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Dietary assessment methods are important tools for nutrition research. Online dietary assessment tools have the potential to become invaluable methods of assessing dietary intake because, compared with traditional methods, they have many advantages including the automatic storage of input data and the immediate generation of nutritional outputs.
The aim of this study was to develop an online food frequency questionnaire (FFQ) for dietary data collection in the “Food4Me” study and to compare this with the validated European Prospective Investigation of Cancer (EPIC) Norfolk printed FFQ.
The Food4Me FFQ used in this analysis was developed to consist of 157 food items. Standardized color photographs were incorporated in the development of the Food4Me FFQ to facilitate accurate quantification of the portion size of each food item. Participants were recruited in two centers (Dublin, Ireland and Reading, United Kingdom) and each received the online Food4Me FFQ and the printed EPIC-Norfolk FFQ in random order. Participants completed the Food4Me FFQ online and, for most food items, participants were requested to choose their usual serving size among seven possibilities from a range of portion size pictures. The level of agreement between the two methods was evaluated for both nutrient and food group intakes using the Bland and Altman method and classification into quartiles of daily intake. Correlations were calculated for nutrient and food group intakes.
A total of 113 participants were recruited with a mean age of 30 (SD 10) years (40.7% male, 46/113; 59.3%, 67/113 female). Cross-classification into exact plus adjacent quartiles ranged from 77% to 97% at the nutrient level and 77% to 99% at the food group level. Agreement at the nutrient level was highest for alcohol (97%) and lowest for percent energy from polyunsaturated fatty acids (77%). Crude unadjusted correlations for nutrients ranged between .43 and .86. Agreement at the food group level was highest for “other fruits” (eg, apples, pears, oranges) and lowest for “cakes, pastries, and buns”. For food groups, correlations ranged between .41 and .90.
The results demonstrate that the online Food4Me FFQ has good agreement with the validated printed EPIC-Norfolk FFQ for assessing both nutrient and food group intakes, rendering it a useful tool for ranking individuals based on nutrient and food group intakes.
Associations between dietary behaviors and chronic health risks have been established on numerous occasions [
Food records (or diaries), 24-hour recalls, and food frequency questionnaires (FFQ) are the three principle assessment methods that are used traditionally to measure dietary intake [
Internet availability and usage has increased globally over the past decade and, as a result, traditional methods of dietary assessment have been modified for online and electronic use in both research and industry [
The strengths and weaknesses of traditional dietary assessment methods are well documented [
FFQs and 24-hour recalls are the most commonly used approaches for assessing dietary intake for large population studies [
In recent years, many well-established FFQs have been developed into Web-based versions and there is a growing body of evidence demonstrating that data from Web-based FFQs are comparable with data from printed versions and/or have good validity with reference methods such as 24-hour recalls and food diaries [
The present study was conducted as part of the EU 7th European Framework Programme “Food4Me” project [
The objectives of the present study were to develop an online FFQ for dietary data collection in the Food4Me study and to compare estimates of intakes obtained using this tool with those obtained from the validated European Prospective Investigation of Cancer (EPIC) Norfolk printed FFQ [
The online Food4Me FFQ was designed to assess food and nutritional intake across seven centers in Europe, as part of a dietary intervention study within the Food4Me project [
The well-validated EPIC-Norfolk FFQ (version CAMB/PQ/6/1205) [
Frequency of intake was estimated by asking, “How often would you have consumed each of the following in the past month?” and participants could select their frequency from nine categories of intake ranging from “never (<1 per month)” to “6+ per day”. After selecting their frequency of consumption, participants were asked to choose their usual serving size from a range of portion size pictures for each food item (see
Screenshot of the online Food4Me Food Frequency Questionnaire.
