A child's diet is an important determinant of growth and development. Because of this, the accurate assessment of dietary intake in young children remains a challenge. A systematic search of studies validating FFQ methodologies in children 12 to 36 months of age was completed. English-language articles published until March 2016 were searched using three electronic databases (MEDLINE, EMBASE and CINAHL). Quality assessment of the identified studies was carried out using The Reduced Summary Score and EURopean micronutrient RECommendations Aligned (EURRECA) scoring system. Seventeen studies were included and categorised according to whether they reflected long-term (≥7 d) or short-term (<7 d) intake, or used a biomarker. A total score for each micronutrient was calculated from the mean of the correlation coefficients weighted by the study quality score. At least three validation studies per micronutrient were required for inclusion. Fifteen studies (83 %) that considered validity of the FFQ in assessing nutrient intakes had quality scores from 2·5 to 6·0. Of those, ten (67 %) studies found FFQ to have good correlations in assessing dietary intake (>0·4). Of the nutrients with three or more studies available, FFQ validated using a reference method reflecting short-term intake had a good weighted correlation for Ca (0·51), and acceptable weighted correlations for vitamin C (0·31) and Fe (0·33). Semi-quantitative FFQ were shown to be valid and reproducible when estimating dietary intakes at a group level, and are an acceptable instruments for estimating intakes of Ca, vitamin C and Fe in children 12 to 36 months of age.

Maternal vitamin intake during pregnancy is crucial for pregnancy outcomes and the child's subsequent health. However, there are few valid instruments for assessing vitamin intake that address the effects of nausea and vomiting during pregnancy (NVP). This study aimed to investigate the validity of a FFQ concerning vitamin intake during early and late pregnancy with and without NVP. The participants comprised 200 Japanese pregnant women who completed the FFQ and from whom blood samples were taken in early and late pregnancy. Energy-adjusted dietary vitamin intakes (vitamin C, folate, vitamin B6, vitamin B12, vitamin A, vitamin E and vitamin D) from FFQ were compared with their blood concentrations. A subgroup of women with NVP was investigated. In early pregnancy, significant correlations between FFQ and biomarkers were observed for vitamin C (r 0·27), folate (r 0·18) and vitamin D (r 0·26) in women with NVP and for vitamin A (r 0·18), vitamin B12 (r 0·24) and vitamin D (r 0·23) in women without NVP. No significant correlations were observed in either group for vitamins B6 or E. In late pregnancy, similar significant associations were observed for vitamin C (r 0·27), folate (r 0·22), vitamin B6 (r 0·18), vitamin B12 (r 0·27) and vitamin A (r 0·15); coefficients were higher among women without NVP. Our study demonstrates that the FFQ is a useful tool for assessing intake of several important vitamins in early and late pregnancy regardless of NVP status.

Hyperemesis gravidarum (hyperemesis), characterised by severe nausea and vomiting in early pregnancy, has an unknown aetiology. The aim of the present study was to investigate food and nutrient intake before pregnancy and the risk of developing hyperemesis in women participating in the Norwegian Mother and Child Cohort Study. From 1999 to 2002, a total of 7710 pregnant women answered a FFQ about their diet during the 12 months before becoming pregnant and a questionnaire about illnesses during pregnancy, including hyperemesis. Only women who were hospitalised for hyperemesis were included as cases. Nutrient intakes during the year before pregnancy did not differ between the ninety-nine women who developed hyperemesis and the 7611 who did not. However, the intake of seafood, allium vegetables and water was significantly lower among women who developed hyperemesis than among women in the non-hyperemesis group. Relative risks of hyperemesis were approximated as OR, and confounder control was performed with multiple logistic regression. Women in the upper tertile of seafood consumption had a lower risk of developing hyperemesis than those in the lower tertile (OR 0·56, 95 % CI 0·32, 0·98), and women in the second tertile of water intake had a lower risk of developing hyperemesis than those in the first tertile (OR 0·43, 95 % CI 0·25, 0·73). The findings suggest that a moderate intake of water and adherence to a healthy diet that includes vegetables and fish are associated with a lower risk of developing hyperemesis.

