Dietary habits among the JPHC study participants at baseline survey. Japan Public Health Center-based Prospective Study on Cancer and Cardiovascular Diseases

Association between fish and shellfish consumption, n-3 polyunsaturated fatty acids, and gastric cancer risk: the Japan Public Health Center-based Prospective Study

PURPOSE

Fish and shellfish consumption is suggested to be a cancer-protective factor. However, studies investigating this association for gastric cancer, especially considering Helicobacter pylori (H. pylori) and atrophic gastritis (AG), are limited. We investigated gastric cancer risk associated with fish, shellfish, and n-3 polyunsaturated fatty acids (n-3 PUFAs) consumption among Japanese adults.

METHODS

90,504 subjects enrolled in the Japan Public Health Center-based Prospective Study (JPHC Study) were followed until December 2013. Dietary intake data were collected using a food frequency questionnaire. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for gastric cancer risk associated with fish and shellfish consumption and marine n-3 PUFAs (sum of eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA)) using Cox proportional hazards models. Among those with avaliable data, we conducted a subgroup analysis taking H. pylori infection and AG status  into consideration.

RESULTS

There were 2,701 gastric cancer cases during an average of 15 years of follow-up. We observed an increased gastric cancer risk for salted fish consumption for men [HR for fifth quintile versus first quintile 1.43 (95% CI 1.18-1.75)] and for women [HR 1.33 (95% CI 1.00-1.77)]. We observed a weak risk reduction trend for women as the intake of marine n-3 PUFAs increased (p-trend:0.07). When we included H. pylori infection and atrophic gastritis status in the analysis, the associations diminished.

CONCLUSION

Our results suggest that salted fish increases gastric cancer risk for men and women, while marine n-3 PUFAs marginally decreases this risk among women in Japan.

Dairy intake and the risk of pancreatic cancer: the Japan Collaborative Cohort Study (JACC Study) and meta-analysis of prospective cohort studies

Dairy product intake was suggested to reduce the risk of gastrointestinal cancers. This study investigated the association between dairy product intake and the risk of pancreatic cancer (PAC) using a prospective cohort study and meta-analysis of prospective cohort studies. First, we included 59 774 people aged 40-79 years from the Japan Collaborative Cohort Study (JACC Study). The Cox regression was used to compute the hazard ratios (HR) and 95 % CI of incident PAC for individuals who reported the highest intakes of milk, cheese and yogurt compared with not consuming the corresponding dairy products. Then, we combined our results with those from other four prospective cohort studies that were eligible after searching several databases, in a meta-analysis, using the fixed-effects model before evaluating publication bias and heterogeneity across studies. In the JACC Study, the highest v. no intakes of milk, cheese and yogurt were not associated with the reduced risk of PAC after a median follow-up of 13·4 years: HR (95 % CI) = 0·93 (0·64, 1·33), 0·91 (0·51, 1·62) and 0·68 (0·38, 1·21), respectively. The results did not significantly change in the meta-analysis: 0·95 (0·82, 1·11) for milk, 1·16 (0·87, 1·55) for cheese and 0·91 (0·79, 1·05) for yogurt. The meta-analysis showed no signs of publication bias or heterogeneity across studies. To conclude, consumption of milk, cheese and yogurt was not associated with the risk of PAC either in the JACC Study or the meta-analysis.

The Lifelong Health Support 10: a Japanese prescription for a long and healthy life

Background

Although the age-adjusted incidence and mortality of cancer and cardiovascular disease (CVD) have been decreasing steadily in Japan, both diseases remain major contributors to morbidity and mortality along with the aging society. Herein, we aim to provide a prescription of 10 health tips for long and healthy life named the “Lifelong Health Support 10 (LHS10).”

Method

The LHS10 was developed by the preventive medicine specialists at the National Cerebral and Cardiovascular Center in Suita, where it has been used for health guidance to prevent CVD, cancer, and cognitive decline in addition to their major risk factors such as hypertension, diabetes, and obesity. It consisted of the lifestyle modification recommendations of the 2014 Japanese Society of Hypertension guidelines and the 2017 Japan Atherosclerosis Society Guidelines for preventing atherosclerotic CVD. Further, it came in line with other international lifestyle modification guidelines. In this narrative review, we summarized the results of several Japanese epidemiological studies investigating the association between the LHS10 items and the risk of cancer, CVD, and other chronic diseases including dementia, diabetes, and chronic kidney disease.

