Assessing consumption of high-fat foods: the effect of grouping foods into single questions

Reproducibility and relative validity of a FFQ to estimate the intake of fatty acids

We investigated the validity and reproducibility of the FFQ used in the Dutch European Investigation of Cancer and Nutrition cohort, in order to rank subjects according to intakes of fatty acid classes and individual fatty acids. In total, 121 men and women (23-72 years) filled out three FFQ at 6-month intervals between 1991 and 1992. As a reference method, they filled out twelve monthly 24-h dietary recalls (24HDR) during the same year. Intra-class correlation coefficients for the FFQ showed moderate to good reproducibility across all fatty acids (classes and individual) in men (0·56-0·81) and women (0·57-0·83). In men, Spearman's correlation coefficients (r s) for the FFQ compared with the 24HDR indicated moderate to good relative validity (r s=0·45-0·71) for all fatty acids, except for arachidonic acid and marine PUFA (r s<0·40). In women, relative validity was moderate to good for MUFA and trans-fatty acids (TFA) and the majority of SFA (r s=0·40-0·66), was fair for the short-chain SFA and lauric acid (r s=0·30-0·33) and was fair to moderate for PUFA (r s=0·22-0·47). Bland-Altman plots showed good agreement between the FFQ and 24HDR, and proportional bias for fatty acids with very low intakes. In conclusion, the FFQ showed good reproducibility for subject ranking based on intakes of fatty acids (classes and individual). The relative validity measures indicated that the FFQ is an adequate tool to rank subjects according to intakes of high-abundant fatty acids, but less for low-abundant fatty acids.

Dietary patterns within a population are more reproducible than those of individuals

Insight into the stability of dietary behavior over time is important, because only a single measurement of diet is often available to study the association between eating behavior and the occurrence of chronic diseases many years after baseline data collection. Little is known about changes in dietary patterns over time. The current study examined the (internal) stability and reproducibility of dietary patterns and the transition of individuals between patterns over time from 3 surveys within one study population by using cluster analysis. The dietary intake of participants in the Doetinchem Cohort Study in 6113, 4916, and 4520 adults in 1993-1997, 1998-2002, and 2003-2007, respectively, was measured using a validated food-frequency questionnaire. Stability and reproducibility of dietary patterns were studied by examining the optimal number of clusters per survey by comparing the contribution of food groups to total energy intake within the clusters over time and by studying transitions of individuals between clusters over time. A low-fiber bread pattern and a high-fiber bread pattern were identified in all 3 surveys. Over time, dietary patterns were comparable in terms of foods contributing most to total energy intake, suggesting good reproducibility. Nevertheless, only 41.8% of the participants were consistently assigned to the same dietary pattern for all 3 surveys. This implies that, over time, similar dietary patterns were found at the group level, but that ignoring individual transitions between dietary patterns during follow-up may lead to misclassification of a large proportion of the study population.

A comparison of fruit and vegetable intake estimates from three survey question sets to estimates from 24-hour dietary recall interviews

BACKGROUND

Fruit and vegetable (F/V) intake surveillance can provide information critical to the design and evaluation of interventions and the assessment of progress toward national intake objectives. The CDC's Youth Risk Behavior Surveillance System (YRBSS) assesses F/V intake among high school students using six questions about the frequency of intake in times per day. It is not known whether F/V intake frequency in times per day can be used as a proxy for intake in servings per day.

OBJECTIVE

To compare F/V intake estimates based on responses to three sets of survey questions, including the standard set of six YRBSS questions, with criterion F/V intake in servings per day based on data from 24-hour dietary recall interviews.

PARTICIPANTS/SETTING

Study participants were 610 high school students who completed an in-class questionnaire and three telephone-administered 24-hour dietary recall interviews. The questionnaire asked students how many times they consumed 100% fruit juice and ate fruit, carrots, potatoes, green salad, and other vegetables during the "past 7 days" (set 1), the number of times they did so "yesterday" (set 2), and the number of cup-equivalents of fruits and vegetables they consumed per day (set 3).

MAIN OUTCOME MEASURE

Mean estimated F/V intake either as "times/day" or "servings/day" and the percentage of students whose estimated F/V intake was ≥1, ≥2, and ≥3 times/day or servings/day.

