Relative validity of a food-frequency questionnaire developed to assess food intake of schoolchildren living in the Brazilian Western Amazon

This study aimed to assess the relative validity of a food frequency questionnaire (FFQ) developed to assess food intake of schoolchildren from the Brazilian Western Amazon. The dietary intakes of 61 schoolchildren, aged between six and nine 9 years, were measured using two 24-hour dietary recalls and one FFQ, conducted with the children's, mother or guardians. Validity of the FFQ compared to the mean of the two dietary recalls was assessed using Pearson's correlation coefficient adjusted for attenuation and energy intake, Bland & Altman plots and evaluation of agreement levels between the two assessment methods. Energy-adjusted and deattenuated correlation coefficients ranged from -0.03 for vitamin C, to 0.93 for calcium. The mean coefficient was 0.46. The mean proportion of subjects classified within one quintile by the two methods was 66%. The Bland & Altman plots indicated good agreement for almost all nutrients, with a mean limit of agreement of 108%. These results indicate that, although there was a lack of accuracy for certain nutrients, such as vitamins A and C, the FFQ ensures reliable estimates of intake of most nutrients.     

Validation of a short food frequency questionnaire in Australian adults

The aim of this article is to report on the validity and internal consistency of a short food frequency questionnaire (FFQ) to measure dietary intake in Australian adults. A total of 407 individuals completed the short FFQ. The Cronbach’s alpha of 0.66 indicated acceptable internal consistency for the FFQ. Content validity was measured using factor analysis showed that 35% of total variance was explained by factor analysis. The FFQ was also validated against 31 3-day food records (FR). No significant difference between average intake of energy, most macronutrients, and some micronutrients between two instruments was identified. An acceptable levels of correlation (0.39–0.69) was observed between the two instruments. Bland and Altman’s plots showed relative agreement in both instruments with potential bias in measuring iron and iodine. The current FFQ can be an acceptable tool to quickly measuring dietary intake in Australian adults.     

Reproducibility and validity of an interviewer-administered semi-quantitative food frequency questionnaire to assess dietary intake of urban adults in southern India

We report on the reproducibility and validity of a food frequency questionnaire (FFQ) developed for southern India. One hundred and two adult subjects aged > or =20 years drawn from the Chennai Urban Rural Epidemiology Study participated. The FFQ was developed based on local foods and habits, and was administered three times at 0, 6 and 12 month periods (called FFQ1, FFQ2 and FFQ3) to assess the reproducibility. To test the validity of the FFQ, multiple 24-h recalls collected at 2-monthly intervals for a period of 1 year and the estimated energy intake/basal metabolic rate (EI/BMR) ratio were used. The 'EpiNu' in-house food and nutrient database was used to compile dietary intakes, which were analyzed for statistical analysis. The intraclass correlation coefficient for all three FFQs ranged from 0.72 for carbohydrates to 0.45 for folate. The de-attenuated Pearson correlation for the energy adjusted nutrients between FFQ3 and 24-h recalls ranged from 0.73 for carbohydrates to 0.35 for calcium. Bland and Altman plots for energy intake between the two methods showed the limits of agreement ranged from 768 to -1358 calories/day (+/-2 standard deviations). Misclassification was low for most of the nutrients. Under-reporting of the energy intake (EI/BMR ratio<1.2) was higher in females than males. This FFQ appears to be a robust tool to measure dietary intakes in southern India.     

Reproducibility and validity of an interviewer-administered semi-quantitative food frequency questionnaire to assess dietary intake of urban adults in southern India

We report on the reproducibility and validity of a food frequency questionnaire (FFQ) developed for southern India. One hundred and two adult subjects aged ≥20 years drawn from the Chennai Urban Rural Epidemiology Study participated. The FFQ was developed based on local foods and habits, and was administered three times at 0, 6 and 12 month periods (called FFQ1, FFQ2 and FFQ3) to assess the reproducibility. To test the validity of the FFQ, multiple 24-h recalls collected at 2-monthly intervals for a period of 1 year and the estimated energy intake/basal metabolic rate (EI/BMR) ratio were used. The ‘EpiNu’ in-house food and nutrient database was used to compile dietary intakes, which were analyzed for statistical analysis. The intraclass correlation coefficient for all three FFQs ranged from 0.72 for carbohydrates to 0.45 for folate. The de-attenuated Pearson correlation for the energy adjusted nutrients between FFQ3 and 24-h recalls ranged from 0.73 for carbohydrates to 0.35 for calcium. Bland and Altman plots for energy intake between the two methods showed the limits of agreement ranged from 768 to ?1358 calories/day (±2 standard deviations). Misclassification was low for most of the nutrients. Under-reporting of the energy intake (EI/BMR ratio<1.2) was higher in females than males. This FFQ appears to be a robust tool to measure dietary intakes in southern India.     

