According to the American Heart Association, excessive dietary sugars intake, especially in the form of fructose consumption, may contribute to obesity, insulin resistance, type 2 diabetes, hypertension and dyslipidaemia( Reference Johnson, Appel and Brands 1 ). Possible pathways potentially explaining the role of dietary sugars in increasing cardiometabolic risk include: (i) excess energy intake; and/or (ii) high dietary glycaemic load leading to inflammation, insulin resistance and impaired β-cell function( Reference Johnson, Appel and Brands 1 , Reference Hu and Malik 2 ). US Hispanics/Latinos are 25 (95 % CI 13, 38) % more likely to report sugar-sweetened beverage consumption than non-Hispanic/Latino adults according to data from the National Health and Nutrition Examination Survey 2007–2008( Reference Han and Powell 3 ). Type 2 diabetes is highly prevalent among Hispanics/Latinos in the USA, with wide variability based on Hispanic/Latino background, ranging from 10·2 % in South Americans to 18·3 % in Mexicans (P<0·0001)( Reference Schneiderman, Llabre and Cowie 4 ).
Measurement error in self-reported intake has impeded progress in definitively addressing diet–disease hypotheses( Reference Subar, Kipnis and Troiano 5 – Reference Freedman, Commins and Moler 9 ). Identified strategies for mitigating measurement error include statistical approaches that combine two dietary assessment approaches (e.g. FFQ and 24 h recall (24HR) or biomarker with self-reported diet data)( Reference Neuhouser, Tinker and Shaw 10 , Reference Freedman, Kipnis and Schatzkin 11 ), integration of validated biomarkers into epidemiological studies, and the development and validation of new biomarkers that characterize dietary components( Reference Prentice, Huang and Tinker 12 , Reference Bingham 13 ). Nutrient biomarkers have been classified as recovery, concentration, predictive or replacement( Reference Jenab, Slimani and Bictash 14 ), depending upon whether the biomarker reflects an absolute level of intake or is correlated with dietary intake (i.e. recovery v. concentration), the degree to which the biomarker is recovered and quantifiable (i.e. predictive)( Reference Tasevska, Runswick and McTaggart 15 ) or is used as a surrogate measure of intake for nutrients difficult to assess or with no food composition data available (i.e. replacement).
Methodological approaches for incorporating biomarkers within epidemiological studies have been developed( Reference Neuhouser, Tinker and Shaw 10 , Reference Freedman, Kipnis and Schatzkin 11 , Reference Prentice, Mossavar-Rahmani and Huang 16 ) and applications of these approaches have strengthened associations in diet–disease analyses( Reference Prentice, Huang and Kuller 17 – Reference Prentice, Shaw and Bingham 20 ). With combined biomarker and self-reported dietary data, the sample size requirement for estimating diet–disease associations may be reduced by 20–50 % compared with self-reported intake alone( Reference Freedman, Kipnis and Schatzkin 11 ). A predictive biomarker for total sugars intake (i.e. sum of fructose and sucrose in 24 h urine) developed in two controlled feeding studies in the UK showed that the sum of urinary sucrose and fructose in 24 h urine was significantly correlated with total sugars (r=0·841, P<0·001) and sucrose intake (r=0·773, P=0·002)( Reference Tasevska, Runswick and McTaggart 15 ). This biomarker has been recently integrated into two US-based biomarker studies with free-living individuals as a reference instrument against FFQ-, 24HR- and food record-based sugars intake( Reference Tasevska, Midthune and Tinker 21 , Reference Tasevska, Park and Jiao 22 ). The objective of the present study was to compare the consumption of sugars estimated from self-report with values derived from a biomarker of sugars intake nested within a large observational cohort study of Hispanic/Latino adults living in the USA.
