(P12-020-23) Comparing Apples to Apples? Sources of Variability and Standardized Protocols for the Non-Invasive Measurement of Dermal Carotenoids Using Reflectance Spectroscopy

Objectives: Reflectance spectroscopy (RS; Veggie Meter®) provides a convenient and valid assessment of dermal carotenoids, yet RS is relatively new and Veggie Meter® protocols still vary widely among researchers, resulting in potential sources of error and inhibiting future meta-analyses. This research (1) describes within-person variability over time and across devices; (2) describes variability for time since calibration; and (3) tests potential protocol changes (e.g., intervals between measurements, hand and finger used, size of aperture) to improve reliability.

Methods: We discussed protocols and variability concerns with over 20 researchers who use the Veggie Meter® to inform our aims. We then developed a 4 phase study and began collecting RS data (Veggie Meter®) from 15 adults (Phase 1- 10 hours per participant) and 158 adults (Phase II - 1.75 hours per participant) in early 2023. This included measuring all 10 fingers on three Veggie Meter® devices and gathering longitudinal data (scanning every 5-8 minutes). The Brigham Young University IRB approved both studies and consent was given; participants received an incentive ($12/hr).

Results: Preliminary analyses show differences in scores across devices is significant under some circumstances (p < .05), and time since calibration >90 min does affect variability (may become less precise), but was not so on all devices (p < .05). Scores may be significantly different across fingers and across hands within a participant. Taking the mean of 3 scans may allow outliers in measurement to artificially inflate scores; instead, alternate protocols should be considered (e.g., median used or mean of two closest of 3 scans).

Conclusions: Using the revised protocol based on this and similar research may decrease variability and improve the reliability of Veggie Meter® measurements. This would allow for more precision in the assessment of F/V intake interventions and the screening of large populations.

Funding Sources: Funded by Brigham Young University