Validity and reliability of an omega-3 fatty acid food frequency questionnaire for first-generation Midwestern Latinas

This study tested the hypothesis that a culturally developed omega-3 (n-3) fatty acid food frequency questionnaire (FFQ) could be an accurate instrument to capture n-3 fatty acid food intakes of first-generation Midwestern Latinas. The goal of the study was to assess validity and test-retest reliability of an FFQ to estimate total n-3 fatty acid (total n-3), α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) intakes. An n-3 FFQ was developed and pilot tested. Two FFQs and 3 nonconsecutive 24-hour recalls were collected from 162 participants. Pearson correlation and paired t test were used to test the hypothesis. Correlation of the 2 FFQs was 0.71 for total n-3, 0.65 for ALA, 0.74 for EPA, and 0.54 for DHA (P < .01). The means of the 2 FFQs and of the 24-hour recalls were not significantly different for total n-3 and ALA (P > .05), but were significantly different for EPA and DHA. The n-3 FFQ had acceptable reliability, validated only total n-3 and ALA, and provided relevant findings about the n-3 eating habits of Midwestern Latinas.     

Validation of a Short,Qualitative Food Frequency Questionnaire in French Adults Participating in the MONA LISA-NUT Study 2005-2007

BackgroundFood frequency questionnaires (FFQs) are often used to evaluate individuals' food intakes in epidemiologic studies because of their simplicity and low cost.ObjectiveTo assess the validity of a short (24 items), qualitative FFQ used in the MONA LISA-NUT study.DesignCross-sectional study of a representative sample in three French counties.Participants/settingThe sample included 2,630 participants aged 35 to 65 years from the MONA LISA-NUT study.Main outcome measuresFood consumption was measured with the FFQ and via food records for 3 consecutive days. Plasma fatty acids were measured from a subset of participants.Statistical analyses performedThe FFQ items' validity was assessed by calculating crude and deattenuated Pearson correlation coefficients between frequencies reported by the FFQ and average weights reported by the food records. Furthermore, the validity of some items of the FFQ measuring the consumption of fatty foods was assessed by calculating Pearson correlation coefficients between frequencies of consumption of these foods and dosages of the corresponding plasma fatty acids: fish and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), olive oil and oleic acid, margarine and elaidic acid, and dairy products and pentadecanoic and heptadecanoic acids.ResultsThe mean of the deattenuated Pearson correlation coefficients for all items was 0.46, with values ranging from 0.22 (fried food) to 0.77 (breakfast cereal). The correlation coefficient was ≤0.4 for one third of the 24 items. Moderate correlations were found between fish and EPA/DHA (EPA: r=0.43, 95% CI 0.33 to 0.51; DHA: r=0.39, 95% CI 0.30 to 0.47), but not for other food items.ConclusionsOne third of the 24 items in the short, qualitative FFQ evaluated here were not sufficiently valid. However, for the food groups most commonly studied in the literature, this FFQ had the same degree of validity as other questionnaires designed to classify subjects according to their level of intake.     

Direct Determinations of the Fatty Acid Composition of Daily Dietary Intakes Incorporating Nutraceuticals and Functional Food Strategies to Increase n-3 Highly Unsaturated Fatty Acids

Objective: North American diets are low in eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA). This investigation aims to assess the ability to increase EPA and DHA in the Canadian diet using traditional whole food, functional food or nutraceutical strategies.

Methods: A typical Canadian diet (TC) was compared to four diets enriched with EPA and DHA but with similar caloric and macronutrient composition: a nutraceutical fish oil capsule diet (FO), an EPA + DHA-enriched functional foods diet (ED), a traditional whole foods (fish) diet (TW) and a comprehensive diet combining fish with functional foods (FF) containing EPA + DHA and α-linolenic acid. Direct biochemical quantitations were performed for energy, protein, carbohydrate (proximate analysis) and fat (gas chromatography). Costs of each diet and EPA + DHA source were assessed.