Results

The LHS10 included avoiding smoking and secondhand smoke exposure, engaging in physical activity, refraining from excessive alcohol drinking, reducing fried foods and sugary soft drinks, cutting salt in food, consuming more vegetables, fruits, fish, soy foods, and fibers, and maintaining proper body weight. All items of the LHS10 were shown to reduce the risk of cancer, CVD, and other chronic diseases.

Conclusions

The LHS10 can be a helpful tool for health guidance.

Supplementary information

The online version contains supplementary material available at https://doi.org/10.1265/ehpm.22-00085.

Dietary heterocyclic aromatic amine intake and cancer risk: epidemiological evidence from Japanese studies

Heterocyclic aromatic amines (HAAs), which are formed from the reaction of creatine or creatinine, amino acids, and sugars in meat and fish cooked at high temperatures, have been shown to be mutagenic in bacterial assays and carcinogenic in animal models. Following advances in the dietary assessment of HAA intake in epidemiological studies - including development of a validated meat-cooking module and a specialized food composition database - a number of epidemiological studies have specifically examined the association of HAA intake and cancer risk, most of which were conducted in Western countries. Given that dietary habits and cooking methods differ across countries, however, epidemiological investigation of dietary HAA intake requires a population-specific assessment method. Here, we developed a practical method for assessing dietary HAA intake among Japanese using a food frequency questionnaire (FFQ) and evaluated its validity for use in epidemiological studies by comparison with 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) levels in human hair. The Japan Public Health Center-based Prospective Study reported that daily intake of HAAs among Japanese was relatively low, and that more than 50% of total intake in mainland Japan was derived from fish. Only four case-control studies in Japan have been reported so far, for colorectal, stomach and prostate cancer, and colorectal adenoma. A statistically significant positive association was found between 2-amino-3,4-dimethylimidazo [4,5-f] quinoline (MeIQ) and the risk of colorectal adenoma and between individual and total HAAs and the risk of prostate cancer. In contrast, no association was observed for colorectal or stomach cancer, or for colorectal adenoma among men. We also found that the limited and inconsistent findings among epidemiological studies are due to the difficulty in assessing exposure levels of HAAs. In addition to further evidence from prospective cohort studies in Japanese based on dietary HAA intake estimated by FFQs, studies using other methods to assess HAA exposure, such as biomarkers, are highly anticipated.

A comprehensive update on early gastric cancer: defining terms, etiology, and alarming risk factors

INTRODUCTION

Early gastric cancer (EGC) is a well-defined gastric malignancy that is limited to the mucosa or submucosa, irrespective of lymph node metastasis. At an early stage, gastric cancer often does not cause symptoms until it becomes advanced, and it is a heterogeneous disease and usually encountered in its late stages.

AREA COVERED

This comprehensive review will provide a novel insight into the evaluation of EGC epidemiology, defining terms, extensive etiology and risk factors, and timely diagnosis since prevention is an essential approach for controlling this cancer and reducing its morbidity and mortality.

EXPERT OPINION

The causative manner of EGC is complex and multifactorial. In recent years, researchers have made significant contributions to understanding the etiology and pathogenesis of EGC, and standardization in the evaluation of disease activity. Though the incidence of this cancer is steadily declining in some advanced societies owing to appropriate interventions, there remains a serious threat to health in developing nations. Early detection of resectable gastric cancer is crucial for better patient outcomes.

Development and simulated validation of a dish composition database for estimating food group and nutrient intakes in Japan

OBJECTIVE

To develop a dish composition database (DCD) and assess its ability to estimate dietary intake.

DESIGN

The DCD was developed based on 16 d dietary records (DR). We aggregated all reported dishes into 128 dish codes and calculated mean food group and nutrient contents for each code. These data were used to calculate dietary intake in a different population that completed a 4 d DR. The estimated values were compared with those estimated using the standard food composition database (FCD) of Japan.

SETTING

Japan.

PARTICIPANTS

A total 252 adults aged 31-81 years for the 16 d DR (3941 d in total) and 392 adults aged 20-69 years for the 4 d DR (1568 d in total) participated.

RESULTS

There were significant differences in median intakes between the DCD and the FCD for eighteen and twenty (of twenty-six) food groups and for twenty-nine and twenty-two (of forty-three) nutrients (including energy) in men and women, respectively. For food group intakes, Spearman correlation coefficients between the DCD and FCD ranged from 0·19 (animal fats) to 0·90 (fruits and alcoholic beverages) in men (median: 0·61) and from 0·25 (oils) to 0·89 (noodles) in women (median: 0·58). For nutrient intakes, the corresponding values ranged from 0·25 (retinol) to 0·90 (alcohol) in men (median: 0·60) and from 0·15 (retinol) to 0·74 (alcohol) in women (median: 0·53).