Nutritional composition and portion sizes were calculated from the 2008-2010 National Adult Nutrition Survey (NANS) database, which consists of detailed dietary intake data for 1500 Irish adults [
The nutritional composition of the 157 food items, listed in the Food4Me FFQ, was derived from the wider list of corresponding foods within the NANS database. From these, the most frequently consumed foods were identified and used to calculate the composition of the list of foods in the Food4Me FFQ. For example, for all pizzas consumed in the NANS dataset, the nutritional composition per 100g was computed for the three most frequently consumed and the mean of these was then calculated to give a single nutritional composition for pizza. The nutritional composition for the NANS dataset was analyzed using WISP (Tinuviel Software, Anglesey, UK). WISP uses the 5thand 6theditions of McCance and Widdowson’s
For the calculation of portion sizes, the food codes for each of the frequently consumed foods identified from the NANS database were merged and recoded into a single food code for each food item listed in the FFQ. Using the newly assigned food code, PASW Statistics version 18 (SPSS Inc Chicago, IL, USA) was used to calculate the 25th, 50th, and 75thpercentiles of daily intake, which represent small, medium, and large portion sizes of these foods when consumed in the free living population. Options for portion sizes above, below, and in between these percentiles were also provided to accommodate the wide variability in portion size across populations.
Foods were purchased from local supermarkets and bakeries in Dublin. All foods were prepared and photographs taken in the Institute of Food and Health, University College Dublin. Food photographs were taken by a professional photographer over 5 days/sessions. A standard dining set of plates and cutlery, positioned uniformly with the same lighting, was used for each session. The calculated NANS portion sizes were used as a guideline and all foods were weighed out using calibrated portable food scales (Tanita, Japan).
The comparison of the online Food4Me FFQ with the printed EPIC-Norfolk FFQ was conducted in two centers involved in the Food4Me study (University College Dublin and University of Reading) using the English language version of the questionnaire (consisting of 157 food items). The study received approval from the ethical committees at both universities and was carried out between March and October 2012 (LS-11-118-Gibney-Walsh and 01/12-Lovegrove respectively). Participants (n=177) aged ≥18yrs were recruited at both centers. Participants were provided with an information sheet explaining the study, signed a consent form, and completed a brief screening questionnaire either in person or by post. Weight and height were self-reported. Individuals with self-reported/diagnosed food intolerances/allergies or those receiving dietary advice were ineligible to participate.
Eligible participants completed both the online Food4Me FFQ and the printed EPIC-Norfolk FFQ in random order. The printed EPIC-Norfolk FFQ was modified to ask participants’ about their food intake over the past month rather than over the past year. To minimize possible effects of temporal changes in dietary intake, participants with more than 4 weeks between completing both FFQs were excluded from analyses. The printed EPIC-Norfolk FFQ was delivered to the participant in person or by post. The Food4Me FFQ was accessed via a hyperlink to the website sent in an email containing the participant’s individual username and password.
The Henry equation was used to calculate basal metabolic rate (BMR) and BMR was multiplied by 1.1 to calculate the lowest possible estimated energy requirements (EER) for each participant [
Printed EPIC-Norfolk questionnaires were coded using the specified template format and cross-checked before sending to Strangeways Research Laboratory (University of Cambridge) for processing using FETA software [
Data were imported into SPSS for analysis and descriptive statistics were computed to describe the general characteristics of participants. Mean nutrient intakes and standard deviations were determined for both FFQs. General linear model analysis controlling for energy was used to compare nutrient intakes between the FFQs. Correlation coefficients were computed to assess the association between the two methods. The relative agreement between the two FFQs was assessed using cross-classification of nutrient intakes to estimate the percentage of participants who were classified by the two methods into quartiles of “exact agreement”, “exact agreement plus adjacent”, “disagreement”, and “extreme disagreement”. Bland and Altman analysis was performed for the macronutrients to assess the limits of agreement between the two FFQs. For each macronutrient, the differences of the mean between the two methods (EPIC−Food4Me) were plotted against the average of the two methods ([EPIC+Food4Me]/2). Methods were considered comparable if greater than 95% of data plots lay within the limits of agreement (mean ± 2SD).
Differences in food group intakes between the two methods were examined. To do this, the food items in the EPIC-Norfolk and Food4Me FFQs were arranged into 35 food groups. Independent samples
A total of 177 participants were screened to participate in the study with 159 eligible for inclusion. Following initiation of the study, 27 participants dropped out, as shown in
Demographic characteristics of the study population are presented in
Demographic characteristics of the study population in total and across centers, by gender.
