A scoping review of dietary assessment questionnaires potentially suitable for assessing habitual dietary intake in the National Health and Nutrition Survey, Japan.

This scoping review aimed to identify questionnaire-based dietary assessment methods for use in the National Health and Nutrition Survey (NHNS) in Japan. The search was conducted in three databases (PubMed, Web of Science, and Ichushi) to identify questionnaire such as food frequency questionnaire and dietary history questionnaire validated against dietary recalls or food records for the intakes of both food groups and nutrients among Japanese adults. Study quality was assessed based on previously developed criteria. We extracted the questionnaire characteristics and the design and results of the validation studies. We identified 11 questionnaires, with the number of food items ranging from 40 to 196, from 32 articles of good quality. In the validation studies, participants were aged 30-76 years and 90% of the articles used ≥3 d dietary records as reference. The number of nutrients and food groups with a group-level intake difference within 20% against the reference method ranged from 1 to 30 and 1 to 11, respectively. The range of mean correlation coefficients between questionnaire and reference methods were 0.35-0.57 for nutrients and 0.28-0.52 for food groups. When selecting a survey instrument in the NHNS from the 11 existing questionnaires identified in this study, it is important to select one with high group-level comparison and correlation coefficient values on the intended assessment items after scrutinizing the design and results of the validation study. This review may serve as a reference for future studies that explore dietary assessment tools used for assessing dietary intake in specific representative populations.

Web-Based Content on Diet and Nutrition Written in Japanese: Infodemiology Study Based on Google Trends and Google Search.

BACKGROUND: The increased availability of content of uncertain integrity obtained through the internet is a major concern. To date, however, there has been no comprehensive scrutiny of the fitness-for-purpose of web-based content on diet and nutrition. OBJECTIVE: This cross-sectional study aims to describe diet- and nutrition-related web-based content written in Japanese, identified via a systematic extraction strategy using Google Trends and Google Search. METHODS: We first identified keywords relevant for extracting web-based content (eg, blogs) on diet and nutrition written in Japanese using Google Trends. This process included identification of 638 seed terms, identification of approximately 1500 pairs of related queries (top) and search terms, the top 10% of which were extracted to identify 160 relevant pairs of related queries (top) and search terms, and identification of 107 keywords for search. We then extracted relevant web-based content using Google Search. RESULTS: The content (N=1703) examined here was extracted following a search based on 107 keywords. The most common themes included food and beverages (390/1703, 22.9%), weight management (366/1703, 21.49%), health benefits (261/1703, 15.33%), and healthy eating (235/1703, 13.8%). The main disseminators were information technology companies and mass media (474/1703, 27.83%), food manufacturers (246/1703, 14.45%), other (236/1703, 13.86%), and medical institutions (214/1703, 12.57%). Less than half of the content (790/1703, 46.39%) clearly indicated the involvement of editors or writers. More than half of the content (983/1703, 57.72%) was accompanied by one or more types of advertisement. The proportion of content with any type of citation reference was 40.05% (682/1703). The themes and disseminators of content were significantly associated with the involvement of editors or writers, accompaniment with advertisement, and citation of reference. In particular, content focusing on weight management was more likely to clearly indicate the involvement of editors or writers (212/366, 57.9%) and to be accompanied by advertisement (273/366, 74.6%), but less likely to have references cited (128/366, 35%). Content from medical institutions was less likely to have citation references (62/214, 29%). CONCLUSIONS: This study highlights concerns regarding the authorship, conflicts of interest (advertising), and the scientific credibility of web-based diet- and nutrition-related information written in Japanese. Nutrition professionals and experts should take these findings seriously because exposure to nutritional information that lacks context or seems contradictory can lead to confusion and backlash among consumers. However, more research is needed to draw firm conclusions about the accuracy and quality of web-based diet- and nutrition-related content and whether similar results can be obtained in other major mass media or social media outlets and even other languages.

Are popular books about diet and health written based on scientific evidence? A comparison of citations between the USA and Japan.

