Skin carotenoids: a biomarker of fruit and vegetable intake in children.

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. 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. 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. 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). 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.