Consuming high-carotenoid fruit and vegetables influences skin yellowness and plasma carotenoids in young women: a single-blind randomized crossover trial

Background: Consumption of dietary carotenoids from fruits and vegetables (F/V) leads to accumulations in human skin, altering skin yellowness. The influence of the quantity of F/V consumed on skin yellowness and plasma carotenoid concentrations has not been examined previously. Objective: To compare the influence of consuming high-carotenoid-containing F/V (HCFV) (176,425 μg beta carotene/wk) vs low-carotenoid F/V (LCFV) (2,073 μg beta carotene/wk) on skin yellowness and plasma carotenoid concentrations, over 4 weeks. Design and intervention: A single-blind randomized controlled crossover trial from October 2013 to March 2014. Thirty women were randomized to receive 7 daily servings of HCFV or LCFV for 4 weeks. Following a 2-week washout period they followed the alternate intervention. Main outcome measures: Skin color (Commission Internationale de l'Eclairage L*a*b* color space, where L* represents skin lightness and positive values of a* and b* represent degrees of redness and yellowness, respectively) was assessed by reflectance spectroscopy in both sun-exposed and nonexposed skin areas. Fasting plasma carotenoids were determined by high-performance liquid chromatography, before and after each intervention period. Statistical analyses performed: Linear mixed models were used to determine the HCFV and LCFV response on skin color and plasma carotenoids, adjusting for intervention order, time, and interaction between baseline differences and time. Results: There were no significant differences in mean daily fruit (<i>P</i>=0.42) and vegetable (<i>P</i>=0.17) intakes between HCFV and LCFV groups. Dietary alpha carotene, beta carotene, lutein, and beta cryptoxanthin intakes were significantly different between the two groups (<i>P</i><0.01). Following HCFV there was a significantly greater increase in skin yellowness (b*) in both sun-exposed (<i>P</i><0.001) and unexposed areas, (<i>P</i><0.001), with no change in skin lightness (L*) or redness (a*). Significantly higher plasma alpha carotene (<i>P</i>=0.004), beta carotene (<i>P</i>=0.001), and lutein (<i>P</i>=0.028) concentrations were found following the HCFV intervention. Skin yellowness correlated with alpha carotene and beta carotene. Conclusions: Skin yellowness (b*) and fasting plasma carotenoid concentrations were significantly higher following HCFV than LCFV over 4 weeks