Development, validation and reproducibility of a food frequency questionnaire to measure flavonoid intake in older Australian adults.

The developed FFQ appears suitable for satisfactorily ranking individuals according to total flavonoid intake. The FFQ shows limitations for estimating absolute total flavonoid intake and intake of flavonoid subclasses in comparison to a 4-day FR in terms of overestimating intake. Refinement and further validation of this tool may be required.