STATISTICAL ANALYSES PERFORMED

t tests and corrected Pearson correlations were used to compare F/V intake estimates based on survey question responses with estimates based on responses to the 24-hour dietary recall interviews.

RESULTS

Mean F/V intake estimates (in times/day or servings/day) based on responses to all sets of survey questions were significantly more than servings/day estimates based on responses to the 24-hour dietary recall interviews, and the percentages of students meeting each intake cutpoint were also more. Of the three sets of survey questions, the standard YRBSS questions produced estimates and percentages that were most consistently closest to 24-hour dietary recall interview estimates.

CONCLUSIONS

For brief self-administered questionnaires of high school students, the current YRBSS questions are recommended for monitoring F/V intake even though mean intake estimates in times/day will likely be higher than, and are not a proxy for, mean intake estimates in servings/day.

Reliability and validity of child/adolescent food frequency questionnaires that assess foods and/or food groups

OBJECTIVE

Summarize the validity and reliability of child/adolescent food frequency questionnaires (FFQs) that assess food and/or food groups.

METHODS

We performed a systematic review of child/adolescent (6-18 years) FFQ studies published between January 2001 and December 2010 using MEDLINE, Cochrane Library, PsycINFO, and Google Scholar. Main inclusion criteria were peer reviewed, written in English, and reported reliability or validity of questionnaires that assessed intake of food/food groups. Studies were excluded that focused on diseased people or used a combined dietary assessment method. Two authors independently selected the articles and extracted questionnaire characteristics such as number of items, portion size information, time span, category intake frequencies, and method of administration. Validity and reliability coefficients were extracted and reported for food categories and averaged across food categories for each study.

RESULTS

Twenty-one studies were selected from 873, 18 included validity data, and 14 included test-retest reliability data. Publications were from the United States, Europe, Africa, Brazil, and the south Pacific. Validity correlations ranged from 0.01 to 0.80, and reliability correlations ranged from 0.05 to 0.88. The highest average validity correlations were obtained when the questionnaire did not assess portion size, measured a shorter time span (ie, previous day/week), was of medium length (ie, ≈ 20-60 items), and was not administered to the child's parents.

CONCLUSIONS

There are design and administration features of child/adolescent FFQs that should be considered to obtain reliable and valid estimates of dietary intake in this population.

Performance of the quantitative food frequency questionnaire used in the Brazilian center of the prospective study Natural History of Human Papillomavirus Infection in Men: The HIM Study

The Natural History of Human Papillomavirus (HPV) Infection in Men: The HIM Study is a prospective multicenter cohort study that, among other factors, analyzes participants' diet. A parallel cross-sectional study was designed to evaluate the validity and reproducibility of the quantitative food frequency questionnaire (QFFQ) used in the Brazilian center from the HIM Study. For this, a convenience subsample of 98 men aged 18 to 70 years from the HIM Study in Brazil answered three 54-item QFFQ and three 24-hour recall interviews, with 6-month intervals between them (data collection January to September 2007). A Bland-Altman analysis indicated that the difference between instruments was dependent on the magnitude of the intake for energy and most nutrients included in the validity analysis, with the exception of carbohydrates, fiber, polyunsaturated fat, vitamin C, and vitamin E. The correlation between the QFFQ and the 24-hour recall for the deattenuated and energy-adjusted data ranged from 0.05 (total fat) to 0.57 (calcium). For the energy and nutrients consumption included in the validity analysis, 33.5% of participants on average were correctly classified into quartiles, and the average value of 0.26 for weighted kappa shows a reasonable agreement. The intraclass correlation coefficients for all nutrients were greater than 0.40 in the reproducibility analysis. The QFFQ demonstrated good reproducibility and acceptable validity. The results support the use of this instrument in the HIM Study.

Tailored print communication and telephone motivational interviewing are equally successful in improving multiple lifestyle behaviors in a randomized controlled trial

Background

Computer tailoring and motivational interviewing show promise in promoting lifestyle change, despite few head-to-head comparative studies.

Purpose

Vitalum is a randomized controlled trial in which the efficacy of these methods was compared in changing physical activity and fruit and vegetable consumption in middle-aged Dutch adults.

