Non-invasive, reflection spectroscopy measurement of skin carotenoid score in infants is feasible and reliable

Authors: MORAN, NANCY - Children'S Nutrition Research Center (CNRC); CHANG, JOCELYN - Children'S Nutrition Research Center (CNRC); STROH, RACHEL - Baylor College Of Medicine; ZAIDI, YUSUF - Children'S Nutrition Research Center (CNRC); HASON, NOOR - Children'S Nutrition Research Center (CNRC); MUSAAD, SALMA - Children'S Nutrition Research Center (CNRC); O'CONNOR, TERESIA - Children'S Nutrition Research Center (CNRC)

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2022
Publication Date: 8/18/2022
Citation: Moran, N.E., Chang, J., Stroh, R., Zaidi, Y., Hason, N., Musaad, S., O'Connor, T. 2022. Non-invasive, reflection spectroscopy measurement of skin carotenoid score in infants is feasible and reliable. Journal of Nutrition. https://doi.org/10.1093/jn/nxac182 .
DOI: https://doi.org/10.1093/jn/nxac182

Interpretive Summary: Assessing what infants eat is critical for carefully studying the relationship between infant nutrition and health. Optical skin carotenoid measurements can provide an assessment of carotenoid intake. Carotenoids are red, orange, yellow components found predominantly in fruits and vegetables as well as human milk infant formula. This observational study found that skin carotenoids can be measured easily and reliably using a commercially available pressure-mediated reflection spectroscopy device, in 4-, 6-, and 8-month-old infants. Skin carotenoid measurements were correlated with 4-month-olds' blood carotenoid measurements, suggesting that skin carotenoid measurements may provide a non-invasive alternative to carotenoid assessment in 4-month olds. Rapid, and non-invasive dietary assessment methods can advance the study of infant nutrition.

Technical Abstract: 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. 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. 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. 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. Infant skin carotenoids are feasibly and reliably measured by RS, and may provide a biomarker of carotenoid intake in 4-month olds.