Skin carotenoids indicate diet, serum carotenoids, and inflammation across obesity and metabolic status in children

TL;DR

This study shows that skin carotenoids measured non-invasively can reflect diet quality and inflammation in children with obesity and metabolic issues.

Contribution

RS-based skin carotenoids are validated as non-invasive biomarkers for diet and metabolic health in children.

Findings

SCS levels decreased significantly with increasing metabolic dysfunction severity.

SCS strongly correlated with serum carotenoids and partially mediated dietary intake effects.

SCS inversely correlated with inflammation in metabolically disordered groups.

Abstract

To validate reflection spectroscopy (RS)-based skin carotenoids (SCS) as non-invasive biomarkers of fruit and vegetable intake (FVI) in children and adolescents with obesity and metabolic dysfunction.

This case-control study (China, 2023) included 210 children and adolescents aged 7–17 years, categorized into five groups: healthy weight (n = 30), overweight (n = 23), obesity (n = 25), obesity with one metabolic disorder (n = 56), and obesity with two or more metabolic disorders (n = 76). SCS levels were measured using RS, FVI was assessed via a food frequency questionnaire, serum carotenoids were quantified by high-performance liquid chromatography, and inflammatory markers were analyzed using flow cytometry.

SCS and serum carotenoid levels decreased significantly across groups (p for trend < 0.001). SCS correlated strongly with serum carotenoids, except for lycopene, with the strongest association observed in children and adolescents with obesity and two or more metabolic disorders. A quartile increase in FVI resulted in an 11.92–45.98 unit increase in SCS, partially mediated by total serum carotenoids, beta-carotene, and beta-cryptoxanthin. SCS also inversely correlated with inflammation in metabolically disordered groups.

RS-based SCS is a valid, non-invasive biomarker of FVI, closely related to serum carotenoids and inflammatory status, and effectively distinguishes metabolic dysfunction in children and adolescents.

The online version contains supplementary material available at 10.1186/s12986-026-01075-7.

Figures