The salt intake of Japanese at home remains high. To aid in salt reduction and encourage a balanced diet, we conducted a cross-sectional study using data from a previous clinical trial in community-dwelling individuals to evaluate major salt sources and relationships among the intake of different dishes in the Japanese diet at home. Dietary records and urinary salt excretion measurements were performed daily for 1 month in seventy-nine participants. The records were classified into six grain dish categories as staple dishes, seven side dish categories and a snack category. Regression analyses were used to estimate (1) salt intake per meal for each category of grain dish, (2) salt intake per dish from each dish category and its contribution to the total salt intake and (3) the influence of grain dish selection on the frequencies of other dishes. Salt intake per meal was approximately 3 g, regardless of grain dish selection. Fish and meat dishes showed the largest contribution to the total salt intake (35 %), followed by vegetable dishes (19 %). The intake of fish or meat and vegetables was promoted by plain rice and reduced by ramen noodles. The intake of dairy products was only promoted by bread, while that of fruits was not influenced by any grain dish category. These results suggest simple strategies to reduce salt intake while maintaining dietary balance, such as eating plain rice more often and using less salt to cook meat/fish and vegetable dishes.

The limitations for self-reporting of dietary patterns are widely recognised as a major vulnerability of FFQ and the dietary screeners/scales derived from FFQ. Such instruments can yield inconsistent results to produce questionable interpretations. The present article discusses the value of psychometric approaches and standards in addressing these drawbacks for instruments used to estimate dietary habits and nutrient intake. We argue that a FFQ or screener that treats diet as a ‘latent construct’ can be optimised for both internal consistency and the value of the research results. Latent constructs, a foundation for item response theory (IRT)-based scales (e.g. Patient Reported Outcomes Measurement Information System) are typically introduced in the design stage of an instrument to elicit critical factors that cannot be observed or measured directly. We propose an iterative approach that uses such modelling to refine FFQ and similar instruments. To that end, we illustrate the benefits of psychometric modelling by using items and data from a sample of 12 370 Soldiers who completed the 2012 US Army Global Assessment Tool (GAT). We used factor analysis to build the scale incorporating five out of eleven survey items. An IRT-driven assessment of response category properties indicates likely problems in the ordering or wording of several response categories. Group comparisons, examined with differential item functioning (DIF), provided evidence of scale validity across each Army sub-population (sex, service component and officer status). Such an approach holds promise for future FFQ.

The aim of this study was to test the reproducibility and validity of a self-administered FFQ for the Trace Element Study of Korean Adults in the Yeungnam area (SELEN). Study subjects were recruited from the SELEN cohort selected from rural and urban areas in Yeungnam, Korea. A semi-quantitative FFQ with 146 items was developed considering the dietary characteristics of cohorts in the study area. In a validation study, seventeen men and forty-eight women aged 38–62 years completed 3-d dietary records (DR) and two FFQ over a 3-month period. The validity was examined with the FFQ and DR, and the reproducibility was estimated using partial correlation coefficients, the Bland–Altman method and cross-classification. There were no significant differences between the mean intakes of selected nutrients as estimated from FFQ1, FFQ2 and DR. The median correlation coefficients for all nutrients were 0·47 and 0·56 in the reproducibility and validity tests, respectively. Bland–Altman’s index and cross-classification showed acceptable agreement between FFQ1 and FFQ2 and between FFQ2 and DR. Ultimately, 78 % of the subjects were classified into the same and adjacent quartiles for most nutrients. In addition, the weighted κ value indicated that the two methods agreed fairly. In conclusion, this newly developed FFQ was a suitable dietary assessment method for the SELEN cohort study.

New technologies are promising for the use of short-term instruments for dietary data collection; however, innovative tools should be validated against objective biomarkers. The aim of the present study was to investigate the validity of a Web-based, self-administered dietary record (DR) tool using protein, K and Na intakes against 24 h urinary biomarkers (24 h U). Of the total participants, 199 adult volunteers (104 men and 95 women, mean age 50·5 (23–83 years)) of the NutriNet-Santé Study were included in the protocol. They completed three non-consecutive-day DR and two 24 h U on the first and third DR days. Relative differences between reported (DR) and measured (24 h U) intakes were calculated from the log ratio (DR/24 h U) for protein, K and Na intakes: − 14·4,+2·6 and − 2·1 % for men; and − 13·9, − 3·7 and − 8·3 % for women, respectively. The correlations between reported and true intakes were 0·61, 0·78 and 0·47 for men and 0·64, 0·42 and 0·37 for women for protein, K and Na, respectively. Attenuation factors, that represent attenuation of the true diet–disease relationship due to measurement error (a value closer to 1 indicating lower attenuation), ranged from 0·23 (Na, women) to 0·60 (K, men). We showed that the Web-based DR tool used in the NutriNet-Santé cohort study performs well in estimating protein and K intakes and fairly well in estimating Na intake. Furthermore, three non-consecutive-day DR appear to be valid for estimating usual intakes of protein and K, although caution is advised regarding the generalisability of these findings to other nutrients and general population.