Interest in empirically derived dietary patterns has increased over the past decade. However, relatively few studies have evaluated dietary patterns using different dietary methods, or in young populations. We quantitatively compared dietary patterns from a FFQ with those from a 3 d food record (FR) in a cohort of adolescents. Subjects from the Western Australian Pregnancy Cohort (Raine) Study completed a semi-quantitative FFQ and a 3 d FR at 14 years of age (n 783). Major dietary patterns were identified using exploratory factor analysis on thirty-eight food groups. Dietary pattern z-scores were compared using 95 % limits of agreement (LOA) and Spearman's r. Two major dietary patterns were identified in the FFQ and FR: a ‘Healthy’ pattern, which was high in fresh fruit, vegetables, whole grains and grilled or canned fish, and a ‘Western’ pattern, which was high in take-away foods, confectionery, soft drinks, crisps and fried potato. The nutrient profiles of these dietary patterns were similar when estimated by the FFQ and FR. The LOA between dietary pattern scores from the FFQ and FR were − 1·69 to 1·75 (‘Healthy’) and − 1·89 to 1·82 (‘Western’). Minor differences in agreement were observed when boys and girls were analysed separately. Spearman's correlation coefficients between the FFQ and the FR were r 0·45 (‘Healthy’) and r 0·36 (‘Western’). Comparable dietary patterns may be obtained from the FFQ and FR using exploratory factor analysis. This supports the use of major dietary patterns identified using the FFQ in this adolescent cohort.

Whole cereal grain foods are rich in phytate, a Ca chelator, and could increase the risk of hip fracture. The objective of the present study was to investigate the association between baseline whole grain intake and incident hip fracture. In the present study, 29 192 women who at baseline in 1986 were aged 55–69 years, free of diabetes, and reported a plausible energy intake of 2508–20 900 kJ/d and reported no fracture since the age of 35 years were followed. Hip fracture (n 746) was self-reported in five questionnaires through 2004. Of 1451 hip fractures identified passively by Medicare linkage through 31 December 2004 (Medicare hip fracture), 507 had also been self-reported. Whole grain intake was inversely related to Medicare hip fracture (Ptrend = 0·02), but it was unrelated to self-reported hip fracture (Ptrend = 0·27). The hazard ratio in the highest to lowest quintile of whole grain intake for incident Medicare-only hip fracture (n 944) was 0·66 (95 % CI 0·53, 0·82) after adjustment for age, energy intake, education, BMI, waist-to-hip ratio, farm residence, physical activity, oestrogen use, smoking, alcohol use, history of cancer and other dietary variables. Medicare-only cases may have failed to self-report due to severe illness; hazard ratio for total mortality after hip fracture was 2·92 (2·37, 3·59) for Medicare-only cases v. Medicare-confirmed self-reported cases. In conclusion, in this cohort, the inverse association between whole grain intake and hip fracture was explained by ascertainment bias. Whole grain intake may increase the ability to respond to a questionnaire and self-report hip fracture, and could reflect less undocumented frailty.

The diet quality index (DQI) for preschool children is a new index developed to reflect compliance with four main food-based dietary guidelines for preschool children in Flanders. The present study investigates: (1) the validity of this index by comparing DQI scores for preschool children with nutrient intakes, both of which were derived from 3 d estimated diet records; (2) the reproducibility of the DQI for preschoolers based on a parentally reported forty-seven-item FFQ DQI, which was repeated after 5 weeks; (3) the relative validity of the FFQ DQI with 3 d record DQI scores as reference. The study sample included 510 and 58 preschoolers (2·5–6·5 years) for validity and reproducibility analyses, respectively. Increasing 3 d record DQI scores were associated with decreasing consumption of added sugars, and increasing intakes of fibre, water, Ca and many micronutrients. Mean FFQ DQI test–retest scores were not significantly different: 72 (sd 11) v. 71 (sd 10) (P = 0·218) out of a maximum of 100. Mean 3 d record DQI score (66 (sd 10)) was significantly lower than mean FFQ DQI (71 (sd 10); P < 0·001). The reproducibility correlation was 0·88. Pearsons correlation (adjusted for within-person variability) between FFQ and 3 d record DQI scores was 0·82. Cross-classification analysis of the FFQ and 3 d record DQI classified 60 % of the subjects in the same category and 3 % in extreme tertiles. Cross-classification of repeated administrations classified 62 % of the subjects in the same category and 3 % in extreme categories. The FFQ-based DQI approach compared well with the 3 d record approach, and it can be used to determine diet quality among preschoolers.