CONCLUSIONS

Whereas it is difficult to accurately estimate absolute dietary intake values using the present DCD, it has acceptable ability to rank the intakes of many food groups and nutrients.

Association between NAT2, CYP1A1, and CYP1A2 genotypes, heterocyclic aromatic amines, and prostate cancer risk: a case control study in Japan

Background

Heterocyclic aromatic amines (HAAs) may confer prostate cancer risk; however, the evidence is inconclusive and the activity of HAA-metabolizing enzymes is modulated by gene variants. The purpose of our study was to determine whether there was evidence of an association between HAA intake, polymorphisms in NAT2, CYP1A1, and CYP1A2 and prostate cancer risk in Japanese men.

Methods

Secondary data analysis of an observational case control study was performed. Among 750 patients with prostate cancer and 870 healthy controls, 351 cases and 351 age-matched controls were enrolled for analysis. HAA intake was estimated using a food frequency questionnaire and genotypes were scored by TaqMan real-time PCR assay. Logistic regression analysis was conducted according to affected/control status.

Results

We found that high HAA intake was significantly associated with an increased risk of prostate cancer (odds ratio (OR), 1.90; 95% confidence interval (95% CI), 1.40–2.59). The increased risk of prostate cancer was observed among individuals with the NAT2 slow acetylator phenotype (OR, 1.65; 95% CI, 1.04–2.61), CYP1A1 GA + GG genotype (OR, 1.27; 95% CI, 1.02–1.59), and CYP1A2 CA + AA genotype (OR, 1.43; 95% CI, 1.03–2.00). In addition, CYP1A1 GA + GG genotypes were associated with increased cancer risk in low (OR, 2.05; 95% CI, 1.19–3.63), moderate (OR, 1.72; 95% CI, 1.07–2.76), and high (OR, 2.86; 95% CI, 1.83–4.47) HAA intake groups.

Conclusions

Our results suggest that high HAA intake is a risk factor of prostate cancer, and genotypes related to HAA metabolic enzymes can modulate the degree of the risk.

Validity and reliability of a self-administered food frequency questionnaire for the JPHC study: The assessment of amino acid intake

Background

The Japanese database of food amino acid composition was revised in 2010 after a 24-year interval. To examine the impact of the 2010 revision compared with that of the 1986 revision, we evaluated the validity and reliability of amino acid intakes assessed using a food frequency questionnaire (FFQ).

Methods

A FFQ including 138 food items was compared with 7-day dietary records, completed during each distinct season, to assess validity and administered twice at approximately a 1-year interval, to assess reliability. We calculated amino acid intakes using a database that compensated for missing food items via the substitution method. Subjects were a subsample of two cohorts of the Japan Public Health Center-based prospective study. A total of 102 men and 113 women in Cohort I and 174 men and 176 women in Cohort II provided complete dietary records and the FFQ, of whom 101 men and 108 women of Cohort I and 143 men and 146 women of Cohort II completed the FFQ twice.

Results

In the comparison of the FFQ with dietary records, the medians (ranges) of energy-adjusted correlation coefficients for validity were 0.35 (0.25–0.43) among men and 0.29 (0.19–0.40) among women in Cohort I, and 0.37 (0.21–0.52) and 0.38 (0.24–0.59), respectively, in Cohort II. Values for reliability were 0.47 (0.42–0.52) among men and 0.43 (0.38–0.50) among women in Cohort I, and 0.59 (0.52–0.70) and 0.54 (0.45–0.61), respectively, in Cohort II.

Conclusions

The FFQ used in our prospective cohort study is a suitable tool for estimating amino acid intakes.

•

The Japanese database for food amino acid compositions was revised in 2010.

•

We evaluated the validity and reliability of amino acid intakes assessed via a FFQ.

•

The estimation via a new database had better validity than via the former database.

•

The estimation using the new database indicated good reliability.