Development,relative validity,and reliability of a food frequency questionnaire for a case-control study on dietary advanced glycation end products and diabetes complications

Abstract

Dietary advanced glycation end products (dAGEs) could be involved on diabetes complications, yet their quantification is not standardized. The objective of this study was to design a food frequency questionnaire (FFQ) for dAGEs, and to assess its reliability and validity. For the design, data from 30 subjects was used. The final instrument had 90 food items. To measure reliability and validity, 20 participants with type 2 diabetes filled out twice the FFQ (FFQ-T1, FFQ-T2) and 7-day food records (7-dFR). The Shrout–Fleiss coefficient was 0.98 showing good reliability. For validation, the results for the weighted kappa were 0.55 (moderate agreement) for FFQ-T1 and 0.64 (good agreement) for FFQ-T2, and 75% and 80% of subjects respectively were correctly classified into tertiles; Bland–Altman graphics showed no systematic bias. This FFQ is comparable to 7-dFR for measuring dAGEs. To our knowledge, this is the first questionnaire designed to measure specifically dAGEs.     

Development and evaluation of a semi-quantitative food frequency questionnaire for use in urban and rural India

The objective of this study was to develop and evaluate a semi-quantitative food frequency questionnaire (FFQ) for use in urban and rural India. A single FFQ was developed for use in cities and rural areas of four regions of India. To assess validity, the FFQ was administered to 530 factory workers and rural dwellers, and subsequently three 24 hour recalls were administered on different days. Nutrient and food group intake calculated from these two methods were compared using medians, kappa statistics, Spearman's correlation coefficients and Bland- Altman plots. Dietary intake was overestimated by the FFQ compared to the 24 hour recalls (mean difference in energy intake = 1743 kJ), with kappa statistics ranging from 0.07 (egg) to 0.51 (carbohydrate). The results showed acceptable validity for measuring intakes of groups, and demonstrated that it is feasible to measure dietary intake in diverse regions of India with a single FFQ.     

Development and Relative Validity of a Semiquantitative Food Frequency Questionnaire to Estimate Dietary Intake among a Multi-Ethnic Population in the Malaysian Cohort Project

Measuring dietary intakes in a multi-ethnic and multicultural setting, such as Malaysia, remains a challenge due to its diversity. This study aims to develop and evaluate the relative validity of an interviewer-administered food frequency questionnaire (FFQ) in assessing the habitual dietary exposure of The Malaysian Cohort (TMC) participants. We developed a nutrient database (with 203 items) based on various food consumption tables, and 803 participants were involved in this study. The output of the FFQ was then validated against three-day 24-h dietary recalls (n = 64). We assessed the relative validity and its agreement using various methods, such as Spearman’s correlation, weighed Kappa, intraclass correlation coefficient (ICC), and Bland–Altman analysis. Spearman’s correlation coefficient ranged from 0.24 (vitamin C) to 0.46 (carbohydrate), and almost all nutrients had correlation coefficients above 0.3, except for vitamin C and sodium. Intraclass correlation coefficients ranged from −0.01 (calcium) to 0.59 (carbohydrates), and weighted Kappa exceeded 0.4 for 50% of nutrients. In short, TMC’s FFQ appears to have good relative validity for the assessment of nutrient intake among its participants, as compared to the three-day 24-h dietary recalls. However, estimates for iron, vitamin A, and vitamin C should be interpreted with caution.     

