Eur J Nutr DOI 10.1007/s00394-015-0942-x
ORIGINAL CONTRIBUTION
Estimated intake and major food sources of flavonoids among US adults: changes between 1999–2002 and 2007–2010 in NHANES Kijoon Kim1,2 · Terrence M. Vance1 · Ock K. Chun1
Received: 19 February 2015 / Accepted: 23 May 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Purpose This study was conducted to: (1) demonstrate an updated method for estimating flavonoid intake of US adults by combining USDA flavonoid databases and NHANES food consumption data; (2) document the intake and major food sources of flavonoids among US adults; and (3) determine whether the intake and major sources of dietary flavonoids have changed during the past decade in the USA. Methods A cross-sectional population-based study. Differences over time in the average daily intake and food sources of flavonoids were estimated using food consumption data from NHANES 1999–2002 (n = 8833) and 2007– 2010 (n = 9801). Results The total flavonoid intake of US adults aged 19 years and older remained unchanged between 1999– 2002 (201.9 mg/d) and 2007–2010 (200.1 mg/d), with tea being the top food source of flavonoids. However, intake of anthocyanidins increased during this period, mainly due to greater consumption of berries and wine, which was consistent with the increase in per capita consumption of these foods based on USDA food availability data.
Electronic supplementary material The online version of this article (doi:10.1007/s00394-015-0942-x) contains supplementary material, which is available to authorized users. * Ock K. Chun [email protected] 1
Department of Nutritional Sciences, University of Connecticut, 3624 Horsebarn Road Extension Unit 4017, Storrs, CT 06269‑4017, USA
2
BOM Research Institute, Seoul National University, 599 Gwanak‑ro, Gwanak‑gu, Seoul 151‑742, Korea
Conclusions The results of this study provide updated information on flavonoid intake and food contributors and warrant further studies on the health implications of flavonoid intake. Keywords Diet · Flavonoid · Food sources · USDA flavonoid database · NHANES
Introduction Accumulating evidence suggests that greater intake of dietary flavonoids may reduce the risk of some chronic diseases, particularly cardiovascular disease and certain types of cancer [1–5]. Flavonoids are polyphenolic compounds commonly distributed in plant-based foods. Despite growing evidence for the health effects of dietary flavonoids, estimates of flavonoid intake in studies have relied on incomplete and independently developed databases or data based on published reports of the flavonoid content of foods [6–9], which exhibit considerable variation depending on the dietary database available, types of flavonoids included, and methods used for estimation [10–16]. While these studies have provided estimates of flavonoid intake, comprehensive databases and validated methods are essential to accurately estimate flavonoid intake and allow for comparisons among studies and over time. The United States Department of Agriculture (USDA) has released and updated flavonoid databases for foods that are commonly consumed in the USA and reported to be rich in flavonoids [17–23]. Although these databases are still unlikely to be representative of all foods consumed [24–27], they have facilitated research on estimating flavonoid intake and its association with health outcomes in the USA [16, 28, 29] and foreign countries [25, 30, 31].
13
Our research group has estimated the flavonoid intake of a representative sample of US adults by developing an investigative research tool by which we could expand the number of foods covered by the USDA flavonoid database [16]. This method has been validated by comparing the isoflavone intakes of US adults with their urinary isoflavone metabolites in the NHANES 1999–2002 [32]. As the food consumption patterns of the US population have changed over time and the USDA databases have been expanded, it is timely to determine whether the intake of flavonoids in the US diet has changed over the past decade. In this study, we implemented an updated method to expand the USDA flavonoid database, estimated the total and individual flavonoid intake of US adults and in sociodemographic subgroups, and documented changes in the intake and major food sources of flavonoids by comparing NHANES 1999–2002 and NHANES 2007–2010.
