Dietary flavonols intake does not differ throughout a year

Flavonols got particular attention in the last few years. We hypothesized that the seasonal changes in the availability of their sources do not impact the general flavonols intake. Forty volunteers were enrolled in the study. The 3-day food interviews were performed in 3-month intervals for one year and compared with the FFQ dedicated to the yearlong assessment of flavonols intake. The analysis did not show significant differences for quercetin, kaempferol, isorhamnetin, and total flavonols throughout the year. Significant differences were observed only for myricetin (P = 0.003). At the same time, the detailed analysis of the categories of the consumed products showed significant differences in the seasonal structure of the intakes of fruits (P = 0.01), vegetables (P = 0.046), herbs and spices (P = 0.002), and tea and coffee (P = 0.01). The analysis of the correlation between the results of the one-year follow-up and the results of the FFQ showed significant correlations for total flavonols (R = 0.55; P = 0.001), kaempferol (R = 0.66; P < 0.001), quercetin (R = 0.48; P = 0.002), isorhamnetin (R = 0.41; P = 0.01), and myricetin (R = 0.49; P = 0.001) intakes. This study showed that despite the fluctuations in the selected product intake, the overall intake of quercetin, kaempferol, isorhamnetin, and total flavonols did not show significant differences throughout the year. The analysis showed good agreement between FFQ dedicated to the yearlong assessment of the flavonols intake and multiple food interviews, which proves the validity of the FFQ.