Checking for completeness of 24-h urine collection using para-amino benzoic acid not necessary in the Observing Protein and Energy Nutrition study

Major Gaps in Understanding Dietary Supplement Use in Health and Disease

Precise dietary assessment is critical for accurate exposure classification in nutritional research, typically aimed at understanding how diet relates to health. Dietary supplement (DS) use is widespread and represents a considerable source of nutrients. However, few studies have compared the best methods to measure DSs. Our literature review on the relative validity and reproducibility of DS instruments in the United States [e.g., product inventories, questionnaires, and 24-h dietary recalls (24HR)] identified five studies that examined validity (n = 5) and/or reproducibility (n = 4). No gold standard reference method exists for validating DS use; thus, each study's investigators chose the reference instrument used to measure validity. Self-administered questionnaires agreed well with 24HR and inventory methods when comparing the prevalence of commonly used DSs. The inventory method captured nutrient amounts more accurately than the other methods. Reproducibility (over 3 months to 2.4 years) of prevalence of use estimates on the questionnaires was acceptable for common DSs. Given the limited body of research on measurement error in DS assessment, only tentative conclusions on these DS instruments can be drawn at present. Further research is critical to advancing knowledge in DS assessment for research and monitoring purposes.

Validation of the smartphone-based dietary assessment tool 'Traqq' for assessing actual dietary intake by repeated 2-hour recalls in adults: comparison with 24h recalls and urinary biomarkers

BACKGROUND

Conventional dietary assessment methods are affected by measurement error. We developed a smartphone-based 2-hour recall (2hR) methodology to reduce participant burden and memory-related bias.

OBJECTIVE

Assessing the validity of the 2hR method against traditional 24-hour recalls (24hRs) and objective biomarkers.

METHODS

Dietary intake was assessed in 215 Dutch adults on six randomly selected non-consecutive days (i.e., three 2hR-days and three 24hRs) during a four-week period. Sixty-three participants provided four 24-hour urine samples, to assess urinary nitrogen and potassium concentrations.

RESULTS

Intake estimates of energy (2,052±503 kcal vs. 1,976±483 kcal) and nutrients (e.g., protein: 78±23 g vs. 71±19 g; fat: 84±30 g vs. 79±26 g; carbohydrates: 220±60 g vs. 216±60 g) were slightly higher with 2hR-days than 24hRs. Comparing self-reported protein and potassium intakes to urinary nitrogen and potassium concentrations indicated a slightly higher accuracy of 2hR-days than 24hRs (protein: -14% vs. -18%; potassium: -11% vs. -16%). Correlation coefficients between methods ranged from 0.41 to 0.75 for energy and macronutrients and from 0.41 to 0.62 for micronutrients. Generally regularly consumed food groups showed small differences in intake (<10%) and good correlations (>0.60). Intakes of and energy, nutrients and food groups showed similar reproducibility (ICC) for 2hR-days and 24hRs.

CONCLUSIONS

Comparing 2hR-days with 24hRs showed relatively similar group-level bias for energy, most nutrients, and food groups. Differences were mostly due to higher intake estimates by 2hR-days. Biomarker comparisons showed less underestimation by 2hR-days as compared to 24hRs, suggesting that 2hR-days are a valid approach to assess intake of energy, nutrients and food groups.

TRIAL REGISTRATION

This trial was registered at the Dutch Central Committee on Research Involving Human Subjects (CCMO) registry as ABR. No. NL69065.081.19.

Measurement Error Affecting Web- and Paper-Based Dietary Assessment Instruments: Insights From the Multi-Cohort Eating and Activity Study for Understanding Reporting Error

Few biomarker-based validation studies have examined error in online self-report dietary assessment instruments, and food records (FRs) have been considered less than food frequency questionnaires (FFQs) and 24-hour recalls (24HRs). We investigated measurement error in online and paper-based FFQs, online 24HRs, and paper-based FRs in 3 samples drawn primarily from 3 cohorts, comprising 1,393 women and 1,455 men aged 45-86 years. Data collection occurred from January 2011 to October 2013. Attenuation factors and correlation coefficients between reported and true usual intake for energy, protein, sodium, potassium, and respective densities were estimated using recovery biomarkers. Across studies, average attenuation factors for energy were 0.07, 0.07, and 0.19 for a single FFQ, 24HR, and FR, respectively. Correlation coefficients for energy were 0.24, 0.23, and 0.40, respectively. Excluding energy, the average attenuation factors across nutrients and studies were 0.22 for a single FFQ, 0.22 for a single 24HR, and 0.51 for a single FR. Corresponding correlation coefficients were 0.31, 0.34, and 0.53, respectively. For densities (nutrient expressed relative to energy), the average attenuation factors across studies were 0.37, 0.17, and 0.50, respectively. The findings support prior research suggesting different instruments have unique strengths that should be leveraged in epidemiologic research.

DIetary ASSessment (DIASS) Study: Design of an Evaluation Study to Assess Validity, Usability and Perceived Burden of an Innovative Dietary Assessment Methodology

During recent years, the integration of technology has substantially improved self-reported dietary assessment methods, such as food frequency questionnaires (FFQ), food records, and 24-h recalls. To further reduce measurement error, additional innovations are urgently needed. Memory-related measurement error is one of the aspects that warrants attention, which is where new smartphone technologies and ecological momentary assessment (EMA) approaches provide a unique opportunity. In this article, we describe the DIASS study, which was designed to evaluate an innovative 2-h recall (2hR) smartphone-based methodology, against traditional 24-h recalls, FFQ, and biomarkers, to assess both actual and habitual dietary intake. It is hypothesized that a 2-h reporting window decreases reliance on memory and reporting burden, and increases data accuracy. We included 215 men (28%) and women (72%), with a mean ± SD age of 39 ± 19 years and a mean ± SD BMI of 23.8 ± 4.0. Most participants were highly educated (58%). Response rates for the various dietary assessment methods were >90%. Besides the evaluation of the accuracy, usability, and perceived burden of the 2hR methodology, the study set-up also allows for (further) evaluation of the other administrated dietary assessment tools.

Methods for the dietary assessment of adult kidney stone formers: a scoping review

BACKGROUND

Kidney stones are a frequent and potentially severe condition, affecting 5-10% of the European population. Causes are multifactorial, diet in particular plays a major role in the formation and management of kidney stones. The aim of this scoping review is to assess the methods used to study the diet of adult kidney stone formers.

