Reproducibility and relative validity of a semi-quantitative food frequency questionnaire designed for assessing the intake of dioxin-like contaminants

Development and validity of a short web-based semi-quantitative Food Frequency Questionnaire applicable in both clinical and research setting: an evolution over time

Background

Assessing dietary intake is valuable both in clinical practice and in research. In research and in clinical practice, long-term habitual dietary intake is most often of interest. Therefore, a web-based semi-quantitative Food Frequency Questionnaire (FFQ) was developed to measure habitual intake of nutrients and foods.

Aim

This study aimed to assess content validity, convergent validity, and reliability of a 32-item semi-quantitative FFQ for adults.

Methods

A total of three different cohorts of Flemish adults were recruited in the past 10 years. The first cross-sectional validation study took place in 2013, consequently in 2019 and 2021. Content validity was assessed in 2019 through a semi-structured cognitive interview. Convergent validity was assessed by examining mean differences, Wilcoxon signed-rank test, Spearman's correlation coefficients (SCC), and Bland-Altman analysis for energy, nutrient, and food group intake compared with a 3-day food record (FR). Additionally, consumers-only analysis was performed together with cross-classification analysis by assessing the ranking capabilities of the FFQ into quartiles and weighted kappa. Reliability was assessed through the evaluation of SCC and intra-class correlation (ICC) of test-retest assessment of the FFQ.

Results

Spearman's correlation coefficient (SCC) for energy and absolute nutrient intake between the FFQ and the FR ranged from 0.02 to 0.54. Compared with absolute macronutrients, higher SCC was found for the majority of the relative macronutrient intake and most food groups. Bland-Altman plots showed improved agreement and decreasing bias between the FFQ and the FR over time. Misclassification of the FFQ for nutrients was acceptable and decreased over time (7.4, 7.5, and 6.8% in 2013, 2019, and 2021, respectively), but weighted kappa remained mostly fair (κ ≤ 0.20). The reliability of the FFQ was good and improved over time (mean SCC of 0.65 and 0.66 p <0.001 in 2013 and 2019).

Conclusion

The short web-based FFQ is an easy, low-cost, and feasible tool with good reliability, low misclassification, and acceptable validity to compare nutrient densities and food group intake at the population level. The measurement of absolute intake remains debatable.

Validation of a food-frequency questionnaire to assess methyl-group donor intake in preschoolers

A good assessment of dietary methyl-group donor intake (folate, choline, betaine, methionine) is needed to investigate the effect of methyl-group donor intake on children's health. The aim is to develop and validate a food-frequency questionnaire (FFQ) to estimate the daily intake of methyl-group donors in preschoolers. For the relative validity and reproducibility of the FFQ, a 7-day estimated dietary record (7d EDR) and repeated measurements 6 weeks apart (n = 77) were used respectively. For the validity (n = 75), a moderate ranking ability was obtained (de-attenuated Pearson correlation = 0.43-0.70; weighted ƙ 0.10-0.40), but the FFQ tends to overestimate the real intake. Cross-classification analysis showed that 38% (choline) and 28% (betaine) of the subjects were misclassified. The FFQ shows a moderate to good reproducibility, intra-class correlation coefficients range between 0.67 (betaine) and 0.76 (choline) with a maximal misclassification of 6.5% for betaine (weighted ƙ 0.37-0.69) (n = 77).

CONCLUSION

The FFQ is a tool with a moderate validity and reproducibility to estimate the consumption of dietary methyl-group donors in preschoolers. This tool might be used in future research epidemiological studies including preschoolers.

WHAT IS KNOWN

• Poor dietary habits during childhood have been associated with chronic disease in adulthood. • Methyl-group donors are important for DNA methylation, which is the underlying mechanism of disease development.

WHAT IS NEW

• For the first time, a food-frequency questionnaire that can assess the intake of methione, folate, choline, and betaine has been developed and validated for the use in preschoolers.

