Nobuo Yoshiike

Criteria and classification of obesity in Japan and Asia‐Oceania

In 1997 when WHO initiated the formation of the International Obesity Task Force (IOTF), the Task Force proposed the cut-offs for overweight and obesity as BMI 25 and BMI 30, respectively. If we accept the criteria of BMI ≥ 30 to indicate obesity, it would appear that the prevalence of obesity in Japan of less than 3% has changed little during the last 40 years, and we cannot explain the rapid increase in incidence of obesityassociated chronic diseases such as diabetes, hypertension and hyperlipidemia. Thus, JASSO decided to define BMI ≥ 25 as obesity. This cut-off has been proposed for use in the Asia-Oceania Region, and WHO Western Pacific Region noted this proposal. According to this criterion the prevalence of obesity in Japan would average 20%, with a high of 30% in men over 30 years old, and women over 40 years old. Thus the rates would have increased four times in men and three times in women during these last 40 years. What has caused the increased prevalence of obesity in Japan? Several causes of obesity have been advanced: (i) overeating (ii) errors of eating pattern (iii) inactivity (iv) heredity, and (v) disturbance in thermogenesis. Hyperphagia and inactivity are two major risk factors for obesity. Hyperphagia may be an important factor in individuals. However, the average energy intake in adult people in Japan has not increased; in fact it has declined (2104 kcal/day to 1967 kcal/day) during these 40 years. During this period, the prevalence of obesity has increased three or more times as mentioned above. This indicates that inactivity may be the main cause for the increased incidence of obesity in Japan. Errors of eating pattern (irregular eating, night eating, etc.), including a high proportion of fat to total energy intake (8.7% increased to 26.5%), and a high incidence of β 3-adrenergic polymorphism, might also have contributed to the increased incidence of obesity in Japan.

A 15.5-year follow-up study of stroke in a Japanese provincial city : The Shibata Study

BACKGROUND AND PURPOSE Change toward Western lifestyles, particularly during the high economic growth period (approximately 1960 to 1975), dynamically altered stroke frequency and the distribution of risk factors in the Japanese. We reexamined their association after this environmental change by a cohort study. METHODS The cohort (2302 subjects) comprised residents aged 40 years or older of the Akadani-Ijimino district in Shibata City, Niigata Prefecture, Japan, who were followed up from 1977 for 15.5 years. RESULTS Crude incidence rates per 1000 person-years for all strokes were 5.22 for men and 4.36 for women (3.02 and 2.18 for cerebral infarction, 0.65 and 1.06 for intracerebral hemorrhage, and 0.41 and 0.34 for subarachnoid hemorrhage, respectively). Multivariate analyses performed with the Cox proportional hazard model revealed these risk factors to be independently significant: for cerebral infarction in men, age, blood pressure, atrial fibrillation, albuminuria, funduscopic abnormality, and current smoking: for cerebral infarction in women, age, atrial fibrillation, and history of ischemic heart disease; for intracerebral hemorrhage in men, age and funduscopic abnormality; for intracerebral hemorrhage in women, age, blood pressure, and light physical activity; for all strokes in men, age, blood pressure, atrial fibrillation, albuminuria, funduscopic abnormality, current smoking, and heavy physical activity; and for all strokes in women, age, atrial fibrillation, and light physical activity. CONCLUSIONS Most traditional risk factors, including blood pressure and its related organ diseases, were confirmed, but serum total cholesterol had almost no effect. Physical activity had both negative and positive effects on stroke risk. In these findings, however, some differences related to sex were also observed.

Thinness Among Young Japanese Women

OBJECTIVES We described changes in body mass index (BMI) and the prevalence of thinness among young Japanese women (aged 15-29 years) from 1976 to 2000 by reanalyzing the nationwide data in the National Nutrition Survey, Japan. METHODS We used height and weight data sets for 30 903 nonpregnant, nonlactating women during the 25-year period. We calculated the mean values of BMI and the prevalence of thinness for 3 age groups (15-19, 20-24, and 25-29 years of age). RESULTS Changes in BMI per 10 years were -0.17 kg/m2, -0.22 kg/m2, and -0.34 kg/m2 for each age group, respectively. Extreme thinness (BMI < 17 kg/m2) increased from 2.4% in 1976-1980 to 4.2% in 1996-2000. CONCLUSIONS Further studies regarding topics such as increased smoking prevalence are needed to identify the underlying causes of increasing thinness.