Validation of a Short Food Frequency Questionnaire to Measure Dietary Intake of a Selection of Micronutrients in Oncology Patients Undergoing Systemic Therapy

Dietary intake, specifically consumption of anti-inflammatory micronutrients, can play a role in both cancer initiation as well as the treatment-related outcomes experienced by patients receiving systemic cancer therapy. Increasing research is being conducted to determine whether micronutrient supplementation can aid in altering the tumor microenvironment (TME), reducing inflammatory side effects and immune-related adverse events (irAEs). However, further research pertaining to the adequacy of dietary micronutrient intake is indicated in the oncology cohort. Currently, no tool measuring dietary intakes of various micronutrients exists in the oncology population. In this study, a 21-item food frequency questionnaire (FFQ) measuring intakes of 14 different micronutrients was validated using diet history as the reference method in 112 oncology patients. Bland Altman plot and Passing Bablok regression analysis were conducted to determine agreement between the two methods. The results showed adequate agreement between FFQ and diet history for 12 nutrients including copper, iron, vitamins A, E, and D, alpha linolenic acid (ALA), long-chain omega 3 fatty acids (LC n3-FA), arginine, glutamic acid, isoleucine, leucine, and valine. This 21-item FFQ, which takes an average of 10 min to complete, can be utilized as a quick screening tool to determine adequacy for 12 different micronutrients in place of a diet history.     

Relative Validity and Reproducibility of a Food Frequency Questionnaire to Assess Food Group Intake in Pregnant Jordanian Women

BackgroundResearch on the relationship between maternal diet and pregnancy outcomes requires valid dietary assessment tools in pregnancy.ObjectiveThis study aimed to develop and examine the relative validity and reproducibility of a quantitative food frequency questionnaire (FFQ) to estimate food group intake in a sample of pregnant Jordanian women.DesignIn this validation study, food group intake from a culturally sensitive quantitative FFQ was compared with food group intake from three 24-hour dietary recalls.Participants and settingThe validation study was conducted from 2015 to 2017 at the maternity clinics in Jordan University Hospital among 131 healthy singleton pregnant Jordanian women. Of these women, 30 also took part in the reproducibility phase, which involved repeated completion of the FFQ in a time frame of 1 month. Pregnant women who had gestational diabetes, preeclampsia, and chronic diseases were excluded.Main outcome measuresRelative validity and reproducibility of a 117-item quantitative FFQ used to estimate usual food intake over a period of 1 month.Statistical analyses performedIntraclass correlation coefficients and weighted κ statistics were calculated to test the reproducibility between the two administrations of the FFQ. Pearson correlations were estimated to validate the FFQ against 24-hour dietary recalls. Cross-classification and Bland-Altman plots were used to examine the agreement between the two dietary assessment methods.ResultsThe intraclass correlation coefficients between the two FFQs ranged from 0.24 for legumes to 0.93 for processed meats. A moderate level of agreement was observed between two FFQs. De-attenuated and energy-adjusted correlations ranged from 0.08 for sweets and sugar to 0.93 for sugary drinks. On average, 50.9% and 45.2% of participants were classified by the FFQ and the 24-hour dietary recalls into the same quartile based on their crude and energy-adjusted food group intake, respectively. Bland-Altman plots showed satisfactory agreement between two methods for most food groups.ConclusionsThe FFQ showed moderate reproducibility and good relative validity for most food groups.     

Relative validity of dietary patterns during pregnancy assessed with a food frequency questionnaire

Abstract

This study aimed to assess the relative validity of maternal dietary patterns derived from a semi-quantitative food frequency questionnaire (FFQ). A total of 162 pregnant women aged 19–40-years-old were enrolled from the Universiti Sains Malaysia (USM) Birth Cohort Study in year 2010 and 2011. The FFQ was compared with three 24-h dietary recalls (DRs). Two major dietary patterns were derived from the principle component analysis which are labeled as Healthy and Less-Healthy patterns. The Pearson correlation coefficients between FFQ and DRs for Healthy and Less-Healthy patterns were 0.59 and 0.63, respectively. At least 45% of the participants were correctly classified into the same third from the FFQ and DR for both dietary patterns. The weighted kappa showed moderate agreement for Healthy pattern while good agreement for Less-Healthy pattern between these two dietary assessment methods. Our results indicate reasonable validity of the dietary patterns identified from the FFQ in pregnant women.     

