Validation of a diet history questionnaire for use with Costa Rican adults

OBJECTIVE: To validate a diet history questionnaire (DHQ) using a weighed food record (WFR) as the standard method in the estimation of food consumption and nutrient intake in a group of adults. DESIGN: WFR: all foods consumed by subjects during 7 consecutive days were weighed and recorded by nutrition students. Two DHQ interviews were carried out on days 1 (first diet history questionnaire, DHQ1) and 28 (second diet history questionnaire, DHQ2). SETTING: Costa Rica. SUBJECTS: Sixty adults: 30 men and 30 women; 30 living in urban and 30 in rural areas. RESULTS: In comparison to the WFR, the DHQ1 gave statistically significant higher estimates of the mean intake of 19 nutrients for men and of three nutrients for women. The uncorrected correlation coefficients for nutrient intake according to both methods ranged from 0.40 to 0.83 for males and from 0.22 to 0.62 for females. Percentage of subjects classified in the same quartiles of nutrient intake according to each method ranged from 33.3% to 63.3% for males and from 23.3% to 53.3% for females. Misclassification in extreme quartiles ranged from 0% to 13.3% for both sexes. The mean food group consumption, according to the DHQ1, when compared with the WFR, gave statistically significant differences for three of the 18 food groups for men and for two groups in the case of women. The two applications of the DHQ gave similar results. CONCLUSION: Validation of a DHQ using a WFR as the standard method gave results that compare favourably with those reported by other authors. This study found important differences in the response of men and women to the DHQ: among men, the estimates of mean nutrient intake from DHQ1 were significantly greater than those of the WFR, while in the case of women, the mean nutrient intake estimates from both methods were not significantly different. There was a higher degree of correlation between the DHQ1 and the WFR mean nutrient intakes among men than among women. The DHQ showed good reproducibility.     

The effect of personal characteristics on the validity of nutrient intake estimates using a food-frequency questionnaire

OBJECTIVE: To assess validity of the Nambour food-frequency questionnaire (FFQ) relative to weighed food records (WFRs), and the extent to which selected demographic, anthropometric and social characteristics explain differences between the two dietary methods.DESIGN: Inter-method validity study; 129-item FFQ vs. 12 days of WFR over 12 months.SETTING: Community-based Nambour Skin Cancer Prevention Trial.SUBJECTS: One hundred and fifteen of 168 randomly selected participants in the trial (68% acceptance rate) aged 25-75 years.RESULTS: Spearman correlations between intakes from the two methods ranged from 0.18 to 0.71 for energy-adjusted values. Differences between FFQ and WFR regressed on personal characteristics were significantly associated with at least one characteristic for 16 of the 21 nutrients. Sex was significantly associated with differences for nine nutrients; body mass index (BMI), presence of any medical condition and age were each significantly associated with differences for three to six nutrients; use of dietary supplements and occupation were associated with differences for one nutrient each. There was no consistency in the direction of the significant associations. Regression models explained from 7% (riboflavin) to 27% (saturated fat) of variation in differences in intakes.CONCLUSIONS: The relative validity of FFQ estimates for many nutrients is quite different for males than for females. Age, BMI, medical condition and level of intake were also associated with relative validity for some nutrients, resulting in the need to adjust intakes estimates for these in modelling diet-disease relationships. Estimates for cholesterol, beta-carotene equivalents, retinol equivalents, thiamine, riboflavin and calcium would not benefit from this.     