Serum Vitamin C Concentration Was Inversely Associated With Subsequent 20-Year Incidence of Stroke in a Japanese Rural Community The Shibata Study

Background and Purpose Epidemiological evidence suggests that vitamin C may decrease the risk of stroke. The purpose of the present study was to examine the association of serum vitamin C concentration with the subsequent incidence of stroke. Methods In a Japanese rural community, a cohort of 880 men and 1241 women aged 40 years and older who were initially free of stroke was examined in 1977 and followed until 1997. The baseline examination included a measurement of serum vitamin C concentration. The incidence of stroke was determined by annual follow-up examinations and registry. Results During the 20-year observation period, 196 incident cases of all stroke, including 109 cerebral infarctions and 54 hemorrhagic strokes, were documented. Strong inverse associations were observed between serum vitamin C concentration and all stroke (sex- and age-adjusted hazard ratios were 0.93, 0.72, and 0.59, respectively, for the second, third, and fourth quartiles compared with the first quartile;P for trend=0.002), cerebral infarction (0.71, 0.59, and 0.51;P for trend=0.015), and hemorrhagic stroke (0.89, 0.75, and 0.45;P for trend=0.013). Additional adjustments for blood pressure, serum total cholesterol, body mass index, physical activity, smoking, alcohol drinking, antihypertensive medication, atrial fibrillation, and history of ischemic heart disease did not attenuate these associations markedly. Conclusions Serum vitamin C concentration was inversely related to the subsequent incidence of stroke. This relationship was significant for both cerebral infarction and hemorrhagic stroke. Additional mechanistic hypotheses may be required to explain our findings.

Increase in low-birth-weight infants in Japan and associated risk factors, 1980-2000.

Aim: To investigate possible factors related to the recent rise in prevalence of low‐birth‐weight (LBW) infants in Japan.

NOS3 Genotype–Dependent Correlation Between Blood Pressure and Physical Activity

Abstract—Endothelium-dependent vasorelaxation plays an important role in reduction of blood pressure and is mediated through release of nitric oxide (NO), which is generated by constitutively expressed endothelial nitric oxide synthase (NOS3). Exercise also augments NO release and has been recommended for primary prevention and improvement of hypertension, but individual responses are highly variable. We therefore postulated that genetic polymorphisms of NOS3 might interact with physical activity level to differentially influence blood pressure level. We genotyped 832 healthy Japanese (mean age of 54.4±8.6 years, 372 men and 460 women) for a polymorphism of NOS3 in intron 4 (ecNOS4a/b), using the polymerase chain reaction method, and scored their habitual physical activity level by using the rate of energy expenditure per resting metabolic rate through an interview according to a semiquantitative assessment method. Only in the subjects who had the rarer a allele (aa +ba type), systolic blood pressure was found to be inversely correlated with physical activity level (P for linear trend=0.0496, for interaction=0.0071). Eventually, this polymorphism was significantly associated with the prevalence of systolic hypertension only in the subjects who were in the lowest tertile of physical activity level (OR=2.4, 95% CI, 1.1 to 5.6, P for interaction=0.0474). In the present study, we found a significant interaction between the genotype and physical activity level on systolic blood pressure. These results might allow a better understanding of the mechanism to improve hypertension by exercise and to thereby reduce the risk of cardiovascular disease.

Internet Use for Health-Related Information via Personal Computers and Cell Phones in Japan: A Cross-Sectional Population-Based Survey