METHODS

We conducted a systematic search in Medline Ovid SP, Embase, Cinahl, Cochrane (CENTRAL), Web of Sciences databases on June 10th, 2020. Self-report methods (such as food frequency questionnaires or 24-h dietary recalls), objective nutritional biomarkers and controlled diets were considered. We analyzed the selected publications based on the origin of participants, study design and dietary assessment methods used.

RESULTS

We screened 871 publications and included 162 of them. Most studies included participants from North America and Europe and were observational. Short and cost-effective tools such as food frequency questionnaires and other questionnaires were the most frequently used. Moreover, food diary was a frequently selected method to study the diet of kidney stone formers. New technologies (e.g. online questionnaires, phone applications, connected tools) were rarely used.

CONCLUSION

Accurate reporting of the methods used in nutritional studies is of key importance to interpret results and build evidence. Assessing long-term dietary intake is still a challenge for nutritional epidemiology. A combination of self-report methods with objective dietary biomarkers and new technologies probably represents the best way forward.

Estimation of sodium and potassium intakes assessed by two 24-hour urine collections in a city of Indonesia

Intakes of excess Na and insufficient K are two major contributors of heart diseases and stroke development. However, no precise study has previously been carried out on Na and K intakes among Indonesian adults. The present study aimed to estimate the Na and K intakes using two consecutive 24-h urine collections. Participants were community-dwelling adults aged between 20 and 96 years, randomly selected from a pool of resident registration numbers. Of the 506 participants, 479 (240 men and 239 women) completed urine collections. The mean Na excretion was 102·8 and 100·6 mmol/d, while the mean K excretion was 25·0 and 23·4 mmol/d for men and women, respectively. Na and K excretions were higher in participants with a higher BMI. A higher K excretion was associated only with younger age. More than 80 % of the participants consumed more than 5 g/d of salt (the upper limit recommended by the Indonesian government), whereas none of them consumed more than 3510 mg/d of K (the lower limit). The high Na and low K intakes, especially high Na among participants with high BMI, should be considered when future intervention programmes are planned in this country.

Development and external validation of the 'Flower-FFQ': a FFQ designed for the Lifelines Cohort Study

Objective:

FFQ assess habitual dietary intake and are relatively inexpensive to process, but may take up to 60 min to complete. This article describes the validation of the Flower-FFQ, which consists of four short FFQ measuring the intake of energy and macronutrients or specific (micro)nutrients/foods that can be merged into one complete daily assessment using predefined algorithms.

Design:

Participants completed the Flower-FFQ and validated regular-FFQ (n 401). Urinary N (n 242) and K excretions (n 361) were measured. We evaluated: (1) group-level bias, (2) correlations and (3) cross-classification.

Setting:

Observational study.

Participants:

Dutch adults, 54 ± 11 (mean ± SD) years.

Results:

Flower-FFQ1, Flower-FFQ2, Flower-FFQ3 and Flower-FFQ4 were completed in ±24, 9, 8 and 9 min (±50 min total), respectively. The regular-FFQ was completed in ±43 min. Mean energy (flower v. regular: 7953 v. 8718 kJ/d) and macronutrient intakes (carbohydrates: 204 v. 222 g/d; protein: 75 v. 76 g/d; fat: 74 v. 83 g/d; ethanol: 8 v. 12 g/d) were comparatively similar. Spearman correlations between Flower-FFQ and regular-FFQ ranged from 0·60 to 0·80 for macronutrients and from 0·40 to 0·80 for micronutrients and foods. For all micronutrients and foods, ≥ 78 % of the participants classified in the same/adjacent quartile. The Flower-FFQ underestimated urinary N and K excretions by 24 and 18 %; 75 and 73 % of the participants ranked in the same/adjacent quartile.

Conclusion:

Completing the Flower-FFQ required 50 min with a maximum of 25 min per short FFQ. The Flower-FFQ has a moderate to good ranking ability for most nutrients and foods and performs sufficiently to study diet–disease associations.

Protein Intake by Source and Breast Cancer Incidence and Mortality: The Women's Health Initiative

Background

Prior studies of dietary protein intake and breast cancer have been mixed and were limited by dietary self-report measurement error.

Methods

Biomarker-calibrated total protein intake and estimated vegetable protein and animal protein intake were determined from baseline food frequency questionnaires in 100 024 Women’s Health Initiative participants. Associations between total, animal, and vegetable protein intake and breast cancer incidence, deaths from breast cancer, and deaths after breast cancer were estimated using Cox proportional hazards regression. Breast cancers were verified by medical record review and survival outcomes enhanced by National Death Index queries. All statistical tests were 2-sided.

Results

After 14 years of follow-up, there were 6340 incident breast cancers, 764 deaths from breast cancer, and 2059 deaths after breast cancer. In multivariable analyses, higher calibrated total protein intake was not associated with breast cancer incidence or deaths from or after breast cancer. Vegetable protein intake was associated with statistically significantly lower breast cancer incidence (hazard ratio [HR] = 0.98, 95% confidence interval [CI] = 0.96 to 0.99, P_trend = .006) and statistically significantly lower risk of death after breast cancer (HR = 0.93, 95% CI = 0.91 to 0.97, P_trend < .001) but not with deaths from breast cancer. In contrast, higher animal protein intake was associated with statistically significantly higher breast cancer incidence (HR = 1.03, 95% CI = 1.01 to 1.06, P_trend = .02) but not with deaths from or after breast cancer.

Conclusions

Calibrated total protein intake was not associated with breast cancer incidence or mortality. Higher vegetable protein intake was associated with lower breast cancer incidence and lower risk of death after breast cancer. Higher animal protein intake was associated with higher breast cancer incidence.

Validation of a new software eAT24 used to assess dietary intake in the adult Portuguese population

OBJECTIVE

The aim of the current study was to evaluate the accuracy of the new software eAT24 used to assess dietary intake in the National Food, Nutrition and Physical Activity Survey (IAN-AF) against urinary biomarkers: N (nitrogen), K (potassium) and Na (sodium).