Methods
Study description
The Study of Latinos: Nutrition & Physical Activity Assessment Study (SOLNAS), an ancillary study of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), included Hispanic/Latino men and women aged 18 to 74 years at HCHS/SOL baseline who were recruited from four centres (Bronx, NY; Chicago, IL; Miami, FL; San Diego, CA) across the USA, as previously described( Reference Sorlie, Aviles-Santa and Wassertheil-Smoller 23 – Reference Mossavar-Rahmani, Shaw and Wong 25 ). After excluding SOLNAS participants having incomplete (<500 ml/d) or missing urine samples (n 26 for the primary study and n 6 for the reliability study), the analytic sample was 450 for the primary sample and ninety for the reliability sample. Dietary recalls were excluded at each time point if reported daily energy intake was <2510 or >12 552 kJ (<600 or >3000 kcal) for women or <3347 or >16 736 kJ (<800 or >4000 kcal) for men (Fig. 1)( Reference Nielsen and Adair 26 ).
Fig. 1 Study flow diagram: estimating self-reported dietary intake using the National Cancer Institute (NCI) method and objective dietary intake using biomarkers of energy and sugars intake within the Study of Latinos: Nutrition & Physical Activity Assessment Study (SOLNAS), an ancillary study of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) cohort. At each time point, 24 h recalls (24HR) were excluded if energy intake was <2510 or >12 552 kJ (<600 or >3000 kcal) for women or <3347 or >16 736 kJ (<800 or >4000 kcal) for men. Combining recalls using the NCI method, the analytic sample size was 450 for the primary study and ninety for the reliability study. For deriving usual intake, 24HR from the entire HCHS/SOL were used (n 15 622 for visit 1 and n 14 709 for visit 2). n, sample size; mo, months; DLW, doubly labelled water
Energy expenditure and self-reported physical activity assessment
Energy expenditure was measured using a doubly labelled water (DLW) protocol( Reference Klein, James and Wong 27 ). Following the collection of a baseline urine sample, participants ingested a DLW mixture that provided 1·38 g of 10 at% 18O-labelled water and 0·086 g of 99·9 at% 2H-labelled water per kilogram body weight and provided in-clinic spot urines at 3 and 4 h( Reference Blanc, Colligan and Trabulsi 28 ). Participants aged ≥60 years provided a blood sample 3 h post-isotope to allow adjustment for age-related post-void urine retention. An additional post-dose sample was collected on day 12 of the DLW protocol. Self-reported physical activity was assessed by the Global Physical Activity Questionnaire that was developed by the WHO to quantify time spent in moderate and vigorous levels of physical activity at work, travel and leisure time( Reference Bull, Maslin and Armstrong 29 , 30 ). Twenty per cent of the participants (n 96) repeated the protocol to obtain reliability measures.
Self-reported sugars intake assessment
Self-reported sugars intake was estimated using the National Cancer Institute (NCI) method( Reference Dodd, Guenther and Freedman 31 ), using all available data to estimate usual dietary intake by combining up to five 24HR recalls (Fig. 1). In-person 24HR were conducted at the HCHS/SOL baseline, SOLNAS baseline and the SOLNAS reliability study visit (see online supplementary material, Supplemental Table 1). Interviews were conducted in Spanish or English depending on the participant’s preference with the Nutrition Data System for Research (NDS-R) software (version 11) developed by the Nutrition Coordinating Center at the University of Minnesota, which uses the multiple-pass method and has a database with >18 000 foods. As described by Tooze et al.( Reference Tooze, Kipnis and Buckman 32 ), the NCI method for estimating usual intake involved two steps. The first step (NCI MIXTRAN macro) specifies the consumption-day amount using linear regression on a transformed scale, with a person-specific effect adjusted for sex, age, Hispanic/Latino background, field centre, weekend (including Friday), self-reported intake amount (more, same or less than usual amount) and sequence (i.e. Fig. 1, first through fifth recall). The second step (NCI INDIVINT macro) calculates the individual’s predicted usual intake using parameter estimates from the first step.
Biomarker-predicted energy assessment
The urine and plasma samples collected within the DLW protocol from SOLNAS participants were analysed by gas-isotope-ratio MS to assess energy expenditure( Reference Wong, Lee and Klein 33 ). The isotopic data were converted to energy expenditure values based on an energy equivalent of 1 litre of CO2 to be 3·815/RQ+1·2321, where RQ is the respiratory quotient equal to 0·86, a standard among populations consuming a Western diet which is based on a high-fat diet( Reference Mossavar-Rahmani, Shaw and Wong 25 , Reference Ravussin, Harper and Rising 34 ).