OBJECTIVES: To describe and compare the references cited in popular books about diet and health between the USA and Japan. DESIGN: Books were selected based on their best-seller rankings in the diet and health category of online bookstores. We identified references throughout all pages of the books and examined the number of references, reference format (identifiable or not) and presence of specific types of references, such as systematic reviews of human research. We compared the characteristics of references between the two countries and examined related factors to citation. SETTING: Cross-sectional study. PARTICIPANTS: Books (n 100 in each country). RESULTS: Among 100 books from each country, sixty-five US and sixty-six Japanese books had references. Forty-five US books cited more than 100 references, against only five Japanese books. The number of books that cited systematic reviews of human research differed between the USA (n 49) and Japan (n 9). Additionally, the number of books that provided identifiable information for all references was significantly higher in the USA (n 63) than in Japan (n 42). Books whose first authors have licences of medical doctors were more likely to cite references than those without in both countries. CONCLUSIONS: Two-thirds of books about diet and health cited references in both the USA and Japan, but Japanese books cited fewer references and were less likely to cite systematic reviews and provide identifiable references than US books. Further research into the scientific reliability of information in books about diet and health is warranted.

Development of a Diet Quality Score for Japanese and Comparison With Existing Diet Quality Scores Regarding Inadequacy of Nutrient Intake.

BACKGROUND: Few studies have explored optimal diet quality scores in Japan. OBJECTIVES: We developed a Diet Quality Score for Japanese (DQSJ) and examined the associations of DQSJ and existing diet quality scores with inadequacy of nutrient intake in Japanese adults. METHODS: Candidate components of the DQSJ were extracted from well-established diet quality scores: Healthy Eating Index-2015 (HEI-2015), Alternate Healthy Eating Index-2010 (AHEI-2010), Alternate Mediterranean Diet score (AMED), and Dietary Approaches to Stop Hypertension (DASH). From candidates, we selected the components of the DQSJ, considering potential health effects of the components (from the Global Burden of Disease Study) and dietary intake in Japan. The DQSJ included 10 components: fruits, vegetables, whole grain, dairy, nuts, legumes, fish, red and processed meat, sugar-sweetened beverages, and sodium. We calculated the DQSJ, HEI-2015, AHEI-2010, AMED, DASH, and Japanese Food Guide Spinning Top score (JFGST) based on 4-d dietary records of 392 Japanese aged 20-69 y. Inadequate intakes of 21 nutrients were assessed using the DRIs for Japanese. Logistic regression was used to examine the prevalence of inadequate nutrient intake according to quartiles of the scores. RESULTS: All examined scores except the JFGST were moderately to strongly correlated with each other (Spearman correlation coefficients: 0.52-0.84). They were inversely associated with the prevalence of inadequate intake of most nutrients (n = 16 for DQSJ and HEI-2015, n = 13 for AHEI-2010 and DASH, n = 17 for AMED, compared with n = 4 for JFGST). AMED was also positively associated with the prevalence of inadequate sodium intake, whereas no such associations were observed for the other scores. CONCLUSIONS: Similar to HEI-2015, AHEI-2010, and DASH, the DQSJ was generally associated with the low prevalence of inadequate intake of most nutrients in Japanese adults. Further evaluations against biomarkers and health outcomes are warranted.

A Scoping Review of Epidemiological Studies on Intake of Sugars in Geographically Dispersed Asian Countries: Comparison of Dietary Assessment Methodology.

Previous systematic reviews, which focused on sugar intake and its relation with health issues, were mainly conducted in Western countries, not Asian countries characterized by differences in dietary habits and disease prevalence. The scarcity of Asian studies may be attributed to the lack of assessment tools for estimating sugar intake. To provide an overview of the epidemiological studies on sugar intake in Asian countries, with a primary focus on dietary assessment methodology for estimating sugar intake, we conducted a scoping review of the epidemiological studies estimating sugar intake in Asian countries (the United Nations' definition) and Taiwan using PubMed and Web of Science. Study quality was evaluated based on its assessment of sugar intake in the whole diet, dietary assessment methods, and data sources used for estimating sugar content. We identified 143 studies from 136 publications from Eastern (n = 63), Southern (n = 30), South-Eastern (n = 26), and Western (n = 24) Asia. Total sugars were investigated in 95 studies, while 23-30 studies investigated sucrose, fructose, added sugars, and free sugars. The main aim of the selected studies was assessment of diet-disease relations (n = 85) and estimation of dietary intake (n = 40), and 62 studies assessed sugars as the primary exposure/outcome. A total of 120 studies assessed sugar intake in the whole diet, and 62 studies used validated FFQs or multiple-day dietary assessment methods. Only 41 studies used country-specific comprehensive food-composition databases or directly measured sugar content. Only 17 studies reported high-quality data. This review elucidated a sufficient number of epidemiological studies estimating sugar intake across Asian countries; however, most studies reported low-quality data. The results from our review showed that both feasible and validated dietary assessment methods, as well as comprehensive country-specific sugar-composition databases, are essential for producing high-quality studies with accurate sugar intake to examine its association with health outcomes.