Energy intake and renal function decrease with age. In patients with chronic kidney disease (CKD), spontaneous food intake decreases in parallel with the loss of renal function. The objective of the present study was to evaluate a possible relationship between renal dysfunction and energy intake in elderly community-dwelling men. A cross-sectional study including 1087 men aged 70 years from the Uppsala Longitudinal Study of Adult Men (ULSAM) community-based cohort was carried out. Dietary intake was assessed using 7 d food records, and glomerular filtration rate was estimated from serum cystatin C concentrations. Energy intake was normalised by ideal body weight, and macronutrient intake was energy-adjusted. The median normalised daily energy intake was 105 (interquartile range 88–124) kJ, and directly correlated with estimated glomerular filtration rate (eGFR) as determined by univariate analysis. Across the decreasing quartiles of eGFR, a significant trend of decreasing normalised energy intake was observed (P =0·01). A multivariable regression model including lifestyle factors and co-morbidities was used for predicting total energy intake. In this model, regular physical activity (standardised β = 0·160; P =0·008), smoking (standardised β = − 0·081; P =0·008), hypertension (standardised β = − 0·097; P =0·002), hyperlipidaemia (standardised β = − 0·064; P =0·037) and eGFR (per sd increase, standardised β = 0·064; P =0·04) were found to be independent predictors of energy intake. Individuals with manifest CKD (eGFR < 60 ml/min per 1·73 m2) were more likely to have lower energy intake than those without. In conclusion, there was a direct and independent correlation between renal function and energy intake in a population-based cohort of elderly men. We speculate on a possible link between renal dysfunction and malnutrition in the elderly.

Online self-administered data collection, by reducing the logistic burden and cost, could advantageously replace classical methods based on dietitian's interviews when assessing dietary intake in large epidemiological studies. Studies comparing such new instruments with traditional methods are necessary. Our objective was to compare one NutriNet-Santé web-based self-administered 24 h dietary record with one 24 h recall carried out by a dietitian. Subjects completed the web-based record, which was followed the next day by a dietitian-conducted 24 h recall by telephone (corresponding to the same day and using the same computerised interface for data entry). The subjects were 147 volunteers aged 48–75 years (women 59·2 %). The study was conducted in February 2009 in France. Agreement was assessed by intraclass correlation coefficients (ICC) for foods and energy-adjusted Pearson's correlations for nutrients. Agreement between the two methods was high, although it may have been overestimated because the two assessments were consecutive to one another. Among consumers only, the median of ICC for foods was 0·8 in men and 0·7 in women (range 0·5–0·9). The median of energy-adjusted Pearson's correlations for nutrients was 0·8 in both sexes (range 0·6–0·9). The mean Pearson correlation was higher in subjects ≤ 60 years (P = 0·02) and in those who declared being ‘experienced/expert’ with computers (P = 0·0003), but no difference was observed according to educational level (P = 0·12). The mean completion time was similar between the two methods (median for both methods: 25 min). The web-based method was preferred by 66·1 % of users. Our web-based dietary assessment, permitting considerable logistic simplification and cost savings, may be highly advantageous for large population-based surveys.

The aim of the present study was to assess reproducibility and relative validity of a self-administered FFQ used in the PREDIMED Study, a clinical trial for primary prevention of CVD by Mediterranean diet in a population at high cardiovascular risk. The FFQ was administered twice (FFQ1 and FFQ2) to explore reproducibility at 1 year. Four 3 d dietary records (DR) were used as reference to explore validity; participants therefore recorded their food intake over 12 d in the course of 1 year. The degree of misclassification in the FFQ was also evaluated by a contingency table of quintiles comparing the information from the FFQ2 and the DR. A total of 158 men and women (aged 55–80 years) were asked not to modify their dietary habits during the study period. Reproducibility for food groups, energy and nutrient intake, explored by the Pearson correlation coefficient (r) ranged 0·50–0·82, and the intraclass correlation coefficient (ICC) ranged from 0·63 to 0·90. The FFQ2 tended to report higher energy and nutrient intake than the DR. The validity indices of the FFQ in relation to the DR for food groups and energy and nutrient intake ranged (r) from 0·24 to 0·72, while the range of the ICC was between 0·40 and 0·84. With regard to food groups, 68–83 % of individuals were in the same or adjacent quintile in both methods, a figure which decreased to 55–75 % for energy and nutrient intake. We concluded that FFQ measurements had good reproducibility and a relative validity similar to those of FFQ used in other prospective studies.

Despite an increasing trend towards the use of convenience food, there is to date little debate on it in the nutritional sciences. In the present study, we present and evaluate data on consumption frequencies and composition of savoury convenience food in German families using data from the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study. The DONALD Study is an ongoing, longitudinal (open cohort) study (started 1985), collecting detailed data on diet, development, and metabolism in infants, children and adolescents. Dietary intake was measured by yearly repeated 3 d weighed dietary records (n 1558) in 554 subjects (278 boys; 276 girls), 3–18 years old, between 2003 and 2006. A total of 1345 (86%) 3 d dietary records mentioned consumption of at least one convenience food. Convenience food consumption (percentage of total food intake, g/d) increased with age from approximately 3% in the 3–8 year olds to 7% in 14–18-year-old boys and 5% in 14–18-year-old girls (P < 0·0001) but remained constant during the study period. Convenience foods contributed more to total fat (g/d) (P < 0·001) and less to total carbohydrate (P < 0·0001) than to total energy (kJ/d) intake. The 700 convenience-food products recorded by our sample had on average fourteen ingredients; 4% were flavourings and 16% were food additives. In conclusion, convenience foods were widely consumed by our sample of German children and adolescents and their consumption increased with age. The composition of convenience food was characterised by a high fat content and a high number of flavourings and food additives.