Biomarker-predicted sugars assessment
At SOLNAS baseline, participants collected one 24 h urine sample that was analysed for sucrose and fructose. Urinary sucrose and fructose were measured by LC-MS at the University of Hawaii Cancer Center( Reference Kuhnle, Joosen and Wood 35 ). Urine samples (20 µl) mixed with internal standards were dried using N2 and reconstituted in 100 µl MeOH. The redissolved sample was centrifuged and the supernatant (10 µl) was injected into the LC-MS system (model Accela ultra HPLC coupled to a TSQ Quantum Ultra tandem mass spectrometer with Xcalibur™ software; ThermoFisher, San Jose, CA, USA). Chromatographic separations were performed on a ZIC®-HILIC column (100 mm×2·1 mm, 3 μm; Merck KGaA, Darmstadt, Germany) by gradient elution using 0·1 % (v/v) formic acid in MeCN and 0·1 % (v/v) formic acid in H2O at a flow rate of 0·3 ml/min. Masses were continuously monitored by atmospheric-pressure chemical ionization in negative mode and selected ion monitoring by extracting the respective accurate mass-to-charge (m/z) ratios.
Among a 10 % blinded quality control sample (collected about once per month from among SOLNAS 24 h urine samples; n 50), the CV were 11·7 % for fructose and 8·0 % for sucrose. Per an internal laboratory quality control (n 11), intra-day CV were 4·6% for fructose and 5·8% for sucrose, and inter-day CV were 10·5 % for both fructose and sucrose.
We used the calibration equation (1) below for total sugars biomarker, previously developed based on data from a feeding study( Reference Tasevska, Runswick and McTaggart 15 , Reference Tasevska, Midthune and Tinker 21 ), to calibrate the biomarker (i.e. sum of 24 h urine sucrose and fructose) and to derive biomarker-predicted sugars (BPS) intake in SOLNAS participants:
$$PM_{{ij}} {\equals}M_{{ij}} {\minus}1\!\!\cdot\!67{\minus}0\!\cdot\!02{\times}S_{i} {\plus}0\!\cdot\!71{\times}A_{i} ,$$
where: PM ij =log-transformed calibrated biomarker, i.e. BPS intake, for individual i on day j; M ij =log-transformed (sum of 24 h urine fructose and sucrose) for individual i on day j; S i =sex of individual i (0 for men, 1 for women); and A i =log-transformed age of individual i.
Statistical analysis
Both self-reported sugars intake and BPS intake were log-transformed to improve normality. Geometric means and 95 % CI were computed for self-reported sugars and BPS intakes, overall and by selected participant characteristics. Participant characteristics (mean and sd for continuous variables; n and % for categorical variables) were summarized by quartile of BPS intake. We assessed the correlations of BPS intake (g/d) with self-reported sugars intake (g/d) using Spearman correlation coefficients. Among the reliability participants, Spearman correlations were calculated to assess the relationship between repeated measures of self-reported and BPS intake.
To examine the sensitivity of the results to the analytic approaches used, results were stratified by accuracy of reporting status, with ‘concordance’ defined as self-reported energy intake within 25 % of energy expenditure estimated by DLW. Analyses were repeated using the ‘raw’ sum of 24 h urine fructose and sucrose (i.e. uncalibrated biomarker), rather than using BPS (i.e. calibrated biomarkers), as a measure of objective sugars intake. Furthermore, BPS was correlated to self-reported estimates of total sugars intake from a single 24HR recall which corresponded to the time point closest to the urine collection (e.g. 24HR administered within 7 d of 24 h urine collection), rather than using the NCI method to estimate usual intake, as the measure of sugars intake. Statistical analyses were conducted using the statistical software package SAS version 9.3.
