Examining the Validity of Spectroscopy-Based Skin Carotenoid Measurements as a Proxy for Fruit and Vegetable Consumption

The purpose of this study was to conduct a systematic review to assess criterion-related validity of spectroscopy-based skin carotenoid measurements against serum/plasma carotenoids and/or dietary intake of fruit and vegetables. PubMed, Embase, ProQuest, Cumulative Index of Nursing and Allied Health Literature, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials were systematically searched in December 2018 to identify articles for inclusion. Articles published from 1990–2018 that correlated spectroscopy-based skin carotenoid measurements to blood carotenoids and/or fruit and vegetable intake met inclusion criteria. The articles were reviewed independently by at least two authors and discrepancies were mediated by a third author. A hand search was conducted of the included papers to ensure no relevant articles were excluded. Of the 7931 articles identified in the literature search, 54 articles met the eligibility criteria for full-text review. Following the full-text review, 22 articles were selected for data extraction and were included in the present review. Following the hand search, seven additional articles were eligible for inclusion, resulting in a total of 29 articles. All 29 articles demonstrated statistically significant correlations between spectroscopy-based skin carotenoid measurements and serum/plasma carotenoids and/or dietary intake of fruits and vegetables. Three methods of spectroscopic detection were used: 20 articles used resonance Raman spectroscopy (RRS), seven articles used spectrophotometers, and two articles used reflection spectroscopy (RS) to measure skin carotenoids. Twenty of the articles described the racial/ethnic demographics of the study population, with seven articles containing more than 20% from a non-white, minority population. Four studies were conducted with infants, six studies included children, and the remaining 19 studies focused on adults. The results of the systematic review support the use of spectroscopy-based skin carotenoid measurements as an alternative measure of fruit and vegetable intake. Additional research is warranted to examine the use of different spectroscopy techniques in diverse populations and populations of varying ages. N/A.