DESIGN

We conducted a cross-sectional study. Two non-consecutive 24-h dietary recalls (24-HDR) were applied, and a 24-h urine sample was collected. We examined differences between estimates from dietary and urine measures, Pearson correlation coefficients were calculated and the Bland-Altman plots were drawn. Multiple linear regression was used to evaluate the factors associated with the difference between estimates.

SETTING

Sub-sample from the Portuguese IAN-AF sampling frame.

PARTICIPANTS

Ninety-five adults (men and women) aged 18-84 years.

RESULTS

The estimated intake calculated using the dietary recall data was lower than that estimated from urinary excretion for the three biomarkers studied (protein 94·3 v. 100·4 g/d, K 3212 v. 3416 mg/d and Na 3489 v. 4003 mg/d). Considering 2 d of recall, the deattenuated correlation coefficients were 0·33, 0·64 and 0·26 for protein, K and Na, respectively. For protein, differences between dietary and urinary estimates varied according to BMI (β = -1·96, P = 0·017). The energy intake and 24-h urine volume were significantly associated with the difference between estimates for protein (β = 0·03, P < 0·001 and β = -0·02, P = 0·002, respectively), K (β = 0·71, P < 0·001 and β = -0·42, P = 0·040, respectively) and Na (β = 1·55, P < 0·001 and β = -0·81, P = 0·011, respectively).

CONCLUSIONS

The new software eAT24 performed well in estimating protein and K intakes, but lesser so in estimating Na intake, using two non-consecutive 24-HDR.

Comparison of Methods Used to Correct Self-Reported Protein Intake for Systematic Variation in Reported Energy Intake Using Quantitative Biomarkers of Dietary Intake

BACKGROUND

Multiple methods of correcting nutrient intake for misreported energy intake have been proposed but have not been extensively compared. The availability of the Women's Health Initiative (WHI) data set, which includes several objective recovery biomarkers, offers an opportunity to compare these corrections with respect to protein intake.

OBJECTIVE

We compared 5 energy-correction methods for self-reported dietary protein against urinary nitrogen-derived protein intake.

METHODS

As part of the WHI Nutritional Biomarkers Study (NBS) 544 participants (50- to 80-y-old women) completed a FFQ and biomarker assessments using doubly labeled water (DLW) for total energy expenditure (TEE) and 24-h urinary nitrogen. Correction methods evaluated were as follows: 1) DLW-TEE; 2) the Institute of Medicine's (IOM's) estimated energy requirement (EER) TEE prediction equation based on sex, height, weight, and age; 3) published NBS total energy TEE prediction (WHI-NBS-TEE) using age, BMI, race, and income; 4) reported protein versus reported energy linear regression-based residual method; and 5) a Goldberg cutoff to exclude subjects reporting energy intakes <1.35 times their basal metabolic rate. Efficacy was evaluated using correlations obtained by regressing corrected protein against biomarker protein (6.25 × urinary nitrogen/0.81).

RESULTS

Unadjusted self-reported protein intake from the FFQ (mean = 66.7 g) correlated weakly (r = 0.31) with biomarker protein (mean = 74.9 g). DLW-TEE-corrected self-reported protein intake (mean = 90.7 g) had the strongest correlation with biomarker protein (r = 0.47). Other energy corrections yielded lower, but still significant correlations: EER, r = 0.44 (mean = 92.1 g); WHI-NBS-TEE, r = 0.37 (mean = 90.4 g); Goldberg cutoff, r = 0.36 (mean = 88.4 g); and residual method, r = 0.35 (mean = 66.7 g).

CONCLUSIONS

Our data indicate that proportional correction of reported protein intake using a measure of energy requirement from DLW-TEE or IOM-EER performed modestly better than other methods in this cohort. These energy adjustments, however, yielded corrected protein exceeding the biomarker protein, indicating that energy adjustment alone does not eliminate all self-reported protein reporting bias.

Validity of Absolute Intake and Nutrient Density of Protein, Potassium, and Sodium Assessed by Various Dietary Assessment Methods: An Exploratory Study

It is suggested that nutrient densities are less affected by measurement errors than absolute intake estimates of dietary exposure. We compared the validity of absolute intakes and densities of protein (kJ from protein/total energy (kJ)), potassium, and sodium (potassium or sodium (in mg)/total energy (kJ)) assessed by different dietary assessment methods. For 69 Dutch subjects, two duplicate portions (DPs), five to fifteen 24-h dietary recalls (24 hRs, telephone-based and web-based) and two food frequency questionnaires (FFQs) were collected and compared to duplicate urinary biomarkers and one or two doubly labelled water measurements. Multivariate measurement error models were used to estimate validity coefficients (VCs) and attenuation factors (AFs). This research showed that group bias diminished for protein and sodium densities assessed by all methods as compared to the respective absolute intakes, but not for those of potassium. However, the VCs and AFs for the nutrient densities did not improve compared to absolute intakes for all four methods; except for the AF of sodium density (0.71) or the FFQ which was better than that of the absolute sodium intake (0.51). Thus, using nutrient densities rather than absolute intakes does not necessarily improve the performance of the DP, FFQ, or 24 hR.

Comparison of 24-hour urine and 24-hour diet recall for estimating dietary sodium intake in populations: A systematic review and meta-analysis

This systematic literature review and meta-analysis examined whether 24-hour diet recall is a valid way to measure mean population sodium intake compared with the gold standard 24-hour urinary assessment. The authors searched electronic databases MEDLINE, Embase, and Scopus using pre-defined terms. Studies were eligible for inclusion if they assessed adult humans in free-living settings, and if they included group means for 24-hour diet recall and 24-hour urinary collection of sodium intake in the same participants. Studies that included populations with an active disease state that might interfere with normal sodium metabolism were excluded. Results of 28 studies are included in the meta-analysis. Overall, 24-hour diet recall underestimated population mean sodium intake by an average of 607 mg per day compared to the 24-hour urine collection. The difference between measures from 24-hour urine and 24-hour diet recall was smaller in studies conducted in high-income countries, in studies where multiple-pass methods of 24-hour diet recall were reported and where urine was validated for completeness. Higher quality studies also reported smaller differences between measures than lower quality studies. Monitoring of population sodium intake with 24-hour urinary excretion remains the most accurate method of assessment. Twenty-four-hour diet recall tends to underestimate intake, although high-quality 24-hour diet recall improves accuracy, and may be used if 24-hour urine is not feasible.