Results
Overall, geometric mean self-reported total sugars intake was 90·6 (95 % CI 87·6, 93·6) g/d v. 167·5 (95 % CI 154·4, 181·7) g/d for biomarker-predicted total sugars intake (Table 1). Whereas self-reported total sugars intake was not associated with participant characteristics, BPS intake was significantly associated with age and ethnicity (Table 2). There was a non-significant trend for a higher proportion of obese individuals and those with lower education level to be in the highest BPS quartile. BPS intake was also higher among older participants and Puerto Ricans. Self-reported total sugars intake was not correlated with BPS (r=−0·06, P=0·20).
Table 1 Geometric mean (95 % CI) of self-reported total sugars and biomarker-predicted sugars intake (n 450); Study of Latinos: Nutrition & Physical Activity Assessment Study (SOLNAS)
Table 2 Characteristics of participants by quartile of biomarker-predicted total sugars intake (n 450); Study of Latinos: Nutrition & Physical Activity Assessment Study (SOLNAS)
DLW, doubly labelled water.
* Self-reported physical activity is the total amount of time spent doing some form of physical activity for work, transportation, recreation and sedentary behaviour in a week from the modified Global Physical Activity Questionnaire (GPAQ; available at https://www2.cscc.unc.edu/hchs/system/files/forms/UNLICOMMPhysicalPAE02182008.pdf).
The self-reported total sugars intake and BPS intake were not related, irrespective of whether energy expenditure estimated by DLW was within 25 % of self-reported total energy intake (P>0·05; Table 3). Usual energy intake was correlated with energy expenditure measured with the DLW method, and it was more highly correlated among true reporters compared with participants who were not classified as concordant reporters (r=0·79 v. r=0·54, P<0·0001). Among the participants in the 20 % reliability sub-samples who repeated the entire protocol about 6 months after the SOLNAS baseline visit, the repeated measures of BPS intake at baseline and 6 months were more highly correlated than repeated self-reported total sugars intake (r=0·59 v. r=0·20; for gender-specific reliability coefficients see Fig. 2).
Fig. 2 Correlation of (a) self-reported (SR) total sugars intake and (b) biomarker-predicted sugars (BPS) intake, by sex (○, women; ●, men), between participants in the reliability sub-sample and participants in the main study; Study of Latinos: Nutrition & Physical Activity Assessment Study (SOLNAS). (a) Women (n 58): Spearman’s ρ=0.21, P=0.11; men (n 32): Spearman’s ρ=0.12, P=0.50. (b) Women (n 57): Spearman’s ρ=0.42, P=0.001; men (n 32), Spearman’s ρ=0.84, P<0.0001
Table 3 Spearman correlations between self-reported and biomarker-based intakes of energy and sugars by concordance with doubly labelled waterFootnote *
* Concordance=reported energy intake within 25 % of energy intake measured with the doubly labelled water method.
Sensitivity analyses also demonstrated the lack of an association between urinary fructose and sucrose and self-reported total sugars intake. Among the primary study participants, the correlation between the ‘raw’/uncalibrated sum of 24HR urinary fructose and sucrose and NCI-based sugars intake was r=0·03 (P=0·58) and the agreement between quartiles of the raw sum and BPS was high (κ=0·72, P<0·0001; see online supplementary material, Supplemental Table 2). Similarly, the correlation between BPS and a single 24HR corresponding to the time point closest to the urine collection as the measure of self-reported total sugars intake, rather than using the NCI method to estimate usual intake, was r=0·02 (P=0·70). Within the reliability study, the correlation between BPS and a single 24HR corresponding to the time point closest to the urine collection was r=0·36 (P<0·0001); the association was stronger in men (r=0·63, P<0·001) than in women (r=0·27, P=0·04; Supplemental Table 3).
