Assessment of the Validity, Reliability, and Sensitivity of Fingerstick δ¹³C as an Added Sugar Biomarker in Adolescents: A Controlled Feeding Study Approach

An estimated 20.5% of adolescents ages 12 – 19 years were obese (≥95th percentile of BMI-for-age) in 2011 – 2014. Consumption of added sugars (AS) has been linked with adverse effects on weight and cardiovascular disease risk factors. Approximately 16% of adolescents’ calories come from AS, of which sugar-sweetened beverages (SSB) are a major contributor. However, the relationship between AS/SSB intake and obesity is controversial, partly due to limitations in self-reported dietary data. Objective dietary intake biomarkers may circumvent this problem. The δ13C biomarker for AS intake is based upon the fact that C4 plants– major source for sugar production in the United States – have elevated δ¹³C values compared to C3 plants, which includes most fruits and vegetables. The δ¹³C value of blood, which is influenced by diet, has been established as a valid, reliable, and sensitive biomarker, but when compared to selfreported AS intake. This investigation evaluated the sensitivity and reliability of the δ13C biomarker, assessed with fingerstick blood samples, in adolescents using a controlled feeding, crossover design. Fingerstick δ¹³C values significantly changed by -0.05‰ and +0.03‰ after subjects completed the 5% and 25% AS diets, respectively (F(1, 30) = 18.828, p < 0.001). High reliability was found between two consecutive fingerstick δ¹³C values on the low (ICC = 0.996) and high (ICC = 0.997) AS diets. Thus, fingerstick δ¹³C may be a sensitive and reliable indicator of AS intake in adolescents. Future investigations should develop an equation to estimate AS intake based on fingerstick δ¹³C