Evaluation of an FFQ for assessment of antioxidant intake using plasma biomarkers in an ethnically diverse population.

OBJECTIVE

To evaluate FFQ estimates of dietary intake of individual antioxidants, fruit and vegetables in comparison to plasma concentrations of each antioxidant, and to determine which individual foods are associated with plasma antioxidant concentrations.

DESIGN

Dietary (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin, lycopene, retinol, and vitamin E) intakes over 12 months were estimated from a 121-item FFQ. Correlation coefficients, corrected for within-person variability in diet and plasma antioxidants, were used to examine associations between antioxidant concentrations in diet and plasma.

SETTING

Melbourne Collaborative Cohort Study (MCCS).

SUBJECTS

Men and women (n 3110) who were randomly selected from the MCCS. Participants were aged 36-72 years and were born in Australia, Greece, Italy or the UK.

RESULTS

Correlation coefficients for the carotenoids ranged from 0.28 for lycopene to 0.46 for beta-cryptoxanthin. There was no association between dietary and plasma retinol or dietary vitamin E with plasma alpha- and gamma-tocopherol. Individual plasma carotenoid concentrations were associated with intakes of fruit and vegetables.

CONCLUSIONS

Our data suggest that the FFQ provides useful information on intakes of each of the carotenoids: alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene and lutein/zeaxanthin. There was no association between diet and plasma markers of retinol or vitamin E; this may reflect the importance of factors other than intake in modifying circulating levels of these nutrients.