Noninvasive Reflection Spectroscopy Measurement of Skin Carotenoid Score in Infants Is Feasible and Reliable

Abstract

Background Skin carotenoid measurement by reflection spectroscopy (RS) offers a non-invasive biomarker of carotenoid intake, but feasibility, reliability, and validity are not established in infants. Objectives To determine feasibility and reliability of 4 month-old infant skin carotenoid score (SCS) measurement and its correlation with total carotenoid intake and plasma concentrations. Methods : SCSs were measured in a prospective, observational study by a modified, portable RS device at the index finger and heel of the foot in 4-months olds (n = 21). Infant plasma, human milk, and formula carotenoid concentrations were measured by HPLC-PDA, and carotenoid intake was estimated from 7-day food diaries corrected for actual milk carotenoid content. Mean SCS, time to acquire measurements, replicate intraclass correlations, and bivariate correlations between SCS, carotenoid intake, and plasma carotenoids were examined. Exploratory analyses of returning 6- (n = 12), and 8- (n = 9) month old infants were conducted. Results Mean ± SD finger and heel SCS in 4, 6, and 8-month-olds were 92 ± 57 and 92 ± 51; 109 ± 41 and 119 ± 44; and 161 ± 89 and 197 ± 128 units, respectively. Replicate SCS measurements were reliable, with high intra-correlation (≥0.70) within subject-visits. Four-month olds’ finger SCSs were correlated with carotenoid intake (rho = 0.48, P = 0.0033), and finger and heel SCS were correlated with total plasma carotenoid concentrations (rho = 0.71, P < 0.0001 and rho = 0.57, P = 0.0006, respectively). Eight-month olds’ finger and heel SCSs were correlated with total carotenoid intake (rho = 0.73, P < 0.001; rho = 0.58, P = 0.0014, respectively), while SCSs in 6-month olds’, in transition from exclusive milk to complementary feeding, did not correlate with plasma carotenoid or dietary carotenoids, despite correlation between plasma and dietary carotenoid intake (rho = 0.86, P = 0.0137). Mixed models suggest plasma total carotenoid concentration, age, carotenoid intake, and age*carotenoid intake, but not measurement site, are determinants of infant SCS. Conclusions Infant skin carotenoids are feasibly and reliably measured by RS, and may provide a biomarker of carotenoid intake in 4-month olds. ClinicalTrials.gov [NCT03996395].

Modulation of Cutaneous Carotenoid Content via Ozone Exposure

“…This method of measuring carotenoids was recently validated by several researchers [26][27][28]. Indeed, the authors found a clear correlation between skin and serum carotenoid levels in both infants and adults by measuring over 300 healthy subjects.…”