5. Determinants of the total flavonoid intake

and vegetables. In the US, some differences in the total flavonoid intake among ethnicities have been observed [22, 36]. Non-Hispanic whites have the highest intake of flavonoids (>300mg/day), whereas non-Hispanic blacks, Mexican Americans, and other ethnicities consume approximately 200mg/day. Data on other countries in America is very limited, and to the best of our knowledge, Brazil [37] and Mexico [23] are the only other countries with available data. The intake of total flavonoids is around 150 and 50mg/day in Mexico and Brazil, respectively. These are the countries with the lowest intake of total flavonoids that have been published worldwide. Although, the studies in these countries did not take thearubigins into account, the contribution of thearubigins to total flavonoids is insignificant because Brazilians and Mexicans rarely drink tea. The main food source of total flavonoids is citrus juices, followed by fruit in Mexico and beans in Brazil [23, 37]. In these Latin-American countries, a potential relevant underestimation of total flavonoids cannot be ruled out because of missing food composition data on some tropical foods, such as fruits and vegetables (e.g., mamey, zapote, papaya, sweet potato, nopal, guava, jicama, and prickly pears)

that are frequently consumed in their diets and may be good sources of flavonoids.

tea in these Middle East populations.

378 Flavonoids - From Biosynthesis to Human Health

and refining the thearubigin data.

In Asian countries, very little complete data are available, as there is only data for East Asian countries (such as China [24, 38] and South Korea [25]). The total flavonoid intake in China ranges from 65mg/day without proanthocyanidins [38] to 225mg/day with proanthocyanidins [24]. In both studies, thearubigins are not included, but Chinese people drink green tea, but not black tea. Thearubigins are formed during the fermentation of green tea to black tea. In South Korea, the intake of total flavonoids is slightly higher than in China (320mg/day) [25]. In East Asian countries, soy and its derived products (the main food sources of isoflavones) are one of the most important contributors to total flavonoids, although proanthocyanidins and flavan-3-ol monomers are the most abundant flavonoids in South Korea and China, respectively. In Japan, China, and South Korea, there are many studies focusing on isoflavones, due to their potential phytoestrogenic effects [42], but not on total flavonoids. In the Middle East, a recent study in Iran has been conducted showing a mean intake of 1650mg/day [39]. This is the highest mean of total flavonoid intake worldwide. This high amount is because of the elevated consumption of black

In summary, there is a high heterogeneity between countries in total flavonoid intake. The highest intake is in Iran [39], followed by the UK (>1000mg/day) [27] and the lowest intake is in Brazil and Mexico (<150mg/day) [23, 37]. The populations with a higher intake of total flavonoids are those with a high consumption of tea, especially black tea. In this case, the main contributor to total flavonoids is thearubigins, and this may be partially explained due to the inaccurate measurement of thearubigin content in black tea [19]. Populations with a lower intake of total flavonoids are those with a low consumption of tea. In these cases, the main food sources are fruit and proanthocyanidins become the main contributor to total flavonoids. In East Asia, isoflavones are also important contributors to total flavonoids due to the high consumption of soy-derived products. Further studies are warranted to estimate the intake of total flavonoids in other regions of the world with little available data, such as Latin America, Africa, and Middle East. More research on the content of flavonoids in food is also needed in order to improve the existent food composition data, adding new foods (e.g., tropical foods) Total flavonoids, as with most nutrients and dietary compounds, are positively correlated to total energy intake. Therefore, subjects consuming more energy are also more likely to be those with a higher intake of total flavonoids, even though one of the most relevant food sources is tea which is a non-caloric beverage. For this reason, if we want to study the determinants of total flavonoid intake, we should adjust our models for total energy intake.

Men usually consume higher amounts of total flavonoids, but after adjusting for total energy, women actually tend to consume more total flavonoids, as reported in the US [22] and South Korean populations [25]. However, men have a higher flavonoid intake in MED countries [21] and France [33] as men tend to drink more wine, particularly red wine. In contrast, the opposite was found in non-MED countries because women tend to consume more tea than men [21].

Young adults are more likely to consume less total flavonoids than older adults [21–23, 33]. The age range with the highest intake of total flavonoids is between 55 and 70 years, probably because they consume a more traditional dietary pattern and therefore more fruit, vegetables, red wine, and tea (depending on the region). On the other hand younger adults (20–40 years) tend to follow a more Westernized diet, with less plant-based foods. Although total flavonoid intake is usually higher in the older age groups, subjects are likely to keep their dietary habits throughout adulthood. Therefore, no significant differences have been found in the estimation of total flavonoid intake after several years of follow-up [22, 41].

Fruit, tea, red wine, and vegetables are the most important food sources of total flavonoids [21, 26]. These plant-based foods are characteristic of healthy and traditional diets, and therefore, subjects with high adherence to healthy dietary and lifestyle habits are more likely to have a higher intake of total flavonoids. For example, individuals with a normal weight (BMI < 25), a high education level, and a high socioeconomic status and who are physically active and nonsmokers (never and former smokers) tend to have a higher total flavonoid intake [22, 23, 26, 33].