Validation of the Oxford WebQ Online 24-Hour Dietary Questionnaire Using Biomarkers

The Oxford WebQ is an online 24-hour dietary questionnaire that is appropriate for repeated administration in large-scale prospective studies, including the UK Biobank study and the Million Women Study. We compared the performance of the Oxford WebQ and a traditional interviewer-administered multiple-pass 24-hour dietary recall against biomarkers for protein, potassium, and total sugar intake and total energy expenditure estimated by accelerometry. We recruited 160 participants in London, United Kingdom, between 2014 and 2016 and measured their biomarker levels at 3 nonconsecutive time points. The measurement error model simultaneously compared all 3 methods. Attenuation factors for protein, potassium, total sugar, and total energy intakes estimated as the mean of 2 applications of the Oxford WebQ were 0.37, 0.42, 0.45, and 0.31, respectively, with performance improving incrementally for the mean of more measures. Correlation between the mean value from 2 Oxford WebQs and estimated true intakes, reflecting attenuation when intake is categorized or ranked, was 0.47, 0.39, 0.40, and 0.38, respectively, also improving with repeated administration. These correlations were similar to those of the more administratively burdensome interviewer-based recall. Using objective biomarkers as the standard, the Oxford WebQ performs well across key nutrients in comparison with more administratively burdensome interviewer-based 24-hour recalls. Attenuation improves when the average value is taken over repeated administrations, reducing measurement error bias in assessment of diet-disease associations.

Can methods based on spot urine samples be used to estimate average population 24 h sodium excretion? Results from the Isfahan Salt Study

OBJECTIVE

To assess agreement between established methods of estimating salt intake from spot urine collections and 24 h urinary Na (24hUNa) and then to develop a valid formula that can be used in the Iranian population to estimate salt intake from spot urine samples.

DESIGN

A validation study. Three spot urine samples were collected (fasting second-void morning; afternoon; evening) on the same day as a 24 h urine collection. We estimated 24hUNa from spot specimens using the Kawasaki, Tanaka and INTERSALT equations. Two new formulas were developed, the Iran formula 1 (Iran 1) and Iran formula 2 (Iran 2), based on our population characteristics.

SETTING

Iranian adults recruited in 2014-2015.

PARTICIPANTS

Healthy volunteer adults aged ≥18 years.

RESULTS

With all three spot urine specimens, predicted population 24hUNa was underestimated based on the INTERSALT equation (-469 to -708 mg/d; all P < 0·05) and conversely overestimation occurred with the Kawasaki equation (926 to 1080 mg/d; all P < 0·01). The Tanaka equation produced comparable estimates to measured 24hUNa (-151 to 86 mg/d; all P > 0·49). The newly derived formulas, Iran 1 and Iran 2, showed less mean bias than the established equations (Iran 1: 43 to 80 mg/d, all P > 0·55; Iran 2: 22 to 90 mg/d, all P > 0·50).

CONCLUSIONS

In this Iranian sample, the Tanaka equation and newly derived formulas produced group-level estimates comparable to measured 24hUNa. The newly developed formulas showed less mean bias than established equations; however, they need to be tested for generalization in a larger sample.

Estimation of the salt intake distribution of Dutch kidney transplant recipients using 24-h urinary sodium excretion: the potential of external within-person variance

BACKGROUND

There is growing interest in assessing a population's prevalence of inadequate nutrient intake using biomarkers. However, within-person variation is generally ignored because repeated data collections are considered costly and burdensome.

OBJECTIVES

The study aimed to show the importance of estimating, from repeated 24-h urine collections, a population's habitual salt intake and to explore the potential of using the ratio of within-person variance to total variance from an external source (W:T variance) with single 24-h urine collection.

METHODS

Salt intake was predicted from data for 24-h urinary sodium excretion in adult kidney transplant recipients in 1992-1997 (n = 432) and 2006-2011 (n = 1159). The salt intake distribution of single-day measurements was compared with estimates from multiple 24-h urine collections, which were statistically corrected for within-person variance. Habitual salt intake was also estimated using single-day measurements and external variance estimates. From each distribution, the proportion below specified cut-off values was estimated.

RESULTS

In 2006-2011 the average habitual salt intake was 10.6 g/d (men) and 8.5 g/d (women); in 1992-1997 these values were 8.6 g/d and 7.5 g/d, respectively. The proportion with salt intake <6 g/d was 5% and 13% in 2006-2011 and 22% and 28% in 1992-1997, respectively, for men and women. Correction for within-person variance significantly narrowed the salt intake distribution-the proportion with salt intake <6 g/d was overestimated by 3-13 percentage points using single-day data. Sensitivity analyses showed the importance of a sufficient sample size for estimating variance components. Variation of the W:T variance showed up to 40 percentage points deviation in the proportion with intakes below a specified cut-off value.

CONCLUSIONS

To estimate a population's salt intake distribution, it is important to correct 24-h urinary sodium excretion for within-person variance. Predicting habitual salt intake distribution using single-day measurements with external variances is promising; a sensitivity analysis is recommended to show the effect of different external variances.

Validity of an online 24-h recall tool (myfood24) for dietary assessment in population studies: comparison with biomarkers and standard interviews

BACKGROUND

Online dietary assessment tools can reduce administrative costs and facilitate repeated dietary assessment during follow-up in large-scale studies. However, information on bias due to measurement error of such tools is limited. We developed an online 24-h recall (myfood24) and compared its performance with a traditional interviewer-administered multiple-pass 24-h recall, assessing both against biomarkers.

METHODS

Metabolically stable adults were recruited and completed the new online dietary recall, an interviewer-based multiple pass recall and a suite of reference measures. Longer-term dietary intake was estimated from up to 3 × 24-h recalls taken 2 weeks apart. Estimated intakes of protein, potassium and sodium were compared with urinary biomarker concentrations. Estimated total sugar intake was compared with a predictive biomarker and estimated energy intake compared with energy expenditure measured by accelerometry and calorimetry. Nutrient intakes were also compared to those derived from an interviewer-administered multiple-pass 24-h recall.