Impact of disaggregation of composite foods on estimates of intakes of meat and meat products in Irish adults

OBJECTIVE: To evaluate the impact of the disaggregation of composite foods on intake estimates of meat and individual meat categories and on the contribution of meat to nutrient intakes in Irish adults. DESIGN: Data were analysed from the North/South Ireland Food Consumption Survey, which used a 7-day food diary to estimate food intake. Of 742 food codes that contained meat, 320 were codes for meat consumed as an individual portion and 422 were composite foods and were disaggregated to estimate the meat content. SUBJECTS: A nationally representative sample of 475 men and 483 women (not pregnant or lactating) from the Republic of Ireland aged 18-64 years. RESULTS: The mean intake of meat was 134 g day(-1) in consumers (98.5%) and men (168 g day(-1)) consumed significantly more (P<0.001) than women (102 g day(-1)). Mean intakes of meat were higher in subjects with manual skilled occupations (P<0.01) and lower in those with third-level educational qualifications (P<0.05). Without disaggregating meat from composite foods, meat intake was overestimated by 43% (57 g day(-1)) and varied widely by meat category. Meat disaggregated from composite foods contributed 25% of meat intake. The contribution meat made to nutrient intakes ranged from 29% for protein, vitamin B12, zinc and niacin to 20% for vitamin D, 16% for vitamin B6, 15% for thiamine and 14% for iron. CONCLUSIONS: Failure to disaggregate meat from composite foods substantially overestimates meat intake, with a large variation between meat categories. This has important implications for estimates of meat intakes in nutritional epidemiological studies and for food safety purposes.     

Validity of carbohydrate, glycaemic index and glycaemic load data obtained using a semi-quantitative food-frequency questionnaire

OBJECTIVE: To assess the ability of a food-frequency questionnaire (FFQ) to rank Australians according to their intake of total carbohydrate, sugar, starch, fibre, glycaemic index (GI) and glycaemic load (GL). DESIGN: Cross-sectional sample from a population cohort. SETTING: Two postcode areas west of Sydney, Australia. SUBJECTS: From 1992 to 1994, a total of 2868 older Australians provided dietary data using a 145-item Willett-derived FFQ. A representative sub-sample of 78 subjects completed three 4-day weighed food records (WFRs). Pearson and Spearman correlations, Bland-Altman plots and weighted kappa values were calculated. RESULTS: Compared with the WFR, the FFQ provided higher mean estimates of all nutrients except starch and GI. All Pearson and/or Spearman correlations were greater than 0.5, except for GL. For GI, sugar, starch and fibre, the regression lines from the Bland-Altman analysis indicated a non-significant linear trend (P = 0.07, P = 0.36, P = 0.28 and P = 0.10, respectively). For GL and total carbohydrate, however, there was a significant linear trend (P = 0.006 and P < 0.0001, respectively), indicating that as the GL and carbohydrate intake of individuals increased, so did the magnitude of the error between the FFQ and WFR. Weighted kappa values all indicated moderate to good agreement, with the exception of GL which was only fair. The proportions of subjects correctly classified within one quintile for all of the nutrients were over 50% and gross misclassification was low (<10%). CONCLUSION: This FFQ was able to rank individuals according to their intakes of total carbohydrate, sugar, starch, fibre and GI, but not as well for GL.     

Issues in assessing the validity of nutrient data obtained from a food-frequency questionnaire: folate and vitamin B12 examples

OBJECTIVE: To compare methods used to assess the validity of nutrient intake data obtained from a food-frequency questionnaire (FFQ), using folate and vitamin B12 as nutrient examples. DESIGN: Cross-sectional sample from a population cohort. SETTING: Two postcode areas west of Sydney, Australia. SUBJECTS: In total, 2895 people aged 49 years and older provided dietary data using a semi-quantitative FFQ (79% of 3654 subjects examined). The validity of the FFQ was assessed against three 4-day weighed food records (WFRs) completed by 78 people (mean age 70 years). RESULTS: Folate and vitamin B12 validity data were assessed using different methods. The Spearman ranked correlations (energy-adjusted) were 0.66 for folate and 0.38 for vitamin B12. Using the Bland-Altman method, following loge transformation, no linear trend existed between the differences and means for folate and vitamin B12. Large differences existed between the FFQ and WFR in individual cases, particularly for vitamin B12. Finally, data were divided into quintile categories for the test and reference method: 79% classified folate within one quintile, 65% classified vitamin B12 within one quintile; there was no gross misclassification for folate and only 3% misclassification for vitamin B12. CONCLUSIONS: Different methods of analysis provided different information about the validity of the FFQ. Correlation coefficients should not be used alone to assess the validity of nutrient data, but should be used in conjunction with Bland-Altman analyses. Depending on the use of the data, additional assessment of classification categories is recommended. This worked example demonstrates that absolute intakes of folate and vitamin B12 should be used with caution.     

