Objective: Globally, the Na consumption of most people exceeds the WHO recommendation. To be effective, salt reduction programmes require assessment of the dietary sources of Na. Due to methodological difficulties however, comprehensive assessments are rare. Here, we identified Na sources in the Japanese diet using a 4 d diet record that was specifically designed for Na source description. Design: A cross-sectional study. Subjects: Apparently healthy men (n 196) and women (n 196) aged 20-69 years. Setting: The subjects were recruited from twenty-three of forty-seven prefectures in Japan.Results: The proportion of discretionary Na intake in total Na intake was 52·3 % in men and 57·1 % in women, and was significantly lower in younger subjects. The two major food groups contributing to Na intake were seasonings such as salt or soya sauce (61·7 % of total Na intake in men, 62·9 % in women) and fish and shellfish (6·7 % in men, 6·6 % in women). The third major contributor differed between men and women (noodles in men, 4·9 %; bread in women, 5·0 %). Further, the contribution of each food group to total Na intake differed among age groups. Conclusions: While individual efforts to decrease Na intake remain important, population approaches to reducing Na content in processed foods are already equally important and will assume greater importance in the future even in Japan, an Asian country facing a rapid Westernization in dietary habits.

Excess Na intake and insufficient K intake are well-known risk factors for CVD. International comparative studies have reported that Japan has the highest intake of Na and the lowest intake of K in the world. However, no recent study has precisely assessed Na and K intakes in Japanese adults. In the present study, Na and K intakes were estimated from two 24 h urine collections implemented in twenty-three out of forty-seven prefectures in Japan. Apparently healthy men (n 384) and women (n 376), aged 20 to 69 years, who had been working in welfare facilities were recruited, with data collection conducted in February and March 2013. The mean Na excretion was 206·0 mmol/d in men and 173·9 mmol/d in women. The respective values of K excretion were 51·6 and 47·2 mmol/d. The excretion of both Na and K varied considerably among the prefectures, and was higher in subjects with a higher BMI. In contrast, only K excretion was associated with age. After estimating the usual intakes of Na and K, it was found that none of the male subjects met the recommended Na intake values of the WHO, and that only 3·2 % met those of the Japanese government. The respective values for females were 0·1 and 5·0 %. For K intake, 7·5 % of the total subjects met the recommended values of the WHO and 21·7 % met those of the Japanese government. These findings suggest that there is an urgent need for the development of an effective intervention programme to reduce Na intake and promote K intake in the Japanese population.Key words: Sodium: Potassium: Intake: Japanese adults Recently, the WHO (1,2) published new guidelines for recommended intake levels of Na and K in adults and children. However, most people consume more Na and less K than these recommended values worldwide (3 -5) . Excess Na intake leads to hypertension that is associated with severe adverse health outcomes such as CHD and stroke, and the beneficial effect of salt reduction on these diseases has been confirmed (6,7) . Salt reduction is also a cost-effective means of reducing the risk of CVD (8,9) . Excess Na intake and insufficient K intake independently lead to hypertension and other CVD (10,11) , and higher K intake reduces blood pressure in individuals with hypertension (10,11) .The INTERSALT (3) and INTERMAP studies (5) have reported that Na intake is higher in the East Asian countries of China, the Republic of Korea, and Japan than in other countries. Substantial differences in intake have also been reported between northern and southern China and within Japan (3,5) . Moreover, K intake has been reported to be lower in these East Asian countries than elsewhere (3,5) . Nevertheless, the National Health and Nutrition Survey in Japan reported that Na intake is being continuously decreasing (12) . The reason for this trend is attributed to the Westernisation of the Japanese diet and change in food preservation method, i.e. the change from preservation with salt to the use of home refrigerators. Average Na and K intakes in the 2011 survey were 4287 mg/d (186·4 mmol/d) and...

Due to a lack of a food composition database on starch and sugars, we developed a comprehensive database on starch and seven types of sugars in commonly consumed foods (n = 2222) in Japan. Dietary record data of 368 toddlers (aged 18–35 months), 376 preschool children (aged 3–6 years), 915 schoolchildren (aged 8–14 years) and 392 adults (aged 20–69 years) were used. The mean starch intake ranged from 55.6 g/day (female toddlers) to 206.0 g/day (male schoolchildren). Irrespective of age and sex, >50% of starch was provided by rice and grains. The mean total sugar intake ranged from 46.1 g/day (female toddlers) to 68.7 g/day (male schoolchildren). In all age and sex groups, the major contributors of total sugar included sucrose (mean: 18.2–34.0 g/day), glucose (7.8–13.1 g/day), lactose (5.3–13.1 g/day) and fructose (7.6–11.1 g/day). The top food sources were dairy products (toddlers) and confectionaries (other age groups) for total sugar, confectionaries for sucrose, fruits (toddlers) and vegetables (other age groups) for glucose, dairy products for lactose and fruits (toddlers and preschool children) and vegetables (schoolchildren and adults) for fructose. In conclusion, this study clarified the starch and sugar intake in Japan and provides a foundation for future research.

Objective: To develop a greenhouse gas emissions (GHGE) database for Japanese foods using three different approaches, compare the results of estimated diet-related GHGE and determine major food contributors among Japanese adults. Design: Cross-sectional. Three GHGE databases were developed: (1) a literature-based method including a literature review of life cycle assessment studies of Japanese foods and (2) production- and (3) consumption-based input–output tables (IOT)-applied methods using the Japanese IOT. All databases were linked to the Japanese food composition table and food consumption data. Diet-related GHGE was estimated based on each database and the 4-d dietary record data. Diet-related GHGE were compared in both total and food group level between the databases. Setting: Japan. Participants: 392 healthy adults aged 20–69 years. Results: The mean diet-related GHGE significantly differed according to the calculation methods: 4145 g CO2-equivalent (CO2-eq)/d by the literature-based method, 4031 g CO2-eq/d by the production-based method and 7392 g CO2-eq/d by the consumption-based IOT-applied methods. It significantly differed in food group level as well. Spearman’s correlation coefficients between three methods ranged from 0·82 to 0·86. Irrespective of the methods, the top contributor to GHGE was meat (19·7–28·8 %) followed by fish and seafood (13·8–18·3 %). Conclusions: Although the identified major food contributors to GHGE were comparable between the three methods, the estimated GHGE values significantly differed by calculation methods. This finding suggested that caution must be taken when interpreting the estimated diet-related GHGE values obtained using the different calculation methods of GHGE.

We examined food combinations in relation to the quality of the overall diet and individual meals using a newly developed food combination questionnaire (FCQ) in a nationwide sample of Japanese adults aged 19–80 years (n = 2233). The quality of the overall diet and of each meal was assessed by the Healthy Eating Index-2015 (HEI-2015) and Nutrient-Rich Food Index 9.3 (NRF9.3). For all main meals (breakfast, lunch, and dinner), the most commonly consumed food combinations consisted of ‘rice, total vegetables, and tea and coffee’. Consistently positive associations between these food combinations and diet quality were found for breakfast (Spearman r: ≥0.46). Positive rather weak associations between these food combinations and diet quality were also observed for lunch (Spearman r: ≤0.48). Conversely, the associations were inconsistent for dinner: inverse associations with HEI-2015 (Spearman r: ≤−0.35) and generally weak positive associations with NRF9.3 (Spearman r: ≥0.09). For snacks, the most commonly consumed food combinations consisted of ‘confectioneries and tea and coffee’, but these showed rather weak associations with diet quality. Similar results were obtained when associations with the quality of overall diet were investigated. The FCQ may be useful in capturing the complex nature of food combinations in Japanese adults.