Natural 13C abundance of plasma glucose as a potential biomarker for dietary “simple” sugar intake.

Abstract

INTRODUCTIONA need exists for objective biomarkers of dietary intake, as self‐report is often subject to inaccuracies.PURPOSEWe tested the validity of measuring the fraction of dietary carbohydrate (CHO) from cane sugar and high fructose corn syrup (C4 sugars) using natural 13C abundance of plasma glucose (Glc).METHODSIn a randomized cross‐over design, 5 subjects were fed 3 weight‐maintaining diets for 7 days, with a two‐week washout between diets. Diets differed in the fraction of total CHO energy from C4 sugars (5%, 16%, or 32%). During each diet, blood samples were drawn at 8am and 4pm on days 1, 3, and 5 and at 8am, 10am, 12pm, 2pm, and 4pm on day 7. δ13C abundance of plasma Glc was analyzed using isotope ratio mass spectrometry.RESULTSWithin each diet, δ13C of 8am Glc did not change from baseline with increasing time on diet. There was a positive correlation (R2 = 0.88) between Day 7 ‐ 10am δ13C Glc and % of breakfast CHO from C4 sugars. Also, δ13C Glc of combined 10am ‐ 4pm plasma from Day 7 within each diet demonstrated a positive correlation (R2 = 0.90) with % of total daily CHO from C4 sugars.CONCLUSIONGluconeogenesis attenuates δ13C abundance of fasting Glc, as the δ13C abundance of Glc from C4 sugar consumption does not persist overnight. Postprandial plasma Glc could be used as a biomarker for contributions of C4 sugars to a previously ingested meal. (Funding provided by The National Dairy Council).