Participants |
|
Demographic characteristics, mean (SD) | |||
n | Age (y) | Weight (kg) | BMI (kg/m2)a | ||
|
|||||
|
Male | 46 | 32.0 (12.6) | 77.3 (11.3) | 24.3 (3.0) |
|
Female | 67 | 29.0 (8.0) | 62.2 (9.4) | 22.6 (2.6)d |
|
All | 113 | 30.0 (10.2) | 68.4 (12.6) | 23.3 (2.9) |
|
|||||
|
Male | 32 | 35.1 (13.0) | 78.6 (10.6) | 24.8 (2.8) |
|
Female | 32 | 30.2 (7.2) | 64.3 (8.9) | 23.1 (2.5)e |
|
All | 64 | 32.6 (10.7) | 71.5 (12.1) | 24.0 (2.8) |
|
|||||
|
Male | 14 | 24.2 (7.6)b | 74.3 (12.4) | 23.1 (3.2) |
|
Female | 35 | 27.9 (8.6) | 60.3 (9.4) | 22.2 (2.6) |
|
All | 49 | 26.9 (8.4)b | 64.3 (12.1)b | 22.5 (2.8)c |
aBody mass index (BMI) based on self-reported weight and height.
bSignificantly different between centers,
cSignificantly different between centers,
dSignificantly different from males,
eSignificantly different from males,
Flow of participants through the study. FFQ: food frequency questionnaire.
Mean energy and nutrient intakes estimated from the two FFQs are presented in
After controlling for energy, intakes of macronutrients showed relatively good agreement with no significant differences in energy derived from total fat, saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), or carbohydrates. Significant differences were observed in both total polyunsaturated fatty acid intake and % energy derived from polyunsaturated fatty acids (PUFA), at
Bland and Altman plots for mean daily energy, total fat, protein, and carbohydrate intakes are presented in
As illustrated in
Mean daily nutrient intakes estimated by printed EPIC-Norfolk FFQaand online Food4Me FFQ (n=113).
Nutrient | EPIC-Norfolk FFQ,mean (SD) | Food4Me FFQ,mean (SD) |
|
|
Energy (kcal) | 1684.62 (483.41) | 2356.08 (809.36) | - | - |
Total Fat (g) | 66.10 (24.27) | 89.48 (38.23) | .001 | .001 |
Total Fat (% TEd) | 34.88 (6.18) | 33.50 (5.31) | .07 | .03 |
SFAe (g) | 24.91 (10.50) | 36.03 (16.52) | .29 | .29 |
SFA (% TE) | 13.13 (3.40) | 13.39 (2.78) | .52 | .73 |
MUFAf(g) | 23.26 (8.75) | 32.82 (14.84) | .09 | .09 |
MUFA (% TE) | 12.26 (2.35) | 12.27 (2.54) | .99 | .99 |
PUFAg(g) | 12.18 (6.33) | 14.33 (5.97) | <.001 | <.001 |
PUFA (% TE) | 6.44 (2.63) | 5.46 (1.15) | <.001 | <.001 |
Protein (g) | 75.53 (21.82) | 96.92 (36.87) | .26 | .91 |
Protein (% TE) | 18.33 (4.24) | 16.56 (3.35) | .001 | .001 |
Carbohydrate (g) | 197.09 (69.81) | 281.89 (96.48) | .09 | .12 |
Carbohydrate(% TE) | 46.82 (8.14) | 48.41 (6.91) | .11 | .06 |
Total sugars (g) | 103.92 (45.78) | 130.00 (48.61) | .04 | .001 |
Alcohol (g) | 7.21 (9.10) | 13.61 (15.72) | .18 | .18 |
Calcium (mg) | 835.03 (255.85) | 1159.12 (459.22) | .17 | .17 |
Total folate (µg) | 250.16 (68.70) | 375.16 (136.40) | <.001 | <.001 |
Iron (mg) | 9.70 (2.74) | 15.91 (5.97) | <.001 | <.001 |
Total carotene (µg) | 3512.61 (2004.14) | 5811.99 (4180.17) | .001 | .02 |
Riboflavin (mg) | 1.74 (0.47) | 2.42 (0.92) | .02 | .02 |
Thiamin (mg) | 1.34 (0.37) | 2.42 (1.66) | <.001 | <.001 |
Vitamin B6 (mg) | 2.03 (0.52) | 2.84 (1.08) | .03 | .01 |
Vitamin B12 (µg) | 5.93 (2.79) | 7.22 (3.24) | .49 | .49 |
Vitamin C (mg) | 107.12 (55.87) | 164.50 (87.85) | .003 | .11 |
Vitamin A (RE) (µg) | 984.94 (470.95) | 1735.23 (3712.62) | .04 | .95 |
Retinol (µg) | 385.73 (300.15) | 445.73 (277.59) | .02 | .02 |
Vitamin D (µg) | 2.96 (1.90) | 3.67 (2.15) | .44 | .48 |
Vitamin E (mg) | 10.64 (4.63) | 10.71 (4.32) | <.001 | <.001 |
Sodium (mg) | 2442.27 (772.86) | 2597.38 (1070.53) | <.001 | <.001 |
Salt (g) | 6.11 (1.93) | 6.49 (2.68) | <.001 | <.001 |
aFFQ: food frequency questionnaire.