Development and simulated validation of a food-frequency questionnaire for the Colombian population

OBJECTIVE: To develop a food-frequency questionnaire (FFQ) useful for ranking of nutrient intakes. DESIGN: Subjects consuming their regular diet completed 7 days of weighed intake registry (7-WIR). Foods for the FFQ were selected by stepwise multiple regression. The FFQ was then completed for each subject using data on individual food consumption from the 7-WIR. The correlation and agreement between the extrapolated FFQ and the 7-WIR data were assessed using Spearman's rank correlation coefficients (rS) and Bland and Altman's limits of agreement (LOA). SETTING: Bucaramanga, Colombia. SUBJECTS: We studied 97 randomly selected 20-40-year-old subjects. RESULTS: Sixty foods were selected for the FFQ. The 7-WIR and the extrapolated FFQ intake estimates correlated well. rS was 0.58 for energy, 0.53 for carbohydrate, 0.50 for total fat, and 0.48 for protein. For micronutrients, rS varied from 0.46 (manganese) to 0.71 (vitamin B12). FFQ average intake estimates were 83%, 80%, 86.2% and 86.4% of 7-WIR estimates for energy, carbohydrate, total fat and protein, respectively. LOA for these nutrients ranged between 45% and 165%. FFQ micronutrient intakes were on average 96% (median) of those from the 7-WIR, and the median lower and upper LOA were 50% and 203%. However, there was no indication that the degree of agreement varied with the level of intake. CONCLUSIONS: According to our simulated validation, this FFQ may be useful to rank subjects by nutrient intake. Its validity against standard independent measurements and its applicability to other subsets of the Colombian population should be carefully considered.     

What do babies eat? Evaluation of a food frequency questionnaire to assess the diets of infants aged 6 months

OBJECTIVE: To evaluate the relative validity of a food frequency questionnaire (FFQ) for assessing nutrient intakes in 6-month-old infants. DESIGN AND SETTING: The FFQ was developed to assess the diets of infants born to women in the Southampton Women's Survey (SWS), a population-based survey of young women and their offspring. The energy and nutrient intakes obtained from an interviewer-administered FFQ were compared with those obtained from a 4-day weighed diary. SUBJECTS AND METHODS: A sub-sample of 50 infants aged 6 months from the SWS had their diets assessed by both methods. The FFQ recorded the frequencies and amounts of milks, baby foods, regular foods and drinks consumed by the infants over the previous seven days. The diaries recorded the weights of all foods and drinks consumed by the infants on four separate days within 15 days following FFQ completion. RESULTS: Spearman rank correlation coefficients for intakes of energy, macronutrients and 18 micronutrients, determined by the two methods, ranged from r = 0.39 to 0.86; adjustment for energy intake tended to increase the correlation coefficients, range r(a) = 0.55 to 0.89. Bland-Altman statistics showed that mean differences between methods were in the range of -12.5% to +12.5% except for vitamin B12 (-18.9%). CONCLUSION: Although there were differences in absolute energy and nutrient intakes between methods, Spearman rank correlation coefficients indicated reasonable agreement in the ranking of intakes. The interviewer-administered FFQ is a useful tool for assessing energy and nutrient intakes of healthy infants aged about 6 months.     

