13. Conclusions

is in China (∼5mg/day) [24, 38]. Flavanone intake patterns perfectly match the consumption of

Flavonols are usually the third principal flavonoid class (7–9%) [21]. The mean intake of flavonols generally varies between 20 and 40mg/day (Table 2). In some countries (South Korea, China, and Poland) [25, 32, 62], a higher intake of flavonols is reported (>60mg/day as aglycones), but some of these values are probably overestimated. Flavonols are widely distributed in fruit and vegetables, particularly apples, onions, some leafy vegetables, and red wine [1].

Anthocyanidins are present in all red-blue-purple fruits and vegetables (e.g., berries, apples, pears, grapes, plums, and aubergine) along with red wine. They are responsible for the color of these foods. Depending on the region, anthocyanidins fluctuate from the second to the fourth most consumed flavonoid class (7–10%) [21]. The mean intake of anthocyanidins range from 20 to 40mg/day in most of the countries (Table 2). Countries with a high consumption of berries, such as Finland, are the top consumers of anthocyanidins (∼50mg/day) [31], while Brazil and

Flavones are the fifth most common flavonoid class, accounting for 1–2% of total flavonoids [21]. Their intake varies between 1 and 5mg/day using the USDA database [13] and 5–20mg/ day as aglycones using the Phenol-Explorer [16] (Table 2). Flavones are widely distributed in plant-based foods, fruits, vegetables, juices, wine, etc. It is important to highlight that the richest sources of flavones are herbal teas, and this food item is rarely recorded in dietary

Isoflavones are the flavonoid class with the lowest intake among the typical flavonoid classes (flavanols, flavanones, flavonols, anthocyanidins, flavones, and isoflavones). The intake of flavonoids is normally <2mg/day in Westernized countries, as they mainly occur in soy products [48]. However, in the UK health conscious group of the EPIC study, including vegans and vegetarians, the mean intake rises to 18mg/day [48]. In Asian countries, where the consumption of soy is very common, the mean intake of isoflavones ranges from 30 to 70mg/day,

questionnaires, and therefore, an underestimation of flavone intake is quite probable.

their main food sources: citrus fruit and citrus juices [1].

9. Anthocyanidins: intake and food sources

10. Flavones: intake and food sources

11. Isoflavones: intake and food sources

contributing to almost 20% of total flavonoids.

the US have a particularly low intake (<15mg/day) [20, 34, 35, 37, 60].

8. Flavonols: intake and food sources

384 Flavonoids - From Biosynthesis to Human Health

Overall, the mean intake of total flavonoids worldwide is around 400mg/day, ranging from 150 mg/day in Latin-American countries to 600mg/day in Australia and the UK, without considering thearubigins. Tea (rich in flavan-3-ol monomers and thearubigins) is the most important food source of total flavonoids in countries with a tea culture, while fruits (rich in proanthocyanidins) are the main food source in the remaining countries. Flavanols is the main contributor to total flavonoids (75%), followed by far by flavanones, flavones, and anthocyanidins (7–10% each) and flavones and isoflavones (1–2% each). Chalcones, dihydrochalcones, and dihydroflavonols are also minor flavonoid subclasses. It is important to highlight that the intake of isoflavones is extremely high in East Asian countries (30–70mg/day) compared to Western countries (<2mg/ day), since isoflavones mostly occur in soy products. Older women with healthy lifestyle and dietary habits and higher educational levels and incomes are the sector with the highest intake of total flavonoids.

Finally, more composition data are needed, particularly for tropical foods, to improve the estimation of total flavonoids, especially in some specific regions. Further studies are warranted to increase the descriptive analyses in several areas where little data are available to date, such as Latin America, Africa, and the Middle East. An accurate estimation of flavonoid intake is the first step before estimating their potential protective effects against chronic diseases and is an essential step for developing future dietary guidelines on flavonoids.