LInking EDCs in maternal Nutrition to Child health (LINC study) - protocol for prospective cohort to study early life exposure to environmental chemicals and child health

Background

The presence of chemicals in the environment is ubiquitous. Human biomonitoring studies have shown that various chemicals can be detected in the majority of the population, including pregnant women. These compounds may pass the placenta, and reach the fetus. This early life exposure in particular may be detrimental as some chemicals may disrupt the endocrine system, which is involved in various processes during development. The LINC study is a prospective birth cohort designed to study associations between early life environmental exposures and child health, including growth and neurodevelopment. The purpose of this paper is to give an overview of this cohort.

Methods and design

Recruitment for this cohort has started in 2011 in three Dutch areas and is still ongoing. To date over 300 mother-child pairs have been included. Women are preferably included during the first trimester of pregnancy. Major congenital anomalies and twin births are reasons for exclusion. To assess exposure to environmental chemicals, cord blood, placenta, meconium and vernix are collected. Parents collect urine of the child shortly after birth and breast milk in the second month of life. Exposure to a broad range of environmental chemicals are determined in cord plasma and breast milk. Furthermore various hormones, including leptin and cortisone, are determined in cord plasma, and in heel prick blood spots (thyroxine). Data on anthropometry of the child is collected through midwives and youth health care centres on various time points until the child is 18 months of age. Furthermore cognitive development is monitored by means of the van Wiechen scheme, and information on behavioral development is collected by means of the infant behavior questionnaire and the child behavior checklist. When the child is 12 months of age, a house visit is scheduled to assess various housing characteristics, as well as hand-to-mouth behavior of the child. At this visit exposure of the child to flame retardants (with endocrine disrupting properties) in house dust is determined by means of body wipes. They are furthermore also measured in a saliva sample of the child. Next to these measurements, women receive questionnaires each trimester regarding amongst others lifestyle of the parents, general health of the parents and the child, and mental state of the mother.

Discussion

This study was approved by the medical ethics committee of the VU University Medical Centre. Consent for the infant is given by the mother, who is specifically required to give consent for both herself as well as her child. Results will be published regardless of the findings of this study, and will be widely disseminated among related medical stakeholders (e.g. midwives and pediatricians), policy makers, and the general public.

Validation of a quantitative food frequency questionnaire developed to under graduate students

A validity test of a Food Frequency Questionnaire was carried out using 50 students of health occupation in São Paulo, Brazil. Therefore, a three day dietary record was used as reference method and variables such as energy, macronutrients and dietary fiber were analyzed. The accordance between the Food Frequency Questionnaire and average data from dietary record was tested with kappa statistics and intra-class correlation coefficients (ICC). Limits of agreement were estimated by the Bland-Altman's method. Better results were found for calories (ICC 0.43; 95%CI 0.17 - 0.63) and non-energy-adjusted nutrients, except dietary fiber (ICC 0.34; 95%CI 0.07 - 0.56). The percentage of individuals classified in the same category of consumption was nearly half (49.8%), while only 16% of them were classified in opposite categories. With the exception of lipids, other analyzed variables tended to be overestimated by the Food Frequency Questionnaire. The Food Frequency Questionnaire is recommended as a method of assessing food intake of university students in studies which focus on calorie estimates and also intend to classify groups into intake categories.

Estimated dietary dioxin exposure and breast cancer risk among women from the French E3N prospective cohort

Introduction

Dioxins are environmental and persistent pollutants mostly emitted from combustion facilities (e.g. waste incinerators, metal and cement industries). Known to be endocrine disrupting chemicals, dioxins are suspected to increase breast cancer (BC) risk. Although diet is considered the primary source of dioxin exposure, no previous study has been published on dietary dioxin exposure in relation to BC risk. We aimed to assess dietary dioxin exposure among women from the E3N cohort and estimate BC risk associated with this exposure.

Methods

The study included 63,830 women from the E3N cohort who completed a diet history questionnaire (DHQ) in 1993 and were followed until 2008. Dietary dioxin exposure was estimated by combining consumption data from the E3N DHQ and food dioxin contamination data from a French national monitoring program. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated by Cox models adjusted for BC risk factors.

