Objective　During the two decades following Japan's World War II surrender in 1945, tremendous improvement in the population's health was observed, particularly in infant mortality and life expectancy. How did Japanese rural dwellers achieve such remarkable health improvement during this relatively short time span while its economy remained heavily damaged following the war? While the efforts from government-driven public health strategies and programs are well known, relatively little is known about the contributions of policies in non-health sectors. Therefore, the main aim is to verify, using literature based sources, whether non-health sectors contributed to the betterment of the population's health in addition to the public health sector policies.

Hypotheses　Synergistic efforts of diverse interventions from different policies and programs likely catalyzed the drastic health improvement observed in the Japanese population in the two decades after World War II. The Ministry of Health and Welfare, for example, implemented programs to provide health care services. These are thought to have contributed directly to reducing maternal and child mortality, as well as tuberculosis-related mortality. Additionally, the Ministry of Agriculture and Forestry carried out a nationwide livelihood improvement program to enhance individual and family lifestyles, improve indoor and outdoor environments, and strengthen social solidarity. The ministry also attempted to generate income stability for farmers through an agricultural improvement program to ensure allocation of household income to family health. The Ministry of Education also had an initiative to disseminate the concepts of democracy and rational thought to the Japanese population through a social education program. Through these efforts, superstition and pre-modern customs were reduced, and subsequently health awareness increased, leading to an improvement in the population's health.

Conclusion　The public health policies implemented in Japan as well as the integration of various policies and programs addressing livelihoods, economics, and education greatly improved the population's health in a relatively short time. These non-health initiatives intersected with a wide range of health determinants. Verifying these hypotheses in detail would help develop effective measures for international aid to poverty-stricken regions. It also encourages alternative ways through which Japan could overcome its present-day challenges such as a rapidly aging population with limited access to national schemes for social security.

Objectives　The distribution of serum 25-hydroxyvitamin D [25(OH)D] levels among reproductive age Japanese perinatal (prepartum, intrapartum, postpartum) and non-perinatal women remains unknown. In addition to this, vitamin D deficiency cut-off values, which consider the effects of these levels during the perinatal period and infant development, have not been determined. Thus, we systematically reviewed the distribution of serum 25(OH)D levels among reproductive age Japanese women, in order to provide basic data to determine vitamin D deficiency cut-off values.

Methods　A systematic literature review was conducted on research published between 1963 and 2015, using PubMed web and Japan Medical Abstracts Society web. The key words “Japan,” “Vitamin D,” “women,” and “pregnant women,” were used. After filtering for age, sex, race, indication of numerical number, and duplications, 18 papers were extracted and categorized into reproductive age non-perinatal women (13 papers/22 groups), and reproductive age perinatal women (6 papers/8 groups). The mean serum 25(OH)D levels were grouped by age, test period, and measuring methods.

Results　Mean serum 25(OH)D levels among reproductive age non-perinatal women were lower than 20 ng/ml in 10 out of 22 groups (45.4%), and lower than 30 ng/ml in 21 groups (95.5%). The mean serum 25(OH)D level among reproductive age perinatal women was lower than those among reproductive age non-perinatal women. Among reproductive age perinatal women, except for one group that included women in the first trimester of pregnancy (5-10 weeks), the mean serum 25(OH)D levels of the other groups were lower than 20 ng/ml.

Conclusion　Serum 25(OH)D levels among reproductive age Japanese women, especially perinatal women, appear to be low. Studies of serum 25(OH)D levels among reproductive age Japanese women are limited; hence, further investigation is required.

Objectives　If children in formative stages ingest foods that are too hard or too soft, they can experience delays in oral cavity functions. Therefore, it is important for young children to receive foods of appropriate hardness in relation to their chewing ability. We investigated the relationship between the ingestion of 15 different food items and tooth eruption among children aged 18-20 months.

Methods　Caregivers from Japanese municipalities who took their children for an 18-month health check-up were given an anonymous questionnaire. Questionnaires were only given to caregivers who provided direct consent and were returned by mail upon completion. The questions inquired about the ingestion of 15 different food items in an attempt to elucidate a correlation between the degree of food hardness that children can chew, tooth eruption, and development of oral functions. A chi-squared test and Fisher's exact test were used to evaluate the relationship between the ingestion of the 15 food items and tooth eruption. The Hokkaido University Human Research Ethics Committee approved this study.

Results　Of the 501 caregivers who received the questionnaire, there were 210 responses (40.9%) and 202 (40.3%) of those were used in the analysis. Thirty children (14.9%) had non-eruption of the premolars. Children without absolute eruption of the premolars ate pork and/or beef steak more frequently than those who had their first four premolars.

Conclusion　Our results suggest that at least 10% of children at the standard tooth eruption age experience delays in oral cavity maturation. This percentage indicates some children consume hard foods inappropriate for premolar development. We propose that caregivers prepare fresh greens and meat of suitable hardness according to the chewing ability of developing children.

Objective　The present study aimed to explore the effects of sense of coherence (SOC) on depressive symptoms after employment in the Japan Self-Defense Force among male young adults.

Methods　In April 2013, 953 new male members of the Japan Ground Self-Defense Force (JGSDF; age range: 18-24 years) participated in this study. Depressive symptoms were assessed using the 20-item version of the Center for Epidemiologic Studies Depression scale (CES-D), which defines a score of 16 or greater as indicating the presence of depressive symptoms. The SOC score was assessed using a 13-item version (SOC-13), in which a score of 59 or greater is as assigned to the high score group. A second survey was conducted two months later, in June of 2013. For the analysis, we selected participants without depressive symptoms at the baseline survey. The association between SOC scores at baseline and the onset of depressive symptoms was examined using a logistic regression analysis.

Results　The final analysis was conducted on data on 389 new male members of the JGSDF. The logistic regression analysis showed a significant reduction in the onset of depressive symptoms among the group with high SOC scores (odds ratios: 0.59, 95% confidence interval=0.35-0.98) as compared with that observed in the group with low SOC scores.

Conclusions　The present study clarified that SOC among male young adults has a buffering effect on the risk of developing depressive symptoms after employment in the Japan Self-Defense Force. Our results may be useful for improving the mental health of new employees.