Methods

Participants (n = 1,629) were recruited via 23 general practices and randomly received either four tailored print letters, four motivational telephone calls, two of each type of intervention, or no information. The primary outcomes were absolute change in self-reported physical activity and fruit and vegetable consumption.

Results

All three intervention groups (i.e., the tailored letters, the motivational calls, and the combined version) were equally and significantly more effective than the control group in increasing physical activity (hours/day), intake of fruit (servings/day), and consumption of vegetables (grams/day) from baseline to the intermediate measurement (week 25), follow-up 1 (week 47) and 2 (week 73). Effect sizes (Cohen’s d) ranged from 0.15 to 0.18. Participants rated the interventions positively; interviews were more positively evaluated than letters.

Conclusions

Tailored print communication and telephone motivational interviewing or their combination are equally successful in changing multiple behaviors.

Electronic supplementary material

The online version of this article (doi:10.1007/s12160-010-9231-3) contains supplementary material, which is available to authorized users.

Nutritional and toxicological aspects of seafood consumption--an integrated exposure and risk assessment of methylmercury and polyunsaturated fatty acids

Seafood consumption is associated with both risks and beneficial effects to human health. Consequently, an integrated exposure assessment of intake of toxic and nutritious agents in seafood is of importance prior to determination of dietary advisories. We have developed a probabilistic model for the estimation of simultaneous intake of methylmercury (MeHg) and long-chain n-3 polyunsaturated fatty acids (LC-n3 PUFAs) from seafood, to estimate the population proportion at risk for exceeding tolerable MeHg intake and not reaching adequate intake of PUFAs. Seafood consumption data was collected among women of childbearing age using a food frequency questionnaire. A database of mercury and fatty acids concentration in seafood was constructed. A Latin Hypercube simulation was used to calculate the intake of MeHg and LC n-3 PUFAs. Eleven percent of the population exceeded the MeHg reference dose of 0.1 μg/kg bw/day, whereas only 44% reached an adequate PUFA intake. A small proportion (3.7%) exceeded the MeHg reference dose while at the same time did not reach an adequate PUFA intake. Furthermore, we simulated two scenarios in which seafood is consumed according to a general recommendation of three servings per week, whereof one serving of oily seafood. The first scenario included seafood with typically low MeHg concentrations (mean 0.056 and 0.027 μg MeHg/g fish in lean and oily species, respectively), and the second included seafood typically high in MeHg concentrations (mean 0.50 and 0.26 μg MeHg/g fish in lean and oily species, respectively). In the "high"scenario, almost 100% of the population exceeded the reference dose, whereas the corresponding proportion was only 5% in the "low" scenario. Overall, the results stress the importance of communicating species specific seafood consumption advisories for women of childbearing age in general and for pregnant women in particular, while at the same time encourage them to consume more seafood.

Fish consumption and mercury exposure among Louisiana recreational anglers

BACKGROUND

Methylmercury (MeHg) exposure assessments among average fish consumers in the United States may underestimate exposures among U.S. subpopulations with high intakes of regionally specific fish.

OBJECTIVES

We examined relationships among fish consumption, estimated mercury (Hg) intake, and measured Hg exposure within one such potentially highly exposed group, recreational anglers in the state of Louisiana, USA.

METHODS

We surveyed 534 anglers in 2006 using interviews at boat launches and fishing tournaments combined with an Internet-based survey method. Hair samples from 402 of these anglers were collected and analyzed for total Hg. Questionnaires provided information on species-specific fish consumption during the 3 months before the survey.

RESULTS

Anglers' median hair Hg concentration was 0.81 µg/g (n = 398; range, 0.02-10.7 µg/g); 40% of participants had levels >1 µg/g, which approximately corresponds to the U.S. Environmental Protection Agency's reference dose. Fish consumption and Hg intake were significantly positively associated with hair Hg. Participants reported consuming nearly 80 different fish types, many of which are specific to the region. Unlike the general U.S. population, which acquires most of its Hg from commercial seafood sources, approximately 64% of participants' fish meals and 74% of their estimated Hg intake came from recreationally caught seafood.