RESULTS

Biomarker samples were received from 212 participants on at least one occasion. Both self-reported dietary assessment tools led to attenuation compared to biomarkers. The online tools resulted in attenuation factors of around 0.2-0.3 and partial correlation coefficients, reflecting ranking intakes, of approximately 0.3-0.4. This was broadly similar to the more administratively burdensome interviewer-based tool. Other nutrient estimates derived from myfood24 were around 10-20% lower than those from the interviewer-based tool, with wide limits of agreement. Intraclass correlation coefficients were approximately 0.4-0.5, indicating consistent moderate agreement.

CONCLUSIONS

Our findings show that, whilst results from both measures of self-reported diet are attenuated compared to biomarker measures, the myfood24 online 24-h recall is comparable to the more time-consuming and costly interviewer-based 24-h recall across a range of measures.

Validation of the use of p-aminobenzoic acid to determine completeness of 24 h urine collections in surveys of diet and nutrition

Sodium intake is assessed using 24 h urinary excretion; it is important to ensure urine collections are complete. This can be validated by monitoring urinary excretion of p-aminobenzoic acid (PABA) administered in tablet form at intervals during the urine collection. Unavoidable change of PABA tablet supplier and analytical procedure required re-establishment of the thresholds consistent with a complete collection. Reference ranges for adults without reported intestinal or renal disease were determined by HPLC (70–103%) and colorimetry (84–120%). Some individuals excreted a small, measurable amount of PABA the following day but this did not represent the balance of the PABA ingested. Assay of the PABA tablets confirmed the stated dose (80 mg) and demonstrated their stability up to 8 years (duration of study) at room temperature. These tablets have been used and the reference ranges applied in UK national population surveys since 2008.

Comparison of self-reported dietary intakes from the Automated Self-Administered 24-h recall, 4-d food records, and food-frequency questionnaires against recovery biomarkers

Background

A limited number of studies have evaluated self-reported dietary intakes against objective recovery biomarkers.

Objective

The aim was to compare dietary intakes of multiple Automated Self-Administered 24-h recalls (ASA24s), 4-d food records (4DFRs), and food-frequency questionnaires (FFQs) against recovery biomarkers and to estimate the prevalence of under- and overreporting.

Design

Over 12 mo, 530 men and 545 women, aged 50-74 y, were asked to complete 6 ASA24s (2011 version), 2 unweighed 4DFRs, 2 FFQs, two 24-h urine collections (biomarkers for protein, potassium, and sodium intakes), and 1 administration of doubly labeled water (biomarker for energy intake). Absolute and density-based energy-adjusted nutrient intakes were calculated. The prevalence of under- and overreporting of self-report against biomarkers was estimated.

Results

Ninety-two percent of men and 87% of women completed ≥3 ASA24s (mean ASA24s completed: 5.4 and 5.1 for men and women, respectively). Absolute intakes of energy, protein, potassium, and sodium assessed by all self-reported instruments were systematically lower than those from recovery biomarkers, with underreporting greater for energy than for other nutrients. On average, compared with the energy biomarker, intake was underestimated by 15-17% on ASA24s, 18-21% on 4DFRs, and 29-34% on FFQs. Underreporting was more prevalent on FFQs than on ASA24s and 4DFRs and among obese individuals. Mean protein and sodium densities on ASA24s, 4DFRs, and FFQs were similar to biomarker values, but potassium density on FFQs was 26-40% higher, leading to a substantial increase in the prevalence of overreporting compared with absolute potassium intake.

Conclusions

Although misreporting is present in all self-report dietary assessment tools, multiple ASA24s and a 4DFR provided the best estimates of absolute dietary intakes for these few nutrients and outperformed FFQs. Energy adjustment improved estimates from FFQs for protein and sodium but not for potassium. The ASA24, which now can be used to collect both recalls and records, is a feasible means to collect dietary data for nutrition research.

Applying recovery biomarkers to calibrate self-report measures of sodium and potassium in the Hispanic Community Health Study/Study of Latinos

Measurement error in assessment of sodium and potassium intake obscures associations with health outcomes. The level of this error in a diverse US Hispanic/Latino population is unknown. We investigated the measurement error in self-reported dietary intake of sodium and potassium and examined differences by background (Central American, Cuban, Dominican, Mexican, Puerto Rican and South American). In 2010-2012, we studied 447 participants aged 18-74 years from four communities (Miami, Bronx, Chicago and San Diego), obtaining objective 24-h urinary sodium and potassium excretion measures. Self-report was captured from two interviewer-administered 24-h dietary recalls. Twenty percent of the sample repeated the study. We examined bias in self-reported sodium and potassium from diet and the association of mismeasurement with participant characteristics. Linear regression relating self-report with objective measures was used to develop calibration equations. Self-report underestimated sodium intake by 19.8% and 20.8% and potassium intake by 1.3% and 4.6% in men and women, respectively. Sodium intake underestimation varied by Hispanic/Latino background (P<0.05) and was associated with higher body mass index (BMI). Potassium intake underestimation was associated with higher BMI, lower restaurant score (indicating lower consumption of foods prepared away from home and/or eaten outside the home) and supplement use. The R² was 19.7% and 25.0% for the sodium and potassium calibration models, respectively, increasing to 59.5 and 61.7% after adjusting for within-person variability in each biomarker. These calibration equations, corrected for subject-specific reporting error, have the potential to reduce bias in diet-disease associations within this largest cohort of Hispanics in the United States.

Feasibility of collecting 24-h urine to monitor sodium intake in the National Health and Nutrition Examination Survey

BACKGROUND

Twenty-four-hour urine sodium excretion is recommended for monitoring population sodium intake. Because of concerns about participation and completion, sodium excretion has not been collected previously in US nationally representative surveys.

OBJECTIVE

We assessed the feasibility of implementing 24-h urine collections as part of a nationally representative survey.

DESIGN

We selected a random half sample of nonpregnant US adults aged 20-69 y in 3 geographic locations of the 2013 NHANES. Participants received explicit instructions, started and ended the urine collection in a urine study mobile examination center, and answered questions about their collection. Among those with a complete 24-h urine collection, a random one-half were asked to collect a second 24-h urine sample. Sodium, potassium, chloride, and creatinine excretion were analyzed.