Comparison of a food frequency questionnaire with an online dietary assessment tool for assessing preschool children’s dietary intake

Background: It is important to assess the dietary habits of children as they progress from early childhood to adolescence. However, there are few validated tools available to assess the diet of this group of children. The present study aimed to investigate the relative validity of a food frequency questionnaire (FFQ) developed for use in a biennial longitudinal study. Methods: The parents of 216 Belgian–Flemish preschool children completed a FFQ (including questions on 77 food groups) and an online dietary assessment tool for three nonconsecutive days on their child’s diet. Intakes of energy, macronutrients, fibre, calcium and 20 food groups recorded by both methods were compared using Spearman’s correlations, Wilcoxon’s signed rank test and Bland and Altman analyses. Results: At the group level, good agreement was found for energy, fat and protein intake, an overestimation was found for carbohydrates (5.6%) and fibre (13.3%), and an underestimation was found for calcium (9%). For the food groups, overestimation as well as underestimation and good agreement were found, although overestimation was most common. Good agreement was found in ranking the children’s fruit (r = 0.53), beverages (r = 0.58–0.76), soup (r = 0.51), breakfast cereals (r = 0.55) and calcium (r = 0.59) intake according to both methods. Conclusion: The results obtained revealed that the FFQ was a useful alternative for estimating energy and macronutrient intake at a group level; however, when used to estimate fibre and calcium intake, respectively, over‐ and underestimation need to be considered. The short reference period (3 days) may have compromised agreement in ranking and agreement at the individual level.     

Reliability and Concurrent and Construct Validity of a Food Frequency Questionnaire for Pregnant Women at High Risk to Develop Fetal Growth Restriction

Accuracy of dietary assessment instruments such as food frequency questionnaire (FFQ) is crucial in the evaluation of diet–disease relationships. Test–retest reliability and concurrent and construct validity of a FFQ were evaluated in 150 pregnant women at high risk to develop fetal growth restriction randomly selected from those included in the improving mothers for better prenatal care trial Barcelona (IMPACT BCN). The FFQ and dietary records were performed at baseline and 34–36 weeks of gestation. Test–retest reliability of the FFQ for 12 food groups and 17 nutrients was moderate (ICC = 0.55) and good (ICC = 0.60), respectively. Concurrent validity between food, nutrients and a composite Mediterranean diet score (MedDiet score) and food records was fair for foods and nutrients (ρ average = 0.38 and 0.32, respectively) and moderate (r = 0.46) for the MedDiet score. Validation with biological markers ranged from poor (r = 0.07) for olives to moderate (r = 0.41) for nuts. A fair concordance between methods were found for nutrients (weighted κ = 0.22) and foods (weighted κ = 0.27). The FFQ-derived MedDiet score correlated in anticipated directions with intakes of nutrients and foods derived by food records. The FFQ showed a moderate test–retest reliability and reasonable validity to rank women according to their food and nutrient consumption and adherence to the Mediterranean diet.     

Validity and reliability of a self-administered food frequency questionnaire for the JPHC study: The assessment of amino acid intake

Background

The Japanese database of food amino acid composition was revised in 2010 after a 24-year interval. To examine the impact of the 2010 revision compared with that of the 1986 revision, we evaluated the validity and reliability of amino acid intakes assessed using a food frequency questionnaire (FFQ).

EURRECA: EURopean micronutrient RECommendations Aligned. Preparing the way

Background There is increasing evidence that higher intakes of carotenoids could protect against oxidative and light damage in premature infants and may promote other health benefits in both mothers during pregnancy and lactation and in newborn infants. Aim of the study To develop and validate a brief quantitative food frequency questionnaire (FFQ) aimed at assessing lutein and zeaxanthin intake in women. Methods In this cross-sectional study, estimates of lutein and zeaxanthin intake from the FFQ were compared with a 7-day dietary record and with plasma concentrations of these carotenoids. This primary care study was conducted in Pavia, Italy. Subjects were all female volunteers, aged 20–25 years (mean age 22.7 ± 2.1 years), university students. Of the 110 women initially recruited, 87 completed diet questionnaires and donated a blood sample. Dietary intake was assessed by the FFQ by interview and 7-day dietary records chosen as a reference standard, using photographic estimations of portion sizes. Plasma concentrations of lutein and zeaxanthin were measured by HPLC. Pearson’s correlation coefficient and Bland Altman Regression analysis were used. Results Mean dietary lutein and zeaxanthin intakes were 1,107 ± 113 μg/day from the FFQ questionnaire and 1,083 ± 116 μg/day from the 7 day dietary records. The mean difference in intake assessed by the two methods (−24.5 ± 38.3 μg/day) did not differ significantly from zero. Dietary intake of lutein and zeaxanthin measured with the FFQ and plasma nutrient concentration among this sample were significantly correlated (r = 0.76, P < 0.0001). Mean plasma lutein and zeaxanthin concentrations were 0.33 ± 0.09 μmol/l. Conclusions This FFQ could be used to assess lutein and zeaxanthin intake in adult women.     

