Reproducibility of nutrient intake in a food frequency questionnaire used in a general population

Be aware of the sodium intake outside student canteens: development and validation of a sodium food frequency questionnaire in Chinese undergraduates

Background

Chinese college students used to eat in student canteens, making dietary consumption outside the cafeterias the main reason for the difference in sodium intake. This study aims to develop and validate a food frequency questionnaire (Sodium-FFQ) targeting dietary sodium intake outside the canteens among undergraduates in China.

Methods

This cross-sectional study included 124 and 81 college students from comprehensive universities in the development and validation stage. A 24 h dietary recall and a food frequency questionnaire were used to develop the Sodium-FFQ. Food items were selected according to the foods that contributed more to the total sodium intake. Test-retest correlation coefficients with an interval of 14 days were employed to evaluate reproducibility. Validity was assessed against a single 24 h urine collection and a 3-day dietary record using correlation coefficients, Bland-Altman analyses, and cross-classification analysis of Kappa coefficients.

Results

The Sodium-FFQ consists of 12 groups of foods with 48 items. The Spearman correlation coefficient of test-retest on sodium intake was 0.654 (p < 0.05), and that between the Sodium-FFQ, 3 × 24 h dietary record, and 24-h urinary sodium were 0.393 (p < 0.05) and 0.342 (p < 0.05), respectively. The Sodium-FFQ was correlated to 24 h urinary sodium-to-potassium ratio, with a Spearman coefficient of 0.370 (p < 0.05). The classification agreement of the Sodium-FFQ and 24 h urinary sodium was 68.4%, and the Kappa coefficient was 0.371 (p < 0.001).

Conclusion

The Sodium-FFQ developed in this study presented an acceptable reproducibility, validity, and classification agreement. It indicates that the Sodium-FFQ could be a potential tool for promoting sodium restriction in college students.

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

BACKGROUND/OBJECTIVES

This study aimed to examine the reproducibility of food frequency questionnaires (FFQs) designed for young female nurses in the Korea Nurses' Health Study.

SUBJECTS/METHODS

The 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.

RESULTS

Pearson 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.

CONCLUSIONS

The results indicated that the web-based FFQ used in the Korea Nurses' Health Study has acceptable reproducibility.

Transport of Vitamin C in Cancer

Significance: Vitamin C is a powerful antioxidant that has an intricate relationship with cancer and has been studied for more than 60 years. However, the specific mechanisms that allow malignant cells to uptake, metabolize, and compartmentalize vitamin C remain unclear. In normal human cells, two different transporter systems are responsible for its acquisition: glucose transporters (GLUTs) transport the oxidized form of vitamin C (dehydroascorbic acid) and sodium-coupled ascorbic acid transporters (SVCTs) transport the reduced form (ascorbic acid [AA]). In this study, we review the mechanisms described for vitamin C uptake and metabolization in cancer. Recent Advances: Several studies performed recently in vivo and in vitro have provided the scientific community a better understanding of the differential capacities of cancer cells to acquire vitamin C: tumors from different origins do not express SVCTs in the plasma membrane and are only able to acquire vitamin C in its oxidized form. Interestingly, cancer cells differentially express a mitochondrial form of SVCT2. Critical Issues: Why tumors have reduced AA uptake capacity at the plasma membrane, but develop the capacity of AA transport within mitochondria, remains a mystery. However, it shows that understanding vitamin C physiology in tumor survival might be key to decipher the controversies in its relationship with cancer. Future Directions: A comprehensive analysis of the mechanisms by which cancer cells acquire, compartmentalize, and use vitamin C will allow the design of new therapeutic approaches in human cancer. Antioxid. Redox Signal. 35, 61-74.

A meta-analysis of the reproducibility of food frequency questionnaires in nutritional epidemiological studies

BACKGROUND

Reproducibility of FFQs measures the consistency of the same subject at different time points. We performed a meta-analysis to explore the reproducibility of FFQs and factors related to reproducibility of FFQs.

METHODS AND FINDINGS

A systematic literature review was performed before July 2020 using PubMed and Web of Science databases. Pooled intraclass and Spearman correlation coefficients (95% confidence interval) were calculated to assess the reproducibility of FFQs. Subgroup analyses based on characteristics of study populations, FFQs, or study design were performed to investigate factors related to the reproducibility of FFQs. A total of 123 studies comprising 20,542 participants were eligible for the meta-analysis. The pooled crude intraclass correlation coefficients ranged from 0.499 to 0.803 and 0.499 to 0.723 for macronutrients and micronutrients, respectively. Energy-adjusted intraclass correlation coefficients ranged from 0.420 to 0.803 and 0.507 to 0.712 for macronutrients and micronutrients, respectively. The pooled crude and energy-adjusted Spearman correlation coefficients ranged from 0.548 to 0.851 and 0.441 to 0.793, respectively, for macronutrients; and from 0.573 to 0.828 and 0.510 to 0.744, respectively, for micronutrients. FFQs with more food items, 12 months as dietary recall interval (compared to less than 12 months), and a shorter time period between repeated FFQs resulted in superior FFQ reproducibility.