RESULTS

The final NHANES examination response rate for adults aged 20-69 y in these 3 study locations was 71%. Of those examined (n = 476), 282 (59%) were randomly selected to participate in the 24-h urine collection. Of these, 212 persons [75% of those selected for 24-h urine collection; 53% (equal to 71% × 75% of those selected for the NHANES)] collected a complete initial 24-h specimen and 92 persons (85% of 108 selected) collected a second complete 24-h urine sample. More men than women completed an initial collection (P = 0.04); otherwise, completion did not vary by sociodemographic characteristics, body mass index, education, or employment status for either collection. Mean 24-h urine volume and sodium excretion were 1964 ± 1228 mL and 3657 ± 2003 mg, respectively, for the first 24-h urine sample, and 2048 ± 1288 mL and 3773 ± 1891 mg, respectively, for the second collection.

CONCLUSION

Given the 53% final component response rate and 75% completion rate, 24-h urine collections were deemed feasible and implemented in the NHANES 2014 on a subsample of adults aged 20-69 y to assess population sodium intake. This study was registered at clinicaltrials.gov as NCT02723682.

A national FFQ for the Netherlands (the FFQ-NL 1.0): validation of a comprehensive FFQ for adults

A standardised, national, 160-item FFQ, the FFQ-NL 1.0, was recently developed for Dutch epidemiological studies. The objective was to validate the FFQ-NL 1.0 against multiple 24-h recalls (24hR) and recovery and concentration biomarkers. The FFQ-NL 1.0 was filled out by 383 participants (25-69 years) from the Nutrition Questionnaires plus study. For each participant, one to two urinary and blood samples and one to five (mean 2·7) telephone-based 24hR were available. Group-level bias, correlation coefficients, attenuation factors, de-attenuated correlation coefficients and ranking agreement were assessed. Compared with the 24hR, the FFQ-NL 1.0 estimated the intake of energy and macronutrients well. However, it underestimated intakes of SFA and trans-fatty acids and alcohol and overestimated intakes of most vitamins by >5 %. The median correlation coefficient was 0·39 for energy and macronutrients, 0·30 for micronutrients and 0·30 for food groups. The FFQ underestimated protein intake by an average of 16 % and K by 5 %, relative to their urinary recovery biomarkers. Attenuation factors were 0·44 and 0·46 for protein and K, respectively. Correlation coefficients were 0·43-0·47 between (fatty) fish intake and plasma EPA and DHA and 0·24-0·43 between fruit and vegetable intakes and plasma carotenoids. In conclusion, the overall validity of the newly developed FFQ-NL 1.0 was acceptable to good. The FFQ-NL 1.0 is well suited for future use within Dutch cohort studies among adults.

Application of a New Statistical Model for Measurement Error to the Evaluation of Dietary Self-report Instruments

Most statistical methods that adjust analyses for dietary measurement error treat an individual's usual intake as a fixed quantity. However, usual intake, if defined as average intake over a few months, varies over time. We describe a model that accounts for such variation and for the proximity of biomarker measurements to self-reports within the framework of a meta-analysis, and apply it to the analysis of data on energy, protein, potassium, and sodium from a set of five large validation studies of dietary self-report instruments using recovery biomarkers as reference instruments. We show that this time-varying usual intake model fits the data better than the fixed usual intake assumption. Using this model, we estimated attenuation factors and correlations with true longer-term usual intake for single and multiple 24-hour dietary recalls (24HRs) and food frequency questionnaires (FFQs) and compared them with those obtained under the "fixed" method. Compared with the fixed method, the estimates using the time-varying model showed slightly larger values of the attenuation factor and correlation coefficient for FFQs and smaller values for 24HRs. In some cases, the difference between the fixed method estimate and the new estimate for multiple 24HRs was substantial. With the new method, while four 24HRs had higher estimated correlations with truth than a single FFQ for absolute intakes of protein, potassium, and sodium, for densities the correlations were approximately equal. Accounting for the time element in dietary validation is potentially important, and points toward the need for longer-term validation studies.

New markers of dietary added sugar intake

PURPOSE OF REVIEW

Added sugar consumption is associated with adverse health outcomes, including weight gain and cardio-metabolic disease, yet the reliance on self-reported methods to determine added sugar intake continues to be a significant research limitation. The purpose of this review is to summarize recent advances in the development of two potential predictive biomarkers of added sugar intake: δC and urinary sugar excretion.

RECENT FINDINGS

The results of numerous cross-sectional investigations have indicated modest associations of the δC sugar biomarker measured in a variety of sample types (e.g., fingerstick blood, serum, red blood cells, and hair) with self-reported added sugar and sugar-sweetened beverage intake, and δC values have been reported to change over time with changes in reported sugar-sweetened beverage intake. Results from large-scale trials have suggested modest associations of urinary sugar excretion with reported sugar intake, and a dose-response relation has been demonstrated between urinary sugar excretion and actual sugar intake.

SUMMARY

Valid markers of sugar intake are urgently needed to more definitively determine the health consequences of added sugar intake. Adequately powered controlled feeding studies are needed to validate and compare these two biomarkers of sugar intake, and to determine what individual characteristics and conditions impact biomarker results.

Accuracy and Usefulness of Select Methods for Assessing Complete Collection of 24-Hour Urine: A Systematic Review

Twenty-four-hour urine collection is the recommended method for estimating sodium intake. To investigate the strengths and limitations of methods used to assess completion of 24-hour urine collection, the authors systematically reviewed the literature on the accuracy and usefulness of methods vs para-aminobenzoic acid (PABA) recovery (referent). The percentage of incomplete collections, based on PABA, was 6% to 47% (n=8 studies). The sensitivity and specificity for identifying incomplete collection using creatinine criteria (n=4 studies) was 6% to 63% and 57% to 99.7%, respectively. The most sensitive method for removing incomplete collections was a creatinine index <0.7. In pooled analysis (≥2 studies), mean urine creatinine excretion and volume were higher among participants with complete collection (P<.05); whereas, self-reported collection time did not differ by completion status. Compared with participants with incomplete collection, mean 24-hour sodium excretion was 19.6 mmol higher (n=1781 specimens, 5 studies) in patients with complete collection. Sodium excretion may be underestimated by inclusion of incomplete 24-hour urine collections. None of the current approaches reliably assess completion of 24-hour urine collection.

