longevity of the population in the Okinawa Islands of Japan has been ascribed to genetic factors and the traditional Okinawa cuisine, which is low in calories and high in plant content. This diet includes shell ginger (Alpinia zerumbet (Pers.) B.L. Burtt & R.M. Sm) of the ginger family (Zingiberaceae). Due to its local popularity, Alpinia zerumbet has become the subject of a good deal of study at the University of the Ryukyus in Okinawa. Personal local experience and review of the literature now suggest that culinary shell ginger may contribute to longevity among the population in Okinawa. This is supported by its abundant phytochemical content, with antioxidant and anti-obesity properties. The major bioactive phytochemicals are dihydro-5,6-dehydrokawain (DDK; 80–410 mg g−1 fresh weight), 5,6-dehydrokawain (DK; ≤100 mg g−1), and essential oils, phenols, phenolic acids, and fatty acids (≤150 mg g−1 each). Further, Alpinia zerumbet extends the lifespan in animals by 22.6%. In conclusion, culinary shell ginger may significantly contribute to human longevity in Okinawa.
... Since some of the factors supposedly involved in BZ emergence tend to disappear, it might arise that the phenomenon of population longevity be transitory in itself. In fact, there is some evidence that attenuation of the phenomenon is underway in Okinawa (Hokama and Binns, 2008), and the same tendency may occur in other BZ in the future. An interesting aspect is that what BZ have achieved on a small scale could be extended to larger human aggregates. ...
A number of geographical areas have been identified in the world where the proportion of age–validated oldest old, is significantly greater compared with the surrounding regions. They have been termed Blue Zone (BZ) owing to the color used to outline them in the maps of the regions to whom they belong. They are isolated o nearly–isolated population pockets sharing homogeneous genetic background, traditional lifestyle and dietary habits. Up to now, four regions fulfill the criteria to claim a Blue Zone status. They are located in Okinawa, Sardinia, Costa Rica, and Greece. Over the years, the Blue Zones concept has been increasingly accepted by the scientific community and they are no longer considered an anthropological curiosity but an effective model of healthy aging that might be transferred, at least in part, to the post–industrial societies of the 20th century, to face the challenge of aging societies and the rise of healthcare costs.
... According to the United Nations, Japan has the greatest proportion of centenarians in the world, with the island of Okinawa already having had over 4000 centenarians by the early 2000s [11]. By 2015, Japanese women were leading the world for the longest life expectancy at 86.8 years (up to 90 years in some areas) with Japanese men living to the age of 80.5 years (up to 84 years in some areas) [12]. ...
... One of the easiest to implement strategies for obesity prevention is to continue to promote exclusive breastfeeding for every infant, which of course has many other health benefits. 8,9 In this issue of the journal, we revisit island health with a special section on "Islands, Disasters, and Public Health" sponsored by the University of the Ryukyus, a strong supporter of APACPH, a sponsor of research, and a service provider in island health services and public health. As a small island, with less than 1% of the population of mainland Japan, Okinawa has been a public health laboratory for the past century. ...
Dietary restriction (DR) often increases longevity and it may improve aging in rodents. Up to now, studies in non-human primates, which are carried out for 25 years, have not shown positive effects on longevity. Studies in human beings are also underway. This article argues that positive effects of dietary restriction on human longevity are not expected and results on the Okinawa diet seem to confirm this hypothesis. Moreover, dietary restriction can entail risky outcomes for health. However, as positive effects on healthspan in obese people have been reported, studies of DR should focus on obesity, rather than to look for not very probable positive effects of DR on longevity and aging.
In their response to my letter to the editor, Drs. Gavrilova and Gavrilov disagree with some of my arguments and argue that dietary restriction studies in humans ‘should not be dismissed as a valid tool to extending life span in non-obese individuals’. I would now like to answer their arguments and stress that studying dietary restriction in people with no health problems in the hope to increase their longevity is perhaps futile, but focusing studies in obese people bears the hope for more success in improving health in a significant part of the population.
Low birth weight (LBW) is defined as a weight of 2499 g or less and in Japan it is considered an important determinant of infant health status. The number of LBW infants is included in monthly reports to the Ministry of Health and Labor and prefectural authorities. Reporting has been universal for all prefectures since 1973. The LBW rate in Japan declined until the 1970s, reaching a low point for the whole country in 1978–1979 when it was 5.2%, but has since steadily increased to 9.5%. The prefecture of Okinawa was returned to Japan in 1972 and the proportion of LBW declined from 8.1% in 1973 to a low of 7% in 1978, but then rose again to reach 10.9% in 2005. The LBW rate in Japan is now equal with Mexico, the highest of all the OECD countries. The total number of births in Japan declined from 1,246,802 in 1989 to 1,062,530 in 2005, but during this period the number of infants born with a birth weight below 2500 g increased from 75,527 to 101,272. Japanese mothers in the USA also have had an increase in the proportion of LBW births, but not nearly as great as in Japan itself. While increased rates of smoking, multiple births, and interventional obstetrics account for some of the increase in the LBW rate, most of the increase is due to the practice of restricting weight gain in pregnancy to a maximum of 8 kg. The neonatal mortality rate has continued to decrease despite the increase in the LBW rate, but at a cost of the provision of transport and neonatal intensive care. The high LBW rate will result in public health implications from the projected increase of chronic disease in adults. There is a need to change obstetric policy on weight gain during pregnancy to reverse the LBW rate trend.
