Objective: To determine dietary carotenoid concentrations using an established and newly developed food frequency questionnaire (FFQ) method, to determine plasma carotenoid concentrations and to determine the relationship between these dietary and plasma variables in 24-45 y and > or = 65 y groups.
Design: Descriptive assessment of (FFQ), 7-d estimated records, and plasma carotenoids and their relationships in 24-45 y and > or = 65 y groups.
Setting: Free living urban adults in Ireland.
Subjects: Sixty-four volunteers aged 24-45 y and 54 volunteers aged > or = 65 y.
Results: Beta-carotene was the predominant plasma carotenoid, but older groups had lower plasma concentrations of several carotenoids compared to younger groups (P < 0.005). Beta-carotene and lycopene were the major dietary carotenoids reported by estimated records and FFQ. Several estimated record and plasma carotenoid concentrations were positively associated in younger groups but not in older groups. FFQ overestimated dietary carotenoids relative to estimated records (P < or = 0.05), generally did not reflect estimated record carotenoid concentrations and showed positive associations with plasma carotenoids only in older men. Neither of the dietary methods revealed a positive association between plasma and dietary beta-carotene concentrations, whereas beta-cryptoxanthin was strongly associated.
Conclusions: Dietary and plasma concentrations of individual carotenoids are documented in young and elderly groups of a European country. Estimated record data reveals positive associations between diet and plasma carotenoids in younger, but not elderly groups. Further work examining diet-plasma relationship in older groups and developing a common FFQ suitable for use in several European countries is required.