Associations Between Dietary Carotenoid Intake and Plasma Carotenoid Concentrations and Skin Yellowness, a Validation Study.

BACKGROUND:Carotenoids are pigments abundant in fruits and vegetables and can be measured in plasma and skin. This study aimed to evaluate associations between carotenoid intake, assessed by self-reported usual diet against plasma carotenoid and skin yellowness concentrations in Australian adults (n = 50, aged 39.3 ± 15.4 years, 68% female). METHODS:Dietary carotenoid intakes were quantified using the Australian Eating Survey (AES) food frequency questionnaire (total, α- and β-carotene, lycopene, β-cryptoxanthin, and lutein/zeaxanthin). Plasma concentrations of these carotenoids were measured using high-performance liquid chromatography, while skin yellowness was measured using skin reflectance spectroscopy as a proxy for skin carotenoids. Associations between AES carotenoids, plasma carotenoids and total skin yellowness were analysed using linear regressions. RESULTS:AES-derived carotenoid intakes were positively associated with skin yellowness for all dietary carotenoids (β range 0.25-0.46, p < 0.05) and total dietary carotenoids (β = 0.35 [95% CI 0.07, 0.63], p < 0.05), except lycopene. Similarly, each individual plasma carotenoid was significantly positively associated with their respective individual dietary carotenoids (β range 0.42-0.53, p < 0.05) and total dietary carotenoids (β = 0.38 [95% CI 0.04, 0.73], p < 0.05), except for lycopene. Significant positive associations were identified between skin yellowness and total (β = 0.36 [0.20, 0.52], p < 0.001) and individual plasma carotenoids (β range 0.30-0.37, p < 0.01), excluding α-carotene and lycopene. CONCLUSION:Dietary carotenoid intakes were significantly associated with plasma carotenoid concentrations and skin yellowness values. Results support use of all three methods for assessment of carotenoid intake, with the exception of lycopene. Future studies should consider cost, accessibility of assessment methods and participant burden when selecting dietary assessment methods. TRIAL REGISTRATION:The original study was registered with Australian New Zealand Clinical Trials Registry (ANZCTR-12619001415190).