CONCLUSIONS

Study participants had relatively elevated hair Hg concentrations and reported consumption of a wide variety of fish, particularly locally caught fish. This group represents a highly exposed subpopulation with an exposure profile that differs from fish consumers in other regions of the United States, suggesting a need for more regionally specific exposure estimates and public health advisories.

Energy intake during pregnancy in relation to offspring gender by maternal height

Male newborns are somewhat heavier than female ones and it has been reported, in a Caucasian population, that mothers carrying boys have higher energy intake during pregnancy compared to those carrying girls. In the context of a prospective study comprising 150 Caucasian women in Boston, USA and 243 Asian women in Shanghai China, energy intake at the second trimester of pregnancy was estimated based on center-specific food frequency questionnaires. There was a significant interaction (P = 0.01) of maternal height with offspring gender with respect to maternal daily energy intake. Among taller women, male gender of the offspring was associated with higher maternal energy intake (difference 341 kcal/day, 95% Confidence Interval 77-604; P = 0.01), whereas among shorter women, no significant association existed between offspring gender and maternal daily energy intake (difference -213 kcal/day, 95% Confidence Interval -479 to 54; P = 0.12). Our findings indicate that the higher somatic growth potential of boys in intrauterine life is realized only when there are no constrains imposed by maternal anthropometry and it is, then, associated with higher maternal energy intake during pregnancy.

Selecting informative food items for compiling food-frequency questionnaires: comparison of procedures

The authors automated the selection of foods in a computer system that compiles and processes tailored FFQ. For the selection of food items, several methods are available. The aim of the present study was to compare food lists made by MOM2, which identifies food items with highest between-person variance in intake of the nutrients of interest without taking other items into account, with food lists made by forward regression. The name MOM2 refers to the variance, which is the second moment of the nutrient intake distribution. Food items were selected for the nutrients of interest from 2 d of recorded intake in 3524 adults aged 25-65 years. Food lists by 80 % MOM2 were compared to those by 80 % explained variance for regression on differences between the number and type of food items, and were evaluated on (1) the percentage of explained variance and (2) percentage contribution to population intake computed for the selected items on the food list. MOM2 selected the same food items for Ca, a few more for fat and vitamin C, and a few less for carbohydrates and dietary fibre than forward regression. Food lists by MOM2 based on 80 % of variance in intake covered 75-87 % of explained variance for different nutrients by regression and contributed 53-75 % to total population intake. Concluding, for developing food lists of FFQ, it appears sufficient to select food items based on the contribution to variance in nutrient intake without taking covariance into account.

Single-item and multiple-item measures of adherence to public health behavior guidelines were incongruent

OBJECTIVE

Physical activity (PA) and fruit and vegetable consumption may prevent or delay the development of hypertension and cardiovascular diseases. We examined adherence rates to single and combinations of Dutch public health guidelines for these behaviors by comparing and combining two self-report measurements.

STUDY DESIGN AND SETTING

The behaviors of 2,568 Dutch participants aged 45-70 years were measured using one item and multiple items. Patients were classified as meeting or not meeting a guideline using both measurements separately and combined.

RESULTS

Substantially more participants met guidelines when measured with multiple items than when measured with one item, with differences of 21-39%. Combined measurements resulted in fewer participants meeting guidelines than multiple-item measurements used alone. Combined measurements showed that 17%, 12%, and 34% of participants met the guidelines for fruit and vegetable consumption and PA, respectively; only 3% met all three guidelines. Sociodemographic variables explained less than 4% of the variance of congruency between single- and multiple-item measurements.

CONCLUSION

When assessing adherence rates, the level appears dependent on the method of self-report chosen. Hence, more research must analyze which adherence measurement will result in valid responses and which variables are associated with congruency between single- and multiple-item measurements.

Vitalum study design: RCT evaluating the efficacy of tailored print communication and telephone motivational interviewing on multiple health behaviors

Background

A large proportion of adults fail to meet public health guidelines for physical activity as well as fruit, vegetable and fat intake. Interventions are needed to improve these health behaviors. Both computer tailoring and motivational interviewing have shown themselves to be promising techniques for health behavior change. The Vitalum project aims to compare the efficacy of these techniques in improving the health behaviors of adults aged 45–70. This paper describes the design of the Vitalum study.

