Stable isotope models of sugar intake using hair, red blood cells, and plasma, but not fasting plasma glucose, predict sugar intake in a Yup'ik study population

Abstract

Objectively measured biomarkers will help to resolve the controversial role of sugar intake in the etiology of obesity and related chronic diseases. We recently validated a dual-isotope model based on RBC carbon (δ(13)C) and nitrogen (δ(15)N) isotope ratios that explained a large percentage of the variation in self-reported sugar intake in a Yup'ik study population. Stable isotope ratios can easily be measured from many tissues, including RBCs, plasma, and hair; however, it is not known how isotopic models of sugar intake compare among these tissues. Here, we compared self-reported sugar intake with models based on RBCs, plasma, and hair δ(13)C and δ(15)N in Yup'ik people. We also evaluated associations of sugar intake with fasting plasma glucose δ(13)C. Finally, we evaluated relations between δ(13)C and δ(15)N values in hair, plasma, RBCs, and fasting plasma glucose to allow comparison of isotope ratios across tissue types. Models using RBCs, plasma, or hair isotope ratios explained similar amounts of variance in total sugar, added sugar, and sugar-sweetened beverage intake (∼53%, 48%, and 34%, respectively); however, the association with δ(13)C was strongest for models based on RBCs and hair. There were no associations with fasting plasma glucose δ(13)C (R(2) = 0.03). The δ(13)C and δ(15)N values of RBCs, plasma, and hair showed strong, positive correlations; the slopes of these relations did not differ from 1. This study demonstrates that RBC, plasma, and hair isotope ratios predict sugar intake and provides data that will allow comparison of studies using different sample types.

FIGURE 1

Associations of reported total sugar intake with predicted total sugar intake for all participants in the Neqem Nallunailkutaa study with a full suite of RBC, plasma, and hair isotopic measurements (n = 52). Total sugar intake was predicted using the formulae that were generated from the models of total sugar intake using RBC (dotted line), hair (dashed line), and plasma (solid line) δ¹³C and δ¹⁵N as predictors (Table 2).

FIGURE 2

Relations [R²; β (95% CI)] of RBC δ¹³C (A) and RBC δ¹⁵N (B) isotope ratios with hair and plasma isotope ratio intake for all participants in the Neqem Nallunailkutaa study with a full suite of RBC, plasma, and hair isotopic measurements (n = 52). The associations between δ¹³C and δ¹⁵N of hair and plasma were also strong and positive [R² = 0.72; β: 0.90; 95% CI: 0.74, 1.06 (δ¹³C)] and [R² = 0.94; β: 0.87; 95% CI: 0.81, 0.93 (δ¹⁵N)]. All P < 0.0001.