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

Abstract

A lack of consistency exists in the literature regarding the most appropriate time to measure the effectiveness of nutrition interventions by way of pressure-mediated reflectance spectroscopy (RS). There is a growing use of non-invasive methods like pressure-mediated RS to objectively measure fruit and vegetable intake in different populations, particularly in the context of nutrition interventions. This study evaluated the changes in those measurements, skin carotenoid scores (SCS), from baseline SCS values both during and following a two-week intervention promoting increased red-orange vegetable consumption on top of a participant’s usual diet. Specifically, it investigated a general time frame where measurement of SCS would be most advantageous for determining the effectiveness of a nutrition intervention. To test the hypothesis that SCS values would be different from baseline SCS values both during and following the intervention, participants took part in a three-phase nutrition intervention that included a 1-week baseline period, a feeding period in which participants were fed a sweet potato snack 3 times a week for two weeks on top of their usual diet, and a 4-week monitoring period. SCS were measured through each of the three periods with pressure-mediated RS. The scores were analyzed using a linear mixed model with repeated measures for participants over time to determine whether skin carotenoids increased from baseline to the follow up points of the intervention and post-intervention periods. The results showed that change in mean SCS from baseline over time was significant. While SCS during the intervention period were not significantly higher than baseline, SCS at post-intervention were significantly higher than baseline on average. Observations of these data suggest that 2 to 3 weeks after the beginning of a two-week intervention may be a period of interest when measuring the efficacy of such an intervention. On this basis, future studies should be designed for participant final measurements to be made approximately 2 to 3 weeks following a similar dietary intervention.