Methods/Design

Dutch general medical practices (N = 23) were recruited via a registration network or by personal invitation. The participants were then enrolled through these general practices using an invitational letter. They (n = 2,881) received a written baseline questionnaire to assess health behaviors, and potential psychosocial and socio-demographic behavioral determinants. A power analysis indicated that 1,600 participants who were failing to meet the guidelines for physical activity and either fruit or vegetable consumption were needed. Eligible participants were stratified based on hypertension status and randomized into one of four intervention groups: tailored print communication, telephone motivational interviewing, combined, and control. The first two groups either received four letters or took part in four interviews, whereas the combined group received two letters and took part in two interviews in turns at 5, 13, 30 and 43 weeks after returning the baseline questionnaire. Each letter and interview focused on physical activity or nutrition behavior. The participants also took part in a telephone survey 25 weeks after baseline to gather new information for tailoring. There were two follow-up questionnaires, at 47 and 73 weeks after baseline, to measure short- and long-term effects. The control group received a tailored letter after the last posttest. The process, efficacy and cost-effectiveness of the interventions will be examined by means of multilevel mixed regression, cost-effectiveness analyses and process evaluation.

Discussion

The Vitalum study simultaneously evaluates the efficacy of tailored print communication and telephone motivational interviewing, and their combined use for multiple behaviors and people with different motivational stages and education levels. The results can be used by policymakers to contribute to evidence-based prevention of chronic diseases.

Trial Registration

Dutch Trial Register NTR1068

Development of a meat frequency questionnaire for use in diet and cancer studies

OBJECTIVE

To develop a meat frequency questionnaire to assess dietary heterocyclic amine intake. The meat frequency questionnaire is designed to obtain information on meat types, cooking methods, and doneness preferences that predict heterocyclic amine concentrations in different meats.

DESIGN

Total and specific meat intakes were determined by a standard food frequency questionnaire (FFQ) and compared with that determined by the meat frequency questionnaire.

SUBJECTS/SETTING

Three-hundred fourteen African-American males participating in a clinic-based study of prostate disease and heterocyclic amine intake were administered the two questionnaires in a cancer education center prior to undergoing screening evaluations for prostate disease.

MAIN OUTCOME MEASURES

Fried, broiled, and grilled vs total meat intake was assessed using the meat frequency questionnaire vs FFQ, respectively. Specific meat items included in the meat frequency questionnaire were evaluated as factors potentially explaining discrepancies in meat intake estimated using the two questionnaires. Seasonal variation in meat intake was also examined.

STATISTICAL ANALYSIS

Correlation coefficients for intake of total meat and individual meat groups determined by FFQ vs meat frequency questionnaire were calculated. Seasonal differences in meat and estimated heterocyclic amine intakes were evaluated by t test, adjusted for multiple comparisons.

RESULTS

Meat intakes determined by the two questionnaires were well-correlated (Pearson r=0.69); however, total meat assessed by the meat frequency questionnaire exceeded total meat assessed by the FFQ in 30% of participants. Total energy and intake of heterocyclic amine-associated meat were greatest when the meat frequency questionnaire was administered during winter months.

CONCLUSIONS

The heterocyclic amine meat frequency questionnaire provided a fractional measure of total meat intake and identified specific heterocyclic amine-containing meat items underreported in a standard FFQ.

