Analysing dietary flavonoid intake: methods, limitations and implications for research in ageing

Flavonoids are a group of dietary polyphenols consumed through plant-based foods. Their consumption is associated with a risk reduction for diseases associated with ageing, including cancers, cardiovascular diseases and neurodegenerative diseases. Our knowledge on habitual consumption of dietary flavonoids is inadequate as there are only a few estimations available in the literature. Flavonoid intake is hard to quantify and methods to estimate flavonoid intake have fundamental limitations, restricting our ability to correlate flavonoid intake with health outcomes on a population level. The various methods employed to estimate flavonoid intake are described and evaluated, including dietary assessment and biomarker analysis. The implications associated with the limitations to each method are outlined and evaluated in light of research in ageing.