bAll
cControlled for energy and, where appropriate, center, gender, and randomization group using general linear model analysis. No significant interactions were observed between method and gender, center and randomization group.
dTE: total energy.
eSFA: saturated fatty acids.
fMUFA: monounsaturated fatty acids.
gPUFA: polyunsaturated fatty acids.
Mean daily nutrient intakes estimated by printed EPIC FFQa(n=55) and online Food4Me FFQ (n=93) with under-reporters removed.
Nutrient | EPIC (n=55),mean (SD) | Food4Me (n=93),mean (SD) |
|
|
Energy (kcal) | 2023.79 (402.71) | 2573.63 (714.10) | - | - |
Total Fat (g) | 80.68 (20.15) | 98.82 (35.18) | .01 | .01 |
Total Fat (% TE d) | 35.84 (4.72) | 34.11 (5.08) | .04 | .04 |
SFAe(g) | 30.43 (9.44) | 39.88 (15.46) | .60 | .60 |
SFA (% TE) | 13.54 (3.02) | 13.68 (2.71) | .76 | .76 |
MUFAf(g) | 28.51 (7.58) | 36.33 (13.82) | .30 | .30 |
MUFA (% TE) | 12.65 (1.97) | 12.55 (2.47) | .78 | .78 |
PUFAg(g) | 14.80 (5.29) | 15.72 (5.57) | <.001 | <.001 |
PUFA (% TE) | 6.57 (1.97) | 5.50 (1.13) | <.001 | <.001 |
Protein (g) | 85.69 (17.42) | 105.73 (33.99) | .85 | .30 |
Protein (% TE) | 17.21 (3.29) | 16.53 (3.26) | .22 | .22 |
Carbohydrate (g) | 239.40 (70.54) | 306.18 (87.44) | .48 | .48 |
Carbohydrate (% TE) | 47.04 (7.61) | 47.97 (6.94) | .45 | .36 |
Total sugars (g) | 131.41 (47.46) | 141.51 (44.27) | .009 | .001 |
Alcohol (g) | 8.50 (11.60) | 14.80 (16.84) | .33 | .33 |
Calcium (mg) | 956.48 (226.18) | 1256.82 (442.11) | .14 | .14 |
Total folate (µg) | 285.67 (63.38) | 403.13 (125.66) | <.001 | <.001 |
Iron (mg) | 10.91 (2.58) | 17.18 (5.61) | <.001 | <.001 |
Total carotene (µg) | 4078.51 (2051.75) | 6280.68 (4311.00) | .004 | .004 |
Riboflavin (mg) | 1.97 (0.41) | 2.60 (0.90) | .03 | .03 |
Thiamin (mg) | 1.55 (0.35) | 2.48 (1.48) | .001 | .001 |
Vitamin B6 (mg) | 2.32 (0.47) | 3.09 (1.01) | .02 | .01 |
Vitamin B12 (µg) | 6.88 (2.93) | 7.82 (3.20) | .72 | .72 |
Vitamin C (mg) | 126.64 (57.42) | 178.47 (87.62) | .01 | .11 |
Vitamin A (RE) (µg) | 1190.08 (471.67) | 1917.85 (4067.44) | .53 | .53 |
Retinol (µg) | 490.82 (323.56) | 481.24 (287.30) | .01 | .01 |
Vitamin D (µg) | 3.48 (2.03) | 3.98 (2.21) | .58 | .58 |
Vitamin E (mg) | 13.06 (4.56) | 11.65 (4.07) | <.001 | <.001 |
Sodium (mg) | 2879.23 (712.59) | 2841.48 (1009.77) | <.001 | <.001 |
Salt (g) | 7.20 (1.78) | 7.10 (2.52) | <.001 | <.001 |
aFFQ: food frequency questionnaire.