Results: The FO (1.03 ± 0.01g EPA + DHA), ED (0.59 ± 0.02g), TW (3.23 ± 0.09g) and FF (3.15 ± 0.06g) diets provided significantly higher amounts of EPA + DHA compared to the TC diet (0.08 ± 0.01g). Using the TC diet as a baseline, the daily cost increase for each revised diet was $0.53 (FO), $0.82 (TW), $0.93 (ED) and $1.62 (FF). The cost per gram of EPA + DHA was lowest for fish oil nutraceuticals ($0.53/g), followed by fish (～$1.05/g).

Conclusions: The EPA and DHA content of daily diets can be increased significantly and cost effectively using nutraceuticals, functional foods and whole foods. Several North American EPA + DHA recommendations for healthy individuals can be met using these strategies and American Heart Association recommendations for secondary coronary heart disease prevention can be met via traditional whole food, nutraceutical or combination approaches.     

Reproducibility of a food frequency questionnaire: Korea Nurses' Health Study

BACKGROUND/OBJECTIVESThis study aimed to examine the reproducibility of food frequency questionnaires (FFQs) designed for young female nurses in the Korea Nurses'' Health Study.SUBJECTS/METHODSThe reproducibility of web-based, self-administered FFQs was evaluated among 243 Korean female nurses. The first FFQ (FFQ1) was administered from March 2014 to February 2019 and the second FFQ (FFQ2) from November 2019, with a mean interval of 2.8 years between the FFQs (range, 9 months–5.6 years). Pearson and Spearman correlation coefficients (r values) and quartile agreements between FFQ1 and FFQ2 were calculated for intakes of energy, nutrients, and foods.RESULTSPearson correlation coefficients ranged from 0.41 to 0.55 (median r = 0.51) for energy and raw nutrients and from 0.16 to 0.46 (median r = 0.36) for energy-adjusted nutrients. Spearman correlation coefficients ranged from 0.25 to 0.72 (median r = 0.41) for food items. The percentages of women who were classified into the same or adjacent quartile were 77% to 84% (median = 82%) for raw nutrients and 69% to 86% (median = 78%) for foods.CONCLUSIONSThe results indicated that the web-based FFQ used in the Korea Nurses'' Health Study has acceptable reproducibility.     

Reproducibility and validity of semi-quantitative food frequency questionnaire measuring dietary trans-fatty acids intake among Korean adults

BACKGROUND/OBJECTIVESCompelling evidence indicates that consumption of trans-fatty acids (TFA) is associated with a wide range of diseases. However, few validated tools for TFA intake assessment are available in Korea. We aimed to validate a food frequency questionnaire (FFQ) estimating usual intake of TFA in Korean adults.MATERIALS/METHODSEighty-two healthy adults completed an FFQ with a 3-day diet record (3DDR), and 58 completed a second FFQ at a 1-month interval. To assess the reproducibility of the FFQ, we compared estimated TFA intakes from each FFQ. To assess the validity, we compared estimates from the FFQ with those from the 3DDR.RESULTSThe FFQ was reproducible (Spearman r = 0.71) and provided modest correlations with the 3DDR (Spearman r = 0.38). After adjustment for total energy intake, the correlations increased (r = 0.45). Measurement-error correction also de-attenuated the correlations (r = 0.57). When quintiles of the FFQ and 3DDR were joint-classified, 9% on average were misclassified into extreme quintiles.CONCLUSIONSOur findings suggest that the developed FFQ is reproducible and reasonably valid in categorizing individuals according to TFA intakes among healthy young and middle aged adults in Korea.     

