The carbon isotope ratios of nonessential amino acids identify sugar-sweetened beverage (SSB) consumers in a 12-wk inpatient feeding study of 32 men with varying SSB and meat exposures

Abstract

Background The carbon isotope ratios (CIRs) of individual amino acids (AAs) may provide more sensitive and specific biomarkers of sugar-sweetened beverages (SSBs) than total tissue CIR. Because CIRs turn over slowly, long-term controlled-feeding studies are needed in their evaluation. Objective We assessed the responses of plasma and RBC CIRAA's to SSB and meat intake in a 12-wk inpatient feeding study. Methods Thirty-two men (aged 46.2 ± 10.5 y) completed the feeding study at the National Institute of Diabetes and Digestive and Kidney Diseases in Phoenix, Arizona. The effects of SSB, meat, and fish intake on plasma and RBC CIRAA's were evaluated in a balanced factorial design with each dietary variable either present or absent in a common weight-maintaining, macronutrient-balanced diet. Fasting blood samples were collected biweekly from baseline. Dietary effects on the postfeeding CIR of 5 nonessential AAs (CIRNEAA's) and 4 essential AAs (CIREAA's) were analyzed using multivariable regression. Results In plasma, 4 of 5 CIRNEAA's increased with SSB intake. Of these, the CIRAla was the most sensitive (β = 2.81, SE = 0.38) to SSB intake and was not affected by meat or fish intake. In RBCs, all 5 CIRNEAA's increased with SSBs but had smaller effect sizes than in plasma. All plasma CIREAA's increased with meat intake (but not SSB or fish intake), and the CIRLeu was the most sensitive (β = 1.26, SE = 0.23). CIRs of leucine and valine also increased with meat intake in RBCs. Estimates of turnover suggest that CIRAA's in plasma, but not RBCs, were in equilibrium with the diets by the end of the study. Conclusions The results of this study in men support CIRNEAA's as potential biomarkers of SSB intake and suggest CIREAA's as potential biomarkers of meat intake in US diets. This trial was registered at clinicaltrials.gov/ct2/show/NCT01237093 as NCT01237093.

A Systematic Review of Metabolomic Biomarkers for the Intake of Sugar-Sweetened and Low-Calorie Sweetened Beverages

“…A recent study [ 49 ], not included in Table 1 because it was published outside the records search period, corroborates evidence on the specificity of δ 13 C alanine for AS and SBBs. In this study, the δ 13 C of alanine and δ 13 C of glutamate were individual predictors of SSBs intake, with a predictive accuracy of AUC ≥ 0.97 and no evident association with meat intake.…”

“…The C4 derived AS has distinctly high δ 13 C values compared with any other dietary source, which proves the distal cause of the biomarker signal, while the proximal link between serum alanine and glucose is explained by the glucose−alanine cycle [ 50 ]. This also improves our understanding on the accumulating evidence demonstrating strong δ 13 C of alanine correlation with dietary AS, but not with other dietary components [ 41 , 42 , 49 ].…”

“…Previous studies showed that δ 13 C total tissue was more strongly related to meat and/or animal protein intake than AS and SSBs [ 40 , 41 ]. The results of Yun et al, Choy et al, and Johnson et al collectively validate the specificity of δ 13 C alanine as a biomarker for SSBs intake and not animal proteins [ 29 , 42 , 49 ]. Given that these three studies were conducted in diverse populations, this also demonstrates the robustness of this biomarker.…”

“…In this study, the δ 13 C of alanine and δ 13 C of glutamate were individual predictors of SSBs intake, with a predictive accuracy of AUC ≥ 0.97 and no evident association with meat intake. The findings also suggested that using a multiple amino acids approach could improve the biomarker estimation of the SSBs intake [ 49 ]. On the other hand, the δ 13 C of essential amino acids, especially the δ 13 C of leucine, was the most promising predictor of meat intake (AUC ≥ 0.92).…”

“…On the other hand, the δ 13 C of essential amino acids, especially the δ 13 C of leucine, was the most promising predictor of meat intake (AUC ≥ 0.92). Moreover, an important addition of this study to the current literature was the observation that the concentration of δ 13 C of non-essential amino acids is not influenced by meat intake, reflected greater sensitivity, and was more specific to SSBs intake, unlike when the δ 13 C values of the total tissue (plasma and red blood cells) were measured [ 49 ]. Previous studies showed that δ 13 C total tissue was more strongly related to meat and/or animal protein intake than AS and SSBs [ 40 , 41 ].…”