The infant mortality rate (IMR) and neonatal mortality rate (NMR) defined as the number of infant and newborn deaths per 1000 live births, respectively, are widely accepted as population indicators of the level of perinatal and postnatal health. Since the end of World War II, Japan has made substantial progress in reducing its IMR and NMR. This resulted from improving living standards and the provision of universal maternal and child health care (MCH) services. Okinawa, the island prefecture that is the furthest from mainland Japan, had the third highest IMR and the highest low-birth-weight rate (LBW) among all prefectures when its statistics were integrated into Japan in 1973. Even though the LBW rate in Okinawa has remained higher than the all-Japan average, Okinawa has shown a considerable improvement in IMR and NMR. The aim is to review the trends in IMR, NMR, and LBW in Japan and Okinawa and to discuss sociodemographic trends, economics, and the provision of health care services. The IMR and NMR in Okinawa decreased during that time from 14.8 to 2.4 and from 7.5 to 0.8, respectively. The LBW rate decreased until the mid-1980s, but since then it has increased to 11.5 (Okinawa) and 9.6 (Japan) in 2009. Okinawa's public health and primary health care model for infants has been very successful and may be applicable to child health in island nations of the Asia-Pacific region.
The topic of this article is the exceptional longevity in Okinawa. This phenomenon should be thoroughly validated at both the individual and population levels. This contribution analyzes the demographic data available for the population of Okinawa, in order to explain the presence of large numbers of centenarians. The mortality crossover obtained by comparing mortality rates in Okinawa and Japan could be attributed either to different behavior of the generations born before and after WW II, or to bad data. Arguments are presented in favor of both possible explanations. The reconstruction of the Koseki to replace the original, which was destroyed during WW II, could be a source of misreporting of age and would support the bad data hypothesis. Nevertheless, no concrete proof of invalid data has been found. Therefore, the author does not favor either of these explanations, but is calling for a more in-depth validation of longevity in Okinawa.
Dietary restriction (DR: food restriction without malnutrition) is often considered as a nearly universal means to extend longevity in animal species and we could make the hypothesis that DR could increase longevity in humans. Some authors support the opinion that DR has already increased longevity in Okinawa inhabitants, and thus that DR can increase longevity in humans. The purpose of this article is to stress that no data on humans with a normal body mass index (neither overweight nor obese) indicate that DR can increase life span and health span, particularly because the results observed in Okinawa inhabitants can probably be considered as showing mainly deleterious effects of malnutrition rather than positive effects of DR. Since DR does not appear to increase human life span, studies testing for the effect of DR in humans should focus on the health effects of a mild DR in overweight and obese people, rather than in normal-weight people.
The Asia-Pacific region is a region of small islands, perhaps 100 000 of them. The health, communication, and development problems of islands present difficult challenges for the delivery of health care. The discussions at the Okinawa Symposium centred on how health can be provided to all in the region, not only those in metropolitan areas, but also the poor in rural areas and those on living on far-flung island archipelagos. It is important to apply principles of "public health" and "primary health care" so that all island residents may have a reasonable expectation of health care. Schools of public health have a special responsibility to educate those who are responsible for the delivery and management of health care in these remote locations. The development of telehealth systems will be important to support health workers in remote locations and to deliver continuing education programs.
Secondhand smoke (SHS) is a major threat to public health worldwide. Previous studies have suggested that home smoking bans effectively reduce SHS exposure to nonsmokers in the home. In China, the world's largest tobacco producer and consumer, more than 540 million nonsmokers are exposed to SHS. However, to our knowledge, no published studies have examined the prevalence or correlates of home smoking bans in mainland China. This paper presents a quantitative study on home smoking bans in an urbanizing community in Shanghai, China.
In 2006, a cross-sectional survey based on probability sampling (N=243) was conducted in Changqiao, an urbanizing community in Shanghai, China. Interviews were conducted in person in Mandarin Chinese by trained interviewers. The behavioral ecologic model, which emphasizes the multilevel environmental contingencies of behavior, was applied as the theoretical model. Data were analyzed in 2008 using logistic regression to explore correlates of complete home smoking bans.
In this community, only 26% of respondents reported having complete home smoking bans. Smoking respondents and families were less likely to have complete smoking bans in the home. Home smoking bans were positively associated with the perceived density of smoke-free homes in the community, and with the perceived likelihood of community reprimand for smoking in the home.
Home smoking bans were not widely adopted in this community in China. Future interventions should focus on the community and social environment in order to promote home smoking bans.
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