Estimated daily intake and seasonal food sources of quercetin in Japan

Abstract

Quercetin is a promising food component, which can prevent lifestyle related diseases. To understand the dietary intake of quercetin in the subjects of a population-based cohort study and in the Japanese population, we first determined the quercetin content in foods available in the market during June and July in or near a town in Hokkaido, Japan. Red leaf lettuce, asparagus, and onions contained high amounts of quercetin derivatives. We then estimated the daily quercetin intake by 570 residents aged 20-92 years old in the town using a food frequency questionnaire (FFQ). The average and median quercetin intakes were 16.2 and 15.5 mg day(-1), respectively. The quercetin intakes by men were lower than those by women; the quercetin intakes showed a low correlation with age in both men and women. The estimated quercetin intake was similar during summer and winter. Quercetin was mainly ingested from onions and green tea, both in summer and in winter. Vegetables, such as asparagus, green pepper, tomatoes, and red leaf lettuce, were good sources of quercetin in summer. Our results will help to elucidate the association between quercetin intake and risks of lifestyle-related diseases by further prospective cohort study and establish healthy dietary requirements with the consumption of more physiologically useful components from foods.

Figure 1

(a) Estimated intakes of quercetin and vegetables using two-day weighed food records of female volunteers. (b) Percentage contribution of foods to daily quercetin intake by the volunteers.

Figure 2

(a) Estimated daily quercetin intake by 570 residents of Sobetsu in Hokkaido using the FFQ during summer. (b) Estimated daily quercetin intakes by men and women using the FFQ during summer. Numbers in the figure show the median quercetin intakes by men and women. (c) Correlation between the daily quercetin intakes by men or women and their age. r, correlation coefficient; * p < 0.0001; Pearson correlation test.

Figure 3

Percentage contribution of foods to the daily quercetin intake by residents of Sobetsu in Hokkaido during summer (a) and winter (b).

Figure 4

(a) Estimated daily quercetin intake by 60 residents of Sobetsu in Hokkaido using the FFQ during winter. (b) Estimated daily quercetin intakes by men and women using the FFQ during winter. Numbers in the figure show the median quercetin intakes by men and women. (c) Relationship between quercetin intakes by men or women and their age.

Figure 4

(a) Estimated daily quercetin intake by 60 residents of Sobetsu in Hokkaido using the FFQ during winter. (b) Estimated daily quercetin intakes by men and women using the FFQ during winter. Numbers in the figure show the median quercetin intakes by men and women. (c) Relationship between quercetin intakes by men or women and their age.