bAll
cControlled for energy and, where appropriate, center and/or gender using general linear model analysis. No significant interactions were observed between method and gender or center.
dTE: total energy.
eSFA: saturated fatty acids.
fMUFA: monounsaturated fatty acids.
gPUFA: polyunsaturated fatty acids.
Unadjusted correlation coefficients and cross-classification of quartiles of mean energy and nutrient intakes derived from the online Food4Me FFQaand printed EPIC-Norfolk FFQ.
|
Correlationb | Exact agreementd, (%) | Exact agreement + adjacente, (%) | Disagreementf, (%) | Extreme disagreementg, (%) |
Energy (kcal) | .68 | 52 | 88 | 12 | 1 |
Total Fat (g) | .70 | 46 | 90 | 10 | 1 |
Total Fat (% TEh) | .54c | 39 | 78 | 22 | 4 |
SFAi (g) | .71 | 46 | 91 | 9 | 1 |
SFA (% TE) | .63c | 38 | 84 | 16 | 2 |
MUFAj(g) | .70 | 47 | 93 | 7 | 2 |
MUFA (% TE) | .57c | 39 | 81 | 19 | 2 |
PUFAk(g) | .56 | 39 | 86 | 14 | 4 |
PUFA (% TE) | .43 | 37 | 77 | 23 | 1 |
Protein (g) | .63 | 46 | 86 | 14 | 1 |
Protein (% TE) | .63 | 50 | 85 | 15 | 2 |
Carbohydrate (g) | .63 | 55 | 84 | 16 | 3 |
Carbohydrate (% TE) | .72c | 53 | 88 | 12 | 0 |
Total sugars (g) | .74 | 57 | 94 | 6 | 2 |
Alcohol (g) | .86 | 63 | 97 | 3 | 0 |
Calcium (mg) | .51 | 45 | 81 | 19 | 3 |
Total folate (µg) | .53c | 49 | 81 | 19 | 3 |
Iron (mg) | .48 | 44 | 79 | 21 | 5 |
Total carotene (µg) | .58 | 44 | 80 | 20 | 2 |
Riboflavin (mg) | .52 | 38 | 82 | 18 | 4 |
Thiamin (mg) | .46 | 40 | 84 | 16 | 5 |
Vitamin B6 (mg) | .56 | 49 | 85 | 15 | 4 |
Vitamin B12 (µg) | .49 | 39 | 81 | 19 | 4 |
Vitamin C (mg) | .69 | 52 | 89 | 11 | 2 |
Vitamin A (RE) (µg) | .55 | 42 | 82 | 18 | 3 |
Retinol (µg) | .65 | 48 | 91 | 9 | 3 |
Vitamin D (µg) | .57 | 42 | 87 | 13 | 4 |
Vitamin E (mg) | .57 | 43 | 81 | 19 | 4 |
Sodium (mg) | .58 | 50 | 84 | 16 | 1 |
aFFQ: food frequency questionnaire.
bCorrelation is significant at the .01 level (2-tailed) for all nutrients analyzed.
cPearson’s correlation.
dExact agreement: % of cases cross-classified into the same quartile.
eExact + adjacent agreement: % of cases cross-classified into the same or adjacent quartile.
fDisagreement: % of cases cross-classified 2 quartiles apart.
gExtreme quartiles: % of cases cross-classified into extreme quartiles.
hTE: total energy.
iSFA: saturated fatty acids.
jMUFA: monounsaturated fatty acids.
kPUFA: polyunsaturated fatty acids.
Bland and Altman plots with mean difference and limits of agreement (solid line represents mean difference and dotted lines represent limits of agreement). TE: total energy.