N-Nitroso Compounds: Assessing Agreement between Food Frequency Questionnaires and 7-Day Food Records

BackgroundN-nitroso compounds are recognized as important dietary carcinogens. Accurate assessment of N-nitroso intake is fundamental to advancing research regarding its role with cancer. Previous studies have not used a quantitative database to estimate the intake of these compounds in a US population.ObjectiveTo address this gap, a database of N-nitroso values was developed in conjunction with an existing food frequency questionnaire (FFQ). In this article we report on the relative validity of the FFQ instrument modified to estimate intake of N-nitroso compounds.DesignIntake estimates of 23 N-nitroso compounds from the FFQ were compared with those from 7-day food records in a cross-sectional study conducted from January 2005 through June 2006.SubjectsA sample of 98 healthy adult subjects (aged 50.42±12.84 years) completed an FFQ and then recorded foods and beverages consumed on 7-day food records.ResultsCrude and energy-adjusted N-nitroso compounds intakes were significantly higher in the FFQ than the 7-day food records (P<0.001). Spearman correlations for crude and energy-adjusted N-nitroso intakes ranged from 0.004 to 0.48. By tertiles of N-nitiroso compounds, there was moderate agreement (κ>0.30) for five compounds. Higher estimates of N-nitroso compounds by FFQ was explained by a greater proportion of subjects who reported eating foods high in N-nitroso compounds on FFQ than reported on 7-day food records.ConclusionThe modified FFQ with N-nitroso values is a useful tool for assessing N-nitroso intakes relative to a group, and captures all food items with N-nitroso compounds, including those foods with high concentrations and eaten sporadically.     

Validation of a food frequency questionnaire to assess intake of n-3 polyunsaturated fatty acids in subjects with and without major depressive disorder

The role of n-3 polyunsaturated fatty acids (PUFAs) in psychiatric illness is a topic of public health importance. This report describes development and biomarker validation of a 21-item, self-report food frequency questionnaire (FFQ) intended for use in psychiatric research to assess intake of α-linolenic acid (18:3n-3 [ALA]), docosahexaenoic acid (22:6n-3 [DHA]), and eicosapentaenoic acid (20:5n-3 [EPA]). In a cross-sectional study conducted from September 2006 to September 2008, sixty-one ethnically diverse adult participants with (n=34) and without (n=27) major depressive disorder completed this n-3 PUFA FFQ and provided a plasma sample. Plasma levels of n-3 PUFAs EPA and DHA, and n-6 PUFA arachidonic acid (20:4n-6 [AA]) were quantified by gas chromatography. Using Spearman's ρ, FFQ-estimated intake correlated with plasma levels of DHA (r=0.50; P<0.0001) and EPA (r=0.38; P=0.002), but not with ALA levels (r=0.22; P=0.086). Participants were classified into quartiles by FFQ-estimated intake and plasma PUFA concentrations. Efficacy of the FFQ to rank individuals into same or adjacent plasma quartiles was 83% for DHA, 78.1% for EPA, and 70.6% for ALA; misclassification into extreme quartiles was 4.9% for DHA, 6.5% for EPA, and 8.2% for ALA. FFQ-estimated EPA intake and plasma EPA were superior to plasma AA levels as predictors of the plasma AA to EPA ratio. This brief FFQ can provide researchers and clinicians with valuable information concerning dietary intake of DHA and EPA.     

Relative Validity and Reproducibility of a Food Frequency Questionnaire for Assessing Dietary Patterns and Food Group Intake in Older New Zealand Adults: The Researching Eating,Activity, and Cognitive Health Study

