Skin Carotenoids: a Biomarker of Fruit and Vegetable Intake in Children

Background: Studies of adult subjects have found a strong correlation between serum carotenoids and skin carotenoids measured by resonance Raman spectroscopy (RRS). No published studies have examined correlations between skin and serum carotenoids among children.

Objectives: We aimed to validate skin RRS methodology against serum carotenoid measurements by high-performance liquid chromatography and to determine whether RRS can be used as a valid biomarker of fruit and vegetable (F/V) intake among children.

Design: In our cross-sectional study, participants were 45 healthy children aged 5 to 17 years who provided three blood samples used to assess serum carotenoid concentrations and three RRS skin measurements of the palm within a 4-week period. Dietary intake of F/V was assessed three times within 4 weeks using a 27-item food frequency questionnaire (FFQ) and an automated multiple-pass 24-hour daily recall. Estimates of intake from three FFQs, completed at least 7 days apart, were averaged. Estimates of intake from 24-hour daily recalls were collected on 2 weekdays and 1 weekend day and averaged.

Results: Levels of skin and serum carotenoids were highly correlated (R(2)=0.62; P<0.001). A linear regression model, controlling for child's weight and scanner unit, predicted that for every unit increase of total F/V from FFQ and total F/V as assessed by 24-hour daily recall, RRS intensity was predicted to increase by 3,798 (P=0.001) and 3,504 (P=0.001), respectively. Similar results were observed for reported high-carotenoid vegetable intake. Total carotenoid and beta carotene levels from 24-hour daily recalls correlated to total serum carotenoids levels (P<0.01 and P<0.05, respectively). Total carotenoid, alpha carotene, and beta carotene levels from the 24-hour daily recalls correlated to RRS (P<0.01).

Conclusions: Skin carotenoids measured by RRS were strongly correlated with serum carotenoid levels and were positively associated with estimates of intake from FFQ and an automated multiple-pass 24-hour daily recall among children aged 5 to 17 years. Skin carotenoids may be used as valid biomarker of F/V intake among children.