BACKGROUND: Carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in tissues are proposed biomarkers for dietary intake, with δ13C values reflecting added sugar intake derived from corn and sugarcane, and δ15N values reflecting animal protein intake. Research in young children is limited. OBJECTIVE: We examined associations between hair δ13C and δ15N values and dietary intake among children and also their mothers, to confirm associations found in other adults. METHODS: Hair samples and 24-hour dietary recalls were collected from children (aged 5.6 ± 0.2 y
n=138) and adults (34.1 ± 0.7 y
n=114) in a cross-sectional study in Philadelphia. Hair δ RESULTS: Among adults, regression models revealed δ CONCLUSIONS: Age-related dietary patterns, particularly higher cow's milk consumption in children, may mask δ13C ─added sugar associations, highlighting the importance of accounting for age and dietary complexity in biomarker research. CLINICAL TRIAL REGISTRATION: "Snacks, Smiles and Taste Preferences," NCT03631992 (baseline data only), Website: https://clinicaltrials.gov/study/NCT03631992?cond=sweet%20biomarkers&checkSpell=&rank=2
"Added Sugar Intake, Sweet Taste Phenotypes and Biomarkers" (SWBIO), NCT05047588, Website: https://clinicaltrials.gov/ct2/show/NCT05047588.