BackgroundDietary pattern analysis considers the overall dietary intake and combinations of foods eaten. Valid and reproducible tools for determining dietary patterns are necessary to assess diet–disease relationships.ObjectiveThis study evaluated the relative validity and reproducibility of the Researching Eating, Activity, and Cognitive Health (REACH) Study food frequency questionnaire (FFQ) specifically designed to identify dietary patterns in older adults.DesignA subset of participants from the REACH study completed two identical 109-item FFQs 1 month apart (FFQ1 and FFQ2) to assess reproducibility and a 4-day food record between FFQ administrations to assess relative validity. Foods from each dietary assessment tool were assigned to 57 food groups. Principal component analysis was applied to the food group consumption reported in each dietary assessment tool to derive dietary patterns.Participants and settingDietary data were collected (2018 and 2019) from a subset of the REACH study (n = 294, 37% men) aged 65 to 74 years, living in Auckland, New Zealand.Main outcome measuresDaily intakes of 57 food groups and dietary patterns of older adults participating in REACH living in New Zealand.Statistical analysisAgreement of dietary pattern loadings were assessed using Tucker’s congruence coefficient. Agreement of dietary pattern scores and food group intakes were assessed using Spearman correlation coefficients (acceptable correlation rho = 0.20 to 0.49), weighted kappa statistic (acceptable statistic κ_w = 0.20 to 0.60), and Bland-Altman analysis, including mean difference, limits of agreement, plots, and slope of bias.ResultsThree similar dietary patterns were identified from each dietary assessment tool: Mediterranean style, Western, and prudent. Congruence coefficients between factor loadings ranged from 0.54 to 0.80. Correlations of dietary pattern scores ranged from 0.47 to 0.59 (reproducibility) and 0.33 to 0.43 (validity) (all P values < 0.001); weighted kappa scores from 0.40 to 0.48 (reproducibility) and 0.27 to 0.37 (validity); limits of agreement from ± 1.79 to ± 2.09 (reproducibility) and ± 2.09 to ± 2.27 (validity); a negative slope of bias was seen in the prudent pattern for reproducibility and validity (P < 0.001).ConclusionsThe REACH FFQ generated dietary patterns with acceptable reproducibility and relative validity and therefore can be used to examine associations between dietary patterns and health outcomes in older New Zealand adults.     

Dietary calcium intake in postmenopausal Malaysian women: comparison between the food frequency questionnaire and three-day food records

The objective of this study was to compare the dietary calcium intakes assessed by a quantitative food frequency questionnaire (FFQ) and the three-day food record method in 230 Chinese postmenopausal women aged 50-65 years in Kuala Lumpur. The results showed that the mean calcium intake from the dietary records was 447+/-168 mg/day and 499+/-211 mg/day from the FFQ. The mean difference in intake by the two methods was 51.3 mg (95% CI = -30.8-77.9; SD = 181.2, P>0.05), which did not differ significantly from zero. Pearson's correlation coefficient of 0.56 was obtained between the two methods. Ninety-five percent of the individuals classified by food records fell into the same or within-one-quartile category when classified by FFQ. Forty-eight percent were classified into the same quartile by both methods. No subjects were grossly misclassified by the FFQ. The FFQ correctly identified subjects with calcium intakes below the Malaysian recommended daily allowance (450 mg/day) with 60% specificity and with 92% specificity for women consuming less than 800 mg calcium/day. In conclusion, the FFQ developed was a useful, rapid clinical tool for assessing calcium intake and identifying postmenopausal Chinese women with low calcium intakes in Malaysia.     

Relative and biomarker-based validity of a food frequency questionnaire that measures the intakes of vitamin B12, folate, iron, and zinc in young women

Folate, vitamin B₁₂, iron, and zinc are particularly important nutrients for women of childbearing age. We tested the hypothesis that an electronic, 235-item, semiquantitative food frequency questionnaire (FFQ) is a valid measure of dietary intake when compared with repeat dietary 24-hour recalls. Biomarkers of folate, vitamin B₁₂, iron, and zinc were determined because their measurement errors are unrelated to errors in dietary questionnaires. Female adults (N = 256) aged 18 to 35 years completed the FFQ, and a representative subset (n = 53) completed repeat dietary 24-hour recalls. The FFQ estimates (mean ± SD) were 315 ± 132 μg for folate, 3.1 ± 2.1 μg for vitamin B₁₂, 15.4 ± 5.6 mg for iron, and 15.1 ± 6.4 mg for zinc. The percentage of women classified within the same ±1 quartile for energy intake by the 2 methods was 77.3%. There was moderate agreement between the 2 dietary methods, and no systematic bias was noted for energy, folate, vitamin B₁₂, and zinc. The deattenuated energy-adjusted correlation coefficients ranged from 0.41 (dietary folate equivalents) to 0.60 (folate). Significant correlations between biomarker and nutrient intakes were found for folate (r = 0.37, P < .01) and vitamin B₁₂ (r = 0.27, P < .01). The electronic FFQ developed in the present study is a relatively valid tool that was able to adequately assess and rank individuals according to their nutrient intakes.     