Estimation of whole-grain (WG) food intake in epidemiological and nutritional studies is normally based on general diet FFQ, which are not designed to specifically capture WG intake. To estimate WG cereal intake, we developed a forty-three-item FFQ focused on cereal product intake over the past month. We validated this questionnaire against a 3-d-weighed food record (3DWFR) in thirty-one subjects living in the French-speaking part of Switzerland (nineteen female and twelve male). Subjects completed the FFQ on day 1 (FFQ1), the 3DWFR between days 2 and 13 and the FFQ again on day 14 (FFQ2). The subjects provided a fasting blood sample within 1 week of FFQ2. Total cereal intake, total WG intake, intake of individual cereals, intake of different groups of cereal products and alkylresorcinol (AR) intake were calculated from both FFQ and the 3DWFR. Plasma AR, possible biomarkers for WG wheat and rye intake were also analysed. The total WG intake for the 3DWFR, FFQ1, FFQ2 was 26 (sd 22), 28 (sd 25) and 21 (sd 16) g/d, respectively. Mean plasma AR concentration was 55·8 (sd 26·8) nmol/l. FFQ1, FFQ2 and plasma AR were correlated with the 3DWFR (r 0·72, 0·81 and 0·57, respectively). Adjustment for age, sex, BMI and total energy intake did not affect the results. This FFQ appears to give a rapid and adequate estimate of WG cereal intake in free-living subjects.

The objective of the present study was to evaluate the validity of a FFQ in the estimation of dietary amino acid intake. Amino acid intake was calculated using a composition database developed based on the Standard Tables of Food Composition for amino acids in Japan. Subjects were subsampled from two populations of the Japan Public Health Center-based Prospective Study who volunteered to participate in the validation study of the FFQ. The first group was from the population the FFQ was developed for (internal population; n 215) and the second was a separate population to confirm external validity (external population; n 350). The validity of the FFQ was evaluated using 28 d weighed dietary records (DR) as a reference method. Spearman's rank correlation coefficients (CC) between amino acid intake from the FFQ and DR were calculated. The dietary intake of amino acids was slightly underestimated by the FFQ. Deattenuated CC of energy-adjusted amino acid intake according to the FFQ and corresponding amino acid intake according to the DR ranged from 0·15 to 0·52. The median CC for twenty amino acids were 0·33 for men and 0·25 for women in the internal population, and 0·40 for men and 0·30 for women in the external population. In conclusion, the validity of the FFQ in estimating amino acid intake was low to moderate.

The purpose of the present study was to test the usefulness of dish items selected in developing a dish-based FFQ (DFFQ) to be used for epidemiological studies in Korea. The dietary data of 6817 subjects from the 2001 Korean National Health and Nutrition Examination Survey were used for the analysis. The 24 h recall method was employed for the dietary survey. Initially, ninety-five dish items were selected in developing the DFFQ based on consumption frequency, contribution of selected nutrients and coverage of between-person variations. The usefulness of the selected ninety-five dish items was tested based on their degree of contribution in supplying nutrients in the cumulative percentage contribution (cPC), as well as on their degree of explanation for between-person variation in the cumulative regression coefficient (cMRC). According to the results, the ninety-five selected dish items accounted for an average of 92·3 % of seventeen nutrients consumed by the study subjects based on cPC estimation. The top twenty items among the ninety-five dish items covered 70 to 91 % of the between-person variation for the seventeen nutrients based on cMRC estimation. Thus, the results suggest that the ninety-five items would be useful in developing a FFQ for use in epidemiological studies of Koreans, within less than 10 % underestimation.

A review of the literature concerning the design, utilisation and validation of food-frequency questionnaires (FFQ) has been carried out using a semi-systematic approach to obtaining, reviewing and extracting data from articles. Databases were searched from 1980 to 1999. The present review identified 227 validation (from 1980 to September 1999) and 164 utilisation (for 1998 only) studies. A number of design issues have been evaluated through the present review. These include: the need to consider how portion sizes have been described, self-defined giving higher mean correlations; how an FFQ was administered, interviewer-administered giving higher mean correlations for some nutrients; how many items to include on an FFQ, those with the largest number of items having higher correlations. Validation techniques were described. Most validation studies involved comparing an FFQ against another dietary assessment method; only 19 % compared an FFQ to a biomarker. Measurement differences were most commonly assessed by correlation coefficients as opposed to other more appropriate methods. Mean correlation coefficients were highest for Ca and fat, and lowest for vitamin A and vegetables. The utilisation studies showed that FFQ were most commonly used in cross-sectional surveys, with ninety-three of the FFQ being designed to be disease-specific. The present review results were presented to a group of experts and a consensus arrived at concerning the development, validation and use of FFQ. Recommendations derived from the consensus arising from the literature review are presented as an appendix to the present paper.