To examine differences in food group intakes between the two FFQs, the food items in the EPIC-Norfolk FFQ and Food4Me FFQ were aggregated into 35 food groups. Mean daily intakes estimated from the two FFQs for the 35 food groups are presented in
Bland and Altman analysis for daily food group intake was performed to examine the agreement between both methods. Overall, acceptable levels of agreement were observed for 15 of the 35 food groups, with less than 5% of cases (n<6) falling outside the limits of agreement. The Bland and Altman plots for mean daily intakes for six of the 35 food groups (“rice, pasta, grains, and starches”, “yoghurts”, “eggs and egg dishes”, “other vegetables”, “fish and fish products”, “red meat”) are presented in
SCC and cross-classification of mean daily food group intakes are presented in
Mean daily food group intakes estimated by printed EPIC-Norfolk FFQaand online Food4Me FFQ (n=113).
Food group | EPIC (grams), mean (SD) | Food4Me (grams), mean (SD) |
|
Rice, pasta, grains, and starches | 87.26 (74.30) | 99.03 (87.54) | .28 |
Savories (lasagna, pizza) | 17.69 (17.40) | 34.85 (29.75) | <.001 |
White bread (rolls, tortillas, crackers) | 13.65 (19.69) | 43.93 (69.54) | <.001 |
Wholemeal and brown breads and rolls | 28.20 (37.76) | 54.28 (67.59) | <.001 |
Breakfast cereals and porridge | 50.51 (50.67) | 93.91 (91.64) | <.001 |
Biscuits | 6.43 (10.56) | 18.94 (25.06) | <.001 |
Cakes, pastries, and buns | 17.76 (24.47) | 19.70 (18.55) | .50 |
Milk | 280.97 (166.19) | 240.53 (178.04) | .08 |
Cheeses | 17.36 (22.68) | 24.38 (29.29) | .045 |
Yoghurts | 29.20 (38.112) | 60.98 (99.82) | .002 |
Ice cream, creams, and desserts | 16.60 (28.48) | 12.61 (17.44) | .21 |
Eggs and egg dishes | 18.63 (19.62) | 34.92 (36.39) | <.001 |
Fats and oils (eg, butter, low-fat spreads, hard cooking fats) | 10.34 (10.38) | 14.75 (13.00) | .005 |
Potatoes and potato dishes | 47.39 (35.00) | 68.18 (63.48) | .003 |
Chipped, fried, and roasted potatoes | 11.51 (15.43) | 14.13 (17.30) | .23 |
Peas, beans, and lentils and vegetable and pulse dishes | 25.46 (23.91) | 30.13 (31.56) | .21 |
Green vegetables | 26.31 (27.96) | 28.06 (35.97) | .68 |
Carrots | 18.93 (20.84) | 23.83 (23.43) | .10 |
Salad vegetables (eg, lettuce) | 13.00 (14.45) | 10.28 (10.97) | .11 |
Other vegetables (eg, onions) | 96.05 (53.06) | 111.62 (96.73) | .14 |
Tinned fruit or vegetables | 15.30 (19.10) | 18.84 (26.22) | .25 |
Bananas | 52.00 (55.01) | 61.54 (70.20) | .26 |
Other fruits (eg, apples, pears, oranges) | 156.69 (140.10) | 218.90 (206.63) | .01 |
Nuts and seeds, herbs and spices | 3.54 (6.67) | 2.48 (5.79) | .19 |
Fish and fish products/dishes | 29.99 (31.68) | 48.29 (48.70) | .001 |
Bacon and ham | 12.76 (16.81) | 12.11 (14.33) | .75 |
Red meat (eg, beef, veal, lamb, pork) | 26.87 (31.75) | 41.31 (39.25) | .003 |
Poultry (chicken and turkey) | 31.47 (37.20) | 42.79 (53.92) | .07 |
Meat products (eg, burgers, sausages, pies, processed meats) | 9.15 (10.18) | 19.76 (23.18) | <.001 |
Alcoholic beverages | 104.80 (182.33) | 200.32 (261.08) | .002 |
Sugars, syrups, preserves, and sweeteners | 8.15 (10.21) | 7.04 (9.53) | .40 |
Confectionary and savory snacks | 23.87 (32.88) | 25.31 (24.53) | .71 |
Soups, sauces, and miscellaneous foods | 51.83 (52.32) | 83.76 (84.80) | .001 |
Teas and coffees | 533.78 (398.43) | 472.08 (403.98) | .25 |
Other beverages (eg, fruit juices, carbonated beverages, squash) | 109.73 (123.90) | 213.66 (204.12) | <.001 |
aFFQ: food frequency questionnaire.
bAll
Spearman’s correlation coefficients (SCC) and cross-classification of quartiles of food group intake.
