The δ13C Value of Fingerstick Blood Is a Valid, Reliable, and Sensitive Biomarker of Sugar-Sweetened Beverage Intake in Children and Adolescents

Background: Reliance on self-reported dietary intake methods is a commonly cited research limitation, and dietary misreporting is a particular problem in children and adolescents. Objective indicators of dietary intake, such as dietary biomarkers, are needed to overcome this research limitation. The added sugar (AS) biomarker delta C-13, which measures the relative abundance of C-13 to C-12, has demonstrated preliminary validity in adults. Objective: The purpose of this investigation was to determine the comparative validity, test-retest reliability, and sensitivity of the delta C-13 biomarker to detect AS and sugar-sweetened beverage (SSB) intake using fingerstick blood samples in children and adolescents. Methods: Children (aged 6-11 y, n = 126, 56% male, mean +/- SD age: 9 +/- 2 y) and adolescents (aged 12-18 y, n = 200, 44% male, mean +/- SD age: 15 +/- 2 y) completed 4 testing sessions within a 3-wk period. Participants' height, weight, demographic characteristics, and health history were determined at the first session; 24-h recalls were obtained at each visit and fingerstick blood samples were collected at visits 1 and 3. Samples were analyzed for delta C-13 value using natural abundance stable isotope mass spectrometry. delta C-13 value was compared with dietary outcomes in the full sample, and in child and adolescent subgroups. t Tests and correlational analyses were used to assess biomarker validity and reliability, whereas logistic regression and area under the receiver-operator characteristic curve (AUC) were used to evaluate sensitivity. Results: Reported mean +/- SD AS consumption was 82.2 +/- 35.8 g/d and 329 +/- 143 kcal/d, and SSB consumption was 222 +/- 243 mL/d and 98 +/- 103 kcal/d. Mean delta C-13 value was -19.65 +/- 0.69 parts per thousand, and was lower in children than in adolescents (-19.80 +/- 0.67 parts per thousand compared with -19.56 +/- 0.67 parts per thousand, P = 0.002). d13C values were similar across sessions (visit 1: -19.66 +/- 0.68 parts per thousand; visit 3: -19.64 +/- 0.68 parts per thousand; r = 0.99, P < 0.001) and were associated (P < 0.001) with intake of total AS (grams, kilocalories: r = 0.29) and SSB (milliliters, kilocalories: r = 0.35). The biomarker was able to better discriminate between high and low SSB consumers than high and low AS consumers, as demonstrated by the AUC (0.75 and 0.62, respectively). Conclusions: The d13C biomarker is a promising, minimally invasive, objective biomarker of SSB intake in children and adolescents. Further evaluation using controlled feeding designs is warranted.