Reproducibility of a short semi-quantitative food group questionnaire and its performance in estimating nutrient intake compared with a 7-day diet diary in the Million Women Study

OBJECTIVES: To assess the short- and long-term reproducibility of a short food group questionnaire, and to compare its performance for estimating nutrient intakes in comparison with a 7-day diet diary. DESIGN: Participants for the reproducibility study completed the food group questionnaire at two time points, up to 2 years apart. Participants for the performance study completed both the food group questionnaire and a 7-day diet diary a few months apart. Reproducibility was assessed by kappa statistics and percentage change between the two questionnaires; performance was assessed by kappa statistics, rank correlations and percentages of participants classified into the same and opposite thirds of intake. SETTING: A random sample of participants in the Million Women Study, a population-based prospective study in the UK. SUBJECTS: In total, 12 221 women aged 50-64 years. RESULTS: In the reproducibility study, 75% of the food group items showed at least moderate agreement for all four time-point comparisons. Items showing fair agreement or worse tended to be those where few respondents reported eating them more than once a week, those consumed in small amounts and those relating to types of fat consumed. Compared with the diet diary, the food group questionnaire showed consistently reasonable performance for the nutrients carbohydrate, saturated fat, cholesterol, total sugars, alcohol, fibre, calcium, riboflavin, folate and vitamin C. CONCLUSIONS: The short food group questionnaire used in this study has been shown to be reproducible over time and to perform reasonably well for the assessment of a number of dietary nutrients.     

Effect of the choice of food composition table on nutrient estimates: a comparison between the British and American (Chilean) tables

Objective: To determine the level of agreement between the American (Chilean) and British food composition tables in estimating intakes of macronutrients and antioxidants. DESIGN, SETTING AND SUBJECTS: Information based on a food-frequency questionnaire with emphasis on antioxidants was collected from 95 Chileans aged 24-28 years. Nutritional composition was analysed using the British table of food composition and the American table of food composition modified by Chilean food items. Mean differences and limits of agreement (LOAs) of estimated intake were assessed. RESULTS: Mean differences between the two tables of food composition ranged from 5.3% to 8.9% higher estimates when using the American (Chilean) table for macronutrients. For micronutrients, a bias towards a higher mean was observed for vitamin E, iron and magnesium when the American (Chilean) table was used, but the opposite was observed for vitamin A and selenium. The intra-class correlation coefficient (ICC) ranged from 0.86 (95% confidence interval (CI) 0.81-0.91) to 0.998 (95% CI 0.995-1.00), indicating high to excellent agreement. LOAs for macronutrients and vitamins A and C were satisfactory, as they were sufficiently narrow. There was more uncertainty for other micronutrients. CONCLUSION: The American table gives relative overestimates of macronutrients in comparison to the British table, but the relative biases for micronutrients are inconsistent. Estimates of agreement between the two food composition tables provide reassurance that results are interchangeable for the majority of nutrients.     

A comparison of four dietary assessment methods in materially deprived households in England

OBJECTIVES: Low-income households in the UK concentrate factors associated with poor record-keeping such as lower literacy, numeracy and English language skills. The present study aimed to (1) compare the validity and acceptability of three dietary survey methods against appropriate reference measures and (2) identify a method which was both valid and acceptable in low-income households. DESIGN: Cross-sectional design comparing three 4-day dietary survey methods (multiple-pass 24-hour recall, food checklist and semi-weighed method) against a 4-day weighed inventory and other reference measures within subjects. SETTING: London, UK, 2001. SUBJECTS: Low-income households were selected using a doorstep screening questionnaire in 18 of the 60 most deprived neighbourhoods in London. Results are based on 384 respondents (159 males, 225 females) aged 2-90 years in 240 households. Respondents were mainly White (48%), Black or Black British (31%) or Asian or Asian British (9%). RESULTS: The dietary survey method preferred by interviewers was the 24-hour recall. Most respondents preferred the food checklist. Compared with the weighed inventory, repeat 24-hour recalls and the food checklist yielded higher estimates of energy and nutrient intakes. The semi-weighed method was least liked and yielded the lowest estimates of intake. CONCLUSIONS: Based partly on evidence presented here and partly on evidence to be presented in later publications, four multiple-pass 24-hour recalls were recommended as the most appropriate method for a national study of diet and nutrition in low-income households in the UK.     