The development and evaluation of a food frequency questionnaire used in assessing vitamin D intake in a sample of healthy young Canadian adults of diverse ancestry

Little data exist on vitamin D deficiency related with intake, especially for the Canadian population. The purpose of this study was to develop and evaluate a food frequency questionnaire (FFQ) with 37 items for rapid assessment of vitamin D intake in healthy young adults of diverse ancestry. We recruited 107 subjects in Southern Ontario during the late winter of 2007 who completed an FFQ twice (FFQ-1 and FFQ-2, repeated for reproducibility assessment) and a 7-day food diary (for validation). Serum 25-hydroxyvitamin D (25(OH)D), the major biomarker of vitamin D nutritional status, and skin melanin were determined. The FFQ results were highly correlated with 7-day diary results and with serum 25(OH)D concentrations (r = 0.529, P < .001; r = 0.481, P < .001, respectively). Modifications to the FFQ, by redefining the large serving size and excluding the fortified orange juice category, improved the validity of the FFQ (r = 0.602, P < .001; r = 0.520, P < .001, respectively). The FFQ results were highly correlated (r = 0.663, P < .001), but the mean intakes were different (P < .05). Using results from a modified version of FFQ-1, we examined dietary intakes in 3 predominant groups: East Asian (n = 27), European (n = 31), and South Asian (n = 32). The European group had higher total vitamin D intake (P < .05) and the highest serum 25(OH)D concentrations (P < .05), with a trend for dairy products being responsible for this (P < .10). Because Canadians are reliant on dietary intakes of vitamin D in the wintertime, especially those with higher skin melanin, our FFQ can monitor and provide information on intake and food group consumption.     

A method for assessing dietary intakes of n-3 long-chain polyunsaturated fatty acids and trans fatty acids in an Irish adult population

Abstract

The present study aimed to quantify dietary intakes of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and trans fatty acids (trans FA) in Irish adults using the North/South Ireland Food Consumption Survey (NSIFCS). To update the NSIFCS database, specific approaches were necessary to select accurate data. Published references were the main data source used to update for EPA and DHA (21.7%), while the UK Nutrient Databank was most frequently used to update for trans FA (46.7%). Total EPA and DHA mean daily intake was 275 mg/day whilst trans FA mean daily intake was 0.72% food energy. Younger adults had significantly lower intakes of EPA and DHA than older adults. The present study shows that dietary EPA and DHA intakes in the Irish adult population are below recommendations, especially among the younger population. Conversely, trans FA intakes are within the recommended value of < 2% food energy.     

Validity and reproducibility of an interviewer-administered food frequency questionnaire in Austrian adults at risk of or with overt diabetes mellitus

Food frequency questionnaires (FFQs) provide an inexpensive tool for dietary assessment. Given the scarcity of data on their validity for nutritional analysis in persons with overt diabetes mellitus or with increased risk of diabetes (relatives of patients with diabetes), this study tests the hypothesis that an FFQ, adapted to local dietary habits, yields a reliable estimate of nutrient intake when compared with 7-day food record (7DR) in healthy, prediabetes, and diabetes cohorts. One hundred three volunteers (50 persons with overt diabetes mellitus, 24 relatives of patients with diabetes, and 29 nondiabetic individuals without a family history of diabetes) completed both FFQ and 7DR. A second FFQ was completed by 100 of these volunteers after 3 months to evaluate its reproducibility. Data were compared by correlation and Bland-Altman analyses. Across the entire group, estimates for gram intakes of nutrients and total energy were associated with wide limits of agreement between FFQ and 7DR (correlation coefficients, 0.23-0.72; P < .02). Compared with 7DR, the FFQ overestimated intakes of saturated fat in the entire group (+6.6 ± 14 g; P < .001) and in persons with overt diabetes mellitus (+7.6 ± 15 g; P < .001) but underestimated protein intake in relatives of patients with diabetes (−16.36 ± 31 g; P = .01). The repeated FFQ revealed variable agreement (correlation coefficients, 0.34-0.72; P < .001) and underestimated (P < .01) macronutrient and total energy intakes, with slightly better performance in persons with overt diabetes mellitus and relatives of patients with diabetes than in nondiabetic individuals without a family history of diabetes. Hence, the FFQ allows measuring intakes of total energy and macronutrients in prediabetes and diabetes cohorts but reveals limitations when assessing dietary composition.     