Methyl mercury exposure in Swedish women with high fish consumption

We studied the exposure to methyl mercury (MeHg) in 127 Swedish women of childbearing age with high consumption of various types of fish, using total mercury (T-Hg) in hair and MeHg in blood as biomarkers. Fish consumption was assessed using a food frequency questionnaire (FFQ), including detailed information about consumption of different fish species, reflecting average intake during 1 year. We also determined inorganic mercury (I-Hg) in blood, and selenium (Se) in serum. The average total fish consumption, as reported in the food frequency questionnaire, was approximately 4 times/week (range 1.6-19 times/week). Fish species potentially high in MeHg, included in the Swedish dietary advisories, was consumed by 79% of the women. About 10% consumed such species more than once a week, i.e., more than what is recommended. Other fish species potentially high in MeHg, not included in the Swedish dietary advisories, was consumed by 54% of the women. Eleven percent never consumed fish species potentially high in MeHg. T-Hg in hair (median 0.70 mg/kg; range 0.08-6.6 mg/kg) was associated with MeHg in blood (median 1.7 microg/L; range 0.30-14 microg/L; rs = 0.78; p < 0.001). Hair T-Hg, blood MeHg and serum Se (median 70 microg/L; range 46-154 microg/L) increased with increasing total fish consumption (rs = 0.32; p < 0.001, rs = 0.37; p < 0.001 and rs = 0.35; p = 0.002, respectively). I-Hg in blood (median 0.24 microg/L; range 0.01-1.6 microg/L) increased with increasing number of dental amalgam fillings. We found no statistical significant associations between the various mercury species measured and the Se concentration in serum. Hair mercury levels exceeded the levels corresponding to the EPA reference dose (RfD) of 0.1 microg MeHg/kg b.w. per day in 20% of the women. Thus, there seems to be no margin of safety for neurodevelopmental effects in fetus, for women with high fish consumption unless they decrease their intake of certain fish species.

Is dietary fat intake related to liking or household availability of high- and low-fat foods?

OBJECTIVE

Despite the increasing availability of low- and reduced-fat foods, Americans continue to consume more fat than recommended, which may be a contributing factor to the obesity epidemic. This investigation examined relationships between liking and household availability of high- and low-fat foods and their association with dietary fat intake.

RESEARCH METHODS AND PROCEDURES

A food frequency questionnaire assessed percent calories from fat consumed over the past year in 85 men and 80 women. Participants reported their degree of liking 22 "high-fat foods" (>45% calories from fat) and 22 "low-fat foods" (<18% calories from fat), and the number and percentage (number of high- or low-fat foods/total number of foods x 100) of these high- and low-fat foods in their homes.

RESULTS

Hierarchical regression analyses examined the ability of liking and household availability of low- and high-fat foods to predict percent dietary fat intake. After controlling for age, sex, and BMI, liking ratings for high- and low-fat foods and the interaction of liking for low-fat foods by the percentage of low-fat foods in the household were significant predictors of percent dietary fat consumed. Greater liking of high-fat foods and lower liking of low-fat foods, both alone and combined with a lower percentage of low-fat foods in the home, were predictive of higher dietary fat intake.

DISCUSSION

Interventions designed to reduce dietary fat intake should target both decreasing liking for high-fat foods and increasing liking for low-fat foods, along with increasing the proportion of low-fat foods in the household.

A short dutch questionnaire to measure fruit and vegetable intake: relative validity among adults and adolescents

A short food frequency questionnaire (FFQ) to assess fruit and vegetable (F&V) intake was validated. Forty-nine adults and fifty-one adolescents (12-18 years old) completed the FFQ at home, and subsequently kept diet records for seven successive days. Mean daily intake of F&V was overestimated by the FFQ as compared to the 7-day diet records. For adults, spearman correlations of at least 0.5 were observed between the two methods for intake of total fruit and intake of citrus fruit. For adolescents, acceptable spearman correlations (0.53-0.64) were observed between the two methods for total F&V intake, total fruit intake and consumption of fruit juice. Low correlations (0.22-0.35) between the FFQ and the diet records were found for vegetable intake. Relatively large percentages (22-37%) of respondents were incorrectly classified by the short FFQ as eating according to the Dutch recommendations for fruit and vegetable intake. Based on the results of the present study as well as an overview of the results of 34 earlier validation studies of F&V FFQ's, it is concluded that the available FFQ's have only limited capability to make valid assessment of F&V intake levels. In spite of the practical advantages of the short FFQ tested in the present study and the similar validity scores as compared with other often used F&V FFQ's, it needs further revision, especially to be used for valid measurement of vegetable intake as well as total F&V intake among adults.

Development, validation and utilisation of food-frequency questionnaires - a review

OBJECTIVE

The purpose of this review is to provide guidance on the development, validation and use of food-frequency questionnaires (FFQs) for different study designs. It does not include any recommendations about the most appropriate method for dietary assessment (e.g. food-frequency questionnaire versus weighed record).