Validation of a semi-quantitative food-frequency questionnaire used among 2-year-old Norwegian children

OBJECTIVES: An adequate diet is of profound importance in infancy and early childhood. To ensure an optimal diet, knowledge about actual intake must be obtained. The aims of this study were to assess the validity of a semi-quantitative food-frequency questionnaire (SFFQ) applied in a large nation-wide survey among 2-year-old children and to examine the validity of the SFFQ in relation to different background parameters. DESIGN: The SFFQ was administered to the parents close to the child's second birthday, and one to two weeks later they started to weigh and record the child's diet for 7 days. SUBJECTS: One-hundred and eighty-seven families with a 2-year-old child completed both methods. RESULTS: There were no differences between the intakes of protein, saturated fatty acids, total carbohydrates and calcium estimated from the two methods. The average intake of all micronutrients, except for calcium, was overestimated by the SFFQ. Bland-Altman plots showed a systematic increase in difference between the two methods with increasing intake for most nutrients. Spearman correlation coefficients between methods for nutrient intakes ranged from 0.26 to 0.50, the median correlation was 0.38. The correlations increased when estimates were adjusted for energy intake, the median correlation being 0.52. Differences in observed validity were found according to the number of siblings.CONCLUSIONS: This study indicates that the SFFQ may be a valuable tool for measuring average intakes of energy, macronutrients and several food items among a 2-year-old population in Norway. The ability of the questionnaire to rank children according to intakes of nutrients and food items was rather low.     

An examination of the influence of eating location on the diets of Irish children

OBJECTIVES: To examine the influence of eating location on the quality of the diets of Irish children and to compare intakes at home with intakes at other people's homes and intakes outside the home, and to compare intakes at various locations outside the home. DESIGN: Food intake was measured using a 7-day weighed diary in 594 children from the Republic of Ireland (aged 5-12 years). Details of where the food was prepared or obtained were also recorded. RESULTS: Eighty-nine per cent of all eating occasions occurred at home; < 6% occurred at both other people's homes and outside the home (takeaway, restaurant, shop, other). The percentage of food energy from fat was above the recommended 35% at other people's homes and outside the home, specifically at takeaways and restaurants. Fibre and micronutrient intakes (per 10 MJ) were significantly higher at home than at the other locations (P < 0.05). Within the 'out' locations, fibre and micronutrient intakes were generally higher at restaurants and lower at shops. High consumers of foods outside the home had a statistically significant, but relatively small decline in nutrient intakes compared with non- or low consumers. Chips and processed potatoes, meat products, savouries, sugars and confectionery, and savoury snacks made the greatest contribution to foods consumed outside the home. CONCLUSIONS: The main focus of nutrition policies to improve the diets of Irish children should be the home environment rather than the food service sector. However, guidelines could call for better food choices outside the home to improve nutrient intakes.     

24-hour national dietary survey data: how do we interpret them most effectively?

OBJECTIVE: To illustrate the effect of common mistakes when using 24-hour national dietary survey data to estimate the prevalence of inadequate nutrient intakes. DESIGN: Raw data on nutrient intake from the Australian 1995 National Nutrition Survey were adjusted for within-person variance using standard techniques and corrected for underreporting using the criteria of Goldberg et al. The distributions for six nutrients were compared with current dietary reference values from the UK, USA and Australia. SETTING: A national sample of the Australian population with a 61.4% response rate. RESULTS: Adjusting for within-person variance reduced the range of nutrient intakes to 66-80% of the raw data range and the proportion with intakes below the estimated average requirement (EAR) by up to 20%. Excluding underreporters further reduced the proportion below the EAR by up to 10%. Using the dietary reference values from different countries also resulted in some markedly different estimates. For example, the prevalence of low folate intakes ranged from < 1 to 92% for adult women depending on the reference used. Except for vitamin A and protein, the prevalence of low intakes was invariably higher for women than for men. CONCLUSIONS: Estimates of the prevalence of low nutrient intakes based on raw 24-hour survey data are invariably misleading. However, even after adjustment for within-person variance and underreporting, estimates of the prevalence of low nutrient intakes may still be misleading unless interpreted in the light of the reference criteria used and supported by relevant biochemical and physiological measures of nutritional status.     