A new self-administered semi-quantitative food frequency questionnaire to estimate nutrient intake among Italian adults: development design and validation process

Food Frequency Questionnaires (FFQs) are valuable research tools in nutritional epidemiology. This study aimed to develop and validate a new semi-quantitative FFQ, specifically designed for the Italian population and best fitted for self-administration. During the development process, we adapted to Italian needs the validated FFQ proposed by the Fred Hutchinson Cancer Research Center, revising food items, food frequency scale, portion sizes, and time frame. To assess the validity of the proposed FFQ, we compared the estimated daily intake using FFQ with the mean of 3-day food diaries and one 24-hour recall (considered as reference method). The validation process was conducted among a cohort of 51 healthy subjects enrolled in a clinical trial. Four statistical tests were applied on 23 estimated nutrient intakes. Spearman's coefficients ranged from 0.223 (sodium) to 0.748 (alcohol) and were good (≥0.50) and acceptable (0.20-0.49) for 7 and 16 nutrients, respectively. Cross classification showed a good agreement (≥50% in the same tertile or ≤10% in the opposite tertile) for 7 nutrients. The weighted Cohen's kappa values indicated an acceptable outcome (0.20-0.60) for 13 nutrients. Bland Altman plots did not show heteroscedasticity in the error terms, despite the presence of a bias. Our study provided a new Italian semi-quantitative FFQ for self-administration with an acceptable validation level. Its definitive release requires additional refinements and efforts.     

Comparability of a short food frequency questionnaire to assess diet quality: the DISCOVER study

This study aims to assess comparability of a short food frequency questionnaire (SFFQ) used in the Determinants of Suicide: Conventional and Emergent Risk Study (DISCOVER Study) with a validated comprehensive FFQ (CFFQ). A total of 127 individuals completed SFFQ and CFFQ. Healthy eating was measured using Healthy Eating Score (HES). Estimated food intake and healthy eating assessed by SFFQ was compared with the CFFQ. For most food groups and HES, the highest Spearman’s rank correlation coefficients between the two FFQs were r?>?.60. For macro-nutrients, the correlations exceeded 0.4. Cross-classification of quantile analysis showed that participants were classified between 46% and 81% into the exact same quantiles, while 10% or less were misclassified into opposite quantiles. The Bland–Altman plots showed an acceptable level of agreement between the two dietary measurement methods. The SFFQ can be used for Canadian with psychiatric disorders to rank them based on their dietary intake.     

Validity and reliability of a quantitative food frequency questionnaire measuring n-3 fatty acid intakes in cardiac patients in the Midwest: a validation pilot study

The purpose of this pilot study was to test the validity and reliability of a quantitative n-3 fatty acid food frequency questionnaire (FFQ) for later use with larger groups of individuals. A convenience sample of heart patients provided dietary data via three 24-hour food recalls and FFQs. Participants were women (n=17) and men (n=11), 43 to 77 years of age. The association of mean daily intake of n-3 fatty acids obtained using food recalls and the FFQ was assessed by Pearson correlation. The reliability of the FFQ was assessed using coefficient alpha. Correlation of n-3 fatty acid intake using the food recalls and the FFQ was r=0.42 (P<0.05). The coefficient alpha for the test-retest of the FFQ was .83. The top two foods, walnuts and flaxseed, contributed 58% of the n-3 fatty acid intake, and the third food, salmon, contributed 5%. This quantitative n-3 FFQ is a valid instrument for use in place of food recalls for estimating n-3 fatty acid intakes in heart patients and is a reliable instrument to estimate n-3 fatty acid intakes from plant, animal, and seafood sources. The FFQ should be tested in a larger population. Registered dietitians can use this FFQ to screen for intakes, educate patients on food sources, and measure change in intakes after nutrition intervention.     