Plasma isoflavone concentrations are not associated with gastric cancer risk among Japanese men and women

The incidence of gastric cancer throughout the world is ~2-3 times higher in men than in women. Previous research suggested that isoflavones, which are structurally similar to 17β-estradiol, may prevent gastric cancer. Based on a large, population-based, prospective study, we recently reported a null association between dietary isoflavone intake and gastric cancer. However, epidemiologic studies using blood concentrations of isoflavones might better reflect the effect of isoflavones on gastric cancer carcinogenesis than dietary assessment. We therefore conducted a nested case-control study within the Japan Public Health Center-Based Prospective Study. Participants were followed-up from 1990 to 2004. Among 36,745 participants who answered the baseline questionnaire and provided blood samples, 483 gastric cancer cases matched to 483 controls were used in the analysis. ORs and 95% CIs were estimated with a conditional logistic regression model. The overall distribution of plasma isoflavone concentrations was not associated with the development of gastric cancer. Compared with groups with the lowest plasma concentrations (reference groups), the groups with the highest daidzein and genistein concentrations had adjusted ORs and 95% CIs of 1.11 (0.74-1.66; P-trend = 0.6) and 0.96 (0.64-1.44; P-trend = 0.9), respectively. The results did not change when analysis was based on sex, subsite, or histological type. We found no association of plasma isoflavone concentrations with gastric cancer risk. Our data support the previously observed null association between isoflavone intake and gastric cancer risk.

Iron availability modulates aberrant splicing of ferrochelatase through the iron- and 2-oxoglutarate dependent dioxygenase Jmjd6 and U2AF(65.)

Erythropoietic protoporphyria (EPP) results from partial deficiency of ferrochelatase (FECH). Genetically, EPP patients differ from asymptomatic mutation carriers at the unmutated FECH allele, the expression of which is modulated by single nucleotide polymorphism IVS3-48C/T. The IVS3-48C genotype, which is present among patients, leads to correct splicing of 60% of the pre-mRNA and to alternative splicing of 40%, the latter mRNA-product being destroyed by nonsense-mediated decay. An IVS3-48T genotype generates 80% correct and 20% aberrant products. Our study demonstrated that under iron deficient conditions, the aberrant splice product was increased to 56% and 50% of total FECH mRNA in erythroleukemic K562 and lymphoblastoid cell lines, respectively, both being homozygous for IVS3-48T. Concomitantly, FECH protein was decreased. Iron deficiency had less effect on the FECH splice ratio in an IVS3-48C/C lymphoblastoid cell line. Effects similar to iron deficiency were generated by siRNA knockdown of either splicing factor U2AF(65) or Fe(II)- and 2-oxoglutarate-dependent dioxygenase Jumonji domain-containing protein 6 (Jmjd6), which interacts with U2AF(65) by lysyl-hydroxylation. Based on these results, we propose that the availability of iron, a co-factor of Jmjd6, modulates U2AF(65)-lysyl-hydroxylation. This in turn, influences the relative amounts of correct and aberrant FECH mRNA splice products and thus, regulates the FECH enzyme activity.

Dietary exposure to short-chain chlorinated paraffins has increased in Beijing, China

Short-chain chlorinated paraffins (SCCPs) persist in the environment and bioaccumulate in biota and are under review by the Stockholm Convention on persistent organic pollutants. SCCP levels were measured semiquantitatively in pooled 24 h food composite samples from Chinese (n = 10), Korean (n = 10), and Japanese (n = 40) adults in the 1990 s and 2007-2009. In Japan, SCCPs were detected in 14 of 20 pooled samples in the 1990 s and 13 of 20 pooled samples in 2009. Between these two time points, the geometric mean (GM) of the dietary intake of total SCCPs per body weight was comparable in Japan (54 ng kg-bw(-1) day(-1) in the 1990 s and 54 ng kg-bw(-1) day(-1) in the 2000s). In Beijing, SCCP levels were elevated by 2 orders of magnitude from 1993 to 2009 (GM: 620 ng kg-bw(-1) day(-1) in 2009). The 95th percentile estimate of the dietary intake was 1200 ng kg-bw(-1) day(-1) (>1% of tolerable daily intake). In Seoul, no samples in 1994 contained detectable SCCP levels and only one sample in 2007 showed trace levels of SCCPs. Preliminary evidence on the significant increase in SCCP exposure in Beijing in 2009 warrants urgent investigations to refine dietary intake estimates by targeting food types and source identification.

Iron intake and associated factors in general Japanese population: NIPPON DATA80, NIPPON DATA90 and national nutrition monitoring

OBJECTIVE

The purpose of this study was to investigate the dietary iron intake and associated other dietary factors and clinical characteristics among a representative sample cohort of Japanese population.

METHODS

We obtained data from NIPPON DATA80 and 90 that were conducted with the National Nutrition Surveys in 1980 and in 1990. Then we estimated nutrient and food intakes of individuals in the National Nutrition Survey of 1980 and that of 1990, which were adjusted on the basis of data of the National Nutrition Survey of 1995. Finally, we analyzed data for the 10,422 participants (4585 men and 5837 women) in NIPPON DATA80 and 8342 participants (3488 men and 4854 women) in NIPPON DATA90 having dietary iron intake information.