Assessing long-chain ω-3 polyunsaturated fatty acids: A tailored food-frequency questionnaire is better

ObjectivePolyunsaturated fatty acids (PUFAs), including the long-chain (LC) ω-3 PUFAs, are important for health. The aim was to assess if the Anti-Cancer Council of Victoria Dietary Questionnaire (ACC DQ) accurately determines PUFA intakes compared with the recently validated electronic PUFA food-frequency questionnaire (FFQ).MethodsForty-one study volunteers were recruited from the local Illawarra region of New South Wales, Australia. The method of triads was used to determine validity coefficients by comparing the ACC DQ intakes against a 3-d weighed food record and appropriate blood biomarkers (erythrocytes and plasma fatty acids). These validity coefficients were subsequently compared with previously published validity coefficients from the PUFA FFQ.ResultsUsing erythrocytes as the biomarker, the electronic PUFA FFQ had much higher validity coefficients compared with the ACC DQ for eicosapentaenoic acid (0.92 versus 0.19), docosahexaenoic acid (0.69 versus 0.26), and total LC ω-3 PUFAs (0.78 versus 0.23), respectively, whereas ω-6 PUFAs were comparable. Using plasma as the biomarker, the electronic PUFA FFQ had much higher validity coefficients compared with the ACC DQ for α-linolenic acid (0.96 versus 0.49), eicosapentaenoic acid (0.87 versus 0.19), docosahexaenoic acid (0.64 versus 0.24), and total LC ω-3 PUFAs (0.73 versus 0.21), respectively, whereas ω-6 PUFAs were comparable.ConclusionThe validated electronic PUFA FFQ is better suited to determine ω-3 PUFA intakes than the ACC DQ.     

Validity of the Willett food frequency questionnaire in assessing the iron intake of French-Canadian pregnant women

ObjectiveMaternal intake is crucial to pregnancy outcomes. Evidence shows that both nutrient deficiency and excess can have adverse effects. In pregnancy, changes in iron metabolism occur; therefore, dietary reference intakes increase to support expansion of red cells and maternal–fetal transfer of iron. Appropriate and valid assessment tools are required to investigate nutritional concerns in mothers with and without gestational diabetes mellitus (GDM). The objective of this study was to assess the Willett food frequency questionnaire (FFQ) to assess iron intake in women with (n = 15) and without (n = 45) GDM.MethodsTo validate the modified FFQ, estimated total iron intake during the third trimester was compared with biomarkers of iron status such as serum ferritin, soluble transferrin receptor (sTfR), and the sTfR:F index at delivery. Data were tested for normality using the D’Agostino-Pearson test. Differences between groups were tested using t tests or Mann–Whitney tests. Correlations were tested using Spearman’s ρ. Significance was set at P < 0.05.ResultsSignificant crude and energy-adjusted serum ferritin and total iron intake were related (ρ = 0.30; P < 0.05) in women without GDM. Serum ferritin, sTfR, and the sTfR:F index were different (P < 0.05) between women with intakes above and below the recommended levels. Cross-classification showed agreement between methods in mothers with and without GDM; on average, 63% of the women were classified into the same or adjacent quartile when ranked by FFQ and iron status.ConclusionThese findings suggest the Willett FFQ is a good tool for assessing total iron intake of French-Canadian pregnant women.     