Validation of web-based, multiple 24-h recalls combined with nutritional supplement intake questionnaires against nitrogen excretions to determine protein intake in Dutch elite athletes

Information on dietary composition is vitally important for elite athletes to optimise their performance and recovery, which requires valid tools. The aim of the present study was to investigate the validity of assessing protein intake using three web-based 24-h recalls and questionnaires, by comparing these with three urinary N excretions on the same day. A total of forty-seven Dutch elite top athletes, both disabled and non-disabled, aged between 18 and 35 years, with a BMI of 17·5-31 kg/m2, exercising >12 h/week were recruited. Estimated mean dietary protein intake was 109·6 (sd 33·0) g/d by recalls and questionnaires v. 141·3 (sd 38·2) g/d based on N excretions in urine; the difference was 25·5 (sd 21·3) % between the methods (P<0·05). We found a reasonably good association between methods for protein intake of 0·65 (95 % CI 0·45, 0·79). On an individual level, under-reporting was larger with higher protein intakes than with lower intakes. No significant differences were found in reporting absolute differences between subcategories (sex, under-reporting, BMI, collection of recalls within a certain amount of time and using protein supplements or not). In conclusion, combined, multiple, 24-h recalls and questionnaires underestimated protein intake in these young elite athletes more than that reported for non-athlete populations. The method proved to be suitable for ranking athletes according to their protein intake as needed in epidemiological studies. On an individual level, the magnitude of underestimation was about equal for all athletes except for those with very high protein intakes.

Comparison of duplicate portion and 24 h recall as reference methods for validating a FFQ using urinary markers as the estimate of true intake

As FFQ are subject to measurement error, associations between self-reported intake by FFQ and outcome measures should be adjusted by correction factors obtained from a validation study. Whether the correction is adequate depends on the characteristics of the reference method used in the validation study. Preferably, reference methods should (1) be unbiased and (2) have uncorrelated errors with those in the FFQ. The aim of the present study was to assess the validity of the duplicate portion (DP) technique as a reference method and compare its validity with that of a commonly used reference method, the 24 h recall (24hR), for protein, K and Na using urinary markers as the unbiased reference method. For 198 subjects, two DP, two FFQ, two urinary biomarkers and between one and fifteen 24hR (web based and/or telephone based) were collected within 1·5 years. Multivariate measurement error models were used to estimate bias, error correlations between FFQ and DP or 24hR, and attenuation factors of these methods. The DP was less influenced by proportional scaling bias (0·58 for protein, 0·72 for K and 0·52 for Na), and correlated errors between DP and FFQ were lowest (protein 0·28, K 0·17 and Na 0·19) compared with the 24hR. Attenuation factors (protein 0·74, K 0·54 and Na 0·43) also indicated that the DP performed better than the 24hR. Therefore, the DP is probably the best available reference method for FFQ validation for nutrients that currently have no generally accepted recovery biomarker.

Urinary Sugars--A Biomarker of Total Sugars Intake

Measurement error in self-reported sugars intake may explain the lack of consistency in the epidemiologic evidence on the association between sugars and disease risk. This review describes the development and applications of a biomarker of sugars intake, informs its future use and recommends directions for future research. Recently, 24 h urinary sucrose and fructose were suggested as a predictive biomarker for total sugars intake, based on findings from three highly controlled feeding studies conducted in the United Kingdom. From this work, a calibration equation for the biomarker that provides an unbiased measure of sugars intake was generated that has since been used in two US-based studies with free-living individuals to assess measurement error in dietary self-reports and to develop regression calibration equations that could be used in future diet-disease analyses. Further applications of the biomarker include its use as a surrogate measure of intake in diet-disease association studies. Although this biomarker has great potential and exhibits favorable characteristics, available data come from a few controlled studies with limited sample sizes conducted in the UK. Larger feeding studies conducted in different populations are needed to further explore biomarker characteristics and stability of its biases, compare its performance, and generate a unique, or population-specific biomarker calibration equations to be applied in future studies. A validated sugars biomarker is critical for informed interpretation of sugars-disease association studies.

Applying Recovery Biomarkers to Calibrate Self-Report Measures of Energy and Protein in the Hispanic Community Health Study/Study of Latinos

We investigated measurement error in the self-reported diets of US Hispanics/Latinos, who are prone to obesity and related comorbidities, by background (Central American, Cuban, Dominican, Mexican, Puerto Rican, and South American) in 2010–2012. In 477 participants aged 18–74 years, doubly labeled water and urinary nitrogen were used as objective recovery biomarkers of energy and protein intakes. Self-report was captured from two 24-hour dietary recalls. All measures were repeated in a subsample of 98 individuals. We examined the bias of dietary recalls and their associations with participant characteristics using generalized estimating equations. Energy intake was underestimated by 25.3% (men, 21.8%; women, 27.3%), and protein intake was underestimated by 18.5% (men, 14.7%; women, 20.7%). Protein density was overestimated by 10.7% (men, 11.3%; women, 10.1%). Higher body mass index and Hispanic/Latino background were associated with underestimation of energy (P < 0.05). For protein intake, higher body mass index, older age, nonsmoking, Spanish speaking, and Hispanic/Latino background were associated with underestimation (P < 0.05). Systematic underreporting of energy and protein intakes and overreporting of protein density were found to vary significantly by Hispanic/Latino background. We developed calibration equations that correct for subject-specific error in reporting that can be used to reduce bias in diet-disease association studies.

Use of Urine Biomarkers to Assess Sodium Intake: Challenges and Opportunities

This article summarizes current data and approaches to assess sodium intake in individuals and populations. A review of the literature on sodium excretion and intake estimation supports the continued use of 24-h urine collections for assessing population and individual sodium intake. Since 2000, 29 studies used urine biomarkers to estimate population sodium intake, primarily among adults. More than half used 24-h urine; the rest used a spot/casual, overnight, or 12-h specimen. Associations between individual sodium intake and health outcomes were investigated in 13 prospective cohort studies published since 2000. Only three included an indicator of long-term individual sodium intake, i.e., multiple 24-h urine specimens collected several days apart. Although not insurmountable, logistic challenges of 24-h urine collection remain a barrier for research on the relationship of sodium intake and chronic disease. Newer approaches, including modeling based on shorter collections, offer promise for estimating population sodium intake in some groups.