Food group | SCC | Exact agreementa(%) | Exact agreement + adjacentb(%) | Disagreementc(%) |
Rice, pasta, grains, and starches | .76 | 55 | 94 | 6 |
Savories (lasagna, pizza) | .41 | 36 | 79 | 21 |
White bread (rolls, tortillas, crackers) | .55 | 42 | 83 | 17 |
Wholemeal and brown breads and rolls | .74 | 54 | 92 | 8 |
Breakfast cereals and porridge | .76 | 62 | 93 | 7 |
Biscuits | .67 | 45 | 90 | 13 |
Cakes, pastries, and buns | .48 | 35 | 77 | 23 |
Milk | .55 | 49 | 80 | 20 |
Cheeses | .66 | 50 | 85 | 15 |
Yoghurts | .70 | 58 | 89 | 11 |
Ice cream, creams, and desserts | .49 | 43 | 81 | 19 |
Eggs and egg dishes | .59 | 43 | 83 | 17 |
Fats and oils (eg, butter, low-fat spreads, hard cooking fats) | .64 | 43 | 86 | 14 |
Potatoes and potato dishes | .61 | 44 | 83 | 17 |
Chipped, fried, and roasted potatoes | .63 | 45 | 88 | 12 |
Peas, beans, and lentils and vegetable and pulse dishes | .66 | 49 | 83 | 17 |
Green vegetables | .76 | 56 | 91 | 9 |
Carrots | .65 | 51 | 85 | 15 |
Salad vegetables (eg, lettuce) | .58 | 50 | 84 | 16 |
Other vegetables (eg, onions) | .67 | 47 | 90 | 10 |
Tinned fruit or vegetables | .72 | 53 | 90 | 10 |
Bananas | .88 | 73 | 96 | 4 |
Other fruits (eg, apples, pears, oranges) | .90 | 70 | 99 | 1 |
Nuts and seeds, herbs and spices | .68 | 56 | 83 | 17 |
Fish and fish products/dishes | .73 | 51 | 90 | 10 |
Bacon and ham | .75 | 50 | 91 | 9 |
Red meat (eg, beef, veal, lamb, pork) | .69 | 50 | 93 | 7 |
Poultry (chicken and turkey) | .69 | 48 | 83 | 17 |
Meat products (eg, burgers, sausages, pies, processed meats) | .67 | 53 | 87 | 13 |
Alcoholic beverages | .87 | 66 | 95 | 5 |
Sugars, syrups, preserves, and sweeteners | .79 | 62 | 92 | 8 |
Confectionary and savory snacks | .66 | 53 | 88 | 12 |
Soups, sauces, and miscellaneous foods | .53 | 43 | 82 | 18 |
Teas and coffees | .77 | 59 | 93 | 7 |
Other beverages (eg, fruit juices, carbonated beverages, squash) | .79 | 60 | 92 | 8 |
aExact agreement: % of cases cross-classified into the same quartile.
bExact + adjacent agreement: % of cases cross-classified into the same or adjacent quartile.
cDisagreement: % of cases cross-classified 2 quartiles apart.
Bland and Altman plots for selected food groups with mean difference and limits of agreement (solid line represents mean difference and dotted lines represent the limits of agreement).
