Serum Carbon Isotope Values Change in Adults in Response to Changes in Sugar-Sweetened Beverage Intake

Serum carbon isotope values [C-13-to-C-12 serum carbon isotope ratio (delta C-13)], which reflect consumption of corn- and cane-based foods, differ between persons consuming high and low amounts of sugar-sweetened beverages (SSBs). In this study, we determined whether serum delta C-13 changes in response to change in SSB intake during an 18-mo behavioral intervention trial. Data were from a subset of 144 participants from the PREMIER trial, a completed behavioral intervention (Maryland, 1998-2004). SSB intake was assessed using 2 24-h dietary recall interviews. Blinded serum samples were assayed for delta C-13 by natural abundance stable isotope mass spectroscopy. Multiple linear regression models with generalized estimating equations and robust variance estimation were used. At baseline, mean SSB intake was 13.8 +/- 14.2 fl oz/d, and mean delta C-13 serum value was -19.3 +/- 0.6 units per mil (designated parts per thousand). A reduction of 12 oz (355 mL)/d SSB (equivalent to 1 can of soda per day) was associated with 0.17 parts per thousand (95% Cl: 0.08 parts per thousand, 0.25 parts per thousand; P < 0.0001) reduction in serum delta C-13 values over 18 mo (equivalent to a 1% reduction in delta C-13 from baseline). After adjusting for potential confounders, a reduction of 12 oz/d SSB (equivalent to 1 can of soda per day), over an 18-mo period, was associated with 0.12%,0 (95% CI: 0.01 parts per thousand, 0.22 parts per thousand; P = 0.025) reduction in serum delta C-13. These findings suggest that serum delta C-13 can be used as a measure of dietary changes in SSB intake.