The influence of cereal and dairy consumption on the Irish diet: implications for developing food-based dietary guidelines

OBJECTIVES: To estimate the intakes of cereal and dairy products and their contribution to nutrient intakes in men and women from the Republic of Ireland with a view to formulating food-based dietary guidelines. DESIGN: The North/South Ireland Food Consumption Survey established a database of habitual food and drink consumption using a 7-day food diary. From this database all cereal and dairy products from recipes and identifiable sources were identified and a new database was generated from which analysis of the role of cereal and dairy products in the diet was carried out. RESULTS: Almost 100% of the population consumed cereal and dairy products over the course of the survey week. In general, men consumed significantly more cereal and dairy products than did women (P<0.05). Cereal products made an important contribution to the mean daily intakes of energy (26%), protein (21%), fat (13%), carbohydrate (41%), fibre (45%), iron (43%) and folate (27%). Dairy products also contributed largely to the mean daily intakes of energy (11%), protein (14%), fat (17%), calcium (48%), phosphorus (24%) and vitamin A (27%). Analysis of nutrient intakes across tertiles of cereal and dairy consumption showed that high consumers of wholemeal bread, breakfast cereals, reduced-fat milk and yoghurt had lower fat and higher carbohydrate, fibre and micronutrient intakes than low consumers of these foods. CONCLUSIONS: Findings from the present study could be used to develop effective health strategies to implement changes in cereal and dairy consumption that could alter fat, fibre and micronutrient intakes in the diet.     

Inadequate intakes of dietary zinc among pregnant women from subsistence households in Sidama, Southern Ethiopia

OBJECTIVE: To assess the prevalence of zinc inadequacy based on dietary intakes and plasma zinc concentrations and, simultaneously, the prevalence of inadequate intakes of energy, protein, calcium and iron. DESIGN: A cross-sectional study of a convenience sample of subsistence farming households in Sidama, Southern Ethiopia. SUBJECTS: Dietary intakes were calculated from 1-day weighed food records and 40 repeats from 99 pregnant women in the third trimester using analysed values of major staple foods for zinc, iron, calcium and phytate. The distribution of observed intakes was adjusted for usual intakes and the prevalence of inadequacy estimated using the estimated average requirement (EAR) cutpoint method. Prevalence of inadequacy for zinc, protein and iron intakes were compared with those based on biochemical measures. RESULTS: Prevalence of zinc inadequacy was very high: 99% for US FNB EAR and 100% for IZiNCG EAR compared to 72% based on low plasma zinc concentrations. Corresponding prevalence estimates for iron were much lower: 4% for inadequate intakes based on US FNB EAR vs. 8.7% for iron deficiency anaemia (haemoglobin < 110 g l-1; ferritin < 12 microg l-1) and 32.3% for low storage iron. Prevalence of inadequacy for protein was 100% for adjusted intakes and 91% for serum albumin < 32 g l-1. For calcium, 74% were at risk for inadequate intakes. CONCLUSION: The high prevalence of inadequate intakes of zinc and protein was reasonably consistent with those based on biochemical measures. Such dietary deficits could be overcome by regular consumption of cellular animal protein. In contrast, both dietary and biochemical measures of iron inadequacy were low.     