RESULTS

In NIPPON DATA80 and 90, there was a significant relationship between the dietary iron intake and age for both men and women. Dietary protein intake was associated with iron intake where as dietary fat intake did not show any association. Regarding the minerals, significant relationships were observed between the different minerals and dietary iron intake. Apart from the food group of milk and dairy products, there were significant differences in other food groups according to quintiles of iron intakes for men and women.

CONCLUSIONS

We described the mean dietary iron intake and its relation with other dietary factors and clinical characteristics in Japanese adults as the baseline data in NIPPON DATA80 and in NIPPON DATA90.

Iron intake does not significantly correlate with iron deficiency among young Japanese women: a cross-sectional study

Objectives

We evaluated the association of nutrient intake with Fe deficiency with regard to lifestyle factors and health condition in young Japanese women. Uniquely among developed countries, dietary habits render Japanese populations vulnerable to Fe deficiency, owing to their relatively low intake of Fe and high intake of Fe absorption inhibitors, such as green tea and soyabeans.

Design

A cross-sectional study.

Setting and subjects

The subjects were 1019 female Japanese dietetic students aged 18–25 years. Dietary habits during the preceding month were assessed using a previously validated, self-administered, diet history questionnaire. Blood analysis was performed to assess body Fe status. Subjects were categorized with Fe deficiency when their serum ferritin levels were <12 ng/ml. Twenty-nine dietary variables, i.e. intakes of energy, sixteen nutrients including Fe and twelve food groups, were analysed using multivariate logistic regression models adjusted for possible confounders.

Results

Of the subjects, 24·5 % were categorized with Fe deficiency. However, no dietary factors assessed were significantly associated with Fe deficiency. The risk of Fe deficiency was significantly lower in women with infrequent or no menstrual cycles than in those with regular cycles (OR = 0·58; 95 % CI 0·34, 1·00) and significantly higher in women with heavy menstrual flow than in women with average flow, albeit that these were self-reported (OR = 1·83; 95 % CI 1·35, 2·48).

Conclusions

These results suggest that dietary habits, including Fe intake, do not significantly correlate with Fe deficiency among young Japanese women.

Effect of alcohol consumption, cigarette smoking and flushing response on esophageal cancer risk: a population-based cohort study (JPHC study)

We examined the effect of alcohol consumption, cigarette smoking and flushing response on esophageal squamous cell carcinoma (ESCC) in a large-scale population-based cohort study. 44,970 middle-aged and older Japanese men were followed. A total of 215 cases of ESCC were newly diagnosed. Alcohol consumption and cigarette smoking are strongly associated with the incidence of ESCC. Heavy alcohol consumption increased the risk of ESCC especially among heavy smokers with the flushing response (HR = 3.41, 95% CI = 2.10-5.51). Strong effect modification was detected in heavy smokers. Our results suggest that heavy alcohol consumption together with heavy smoking may increase the risk of ESCC particularly in individuals with the flushing response.

Overweight and obesity trends among Japanese adults: a 10-year follow-up of the JPHC Study

OBJECTIVE

Limited data are available regarding longitudinal changes in body weight. Here, we describe changes in the prevalences of overweight and obesity and calculated the incidence of these indices during a 10-year follow-up period for a large-scale cohort study in Japan.

DESIGN

Longitudinal analysis of data from a population-based cohort study, the Japan Public Health Center (JPHC) Study.

PARTICIPANTS

A total of 65 095 Japanese men and women, who were between the ages of 40 and 69 years at baseline and participated in the 5th- and 10th-year follow-up surveys of the JPHC, were enroled in the study.

MEASUREMENTS

Mean body mass index (BMI), calculated using self-reported height and weight, and the prevalences of overweight (BMI >or=25 kg/m(2)) and obesity (BMI >or=30 kg/m(2)) at each survey period. Incidences of overweight and obesity during the 10-year period.

RESULTS

On an average, individuals living in Okinawa had much higher BMIs than those living on the Main islands for all sex and age groups. During the follow-up period, the prevalences of overweight and obesity steadily increased in the cohorts aged less than 50 years at baseline in both sexes. Men in younger cohorts had a higher mean BMI than those in the same age group of older cohorts, whereas the opposite trend was observed in women. The incidence of overweight individuals was greater in Okinawa than on the Main islands and among younger generations than among older ones.