Discussion
Among a sizeable, diverse sample of Hispanics/Latinos, BPS intake was not correlated with self-reported total sugars intake. Whereas BPS was correlated with age and ethnicity, self-reported total sugars intake was unrelated to participant characteristics. Contrary to expectation, there was no significant association between BMI and BPS( Reference Tasevska 36 ). Using the sugars biomarker measured in spot urines, the European Prospective Investigation into Cancer and Nutrition–Norfolk reported positive associations between sucrose intake and obesity( Reference Kuhnle, Tasevska and Lentjes 37 , Reference Bingham, Luben and Welch 38 ) and a randomized, crossover trial in ten normal-weight and nine overweight/obese participants suggested BMI does not affect the validity of the biomarker( Reference Joosen, Kuhnle and Runswick 39 ). As this biomarker, so far, has not been validated for use among Hispanics/Latinos, we cannot definitively quantify the measurement error in the self-reported total sugars intake v. BPS intake. However, we conducted further analyses to better understand the reasons for the observed low correlations between self-reported and BPS intake. Using the recovery biomarker for energy intake based on DLW data, just over half of the sample (53 %) was categorized as concordant (i.e. self-reported energy intake values were within 25 % of biomarker values), but there was no association between self-reported total sugars and BPS intakes when results were restricted to this subset.
Possible explanations for the lack of any association between BPS and self-reported sugars intake include measurement error in self-reported sugars intake, variability in sugars intake necessitating multiple 24HR recalls and measures of urinary sucrose and fructose to accurately estimate usual intake, and/or the lack of evidence to support the role of urinary sucrose and fructose as a valid proxy for total sugars intake in this study population. Measurement error in the reporting of energy and protein has been well established in several studies comparing self-reported intake with recovery biomarkers( Reference Subar, Kipnis and Troiano 5 , Reference Neuhouser, Tinker and Shaw 10 , Reference Prentice, Mossavar-Rahmani and Huang 16 ). Other studies have nested the predictive urinary sucrose and fructose biomarker into validation studies to compare self-reported intake and biomarker-predicted intake of total sugars( Reference Tasevska, Midthune and Tinker 21 ). In the Women’s Health Initiative Nutrition and Physical Activity Assessment Study (NPAAS; n 450), self-reported sugars intake was substantially, and roughly equally, misreported whether measured by FFQ, 4 d food record or 24HR recall( Reference Tasevska, Midthune and Tinker 21 ). Geometric means of BPS in NPAAS and SOLNAS were similar: 173·9 (95 % CI 142·9, 211·6) g/d v. 167·5 (95% CI 154·4, 181·7) g/d, respectively( Reference Tasevska, Midthune and Tinker 21 ). The biomarker-prediction equation used in ours and each of these validation studies was derived from a highly controlled feeding study among seven men and six women in the UK aged 23–66 years( Reference Tasevska, Runswick and McTaggart 15 , Reference Tasevska, Midthune and Tinker 21 , Reference Tasevska, Midthune and Potischman 40 ). We noted a strong positive association between the BPS and age (Table 1), which may be due to an overcorrection for age at the higher age ranges. In analyses where we did not apply the biomarker-prediction equation and relied on the sum of urinary sucrose and fructose, associations between age and self-reported intake were null. Data from a controlled feeding study including participants representative of the age, race/ethnicity and BMI of this cohort would inform whether the biomarker-prediction equation is generalizable or needs modification based on these or other participant characteristics.
Whereas recovery biomarkers (i.e. DLW and 24 h urinary-N) are unbiased reference instruments that reflect an absolute level of intake, predictive biomarkers, such as 24 h urinary sucrose and fructose, can also be used as reference validation instruments after being calibrated to account for bias in the biomarker, estimable from a feeding study against known intake( Reference Tasevska, Runswick and McTaggart 15 ). We did not observe significant correlations between self-reported sugars intake and sucrose and fructose based on urinary measurements, even when restricting the analysis to individuals who reported energy intake within 25 % of the DLW value. Another possibility for the lack of correlation between self-reported and BPS intake is that high intra-individual variation in sugars intake would necessitate multiple days of measurement in order to estimate usual intake of total sugars. Among the sub-sample of reliability study participants, the reproducibility of self-reported sugars intake was much lower than the reproducibility of the urinary sucrose and fructose biomarkers. Furthermore, the self-reported intake from the 24HR closest to the urine collection and BPS was significant among reliability participants (r=0·36, P<0·001, n 84). However, restricting the analysis to individuals having 24HR within one week of the urinary sucrose and fructose biomarker measurement did not result in significant correlations with self-reported sugars intake. Possible explanations include that the reliability participants were more accurate reporters of dietary intake and more compliant with the urine collection protocols compared with the rest of the SOLNAS participants. Since the equation for predicting biomarker-based sugars intake was developed based on a small sample of individuals in the UK, we examined correlations between both the ‘raw’ sum of urinary sucrose and fructose in addition to applying the biomarker-prediction equation, but this did not substantively alter our results.