Validation of a food-frequency questionnaire for use in pregnancy

OBJECTIVES: As a part of an ongoing project to develop a nutritional screening tool, we evaluated the performance of a semi-quantitative food-frequency questionnaire (FFQ) in terms of validity in a Sheffield Caucasian pregnant population using two different statistical approaches--the correlation coefficient and the limits of agreement (LOA). The FFQ was designed specifically for pregnant women and previously used in a large-scale study. DESIGN: A validation study. SETTING: A community-based field study of a general population of pregnant women booked for their first antenatal appointment at the Jessop Wing, Royal Hallamshire Hospital, Sheffield, UK. SUBJECTS: One hundred and twenty-three women of different socio-economic status, aged between 17 and 43 years, provided complete dietary data. RESULTS: The validity of the FFQ was tested against a series of two 24-hour recalls. As expected, the intakes of all examined nutrients, except for iodine, carotene, vitamin E, biotin, vitamin C and alcohol, were higher when determined by the FFQ than when determined by 24-hour recall. Pearson's correlation coefficient between the two methods ranged from 0.19 (added sugar, zinc) to 0.47 (Englyst fibre). The LOA were broader for some of the nutrients, e.g. protein, Southgate fibre and alcohol, and an increasing lack of agreement between the two methods was identified with higher dietary intakes. CONCLUSIONS: The FFQ gave useful estimates of the nutrient intakes of Caucasian pregnant women and appears to be a valid tool for categorising pregnant women according to dietary intake. The FFQ performed well for most nutrients and had acceptable agreement with the 24-hour recall.     

The contribution of school meals to food consumption and nutrient intakes of young people aged 4-18 years in England

OBJECTIVES: To undertake secondary analyses of the 1997 National Diet and Nutrition Survey of Young People aged 4-18 years in order to describe the contribution of school meals to daily food and nutrient intakes; and to compare the findings from 1997 with data collected in English primary and secondary schools in 2004-2005. DESIGN: Cross-sectional analysis of 7-day weighed inventory food consumption data according to age, sex, household income, free school meals and breakfast consumption. Comparison of food consumption with the Balance of Good Health and of nutrient intake data with the Caroline Walker Trust (CWT) guidelines. SETTING: United Kingdom. SUBJECTS: One thousand four hundred and fifty-six UK schoolchildren aged 4-18 years, 7058 English primary-school pupils and 5695 English secondary-school pupils. RESULTS: Pupils' school meal choices in 1997 did not accord with the Balance of Good Health. Food choices in school were less healthy than choices outside school. School meals failed to make good the shortfalls in daily intakes of non-starch polysaccharides and zinc in primary-school pupils, and of calcium, iron, zinc, vitamin A and non-starch polysaccharides in secondary-school pupils, nor excess daily intakes of saturated fatty acids, non-milk extrinsic sugars and sodium at all ages. School meals typically failed to meet CWT guidelines. They were more likely to meet CWT guidelines when choice of foods was restricted. CONCLUSIONS: School meals need substantial improvement to meet CWT guidelines for healthy eating. The introduction of food-based guidelines for school meals in England in 2001 did not improve the food choices in school meals.     

Separate estimates of portion size were not essential for energy and nutrient estimation: results from the Southern Community Cohort food-frequency questionnaire pilot study

OBJECTIVE: A food-frequency questionnaire (FFQ) was developed to assess habitual dietary intake in the Southern Community Cohort Study (SCCS), a prospective epidemiological study to analyse disparities in cancer and other chronic diseases between African-Americans and Whites. DESIGN: Frequency and portion size estimates were obtained for each of 104 foods. Daily intakes of 13 food groups, energy and 18 nutrients were computed. Each participant's rank and quintile classification of nutrient intakes was determined with and without the use of the subject's reported portion size. SUBJECTS: The sample was obtained from the SCCS pilot study conducted in Tennessee, Mississippi and Florida, and consisted of 209 adults, 54% African-American, with a mean (standard deviation) age of 57.1 (12.5) years. RESULTS: Correlations between the ranks from the two methods of estimation were high, ranging from 0.66 to 0.94 for food groups and 0.81 to 0.94 for nutrients. Pearson correlations were similarly high for food groups and nutrients. Concordance in exact quintile rank across the nutrient indices ranged from 52 to 70%, rising to 90-99% for concordance within adjacent quintiles. CONCLUSIONS: To reduce the respondents' burden and to increase data completeness, the assignment of a uniform portion size when scoring the SCCS FFQ was considered acceptable.     