CONCLUSION

A longitudinal analysis at the individual level showed that the prevalences of overweight and obesity increased among middle-aged Japanese participants during the follow-up period. Among men, an increasing prevalence of obesity was observed among the younger generations. These findings should be taken into consideration when planning preventive strategies for obesity and its related diseases.

Association of dietary intake of soy, beans, and isoflavones with risk of cerebral and myocardial infarctions in Japanese populations: the Japan Public Health Center-based (JPHC) study cohort I

BACKGROUND

Soy and isoflavones have been proposed to reduce the risk of cardiovascular risk factors, but their potential as preventatives for cardiovascular disease remains uncertain. We investigated the association of soy and isoflavone intake with risk of cerebral and myocardial infarctions (CI and MI).

METHODS AND RESULTS

To examine the association of soy and isoflavone intake with the risk of CI and MI, we studied 40,462 Japanese (40 to 59 years old, without cardiovascular disease or cancer at baseline). They completed a food-frequency questionnaire (1990-1992) and received follow-up to 2002. After 503,998 person-years of follow-up, we documented incidence of CI (n=587) and MI (n=308) and of mortality for CI and MI combined (n=232). For women, the multivariable hazard ratios and 95% confidence limits for soy intake > or = 5 times per week versus 0 to 2 times per week were 0.64 (0.43 to 0.95) for risk of CI, 0.55 (0.26 to 1.09) for risk of MI, and 0.31 (0.13 to 0.74) for cardiovascular disease mortality. Similar but weaker inverse associations were observed between intake of miso soup and beans and risk of cardiovascular disease mortality. The multivariable hazard ratios for the highest versus the lowest quintiles of isoflavones in women were 0.35 (0.21 to 0.59) for CI, 0.37 (0.14 to 0.98) for MI, and 0.87 (0.29 to 2.52) for cardiovascular disease mortality. An inverse association between isoflavone intake and risk of CI and MI was observed primarily among postmenopausal women. No significant association of dietary intake of soy, miso soup, and beans and isoflavones with CI or MI was present in men.

CONCLUSIONS

High isoflavone intake was associated with reduced risk of CI and MI in Japanese women. The risk reduction was pronounced for postmenopausal women.

The Cultural Context of “Successful Aging” Among Older Women Weavers in a Northern Okinawan Village: The Role of Productive Activity

Basho-fu (Musa liukiuensis) weaving has long been part of the cultural identity of Ogimi villagers and has continued in the village as a cottage industry despite its almost complete disappearance throughout the rest of the Ryukyu archipelago. It has survived largely due to the concerted efforts of a few villagers and is now carried on mainly by middle-aged and older women. Almost every elderly woman in Ogimi has at least some experience in basho-fu weaving, and most still participate in some stage of the production process. Aged women form the bulk of the core group of workers that carries out the labor-intensive u-umi (spooling) and u-biki (fiber-cleaning) activities. Without this core group of elderly women, the whole production process would be in jeopardy. Thus, older women in Ogimi play a key role as valued workers in maintaining the basho-fu production process. In exchange for their continued participation, these elderly women receive symbolic capital in the form of respect and honors, as well as wages for their labor. We argue that participating in traditional basho-fu weaving helps these older women maintain an active engagement with life as healthy and productive members of society, a role that has been culturally sanctioned and has taken on moral import in Japan's rapidly aging society. Interestingly, "doing basho" may be considered one means to help achieve successful aging in this particular cultural context.

Egg consumption, serum total cholesterol concentrations and coronary heart disease incidence: Japan Public Health Center-based prospective study

Limited egg consumption is often recommended to reduce serum cholesterol concentration for the prevention of CHD. We examined the association of egg consumption and total cholesterol concentration with the risk of CHD. A total of 90 735 subjects (19 856 men and 21 408 women, aged 40-59 years in cohort I; 23 463 men and 26 008 women, aged 40-69 years in cohort II) were followed from 1990-4 to the end of 2001 under the Japan Public Health Center-based prospective study. Total cholesterol was obtained in 36 % of the subjects. Men and women were combined for the analyses. The subjects were categorised into four groups according to egg consumption. Subjects with total cholesterol >or=2200 mg/l were less frequent in frequent egg consumption groups in both cohorts (trend P<0.0001). Subjects with <1 d/week of egg consumption were more likely to avoid a cholesterol-rich diet. Egg consumption was not associated with the risk of CHD, although total cholesterol was significantly related to the risk of CHD. The multivariate hazard ratio of CHD in subjects with total cholesterol >or=2400 v. <1800 mg/l was 2.17 (95 % CI 1.22, 3.85; trend P=0.0018). In conclusion, eating eggs more frequently, up to almost daily, was not associated with an increase in CHD incidence for middle-aged Japanese men and women. Subjects with hypercholesterolaemia were less frequently in frequent egg consumption groups, probably because they avoided eating eggs.

