A dual-carbon-and-nitrogen stable isotope ratio model is not superior to a single-carbon stable isotope ratio model for predicting added sugar intake in Southwest Virginian adults

Abstract

Background: An objective measure of added sugar (AS) and sugar-sweetened beverage (SSB) intake is needed. The δ 13 C value of finger-stick blood is a novel validated biomarker of AS/SSB intake; however, nonsweetener corn products and animal protein also carry a δ 13 C value similar to AS sources, which may affect blood δ 13 C values. The δ 15 N value of blood has been proposed as a ''correction factor'' for animal protein intake. Objectives: The objectives were to 1) identify foods associated with δ 13 C and δ 15 N blood values, 2) determine the contribution of nonsweetener corn to the diet relative to AS intake, and 3) determine if the dual-isotope model (δ 13 C and δ 15 N) is a better predictor of AS/SSB intake than δ 13 C alone. Methods: A cross-sectional sample of southwest Virginian adults (n = 257; aged 42 ± 15 y; 74% overweight/obese) underwent dietary intake assessments and provided finger-stick blood samples, which were analyzed for δ 13 C and δ 15 N values by using natural abundance stable isotope mass spectrometry. Statistical analyses included ANOVAs, pairedsamples t tests, and multiple linear regressions. Results: The mean ± SD daily AS intake was 88 ± 59 g and nonsweetener corn intake was 13 ± 13 g. The mean δ 13 C valuewas -19.1 ± 0.9%, which was significantly correlated with AS and SSB intakes (r = 0.32 and 0.39, respectively; P ≤ 0.01). The δ 13 C value and nonsweetener corn intake and the δ 15 N value and animal protein intake were not correlated. AS intake was significantly greater than nonsweetener corn intake (mean difference = 76.2 6 57.2 g; P ≤ 0.001). The δ 13 C value was predictive of AS/SSB intake (β range: 0.28-0.35; P ≤ 0.01); however, δ 15 N was not predictive and minimal increases in R 2 values were observed when the δ 15 N value was added to the model. Conclusions: The data do not provide evidence that the dual-isotope method is superior for predicting AS/SSB intakes within a southwest Virginian population. Our results support the potential of the δ 13 C value of finger-stick blood to serve as an objective measure of AS/SSB intake. This trial was registered at clinicaltrials.gov as NCT02193009. J Nutr 2015;145:1362-9.