Validity of protein, retinol, folic acid and n-3 fatty acid intakes estimated from the food-frequency questionnaire used in the Danish National Birth Cohort

OBJECTIVE: To validate intakes of protein, folic acid, retinol and n-3 fatty acids estimated from a food-frequency questionnaire in week 25 of pregnancy (FFQ-25). DESIGN: Validation was done against a 7-day weighed food diary (FD) and biomarkers of the nutrients in gestation week 32-38. SUBJECTS AND SETTING: The FFQ-25 to be validated was used in the Danish National Birth Cohort comprising 101 042 pregnant Danish women, of whom 88 participated in the present validation study. RESULTS: Estimated intakes of protein, retinol and folic acid did not differ significantly between the two dietary methods, but intake of n-3 fatty acids was one third larger when estimated from the FFQ-25. The intakes estimated from the two dietary methods were all significantly correlated, ranging from 0.20 for retinol intake to 0.57 for folic acid intake. Sensitivities of being correctly classified into low and high quintiles were between 0.22 and 0.77, and specificities were between 0.62 and 0.89. Urinary protein content did not correlate significantly with protein estimated from the FFQ (r = 0.17, P > 0.05), but did with intake estimated from the FD (r = 0.56, P < 0.0001). Erythrocyte folate correlated significantly with the estimated total intake from the FFQ (r = 0.55, P < 0.0001) and the FD (r = 0.52, P < 0.0001). No correlations with plasma retinol were found. Erythrocyte eicosapentaenoic acid (C20:5n-3) correlated significantly with n-3 fatty acids intake estimated from both the FFQ-25 (r = 0.37, P < 0.001) and the FD (r = 0.62, P < 0.0001). CONCLUSION: The FFQ-25 gives reasonable valid estimates of protein, retinol and folic acid intakes, but seems to overestimate intake of n-3 fatty acids.     

Complementary foods consumed by 6-12-month-old rural infants in South Africa are inadequate in micronutrients

OBJECTIVE: To determine the nutrient composition of complementary foods consumed by 6-12-month-old South African infants. DESIGN: Nutrient intake was determined for infants who were recruited to participate in a randomised controlled trial using a single 24-hour dietary recall. SETTING/SUBJECTS: Infants aged 6-12 months (n=475) residing in The Valley of a Thousand Hills, a rural area in KwaZulu-Natal, South Africa. RESULTS: Energy and protein intakes from complementary foods were adequate. Infants who consumed infant products (commercially available fortified infant cereals/ready-to-eat canned baby foods/formula milk powder) had significantly higher intakes of calcium, iron, zinc, vitamin A, thiamine, riboflavin, niacin, vitamin B6, vitamin B12 and vitamin C than infants who did not consume any infant products. For infants who consumed infant cereals (n=142), these cereals provided 51% of total iron intake. Infant cereals provided more than 25% of total intake for magnesium, thiamine, niacin and vitamin B12. For infants consuming ready-to-eat canned baby foods (n=77), these products contributed less than 15% of total intake for all the micronutrients. The nutrient density of the complementary diet was less than half the desired density for calcium, iron and zinc. Animal products were consumed by 17% of infants, 26% consumed dairy products and 18% consumed vitamin-A-rich fruit and vegetables during the 24-hour recall period. CONCLUSION: The nutrient composition of complementary foods among rural South African infants was inadequate, especially for iron, zinc and calcium. Strategies should be developed to improve the nutritional quality of their diets.