Results

Mean dietary dioxin exposure was estimated at 1.3 ± 0.4 pg/kg body weight (BW)/day. A 0.4 pg/kg BW/d increase in dioxin intake was not associated with overall BC risk (HR = 1.00; 95% CI: 0.96, 1.05). A significant decrease in risk of estrogen receptor negative (ER-)/progesterone receptor negative (PR-) tumors was observed among post-menopausal women in the upper quartile of estimated dioxin intake (HR for Q4 vs. Q1: 0.65; 95% CI: 0.45, 0.96; P for trend across quartiles = 0.0463).

Conclusions

Overall, no association between estimated dietary dioxin exposure and BC risk was found among E3N women. Further studies should include both dietary and environmental exposures to determine whether low-dose dioxin exposure is associated with BC risk.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-015-0536-9) contains supplementary material, which is available to authorized users.

Maternal dietary intake of dioxins and polychlorinated biphenyls and birth size in the Norwegian Mother and Child Cohort Study (MoBa)

Maternal diet not only provides essential nutrients to the developing fetus but is also a source of prenatal exposure to environmental contaminants. We investigated the association between dietary intake of dioxins and PCBs during pregnancy and birth size. The study included 50,651 women from the Norwegian Mother and Child Cohort Study (MoBa). Dietary information was collected by FFQs and intake estimates were calculated by combining food consumption and food concentration of dioxins, dioxin-like PCBs and non-dioxin-like PCBs. We used multivariable regression models to estimate the association between dietary intake of dioxins and PCBs and fetal growth. The contribution of fish and seafood intake during pregnancy was 41% for dietary dioxins and dioxin-like PCBs and 49% for dietary non-dioxin-like PCBs. Further stratified analysis by quartiles of seafood intake during pregnancy was conducted. We found an inverse dose-response association between dietary intake of dioxins and PCBs and fetal growth after adjustment for confounders. Newborns of mothers in the upper quartile of dioxin and dioxin-like PCBs intake had 62g lower birth weight (95% CI: -73, -50), 0.26cm shorter birth length (95% CI: -0.31, -0.20) and 0.10cm shorter head circumference (95% CI: -0.14, -0.06) than newborns of mothers in the lowest quartile of intake. Similar negative associations for intake of dioxins and dioxin-like PCBs were found after excluding women with intakes above the tolerable weekly intake (TWI=14pg TEQ/kg bw/week). The negative association of dietary dioxins and PCBs with fetal growth was weaker as seafood intake was increasing. No association was found between dietary dioxin and PCB intake and the risk for small-for-gestational age neonate. In conclusion, dietary intakes of dioxins and PCBs during pregnancy were negatively associated with fetal growth, even at intakes below the TWI.

Organochlorine and heavy metals in newborns: results from the Flemish Environment and Health Survey (FLEHS 2002-2006)

To collect regional information on internal levels of pollutants in humans in Flanders, 1196 mother-child pairs were systematically recruited in 2002-2003 via 25 maternities across Flanders. Cd, Pb, PCB congeners 118, 170, 138, 153 and 180, p,p'-DDE - a key metabolite of DDT- and hexachlorobenzene (HCB) were measured in cord blood or plasma. Cd was detected in 64% of the samples (geometric mean 0.21 microg/L cord blood). p,p'-DDE (110 ng/g plasma lipids) and Pb (14.7 microg/L blood), were measurable in nearly all samples. The individual PCB congeners could be detected in 40 to 81% of the newborns (138+153+180=64.4 ng/g plasma lipids). HCB (18.9 ng/g plasma lipids) and dioxin-like compounds measured by DR-CALUX(R) (23 pg CALUX-TEQ/g lipids) were above detection limit in more than 75% of the samples. Age and smoking habits of the mothers, did not influence the cord blood Pb and Cd levels. The organochlorines increased 4 to 9% per year of the mother's age (partial R(2)=0.05 to 0.22). Mothers had 2.6% less PCBs in cord blood (partial R(2)=0.02) for each unit increase in pre-pregnancy BMI. Season of delivery, breastfeeding previous children or consumption of local dairy products, were minor determinants. Up to 20% of the variability in organochlorine concentrations was explained by residence area. It was concluded that the place of birth in Flanders is an important determinant of the load of pollutants measured at the start of life. This underlines the validity of human biomonitoring on (relatively) small geographical scale.