METHODS

A comprehensive search of electronic databases was carried out for publications from 1980 to 1999. Findings from the review were then commented upon and added to by a group of international experts.

RESULTS

Recommendations have been developed to aid in the design, validation and use of FFQs. Specific details of each of these areas are discussed in the text.

CONCLUSIONS

FFQs are being used in a variety of ways and different study designs. There is no gold standard for directly assessing the validity of FFQs. Nevertheless, the outcome of this review should help those wishing to develop or adapt an FFQ to validate it for its intended use.

A healthy diet indicator: quantifying compliance with the dietary guidelines using the BRFSS

BACKGROUND

The Behavioral Risk Factor Surveillance System (BRFSS) monitors population prevalence of risk factors related to chronic disease through annual telephone surveys. The purpose of this study was to investigate the feasibility of using the BRFSS to estimate an indicator of overall diet quality among adults.

METHODS

The authors developed a brief set of dietary questions that were included in the 1997 Michigan BRFSS. Responses to these questions were analyzed to calculate the Michigan healthy diet indicator (MI-HDI), which was modeled after the U.S. Department of Agriculture's Healthy Eating Index.

RESULTS

Among 2,532 respondents, the mean MI-HDI was 55.7 points (maximum score = 100). The mean MI-HDI decreased consistently with declining self-rated eating habits, from 61.5 among those with excellent eating habits to 45.2 among those with poor habits. Diet quality, as measured by the MI-HDI, was higher among women than men and improved with age, education, and factors related to certain interactions with health professionals.

CONCLUSIONS

A BRFSS-based indicator can be a feasible and valuable tool for evaluating diet quality among adults using an established state-level surveillance system.

Cognitive research enhances accuracy of food frequency questionnaire reports: results of an experimental validation study

OBJECTIVE

To test whether changing a food frequency questionnaire (FFQ) on the basis of cognitive theory and testing results in greater accuracy. Accuracy was examined for 4 design issues: a) Grouping: asking about foods in a single vs multiple separate questions; b) different forms of a food: asking consumption frequency of each form of a food (eg, skim, 2%, whole milk) vs a nesting approach--asking frequency of the main food (eg, milk) and proportion of times each form was consumed; c) additions (eg, sugar to coffee): asking independent of the main food vs nested under the main foods; d) units: asking frequency and portion size vs frequency of units (eg, cups of coffee).

DESIGN

Participants in two randomly assigned groups completed 30 consecutive daily food reports (DFRs), followed by 1 of 2 FFQs that asked about foods consumed in the past month. One was a new, cognitively-based National Cancer Institute (NCI) Diet History Questionnaire; the other was the 1992 NCI-Block Health Habits and History Questionnaire.

SUBJECTS/SETTING

623 participants, age range 25 to 70 years, from metropolitan Washington, DC. Statistical analyses performed Accuracy was assessed by comparing DFR and FFQ responses using categorical (percent agreement) and continuous (rank order correlation, discrepancy scores) agreement statistics.

RESULTS

Grouping: accuracy was greater using separate questions. Different forms of food: accuracy was greater using nesting. Additions: neither approach was consistently superior; accuracy of the addition report was affected by accuracy of the main food report. Units: both approaches were similarly accurate.

CONCLUSIONS

Accuracy of FFQ reporting can be improved by restructuring questions based on cognitive theory and testing.

A 7-item versus 31-item food frequency questionnaire for measuring fruit, juice, and vegetable intake among a predominantly African-American population

OBJECTIVE

This study sought to determine which of 2 fruit and vegetable food frequency questionnaires (FFQs) most closely approximated intake measured by the average of four 24-hour dietary recalls.

DESIGN

Participants completed either a 31-item FFQ (n = 70) or 7-item FFQ (n = 76) on 2 occasions approximately 2 weeks apart. During the interval between FFQs1 participants provided four 24-hour dietary recalls via telephone interview.

SUBJECTS/SETTING

Participants were 146 persons with food preparation responsibilities in families of students in grades 3 through 5. Respondents were predominantly African-American women in Atlanta, Ga.

STATISTICAL ANALYSIS

Pearson correlation coefficients of log-transformed values estimated the reliability of each FFQ and compared FFQ estimates to reference values. The intraclass correlation coefficient evaluated consistency across 24-hour recalls.