## 6. Flavanols: intake and food sources

Total flavanols or flavan-3-ols is the most consumed flavonoid class by far worldwide (Table 1), contributing to >80% of total flavonoids. Flavanols are divided into three subclasses: flavan-3-ol monomers (including catechins and epicatechins), proanthocyanidins (including oligomers and polymers of flavanols), and flavanol-derived compounds (including thearubigins and theaflavins). In nature, flavanols are predominantly found as aglycones.

The intake of total flavanols ranges from 11mg/day in Brazil [37] to 629mg/day in Australia [29] (Table 2). These large differences among populations are due to different intakes of the main food sources (i.e., tea and fruit). Depending on the intake of tea (a beverage rich in flavan-3-ol monomers and derived compounds) and fruit (foods rich in proanthocyanidins) a rank of countries/ regions can be proposed: (i) countries with a very high consumption of tea (such as Australia,

UK, and Poland), which have a mean intake between 450 and 600mg/day [28, 29, 33, 43, 44]; (ii) countries with a moderate consumption of tea or a very high consumption of fruit (such as MED countries, Germany, and the US), which have a mean intake of 250–400mg/day [17, 35, 43, 45]; (iii) countries with a low consumption of tea and low-moderate consumption of fruit (such as Scandinavian countries, South Korea, and Latin-American countries), with a mean intake ranging from 50 to 150mg/day [23, 25, 31, 37]. In Latin-American countries, an underestimation of the total flavanol intake is probable, since there is little food composition data available on tropical foods, especially on fruit [13–16].

#### 6.1. Flavan-3-ol monomers

Intake of flavan-3-ol monomers varies between 10mg/day in Mexico [23, 58, 59] and 270mg/day in Poland [32], contributing to approximately 15–30% of total flavanols. The main food sources of flavan-3-ol monomers are tea, fruit (e.g., apples, stone fruits), red wine, and cocoa products [1]. The intake of these foods and beverages will determine the levels of flavan-3-ol monomers in the diet. Countries with a high intake of tea have a major intake of these compounds, such as Australia, UK, and Poland (150–250mg/day), followed by countries with a high consumption of fruit and red wine, such MED countries and France (50–100mg/day), and finally countries with a low consumption of tea and certain types of fruit, such as Latin American and Finland (<l50;mg/day) (Table 2).

#### 6.2. Proanthocyanidins

Proanthocyanidins account for >75% of total flavanols in countries with a low intake of tea (MED countries) and <40% of total flavanols in countries with a high intake of tea (non-MED countries) [40, 43]. Proanthocyanidins are characteristic flavonoids in fruit, particularly apples, stone fruits, and berries, as well as red wine, but not in tea [1]. The highest intake of proanthocyanidins is in MED countries, including France (>200mg/day) [17, 43, 53], followed by non-MED countries and the US (150–200mg/day) [32, 35, 36, 43, 45], and finally Latin-American and Asian countries (<150mg/day) [23–25] (Table 2).

#### 6.3. Flavanol-derived compounds

Theaflavins and thearubigins occur exclusively in tea [1]. Theaflavins are consumed in low amounts (<3mg/day) in countries with low tea consumption and larger amounts (10–30mg/ day) in countries with an important tea culture (Table 2) [43]. The same pattern can be applied to thearubigins, which can only be found in black tea. The intake ranges from 1mg/day in Spain to 530mg/day in the UK, where it contributes to almost 50% of total flavonoids [40].

## 7. Flavanones: intake and food sources

Flavanones are normally the second main flavonoid class (8–10%) [21]. The variation in flavanone intakes is relatively small between most of the countries (30–40mg/day) (Table 2). The highest intake is in Greece and Spain (∼60mg/day as aglycones) [27, 55], and the lowest intake


UK, and Poland), which have a mean intake between 450 and 600mg/day [28, 29, 33, 43, 44]; (ii) countries with a moderate consumption of tea or a very high consumption of fruit (such as MED countries, Germany, and the US), which have a mean intake of 250–400mg/day [17, 35, 43, 45]; (iii) countries with a low consumption of tea and low-moderate consumption of fruit (such as Scandinavian countries, South Korea, and Latin-American countries), with a mean intake ranging from 50 to 150mg/day [23, 25, 31, 37]. In Latin-American countries, an underestimation of the total flavanol intake is probable, since there is little food composition data available on tropical

Intake of flavan-3-ol monomers varies between 10mg/day in Mexico [23, 58, 59] and 270mg/day in Poland [32], contributing to approximately 15–30% of total flavanols. The main food sources of flavan-3-ol monomers are tea, fruit (e.g., apples, stone fruits), red wine, and cocoa products [1]. The intake of these foods and beverages will determine the levels of flavan-3-ol monomers in the diet. Countries with a high intake of tea have a major intake of these compounds, such as Australia, UK, and Poland (150–250mg/day), followed by countries with a high consumption of fruit and red wine, such MED countries and France (50–100mg/day), and finally countries with a low consumption of tea and certain types of fruit, such as Latin American and Finland