Higher dietary intake of long-chain ω-3 polyunsaturated fatty acids is inversely associated with depressive symptoms in women

ObjectiveExperimental and observational data suggest that a higher dietary intake of long-chain ω-3 polyunsaturated acids may lead to a decreased risk of depressive disorders. We assessed multivariable-adjusted associations of fish consumption and dietary intakes of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with depressive symptoms in a population-based sample of 3317 African-American and Caucasian men and women from the Coronary Artery Risk Development in Young Adults study.MethodsDiet was assessed in year 7 (1992–1993) and depressive symptoms were measured in years 10 (1995–1996), 15 (2000–2001), and 20 (2005–2006) by the 20-item Center for Epidemiological Studies Depression Scale. Depressive symptoms were defined as a Center for Epidemiological Studies Depression Scale score ≥16 or self-reported use of antidepressant medication.ResultsIn the entire cohort, the highest quintiles of intakes of EPA (≥0.03% energy), DHA (≥0.05% energy), and EPA + DHA (≥0.08% energy) were associated with a lower risk of depressive symptoms at year 10 (P for trends = 0.16, 0.10, and 0.03, respectively). The observed inverse associations were more pronounced in women. For the total number of occasions with depressive symptoms, the multivariable adjusted odds ratios (95% confidence interval) in women were 0.75 (0.55–1.01) for fish intake, 0.66 (0.50–0.89) for EPA, 0.66 (0.49–0.89) for DHA, and 0.71 (0.52–0.95) for EPA + DHA when comparing the highest with the lowest quintiles. Analyses of continuous Center for Epidemiological Studies Depression Scale scores revealed inverse associations with fourth-root–transformed ω-3 variables in women.ConclusionOur findings suggest that dietary intakes of fish and long-chain ω-3 fatty acids may be inversely associated with chronic depressive symptoms in women.     

Food Predictors of Plasma Carotenoids

Empirical prediction models that weight food frequency questionnaire (FFQ) food items by their relation to nutrient biomarker concentrations may estimate nutrient exposure better than nutrient intakes derived from food composition databases. Carotenoids may especially benefit because contributing foods vary in bioavailability and assessment validity. Our objective was to develop empirical prediction models for the major plasma carotenoids and total carotenoids and evaluate their validity compared with dietary intakes calculated from standard food composition tables. 4180 nonsmoking women in the Nurses’ Health Study (NHS) blood subcohort with previously measured plasma carotenoids were randomly divided into training (n = 2787) and testing (n = 1393) subsets. Empirical prediction models were developed in the training subset by stepwise selection from foods contributing ≥0.5% to intake of the relevant carotenoid. Spearman correlations between predicted and measured plasma concentrations were compared to Spearman correlations between dietary intake and measured plasma concentrations for each carotenoid. Three to 12 foods were selected for the α-carotene, β-carotene, β-cryptoxanthin, lutein/zeaxanthin, lycopene, and total carotenoids prediction models. In the testing subset, Spearman correlations with measured plasma concentrations for the calculated dietary intakes and predicted plasma concentrations, respectively, were 0.31 and 0.37 for α-carotene, 0.29 and 0.31 for β-carotene, 0.36 and 0.41 for β-cryptoxanthin, 0.28 and 0.31 for lutein/zeaxanthin, 0.22 and 0.23 for lycopene, and 0.22 and 0.27 for total carotenoids. Empirical prediction models may modestly improve assessment of some carotenoids, particularly α-carotene and β-cryptoxanthin.     