Bowel Movement, State of Stool, and Subsequent Risk for Colorectal Cancer: The Japan Public Health Center–Based Prospective Study

PURPOSE

Evidence about whether irregular bowel movements or unusual stool conditions are associated with colorectal cancer is still inconsistent.

METHODS

We identified 479 newly diagnosed cases of colorectal cancer (303 men and 176 women) during a 7.9-year follow-up of a cohort consisting of 57,940 subjects (27,529 men and 30,411 women) aged 40 to 69 years at baseline. Bowel movements and stool conditions were asked through a self-administered questionnaire.

RESULTS

Neither high nor low frequency of bowel movements was associated with colorectal cancer incidence compared with one bowel movement per day. Multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) for two bowel movements or more per day were 1.03 (95% CI, 0.76-1.41) in men and 1.16 (95% CI, 0.68-2.00) in women. HRs for two to three bowel movements per week were 0.97 (95% CI, 0.61-1.55) in men and 0.75 (95% CI, 0.49-1.13) in women. There was no clear association between an unusual stool state, such as diarrhea or hard stools, and colorectal cancer.

CONCLUSION

Our results suggest that neither bowel movement frequency nor any specific state of stool causes colorectal cancer.

Body mass index, body height, and subsequent risk of colorectal cancer in middle-aged and elderly Japanese men and women: Japan public health center-based prospective study

OBJECTIVE

To investigate the association of body mass index (BMI) or body height with colorectal cancer incidence in a population-based prospective study.

METHODS

We identified 986 (626 men and 360 women) newly diagnosed cases of colorectal cancer during the 9.4-year follow-up of a cohort consisting of 102,949 (49,158 male and 53,791 female) middle-aged and elderly Japanese.

RESULTS

Lower BMI groups (lower than 23) were not associated with colorectal cancer compared with the 23-24.9 BMI group. Any categories of 25-26.9, 27-29.9, or 30 or more BMI were associated with an increased risk of colorectal cancer compared with the lower than 25 BMI (RR, 1.2 for 25-26.9, 1.4 for 27-29.9, and 1.5 for 30 or more; p for trend, 0.004) in men. These associations were more evident only in invasive-type cancer analysis. BMI was not associated with the risk of colorectal cancer in women. No significant association with height was obtained for either men or women.

CONCLUSIONS

The association of BMI with colorectal cancer was confirmed in a Japanese population as well as Western populations. Only invasive-cancer analysis suggested that BMI was important for tumor growth and proliferation. Approximately 6.7% of colorectal cancer was attributable to a BMI of 25 or higher in middle-aged and elderly Japanese men.

Fish, long-chain n-3 polyunsaturated fatty acids, and risk of colorectal cancer in middle-aged Japanese: the JPHC study

Although long-chain n-3 polyunsaturated fatty acids (Ln-3 PUFA), which are abundant in fish, have shown protective effects on colorectal cancer in laboratory studies, epidemiological studies to date have not been consistent. We evaluated the relationship of consumption of fish and Ln-3 PUFA to the colon and rectal cancer risk in the two cohorts of the Japan Public Health Center-based prospective study of 42,525 men and 46,133 women. Dietary and other exposure data were obtained between 1990 and 1994. Through December 1999, 705 cases of colon and rectal cancer were documented. When data from the two cohorts were pooled, multivariable relative risks (RRs) for the highest quartile compared with the lowest quartile of fish consumption were 1.07 (95% confidence interval, CI = 0.77-1.48) for colon cancer and 0.95 (95% CI = 0.63-1.43) for rectal cancer with no dose-risk trend. RRs for the highest quartile compared with the lowest quartile of eicosapentaenoic acid consumption were 1.05 (95% CI = 0.76-1.46) for colon cancer and 0.91 (95% CI = 0.60-1.38) for rectal cancer with no dose-risk trend. This study does not support the role of fish and Ln-3 PUFA in the etiology of colon and rectal cancer in this population whose fish consumption was high and the variation in Ln-3 PUFA consumption was large.