The present study demonstrates the development of a novel online FFQ and its comparison with the validated printed EPIC-Norfolk FFQ [
Overall, the current results demonstrate good agreement between the online Food4Me FFQ and the printed EPIC-Norfolk FFQ for both nutrient and food group intakes. Cross-classification of daily energy and nutrient intakes showed good agreement between the two FFQs indicating that the online Food4Me FFQ generates ranks of dietary intakes that are highly comparable with the previously validated printed EPIC-Norfolk FFQ. Similar to many previous published studies, classification into exact plus adjacent quartiles ranged from 77% to 97% and exact disagreement/misclassification ranged between 0% and 5% [
In the present study, there were moderate to high correlation coefficients, ranging from .43 to .86, between the methods for individual nutrients. For the majority of nutrients analyzed, the correlation coefficients were within the ranges recommended by Willet et al [
Analyses at the food group level also showed good agreement between the EPIC-Norfolk and Food4Me FFQs. Validation studies of FFQs examining food group intakes have reported SCC ranging from .46 to .87 [
While we have demonstrated that the online Food4Me FFQ shows good agreement with the printed EPIC-Norfolk FFQ overall, some disagreement was observed between the two FFQs, particularly in relation to energy intakes. Similar to findings by Beasley et al [
Multiple factors could have contributed to the discrepancies observed in mean daily intakes and the occurrence of under-reporting between the two methods. First, numerous differences in food group consumption were observed between the two FFQs. For 17 of the 35 food groups (49%), mean daily intakes were significantly higher with the online Food4Me FFQ compared with the printed EPIC-Norfolk FFQ. In addition, Bland and Altman plots demonstrated a poor level of agreement between the methods for 20 of the 35 food groups (57%). The low level of agreement for food group consumption between the two methods is most likely attributable to differences in reported food intake between both FFQs. The Food4Me FFQ included an additional 27 food items not present in the printed EPIC-Norfolk FFQ and as a result several of the 35 food groups analyzed in the current study did not contain equal numbers of food items for both methods. For example, the food group “fish and fish products/dishes” consisted of 10 food items for the Food4Me FFQ compared with six food items from the EPIC-Norfolk FFQ. Such variances in the number of food items aggregated into food groups (for both FFQs) could partly explain the differences observed in mean daily food group intakes between the two methods.
The additional 27 food items listed in the Food4Me FFQ would have offered participants a greater selection of food items and, as a result, both food group consumption and subsequent nutrient intakes may be more reflective of true dietary intake. However, it is also possible that the additional food items included in the Food4Me FFQ may have resulted in an overestimation of consumption frequency for particular nutrients and food groups. This can occur when several food items of a single food group are listed in a questionnaire [
A second factor potentially contributing to the differences observed between the two FFQs is portion size estimation. The online Food4Me FFQ incorporates a selection of portion sizes for the majority of food items, as opposed to applying a standard one to each food item. Presuming all participants consume standard portion sizes is a generalization and the use of standard portion sizes in heterogeneous population groups is likely to result in additional inaccuracies [
Third, the differences we observed between the two methods in relation to daily nutrient intakes may have been related to variances in the nutritional composition databases utilized in both methods, as the nutritional composition database used to calculate daily nutrient intakes is more up to date than that used for analysis of the printed EPIC-Norfolk FFQ [
The strengths of the current study include the cross-over design and adequate sample size [
In conclusion, the online Food4Me FFQ has good agreement with the previously validated printed EPIC-Norfolk FFQ for assessing both nutrient and food group intakes of healthy young adults. While some differences were observed between the methods, particularly in relation to mean daily nutrient and food group intakes, good agreement was observed at both the nutrient and food group level using a variety of analyses. The most common use of an FFQ is not to measure absolute intake but to rank individuals by their food and nutrient intakes [
Food4Me Food Frequency Questionnaire screenshots.
body mass index
basal metabolic rate
estimated energy requirements
European Prospective Investigation of Cancer
food frequency questionnaire
monounsaturated fatty acids
National Adult Nutrition Survey
polyunsaturated fatty acids
Spearman’s correlation coefficient
saturated fatty acids
total energy
vitamin A retinol equivalents
This work was funded by Food4Me (KBBE.2010.2.3-02, Project no. 265494). The authors would like to thank Creme Global (Dublin, Ireland) for their considerable involvement in the development of the online Food4Me FFQ and the participants for their time and dedication throughout the study.
All authors participated in the design of the study. HF, RF, CG, and ALM carried out the data collection. HF, MCW, LB, and ERG carried out the statistical analyses and drafted the manuscript. All authors critically reviewed and approved the final manuscript submitted for publication.
None declared.