Absorption estimates improve the validity of the relationship between dietary and serum lycopene

ObjectiveStudies show low correlations between dietary intake and serum concentrations of lycopene, which make it difficult to assess the effectiveness of dietary interventions with this phytonutrient. We hypothesized that 1) combining food-frequency questionnaires (FFQs) and 3-d diet records (3D-DRs) by the triads method would improve the validity of this relation and 2) correcting dietary information for differences in lycopene absorption from food matrices would further improve validity.MethodsWe measured dietary intakes of lycopene from 49 adults by 3D-DR and FFQ. Serum lycopene was measured by high-performance liquid chromatography with diode array detection. Cholesterol and triacylglycerol concentrations were measured spectrophotometrically. Lycopene-containing foods were given absorption factors based on literature and laboratory values. Associations between dietary and serum lycopene were modeled using multiple regression. The triads method was used for validation of relations among FFQ, 3D-DR, and serum lycopene.ResultsRaw data showed low correlations between dietary and serum lycopene (r = +0.15 for 3D-DR, +0.35 for FFQ). Mathematical modeling showed that the 3D-DR and FFQ methods must be used to collect accurate dietary information for lycopene. Validity coefficients calculated by the triads method were +0.34 for 3D-DR and +0.78 for FFQ. Correcting for absorption increased the validity coefficient to +0.72 for 3D-DR and from +0.45 to +0.66 for serum lycopene.ConclusionThe relation between dietary intake and serum concentrations of lycopene and other carotenoids can be improved by collecting 3D-DR and FFQ data and by adjusting dietary information for nutrient absorption.     

Development and evaluation of cultural food frequency questionnaires for South Asians,Chinese, and Europeans in North America

We developed three ethnic food frequency questionnaires (FFQs) to characterize the diets of South Asian, Chinese, and European immigrants. FFQs were developed from foods reported in the diet records and recalls of 29 South Asians, 25 Chinese, and 20 Europeans participating in a pilot study from 1995-1996 in Hamilton, Ontario, Canada. The FFQ and a seven-day diet record were then administered to 342 South Asians, 317 Chinese, and 346 Europeans participating in the Study of Health Assessment and Risk in Ethnic groups (SHARE) in three Canadian centers from 1996-1998. For FFQ validation, a subset of these participants completed a second seven-day diet record and second FFQ 8 to 10 months later. The FFQ generally underestimated macronutrient and overestimated micronutrient intake compared with the records. Consumption of most macronutrients was lower among South Asians. Energy-adjusted deattenuated correlation coefficients between the records and second FFQ ranged from 0.32 to 0.73 (South Asians), 0.17 to 0.84 (Chinese), and 0.30 to 0.83 (Europeans). The FFQs generally performed well and will be used to investigate diet-disease relations in SHARE. Lower correlations for dietary fats among Chinese persons (0.17 to 0.31) may be improved with more direct questions on the FFQ regarding brand, type, and amount of oil consumed in stirfry servings.     

Validation of a short food frequency questionnaire to assess folate intake

A short quantitative food frequency questionnaire (FFQ) to assess folate intake was developed and validated against a 7-d weighed food intake record (7d-WR) and biochemical indices of folate status. Thirty-six men and women completed the self-administered FFQ on two occasions a month apart, kept a 7d-WR and gave two fasting blood samples at the beginning and end of the study for measuring serum and erythrocyte folate, respectively. Mean folate intakes were similar by repeat FFQ and correlated strongly (r 077 and r 072, P<0.001, for men and women, respectively). All other comparisons were done using the results of the FFQ administered on the first occasion. Men reported similar folate intakes on the FFQ and 7d-WR, but women reported greater intakes on the FFQ compared with the 7d-WR (P<0.05). There was a statistically significant correlation (partial, controlling for gender) between folate intakes reported by FFQ and 7d-WR (r 0.53, P<0.01). Folate intakes estimated by FFQ correlated significantly with serum (r 0.47, P<0.01), but not erythrocyte folate (r 0.25, P>0.05), the strength of the association was greater in men than in women. Validity coefficients estimated using the method of triads were higher for the FFQ than for the 7d-WR when serum folate was used as the biomarker. Overall, these results suggest that this short FFQ is a useful method for assessing folate intake, particularly in men.