Association of Hours of Paid Work with Dietary Intake and Quality in Japanese Married Women: A Cross-Sectional Study.

This study investigated the association of hours of paid work with dietary intake and diet quality among Japanese married women. This cross-sectional study was a secondary analysis of a nationwide population survey in 2013. The analytic sample included 644 married women aged 20-59 years. The participants were categorized into five groups according to hours of paid work per week: 0 (housewives), 1-14, 15-34, 35-42, and ≥43 h. Dietary intake was assessed by a self-administered diet history questionnaire. The Nutrient-Rich Food Index 9.3 (NRF9.3) was used to measure the dietary quality. The association of hours of paid work with dietary intake and NRF9.3 score was assessed using a multivariable general linear regression analysis with adjustments for confounders. Hours of paid work were associated with a higher intake of rice and lower intake of vegetables, potatoes, soy products, and seaweeds and nutrients including protein, dietary fiber, and most vitamins and minerals. Hours of paid work were negatively associated with the NRF9.3 score. This study showed that Japanese married women engaging in paid work, especially those who work long hours, have less healthy diets. Efforts to improve the dietary intake of married women with paid work might be needed.

Relationship between vitamin D receptor gene polymorphisms (BsmI, TaqI, ApaI, and FokI) and calcium intake on bone mass in young Japanese women.

BACKGROUND: The high prevalence of low bone mass in young women in Japan has emerged as a serious health issue in recent years. Therefore, the aim of the present study was to reevaluate the relationship between genetic and dietary factors, as well as its influence on bone mass in young Japanese women, with particular emphasis on vitamin D receptor (VDR) gene polymorphisms and calcium intake. METHODS: A total of 499 Japanese women aged 20-24 years were enrolled in the study. The bone mass of the calcaneus was assessed using the quantitative ultrasound method and expressed as the osteo sono-assessment index (OSI). VDR gene polymorphisms (BsmI, TaqI, ApaI, and FokI) were analyzed using DNA extracted from saliva. Calcium intake was assessed using the Food Frequency Questionnaire based on food groups (FFQg) and adjusted with the energy intake. Participants were divided into two groups based on the median calcium intake (250 mg/1000 kcal). RESULTS: Consequently, bone mass was significantly different among the BsmI and TaqI genotypes after adjusting for body mass index (BMI) (p = 0.030 and 0.019, respectively). In addition, the BsmI AA and ApaI GT genotypes showed significant differences in bone mass between the calcium-intake groups, with low OSI in the low-calcium intake group and high OSI in the high-calcium intake group, respectively, even after adjusting for BMI (p = 0.020 and 0.038, respectively). CONCLUSIONS: These findings may prove instrumental in developing a logical approach towards preventing bone loss in young Japanese women.

Effect of Cdx2 Polymorphism on the Relationship between Dietary Calcium Intake and Peak Bone Mass in Young Japanese Women.

Studies investigating the effect of the caudal-type homeobox protein 2 (Cdx2) polymorphism in the vitamin D receptor gene and calcium intake on bone mass have shown inconsistent results. This study investigated whether the effect of calcium intake on peak bone mass is affected by Cdx2 polymorphism in young Japanese women. A cross-sectional study of 500 young women was conducted. Dietary intake was assessed by the Food Frequency Questionnaire. The osteo sono-assessment index (OSI), assessed by the qualitative ultrasound method, was used as a bone mass index. The subjects were divided into two groups by the median calcium intake. The OSI was not different among Cdx2 genotypes and between calcium groups (p = 0.960, p = 0.191, respectively). The interaction between calcium and Cdx2 genotypes on the OSI approached significance (GG versus GA and AA genotypes, p = 0.092). The difference in the OSI between calcium groups was significant in the GG genotype (p = 0.028), but not in the GA or AA genotypes (p = 0.501, p = 0.306, respectively). Adjustment for covariates (body mass index and physical activity) did not change the results. In conclusion, the relationship between dietary calcium intake and peak bone mass may vary according to Cdx2 polymorphism.