Strength of the Relationships Between Three Self-reported Dietary Intake Instruments and Serum Carotenoids: the Observing Energy and Protein Nutrition (OPEN) Study

Objective: To assess the strength of the relationships between serum carotenoids and three self-reported dietary intake instruments often used to characterize carotenoid intake in studies of diet and disease.

Design: Participants completed a Diet History Questionnaire (DHQ), two 24 h dietary recalls (24HR), a fruit and vegetable screener and a fasting blood draw. We derived dietary intake estimates of α-carotene, β-carotene, cryptoxanthin, lutein, zeaxanthin and lycopene from each diet instrument and calculated sex-specific multivariate correlations between dietary intake estimates and their corresponding serum values.

Setting: Montgomery County, Maryland, USA.

Subjects: Four hundred and seventy women and men aged 40-69 years in the National Cancer Institute's Observing Protein and Energy Nutrition (OPEN) Study.

Results: Serum carotenoids correlated more strongly with the DHQ (r = 0·34-0·54 for women; r = 0·38-0·56 for men) than with the average of two recalls (r = 0·26-0·47 for women; r = 0·26-0·40 for men) with the exception of zeaxanthin, for which the correlations using recalls were higher. With adjustment for within-person variation, correlations between serum carotenoids and recalls were greatly improved (r = 0·38-0·83 for women; r = 0·42-0·74 for men). In most cases, correlations between serum carotenoids and the fruit and vegetable screener resembled serum-DHQ correlations.

Conclusions: Evidence from the study provides support for the use of the DHQ, a fruit and vegetable screener and deattenuated recalls for estimating carotenoid status in studies without serum measures, and draws attention to the importance of adjusting for intra-individual variability when using recalls to estimate carotenoid values.