CONCLUSIONS

In conclusion, FFQs with correlation coefficients greater than 0.5 for most nutrients may be considered a reliable tool to measure dietary intake. To develop FFQs with higher reproducibility, the number of food items and dietary recall interval should be taken into consideration.

Complexities and opportunities in monitoring and evaluating US and global changes by the food industry

In developed nations and increasingly in the rest of the world, a large proportion of people's diets comes from manufactured food sources and food not produced at home. These types of products are constantly changing and have significant nutrition and health implications for the world's population. However, researchers, public health workers and policy makers face major complexities in understanding what these changes are and their relationships to diet and health outcomes. This paper will describe some of the complexities faced in monitoring and evaluating the nutritional composition of food products and what it means for population health. Importantly, no existing food composition database is able to keep up with the continuous reformulation and introductions and removals of packaged foods and food services. The paper will also discuss opportunities to improve and update the monitoring and evaluation of changes made by each of these key sectors of the modern food supply and how these changes can influence the nutrients purchased or consumed across the globe. The focus will be on the United States with some examples from other developed nations and a discussion of implications for low- and middle-income countries.

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.

Dietary fat reduction strategies used by a group of adults aged 50 years and older

OBJECTIVE

To investigate the fat-reduction strategies used by a group of older adults who successfully made and maintained positive dietary changes for 5 years or longer.

DESIGN

Participants completed 2 copies of a self-administered food frequency questionaire: The first copy assessed diet before they began making changes and the second copy assessed diet after initiation of healthful dietary changes. Positive food changes were identified from the food frequency questionnaires. During in-person interviews, participants placed food changes onto a time line according to the nearest estimated date of initiation of the change.

SUBJECTS

Participants were 65 free-living older adults (aged >50 years) who had maintained substantial changes to decrease fat intake in their diet for at least 5 years. Statistical analyses performed Quantitative and qualitative data were used to identify the fat-reduction strategies and to confirm and validate the fat-reduction strategy model. Confirmatory factor analysis was performed to confirm the new model. The Kuder-Richardson-20 reliability coefficient (kr) was used to determine internal consistency of the scales developed for the study.

RESULTS

The majority of participants decreased their fat intake gradually, at different time points in their lives, and over a long period of time (5 to 43 years). Mean percent energy intake from fat decreased from 44.3 +/- 5.9% before dietary improvement to 25.9 +/- 7.1% at the time of the study. The final model consisted of 5 fat-reduction strategies with 63 food changes. The strategies were: increase summer fruits (4 items; kr=0.66), increase vegetables and grains (14 items; kr=0.79), decrease recreational foods (14 items; kr=0.76), decrease cooking fat (20 items; kr=0.86), and use fat-modified foods (11 items; kr=0.80).

APPLICATIONS/CONCLUSIONS

Dietetics professionals should base their advice on the dietary strategies used by consumers rather than hypothetical premises such as food or nutrient groupings. Nutrition education interventions will have better chances for success if they are based on a set of customized programs that guide appropriate consumer segments through a series of small, comfortable, and sustainable dietary changes over a prolonged period of time.

Telephone vs face-to-face interviews for quantitative food frequency assessment

OBJECTIVE

To develop and test a quantitative food frequency method for administration by telephone.

DESIGN

A comparison study of telephone and face-to-face interviews was conducted among a representative sample of the five major ethnic groups in Oahu, Hawaii. Two interviews were administered 4 to 6 months apart by trained interviewers using identical questionnaires and color photographs of food items showing three different portion sizes. The order of the interviewing methods was randomly assigned. The questionnaire included 115 food items selected to estimate 80% or more of usual dietary intakes. Frequencies and quantities of each item consumed during the past year were obtained.

SUBJECTS/SETTING

Subjects were recruited from the Health Surveillance Program of the Hawaii State Department of Health and consisted of 167 men and 158 women, aged 45 to 74 years, who provided a telephone number. Eighty percent of the face-to-face interviews were conducted in the subjects' homes and 20% were conducted at the workplace or the University of Hawaii Cancer Research Center, if requested.

STATISTICAL ANALYSES

The paired t test was used to compare the mean daily intakes obtained by the telephone and face-to-face methods. Agreement was measured by the intraclass correlation coefficient (ICC), Pearson correlation coefficient and weighted kappa statistic.

RESULTS

The means of energy and each nutrient were slightly higher in the first interview than the second, regardless of the interviewing method. Because of close correspondence among all 3 statistical measures of agreement, only the ICCs are reported. The ICCs ranged from .61 for protein and vitamin A to .69 for dietary cholesterol among men, and from .61 for vitamin C to .74 for saturated fat among women. Agreement was not significantly affected by age, gender, ethnicity, order of interview, or educational level.

APPLICATIONS

Telephone interviews to obtain quantitative food frequencies are cost-efficient methods for estimating usual dietary intakes among persons in widely scattered geographic areas. Photographs of the foods in 3 portion sizes mailed in advance help the respondents estimate amounts eaten.