There is growing interest in the use of dietary patterns as measures of exposure in studies of diet–disease relationships. However, relatively little is known about the impact of the type of dietary assessment method on the patterns observed. Using FFQ and food diary data collected from 585 women in early pregnancy we used principal component analysis to define dietary patterns. The first pattern was very similar in both datasets and was termed the ‘prudent’ diet. The second pattern, whilst comparable for the FFQ and food diaries, showed greater variation in coefficients than the prudent pattern; it was termed the ‘Western’ diet. Differences between the FFQ and diary scores were calculated for each woman for both the prudent and Western diet patterns. Of the differences in the prudent diet score, 95 % lay within ± 1·58 sd of the mean, and 95 % of the differences in the Western diet scores lay within ± 2·22 sd of the mean. Pearson's correlation coefficients were 0·67 (P < 0·001) for the prudent diet score and 0·35 (P < 0·001) for the Western diet score. The agreement between the FFQ and diary scores was lowest amongst respondents who were younger, had lower educational attainment and whose diaries were coded as ‘poor, probably incomplete’, although these effects were small. The first two dietary patterns identified in this cohort of pregnant women appear to be defined similarly by both FFQ and diary data, suggesting that FFQ data provide useful information on dietary patterns.

Relative validity and reproducibility of a semi-quantitative food-frequency questionnaire (FFQ) for measuring preschool children's usual Ca intake were assessed using parents or guardians as a proxy. Estimated diet records (EDR; 3d) were used as the reference method and reproducibility was measured by repeated FFQ administrations 5 weeks apart. From 2095 preschool children (2·5–6·5 years) randomly selected in Flanders (Flemish region of Belgium), 1052 returned a FFQ and EDR. Stringent exclusion procedures reduced the sample for validity analyses to 509 children. From a separate sample of 244 preschool children, 124 returned two FFQ, of whom sixty were included in the reproducibility analysis. Mean Ca intakes were 838 (sd 305) and 777 (sd 296) mg/d for EDR and FFQ respectively, indicating a mean difference of 60·9 (sd 294·4) mg/d (p<0·001). Pearson's correlation was 0·52. Cross-classification analysis of the FFQ and EDR classified 83%of the subjects in the same or adjacent category and 2·4% in extreme quartiles. Actual values for surrogate FFQ quartiles showed a progressive increase in Ca intake (p<0·001). The FFQ correctly identified 77% of the children consuming less Ca than the age-specific RDA (800mg/d). Correlation between repeated administrations was 0·79. No significant difference between mean Ca intakes was established by two administrations (23·8 (sd 161·2) mg/d). Cross-classification of repeated administrations classified 93·4% of the subjects in the same or adjacent category and no subjects in extreme categories. This FFQ tended to underestimate preschool children's Ca intake when administered by a proxy. However, it demonstrated good repeatability and fairly good ability to classify subjects into extremes of Ca intake.

We have developed a thirty-nine-item semi-quantitative food-frequency questionnaire (FFQ) to assess the dietary consumption of 11 746 men and women in a prospective cohort study that evaluates the health effects of As from drinking water in Bangladesh. In order to validate the FFQ, two 7 d food diaries (FD) were completed for 189 randomly selected cohort participants in two different seasons of the year. Nutrient values were converted based on both the United States Department of Agriculture's National Nutrient Database and a food composition table for the Indian subcontinent. Pearson product-moment and Spearman non-parametric rank correlation coefficients comparing food and nutrient consumptions estimated from FFQ and 7 d FD were calculated based on log-transformed consumption values with or without adjustment for total energy and correction for within-individual variation. Correlations of macronutrients and common micronutrients including total fat, monounsaturated fat, polyunsaturated fat, saturated fat, protein, carbohydrate, dietary fibre, Na, K, vitamin B6, vitamin B12, riboflavin, Mn, thiamin and Fe were moderately good, ranging from 0·30 to 0·76. However, correlations of other micronutrients were weak (<0·30). Large seasonal variations in intakes of retinol equivalents and vitamin C were observed. This analysis documents the degree of validity of the FFQ in measuring specific nutrient intakes in the study population. To our knowledge, the present study is the first to document the validity of a FFQ with the use of 7 d FD in a Bangladeshi population.