RESULTS

The first FFQs overestimated intake approximately twofold. The 31-item FFQ estimates exceeded 7-item FFQ estimates by approximately 30% . Correlations with recall estimates were high for the 7-item FFQ and moderate to low for the 31-item FFQ. The second FFQ estimates were more highly correlated to reference values. From the first to the second administration, 7-item FFQ estimates dropped from 5.2 to 2.7 servings, and 31-item FFQ estimates dropped from 6.7 to 3.5 servings. Neither FFQ produced highly reliable estimates.

CONCLUSIONS

Mean total fruit and vegetable consumption was closer to reference estimates for the first 7-item FFQ and the second 31-item FFQ. The 7-item FFQ correlated more highly with reference estimates than did the 31-item FFQ. Therefore, we conclude that for African-American adults, a 1-time-administered FFQ using 7 broad food categories correlates more highly with reference values than a FFQ using 31 individual fruit and vegetable items.

Food patterns defined by cluster analysis and their utility as dietary exposure variables: a report from the Malmö Diet and Cancer Study

OBJECTIVE

To explore the utility of cluster analysis in defining complex dietary exposures, separately with two types of variables.

DESIGN

: A modified diet history method, combining a 7-day menu book and a 168-item questionnaire, assessed dietary habits. A standardized questionnaire collected information on sociodemographics, lifestyle and health history. Anthropometric information was obtained through direct measurements. The dietary information was collapsed into 43 generic food groups, and converted into variables indicating the per cent contribution of specific food groups to total energy intake. Food patterns were identified by the QUICK CLUSTER procedure in SPSS, in two separate analytical steps using unstandardized and standardized (Z-scores) clustering variables.

SETTING

: The Malmö Diet and Cancer (MDC) Study, a prospective study in the third largest city of Sweden, with baseline examinations from March 1991 to October 1996.

SUBJECTS

A random sample of 2206 men and 3151 women from the MDC cohort (n = 28 098).

RESULTS

Both variable types produced conceptually well separated clusters, confirmed with discriminant analysis. 'Healthy' and 'less healthy' food patterns were also identified with both types of variables. However, nutrient intake differences across clusters were greater, and the distribution of the number of individuals more even, with the unstandardized variables. Logistic regression indicated higher risks of past food habit change, underreporting of energy and higher body mass index (BMI) for individuals falling into 'healthy' food pattern clusters.

CONCLUSIONS

The utility in discriminating dietary exposures appears greater for unstandardized food group variables. Future studies on diet and cancer need to recognize the confounding factors associated with 'healthy' food patterns.

Improving food frequency questionnaires: a qualitative approach using cognitive interviewing

In an attempt to improve data quality and ease of administration of standard self-administered food frequency questionnaires, various alternative approaches were tried for inquiring about frequency of consumption, portion size, seasonal intake, and food preparation. Evaluation consisted of a cognitive interviewing method in which respondents verbalize their thought process while completing several variations of a questionnaire. Interviewers observed and asked follow-up probe questions to evaluate problems or inconsistencies verbalized by respondents. Consensus and judgment by interviewers and observers suggested several problematic features of food frequency questionnaires: formatting of questions about frequency and portion size; computing average frequencies for aggregated food items or for foods eaten seasonally; comprehension of many items; and ordering of foods. These findings led to cognitive refinement and innovations, which included detailed questions regarding preparation or use of low-fat varieties or other alternatives to help better describe specifics of intake for some foods; questions on seasonal intake for several foods; inclusion of portion size ranges; and additional response categories for frequency of intake. Cognitive interviewing is an important step in pinpointing cognitive problems in dietary questionnaires.

Fruit and vegetable intake among adults in 16 states: results of a brief telephone survey

A brief food frequency questionnaire was used to assess daily fruit and vegetable consumption among 23,699 adults in 16 US states sampled in a random-digit dialing telephone survey. Men consumed fewer servings per day (3.3) than did women (3.7). Only 20% of the population consumed the recommended 5 or more daily servings. Intakes varied somewhat by state and were lower among the young and the less educated. Efforts are needed to improve fruit and vegetable consumption among all Americans, especially younger adults and those with lower levels of education.