Ecological study of solar radiation and cancer mortality in Japan

Geographic observation of the increased mortality of some cancers at higher latitudes has led to a hypothesis that vitamin D produced after exposure to solar radiation has anti-carcinogenic effects. However, it is unclear whether such association would be observed in countries like Japan, where fish consumption, and therefore dietary vitamin D intake, is high. Pearson correlation coefficients were calculated between averaged annual solar radiation levels for the period from 1961 through 1990 and cancer mortality in the year 2000 in 47 prefectures in Japan, with adjustments for regional per capita income and dietary factors. A moderate, inverse correlation with solar radiation was observed for cancers of the esophagus, stomach, colon, rectum, pancreas, and gallbladder and bile ducts in both sexes (correlation coefficient, ranging from -0.6 to -0.3). The results of this study support the hypothesis that increased exposure to solar radiation reduces the risk of cancers of the digestive organs.

Salt and salted food intake and subsequent risk of gastric cancer among middle-aged Japanese men and women

Evidence on the association between salt intake and gastric cancer is sparse, especially in prospective studies. We conducted a population-based prospective study in Japan, where the majority of men has been infected with Helicobacter pylori. A total of 18 684 men and 20 381 women aged 40–59 years who reported their dietary habits and did not report any serious disease at baseline were followed from 1990 to 2001. A total of 486 cases, 358 men and 128 women, with histologically confirmed gastric cancer were documented among them. The quintile category of salt intake was dose-dependently associated with gastric cancer risk in men after adjusting for potential confounding factors (P for trend <0.001), while a trend was not clear in women (P for trend=0.48). Although stratification by study area, with varied salt intake and gastric cancer incidence, attenuated the observed clear associations with salt and salted foods, the frequency categories of highly salted foods such as salted fish roe and salted fish preserves were strongly associated with the risk in both sexes. Restriction of salt and salted food intake is a practical strategy to prevent gastric cancer in areas with high risk.

Estimation of dietary HCA intakes in a large-scale population-based prospective study in Japan

Heterocyclic amines (HCAs) are known mutagens and animal carcinogens formed in cooked meat and fish. Japanese people generally consume more fish than animal meat, and chopped and stir-fried method of meat preparation is favored as much as the grilled cooking method. Therefore, it is supposed that the foods contributing to HCA intake in Japan are different from those in western countries. However, dietary HCA intake levels and their main sources have not been estimated in Japan. The purpose of this study was to assess individual intake levels of specific HCAs in subjects of the Japan Public Health Center (JPHC)-based prospective study on cancer and cardiovascular disease (JPHC study). Individual intake levels of six predominant HCAs (Trp-P-1, MeIQ, MeIQx, 7,8-DiMeIQx, 4,8-DiMeIQx, and PhIP) were calculated for 39035 JPHC study participants (18290 men and 20745 women) from four geographic areas (9412 from Iwate, 12018 from Akita, 9896 from Nagano, and 7709 from Okinawa) based on a self-reported food frequency questionnaire (FFQ). Mean daily HCA intake levels (ng/kg per day) for subjects in the mainland areas (Iwate, Akita, and Nagano) were 1.06 (inter quartile range 0.50-1.35) in men and 1.10 (inter quartile range 0.53-1.40) in women. Mean daily HCA intake levels (ng/kg per day) for subjects in Okinawa Island were lower than those in the mainland; 0.83 (inter quartile range 0.33-1.04) in men and 0.92 (inter quartile range 0.33-1.18) in women. PhIP accounted for more than 60% of total HCA intake, followed by MeIQx and MeIQ. More than 50% of total HCA intake was derived from fish in the mainland, whereas more than 50% was from pork in Okinawa. Our study suggests that grilled fish are the major dietary sources of HCAs in Japanese, except those in Okinawa Island.

Dietary factors and stomach cancer mortality

The present study examined the relationship between stomach cancer and the low intake of fresh fruit and vegetables and/or a high intake of pickled, preserved or salted foods and frequent use of cooking oil. During 139,390 person-year of follow-up of over 13,000 subjects, 116 died from stomach cancer. Using a Cox proportional hazards-regression analysis of relative risk (RR, 95% CI) controlling for age, sex, smoking and other dietary factors, a significant decline was found with a high consumption of green and yellow vegetables (RR=0.4, 95% CI=0.2-0.9). Reductions of between 40 and 50% were also observed with a high consumption of fresh foods (fruit, cuttle fish, tofu, and potatoes), but these associations were not statistically significant. The risk was significantly increased by the high consumption of processed meat (RR=2.7, 95% CI=1.0-7.4) and by the frequent use of cooking oil (RR=4.0, 95% CI=1.3-11.8). The high consumption of pickled food and traditional soups also increased risk, but not significantly. The findings suggest that a diet high in salt and low in vitamins may be associated with an increase in stomach cancer.