Background The Internet is known to be used for health purposes by the general public all over the world. However, little is known about the use of, attitudes toward, and activities regarding eHealth among the Japanese population. Objectives This study aimed to measure the prevalence of Internet use for health-related information compared with other sources, and to examine the effects on user knowledge, attitudes, and activities with regard to Internet use for health-related information in Japan. We examined the extent of use via personal computers and cell phones. Methods We conducted a cross-sectional survey of a quasi-representative sample (N = 1200) of the Japanese general population aged 15–79 years in September 2007. The main outcome measures were (1) self-reported rates of Internet use in the past year to acquire health-related information and to contact health professionals, family, friends, and peers specifically for health-related purposes, and (2) perceived effects of Internet use on health care. Results The prevalence of Internet use via personal computer for acquiring health-related information was 23.8% (286/1200) among those surveyed, whereas the prevalence via cell phone was 6% (77). Internet use via both personal computer and cell phone for communicating with health professionals, family, friends, or peers was not common. The Internet was used via personal computer for acquiring health-related information primarily by younger people, people with higher education levels, and people with higher household incomes. The majority of those who used the Internet for health care purposes responded that the Internet improved their knowledge or affected their lifestyle attitude, and that they felt confident in the health-related information they obtained from the Internet. However, less than one-quarter thought it improved their ability to manage their health or affected their health-related activities. Conclusions Japanese moderately used the Internet via personal computers for health purposes, and rarely used the Internet via cell phones. Older people, people with lower education levels, and people with lower household incomes were less likely to access the Internet via cell phone. The Internet moderately improved users’ health-related knowledge and attitudes but seldom changed their health-related abilities and activities. To encourage communication between health providers and consumers, it is important to improve eHealth literacy, especially in middle-aged people. It is also important to make adequate amendments to the reimbursement payment system and nationwide eHealth privacy and security framework, and to develop a collaborative relationship among industry, government, and academia.

Nutritional status of pregnant and lactating women in Japan: A comparison with non‐pregnant/non‐lactating controls in the National Nutrition Survey

Aim:  To describe the nutritional status in Japanese pregnant and lactating women at a national level, through a comparison with their non‐pregnant/non‐lactating controls.

Angiotensin converting enzyme genetic polymorphism is not associated with hypertension in a cross-sectional sample of a Japanese population : the Shibata Study

Background The studies on the association of deletion/insertion (D/I) polymorphism of angiotensin converting enzyme (ACE) gene with blood pressure and hypertension reported contradictory results. Because there was no population-based study in Japan, we examine the hypothesized association in a cross-sectional sample of a Japanese cohort. Methods and results The blood pressure of 464 men and 876 women aged 40–80 years was measured, and their DNA was analyzed for ACE D/I genotypes. The prevalence of the D allele was 38.7 and 39.2% in men and women, respectively (overall 39%). There was a tendency for higher covariate (age, body mass index, albuminuria, hematocrit, alcohol consumption, smoking, diabetes mellitus, ischemic heart disease and antihypertensive medication) adjusted mean levels of diastolic blood pressure for the DD genotype in men but not in women. However, this tendency disappeared after dichotomization of blood pressure into diagnostic categories (normotension and hypertension). Results did not differ when the subjects were divided into two age groups (⩽ 59 and ⩾ 60 years). Covariate-adjusted odds ratios for hypertension for presence of the D allele were close to the null value of one. ACE genetic variation accounted for only 0.1 and 0.7% of the inter-individual variation in systolic and diastolic blood pressure in men. These estimates were 0.2 and 0.1%, respectively, in women. Conclusion Although there is a tendency of higher diastolic blood pressure in men with DD genotypes, there is no convincing evidence that ACE genotypes are associated with hypertension in this Japanese population.

Reproducibility and Validity of a Food Frequency Questionnaire among Vietnamese in Ho Chi Minh City

Objective: Our objective was to assess the reproducibility and validity of a food frequency questionnaire (FFQ) among individuals living in Ho Chi Minh City, Vietnam. Methods: A total of 116 food items in our FFQ were selected by ranking food items according to their contribution to the population intake of nutrients, based on multiple 24-hour recalls (24HRs) from 144 participants in July 2001. The FFQ was validated by using three 24HRs for 118 men and women in Ho Chi Minh City, Vietnam in August 2002. The reproducibility of the FFQ was assessed by repeated administration at 7 ± 3.4 days. Results: The reproducibility study showed that Spearman correlation coefficients, adjusted for energy intake, ranged from 0.47 to 0.72, and that weighted kappa values ranged from 0.42 for lipid to 0.65 for potassium. In the validation study, correlation coefficients, adjusted for energy intake, between the FFQ and the 24HRs ranged from 0.16 (calcium) to 0.45 (retinol). The proportion of subjects classified by the FFQ into the same third as determined by the 24HRs was between 42% and 62%. Conclusions: This food frequency questionnaire measured the usual intake of major nutrients for Vietnamese adults living in Ho Chi Minh City and its urban area, where dietary patterns are similar to those of the Vietnamese population.