Proanthocyanidins account for >75% of total flavanols in countries with a low intake of tea (MED countries) and <40% of total flavanols in countries with a high intake of tea (non-MED countries) [40, 43]. Proanthocyanidins are characteristic flavonoids in fruit, particularly apples, stone fruits, and berries, as well as red wine, but not in tea [1]. The highest intake of proanthocyanidins is in MED countries, including France (>200mg/day) [17, 43, 53], followed by non-MED countries and the US (150–200mg/day) [32, 35, 36, 43, 45], and finally Latin-American

Theaflavins and thearubigins occur exclusively in tea [1]. Theaflavins are consumed in low amounts (<3mg/day) in countries with low tea consumption and larger amounts (10–30mg/ day) in countries with an important tea culture (Table 2) [43]. The same pattern can be applied to thearubigins, which can only be found in black tea. The intake ranges from 1mg/day in Spain to 530mg/day in the UK, where it contributes to almost 50% of total flavonoids [40].

Flavanones are normally the second main flavonoid class (8–10%) [21]. The variation in flavanone intakes is relatively small between most of the countries (30–40mg/day) (Table 2). The highest intake is in Greece and Spain (∼60mg/day as aglycones) [27, 55], and the lowest intake

foods, especially on fruit [13–16].

380 Flavonoids - From Biosynthesis to Human Health

6.1. Flavan-3-ol monomers

(<l50;mg/day) (Table 2).

6.2. Proanthocyanidins

and Asian countries (<150mg/day) [23–25] (Table 2).

7. Flavanones: intake and food sources

6.3. Flavanol-derived compounds

#### An Overview of Global Flavonoid Intake and its Food Sources http://dx.doi.org/10.5772/67655 381



Study name

TOSCA.IT Case-control study in

Greece

SU.VI.MAX study German National Nutrition

Survey II

HAPIEE study Polish National Multicenter

Health Survey Leeds Women's Wellbeing

UK

246 3- 7d FR

 USDA, PE

 Aglycones

 19.1 2.8 58.3 21.4 506

> Study (LWW), the Diet and

Health Study (DH) Case-control study in

Scotland

 1456 SemiQ-FFQ

 Own database Aglycones

 1.0 28.0 20.6

 115.2 33.5

Scotland

FINDIET 2002 Study NIH-AARP Diet and

Health Study NHS I & NHS II & HPFS US

NHANES Women's Health Initiative US Mexican Teachers' Cohort Mexico Mexican case-control study Mexico

Cohort study in the state of

México

50

 FFQ

Morelos

US

8809 24HDR, FFQ USDA

96

106 SemiQ-FFQ

478 FFQ

 PE USDA

USDA

 Aglycones

 7.5 29.3

 Aglycones

 6.6 35.6

6.9 10.0

Glycosides

 27.0 1.0 12.9 60.2 121 17.4 103.9 0.0 0.0 0.0 2.1 <0.01 1.4 <0.01 [23]

 FFQ

USDA

 Aglycones

 Finland

US

491,840 FFQ 156,957 FFQ

USDA

 Aglycones

 Aglycones

 3.0 1.5 12.9 14.4

 230.6 74.1

1.1 2.1

 13.9 1.8 18.4 41.0 307 55.6 251.3

 2007 24-HDR

 Own database Aglycones

USDA

 Aglycones

 12.7 1.2 19.1 37.1

 101.9

 47.0

 5.4 27.0 128 12.0 20.0

0.9 0.6

[31]

[34]

[35]

[20, 36]

[57]

[58]

[59]

Poland Poland

6661 24HDR

 USDA

PE

Glycosides

 22.0 4.3 47.9 7.3 315

 Aglycones

 20.9 0.6 32.0 9.2 462

10,477 FFQ

PE

Glycosides

 29.7 15.5 106.1 103.8

 270.0 176.3

1.6

0.2 0.03 <0.01 7 0.07

2.4

 1.9

 [44] [56]

 11.3

 [32] [33]

 France Germany

 15,371 Diet history

4942 6 24HDR

 PE

 USDA, PE

 Aglycones

Aglycones

 35.0 18.0 34.0 13.0

 87.0 227.0 386 119.8 196.4 69.7

 9.0

5 [17] [45]

Italy Greece

200 SemiQ-FFQ

 USDA

 Aglycones

 12.2 3.0 9.6 58.1

 10.9

2573 FFQ

Country

 N

Dietary

Glycosides

Anthocyanidins

Flavones

Flavonols

Flavanones


olmonomers

Total

PA

Total

Isoflavones

0.07 3.3 2.3 0.2 [30]

0.8

[55]

Theaflavins

Thearubigins

Chalcones

References

Dihydrochalcones

Dihydroflavonols

382 Flavonoids - From Biosynthesis to Human Health

Total Flavanols Flavanolderived compounds

vs.

aglycones

assessment

 FCDB USDA, PE

 Aglycones

 33.1 10.5 39.7 19.0 65

Table2.Intakeofflavonoidclassesandsubclasses(mg/day)indifferentcountries/regions.

is in China (∼5mg/day) [24, 38]. Flavanone intake patterns perfectly match the consumption of their main food sources: citrus fruit and citrus juices [1].