Strengths of the current study include applying a predictive biomarker that has been validated in controlled feeding studies to an ethnically diverse cohort, representing both genders, of Hispanics/Latinos in the USA, as well as accounting for a wide range of other factors previously demonstrated to be associated with measurement error in self-reported diet intake, such as age and BMI. The substantial sample size allowed conduct of several sensitivity analyses to ascertain whether our findings were influenced by the characterization of self-reported intake (i.e. usual intake per NCI method or restricting to 24HR within one week of the 24 h urine collection time point) and the level of concordance between DLW and self-reported energy intake. Our ability to make inferences about the magnitude of measurement error in self-reported sugars intake using the biomarker in this study population is limited. Highly controlled feeding studies with participants representative of the HCHS/SOL population would better characterize the application of this biomarker among Hispanics/Latinos.
Conclusion
In conclusion, in comparing a predictive biomarker of sugars intake among a diverse sample of Hispanics/Latinos, no significant associations were detected between the self-reported and biomarker-predicted sugars intakes. Clinical studies that allow for the control of factors such as the amount of total sugars intake, the optimal time frame between sugars intake and biomarker measurement, and health are needed to better determine the potential use of urinary sucrose and fructose as a biomarker of total sugars intake.
Acknowledgements
Acknowledgements: The authors would like to acknowledge Laurie J. Custer at the University of Hawaii for her LC-MS work. The authors also thank the staff and participants of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) for their important contributions (investigators’ website: http://www.cscc.unc.edu/hchs/). Financial support: The Sackler Institute for Nutrition Sciences funded this study. The Study of Latinos Nutrition & Physical Activity Assessment Study (SOLNAS) was supported by the National Heart, Lung, and Blood Institute (NHLBI; grant #11414319-R01HL095856). The HCHS/SOL was carried out as a collaborative study supported by contracts from the NHLBI to the University of North Carolina (N01-HC65233), the University of Miami (N01-HC65234), Albert Einstein College of Medicine (N01-HC65235), Northwestern University (N01-HC65236) and San Diego State University (N01-HC65237). The following institutes/centres/offices contribute to the HCHS/SOL through a transfer of funds to the NHLBI: the National Center on Minority Health and Health Disparities; the National Institute of Deafness and Other Communications Disorders; the National Institute of Dental and Craniofacial Research; the National Institute of Diabetes and Digestive and Kidney Diseases; the National Institute of Neurological Disorders and Stroke; and the Office of Dietary Supplements. Additional support at the Albert Einstein College of Medicine was provided from the Clinical & Translational Science Award (grant number UL1 TR001073) from the National Center for Advancing Translational Sciences at the National Institutes of Health. The funders had no role in the design, analysis or writing of this article. Conflict of interest: The authors have no conflict of interest to disclose. Authorship: Y.M.-R. and J.M.B. designed the research; W.W.W., P.A.S., A.M.S.-R., D.S.-A., M.D.G., M.S., L.V.H., A.A.F. and Y.M.-R. conducted the research and provided essential materials; M.J., P.A.S., N.T., D.S.-A. and J.M.B. developed the analytic approach and analysed the data; and J.M.B., J.R.K., J.S., J.W.-R. and Y.M.-R. wrote the paper. All authors read and approved the final manuscript. Ethics of human subject participation: This study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures involving human subjects/patients were approved by the Albert Einstein College of Medicine Institutional Review Board. Written informed consent was obtained from all subjects.
Supplementary Material
To view supplementary material for this article, please visit http://dx.doi.org/10.1017/S1368980016001580