Pooled results from 5 validation studies of dietary self-report instruments using recovery biomarkers for potassium and sodium intake

We pooled data from 5 large validation studies (1999-2009) of dietary self-report instruments that used recovery biomarkers as referents, to assess food frequency questionnaires (FFQs) and 24-hour recalls (24HRs). Here we report on total potassium and sodium intakes, their densities, and their ratio. Results were similar by sex but were heterogeneous across studies. For potassium, potassium density, sodium, sodium density, and sodium:potassium ratio, average correlation coefficients for the correlation of reported intake with true intake on the FFQs were 0.37, 0.47, 0.16, 0.32, and 0.49, respectively. For the same nutrients measured with a single 24HR, they were 0.47, 0.46, 0.32, 0.31, and 0.46, respectively, rising to 0.56, 0.53, 0.41, 0.38, and 0.60 for the average of three 24HRs. Average underreporting was 5%-6% with an FFQ and 0%-4% with a single 24HR for potassium but was 28%-39% and 4%-13%, respectively, for sodium. Higher body mass index was related to underreporting of sodium. Calibration equations for true intake that included personal characteristics provided improved prediction, except for sodium density. In summary, self-reports capture potassium intake quite well but sodium intake less well. Using densities improves the measurement of potassium and sodium on an FFQ. Sodium:potassium ratio is measured much better than sodium itself on both FFQs and 24HRs.

Validation of a Web-based, self-administered, non-consecutive-day dietary record tool against urinary biomarkers

New technologies are promising for the use of short-term instruments for dietary data collection; however, innovative tools should be validated against objective biomarkers. The aim of the present study was to investigate the validity of a Web-based, self-administered dietary record (DR) tool using protein, K and Na intakes against 24 h urinary biomarkers (24 h U). Of the total participants, 199 adult volunteers (104 men and 95 women, mean age 50·5 (23–83 years)) of the NutriNet-Santé Study were included in the protocol. They completed three non-consecutive-day DR and two 24 h U on the first and third DR days. Relative differences between reported (DR) and measured (24 h U) intakes were calculated from the log ratio (DR/24 h U) for protein, K and Na intakes: − 14·4,+2·6 and − 2·1 % for men; and − 13·9, − 3·7 and − 8·3 % for women, respectively. The correlations between reported and true intakes were 0·61, 0·78 and 0·47 for men and 0·64, 0·42 and 0·37 for women for protein, K and Na, respectively. Attenuation factors, that represent attenuation of the true diet–disease relationship due to measurement error (a value closer to 1 indicating lower attenuation), ranged from 0·23 (Na, women) to 0·60 (K, men). We showed that the Web-based DR tool used in the NutriNet-Santé cohort study performs well in estimating protein and K intakes and fairly well in estimating Na intake. Furthermore, three non-consecutive-day DR appear to be valid for estimating usual intakes of protein and K, although caution is advised regarding the generalisability of these findings to other nutrients and general population.

Nutritional epidemiology--there's life in the old dog yet!

Consideration is given to the idea that the nutritional epidemiology of cancer is dead, as some in the media have claimed. The basis for the claim does not lie in science nor has anyone with relevant knowledge made such a statement-although that, too, has been claimed. Evidence is adduced for the importance of past achievements of nutritional epidemiology. Attention is similarly drawn to recent contributions. In particular, I note the state of play of cancer and plant foods, fat and breast cancer, meat and cancer, vegetarians, intervention studies, migrant studies, and westernization of diet and lifestyle. Some next steps and some currently important questions are outlined.

Pooled results from 5 validation studies of dietary self-report instruments using recovery biomarkers for energy and protein intake

We pooled data from 5 large validation studies of dietary self-report instruments that used recovery biomarkers as references to clarify the measurement properties of food frequency questionnaires (FFQs) and 24-hour recalls. The studies were conducted in widely differing US adult populations from 1999 to 2009. We report on total energy, protein, and protein density intakes. Results were similar across sexes, but there was heterogeneity across studies. Using a FFQ, the average correlation coefficients for reported versus true intakes for energy, protein, and protein density were 0.21, 0.29, and 0.41, respectively. Using a single 24-hour recall, the coefficients were 0.26, 0.40, and 0.36, respectively, for the same nutrients and rose to 0.31, 0.49, and 0.46 when three 24-hour recalls were averaged. The average rate of under-reporting of energy intake was 28% with a FFQ and 15% with a single 24-hour recall, but the percentages were lower for protein. Personal characteristics related to under-reporting were body mass index, educational level, and age. Calibration equations for true intake that included personal characteristics provided improved prediction. This project establishes that FFQs have stronger correlations with truth for protein density than for absolute protein intake, that the use of multiple 24-hour recalls substantially increases the correlations when compared with a single 24-hour recall, and that body mass index strongly predicts under-reporting of energy and protein intakes.

Effects of para-aminobenzoic acid (PABA) form and administration mode on PABA recovery in 24-hour urine collections

Para-aminobenzoic acid (PABA) has long been used as an objective measure to assess completeness of 24-hour urine collections. However, pharmaceutical-grade PABA for human ingestion is not available in the United States. An alternative, the potassium salt of PABA, aminobenzoate potassium, can be obtained for clinical use, although it has not yet been validated in this role. Both PABA and aminobenzoate potassium can be directly ingested in their tablet or capsule forms or added to food before consumption. Our aim was to investigate the effect of form (PABA vs aminobenzoate potassium) and administration mode (directly ingested as a tablet/capsule vs added to food) on urinary PABA recovery levels. Twenty healthy participants underwent 3 test days separated by two 24-hour wash-out periods. Three test conditions, one on each test day, were investigated in randomized order: PABA tablet, aminobenzoate potassium capsule, and PABA or aminobenzoate potassium in food. Ingestion of each dose was supervised and participants performed the 24-hour urine collections while free-living. The 24-hour urine collections were analyzed for PABA recovery (%R) levels using a colorimetric assay. Recoveries 85% to 110% were deemed complete and those >110% were reanalyzed by high pressure liquid chromatography and mass spectrometry. Only complete collections (>85%R) were included in analyses. The recovery for the PABA tablet, aminobenzoate potassium capsule, and PABA/aminobenzoate potassium in food were similar at 98.8%R±2.0%R, 95.1%R±2.3%R, and 93.2%R±2.1%R, respectively, and did not differ significantly. These results suggest that aminobenzoate potassium may be used as an alternative to PABA for assessing the completeness of 24-hour urine collections and to track compliance with consuming provided diets in community-dwelling studies.