The relative validity of a computerized food frequency questionnaire for estimating intake of dietary iron and its absorption modifiers

OBJECTIVE: To determine the relative validity of an iron food frequency questionnaire (iron FFQ) designed to assess intakes of dietary iron and its absorption modifiers. DESIGN: A computer-administered food frequency questionnaire was designed to estimate intake of total, non-haem, haem and meat iron as well as dietary components which influence iron absorption (vitamin C, phytate, calcium, grammes of meat/fish/poultry, tea and coffee) in women consuming a Western diet. The relative validity of the iron FFQ was assessed by comparing its results with those from weighed diet records collected over 11 days. SETTING: Dunedin, New Zealand. PARTICIPANTS: Forty-nine women aged 19-31 y attending the University of Otago. RESULTS: There was good agreement between the iron FFQ and the weighed diet records for median intakes of total iron, non-haem iron, calcium, tea and coffee. For dietary component intakes, correlations between the two methods ranged from 0.39 (for vitamin C) to 0.87 (for coffee) with 0.52 for total iron, and 0.61 for haem iron. In cross-classification with the weighed diet record, the iron FFQ correctly classified between 22% (for vitamin C) and 51% (for phytate) of participants into the same quartile. Actual values for surrogate categories indicated that the questionnaire can clearly differentiate between low and high intakes of all the dietary components assessed. The questionnaire also showed an acceptable level of agreement between repeat administrations (eg a correlation for total iron of 0.65). CONCLUSIONS: The iron FFQ is appropriate for assessing group intakes of total iron, and iron absorption modifiers, in population studies to assess the aetiology and treatment of iron deficiency states in adult women consuming a Western diet. SPONSORSHIP: This research was supported (in part) by a grant from the Health Research Council of New Zealand.     

Underreporting of Energy Intake in Brazilian Women Varies According to Dietary Assessment: A Cross-Sectional Study Using Doubly Labeled Water

Objective

Underreporting of energy intake is prevalent in food surveys, but there is controversy about which dietary assessment method provides greater underreporting rates. Our objective is to compare validity of self-reported energy intake obtained by three dietary assessment methods with total energy expenditure (TEE) obtained by doubly labeled water (DLW) among Brazilian women.

Design

We used a cross-sectional study.

Subjects/setting

Sixty-five females aged 18 to 57 years (28 normal-weight, 10 overweight, and 27 obese) were recruited from two universities to participate.

Main outcome measures

TEE determined by DLW, energy intake estimated by three 24-hour recalls, 3-day food record, and a food frequency questionnaire (FFQ).

Statistical analyses performed

Regression and analysis of variance with repeated measures compared TEE and energy intake values, and energy intake-to-TEE ratios and energy intake−TEE values between dietary assessment methods. Bland and Altman plots were provided for each method. χ² test compared proportion of underreporters between the methods.

Results

Mean TEE was 2,622 kcal (standard deviation [SD]=490 kcal), while mean energy intake was 2,078 kcal (SD=430 kcal) for the diet recalls; 2,044 kcal (SD=479 kcal) for the food record and 1,984 kcal (SD=832 kcal) for the FFQ (all energy intake values significantly differed from TEE; P<0.0001). Bland and Altman plots indicated great dispersion, negative mean differences between measurements, and wide limits of agreement. Obese subjects underreported more than normal-weight subjects in the diet recalls and in the food records, but not in the FFQ. Years of education, income and ethnicity were associated with reporting accuracy.

Conclusions

The FFQ produced greater under- and overestimation of energy intake. Underreporting of energy intake is a serious and prevalent error in dietary self-reports provided by Brazilian women, as has been described in studies conducted in developed countries.     

西安市50岁以上居民食物频率问卷准确性及重现性研究

目的对用于评价西安城区居民膳食营养状况的西安食物频率问卷(FFQ)的重现性和准确性进行食物组的研究。方法在西安城区随机抽取出125名50～80岁当地居民,共完成6轮的食物摄入情况的调查,其中4轮24小时膳食回顾调查(24HDRs)的结果作为参考,通过第一轮FFQ结果与第二轮FFQ以及4轮24HDRs结果之间的比较分别进行FFQ的重现性和准确性研究。结果各个食物组在两轮FFQ间的Spearman相关系数在0.38(糕点类)～0.74(茶类)。第二轮FFQ与4轮24HDRs均值间的相关系数在0.12～0.74之间,经过个体内方差校正后,相关系数均有所提高。结论西安食物频率问卷可以相对准确、可靠地评价西安城区50岁以上居民的膳食营养状况。