Skin Carotenoid Accumulation in Response to a Two-Week Sweet Potato Snack Added to the Usual Diet

Abstract

Abstract Objectives To evaluate changes in skin carotenoid score (SCS) from baseline, during and following a two-week sweet potato snack added to a participant's usual diet. Methods Forty participants were recruited by convenience for a 7-week longitudinal cohort study with a 1-week period to establish baseline SCS, an intervention consisting of a sweet potato snack fed 3 times/week for 2 weeks in the lab while consuming a usual diet outside of the lab, followed by a 4-week monitoring period. SCS were measured 17 times over the study with pressure-mediated reflectance spectroscopy (Veggie Meter). SCS were analyzed using a linear mixed model (LMM) with repeated measures (fixed effects) to determine whether SCS increased from baseline to the follow up points of the intervention and post-intervention periods (α = 0.05). Data were plotted with a Loess line to visualize change over time. Secondary analyses were conducted to determine if baseline SCS affected time to detect differences post-intervention. Baseline SCS tertiles were analyzed using LMM with repeated measures (fixed effects, α = 0.05). Simple differences in least square means were calculated for each tertile at each time point. Results Participants included 28 (72%) females and 11 (28%) males from 20–62 years who identified themselves as “White” (69.2%), “Asian” (23.1%), “Black/African American” (5.1%), and “Other-Latina” (2.6%). Five participants (12.8%) reported a Hispanic ethnicity. Analyses included 39 of 40 original participants, as one withdrew the first week of the study. Change in mean SCS from baseline over time was significant (P < 0.001). While SCS during the intervention period were not significantly higher than baseline (P = 0.271), those at post-intervention were higher (P < 0.001). The Loess line for mean change in SCS from baseline depicted a period of consistent increase from day 26 to day 36, approximately 3 weeks after the start of the intervention. Change in SCS across periods for all tertiles was significant (P < 0.001). Conclusions These data suggest that 3 weeks after the beginning of a two-week intervention may be a period of interest when measuring the efficacy of such an intervention. Additionally, the difference in mean SCS between periods may depend on baseline SCS. Funding Sources This project was funded in part by Indiana University.