Methods Source of dietary flavonoid databases This study used the USDA Databases for the Flavonoid Content of Selected Foods, version 3.1 [17], containing values for 506 food items of 26 dietary flavonoid compounds classified by flavonoid subclasses: flavonols, flavones, flavanones, flavan-3-ols, and anthocyanidins; and the USDA Database for the Isoflavone Content of Selected Foods, version 2.0, containing values for individual isoflavone compounds for 557 foods [18]. These two databases were combined to a single database of 31 flavonoids: flavonols (isorhamnetin, kaempferol, myricetin, quercetin), flavones (apigenin, luteolin), flavanones (eriodictyol, hesperetin, naringenin), flavan-3-ols [(+)-catechin, (+)-gallocatechin, (−)-epicatechin, (−)-epigallocatechin, (−)-epicatechin 3-gallate, (−)-epigallocatechin 3-gallate, theaflavin, theaflavin 3-gallate, theaflavin 3′-gallate, theaflavin 3,3′-digallate, thearubigins], anthocyanidins (cyanidin, delphinidin, malvidin, pelargonidin, peonidin, petunidin), and isoflavones (daidzein, genistein, glycitein, biochanin A, formononetin). The flavonoid contents in USDA databases are expressed as aglycone. Expansion of the flavonoid database 551 out of 900 food items in the combined flavonoid database were matched to the food items consumed in the NHANES 2007–2010 by the USDA Food and Nutrient Database for Dietary Studies (FNDDS), version 5.0 [33]. Consequently, the number of food items covered by the
13
Eur J Nutr
database is a small fraction of the total number of foods actually consumed by the US population. To overcome this limitation, the database was expanded as described in the previous publication [16]. Briefly, flavonoid values were assigned the same food code as food items that were similar in preparation or processing, but were not included in the original flavonoid or isoflavone databases (e.g., baked, boiled, chopped, cooked, drained, frozen, toasted, steamed, stewed, french-fried, strained, heated, prepared, homeprepared, oven heated, poached, bottled, canned, sliced, minced, salted, kernels, pickled, pitted, fat-free, fortified with calcium, sulfured, sweetened, vitamin and mineral fortified, flavor-added, low sodium, low calorie, nonfat, low fat and vacuum pack). Because certain methods of food processing may greatly affect flavonoid content, flavonoid values were not assigned to similar food items for foods with versus without skin or peel, different color, mature or immature, spear, cultivar and seasoned [34–36], or if processing of foods included the addition of ascorbic acid, syrup, water, or lemon; enrichment; physical processing that influences density (diluted, dried, powdered, concentrated, flour, dehydrated) [37, 38]; and chemical processing that changes physical and chemical properties (with alkali, brown, granules, flakes, puffs, blanched) [39]. Since flavonoid values are only available for brewed coffee in USDA flavonoid database, flavonoid values of brewed coffee were used for brewed espresso, instant coffee, and coffee/ cocoa mix. This might result in an underestimation of flavonoid intake from instant coffee since instant coffee has higher flavonoid content compared to brewed coffee [40]. However, the proportion of instant coffee consumption is much lower compared to brewed coffee consumption in NHANES 2007–2010 (brewed coffee consumers 42.4 %, instant coffee consumers 10.7 %, and both brewed coffee and instant coffee consumers 5.5 %). FNDDS was used to assign flavonoid values to the ingredients of complex food items in NHANES. The flavonoid contents of these food ingredients were summed to derive an estimate of the flavonoid contents of complex foods that were not originally available in the flavonoid database, thereby expanding the number of foods covered by the flavonoid database. The flavonoid content of foods was further adjusted for retention factor, moisture, and fat content [33]. Using this method, the final version of the flavonoid database included 1185 food items by increasing the proportion of major food sources having flavonoid composition data from 36 to 67 %. This method has significantly improved the coverage of the flavonoid database for flavonoid-rich food groups, such as fruits, fruit juices, vegetables, beverages, and legumes [16]. The remaining missing values for flavonoids in databases after expansion were assigned to 0.
Eur J Nutr
Estimation of dietary flavonoid intake Dietary flavonoid intake was estimated by combining the expanded flavonoid database with the food consumption data of the NHANES 1999–2002 (n = 8833) [41, 42] and 2007–2010 (n = 9801), excluding pregnant or breastfeeding women and those with dietary recalls coded as unreliable or incomplete. The daily intake of individual flavonoids was calculated by summing individual flavonoid intakes from all foods reported in 24-h dietary recalls. Total flavonoid intake was determined by summing the daily intake of individual flavonoids. For dietary data from NHANES 2007–2010, mean daily intake was calculated from 2 days of dietary recall data [43, 44]. Using data from dietary recalls, daily flavonoid intake was estimated for US adults aged 19 years and older and by gender, age, ethnicity, poverty status, physical activity, smoking status, alcohol intake, and supplement use. Alcohol consumption was defined as consumption of at least 12 alcoholic drinks per year based on “The National Survey on Drug Use and Health” [45]. Positive smoking status was defined as smoking 100 cigarettes per year with current smokers defined as those who had not quit and former smokers as those who had reported quitting by the time of interview. Poverty income ratio (PIR) was classified into
ORIGINAL CONTRIBUTION
Estimated intake and major food sources of flavonoids among US adults: changes between 1999–2002 and 2007–2010 in NHANES Kijoon Kim1,2 · Terrence M. Vance1 · Ock K. Chun1
Received: 19 February 2015 / Accepted: 23 May 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Purpose This study was conducted to: (1) demonstrate an updated method for estimating flavonoid intake of US adults by combining USDA flavonoid databases and NHANES food consumption data; (2) document the intake and major food sources of flavonoids among US adults; and (3) determine whether the intake and major sources of dietary flavonoids have changed during the past decade in the USA. Methods A cross-sectional population-based study. Differences over time in the average daily intake and food sources of flavonoids were estimated using food consumption data from NHANES 1999–2002 (n = 8833) and 2007– 2010 (n = 9801). Results The total flavonoid intake of US adults aged 19 years and older remained unchanged between 1999– 2002 (201.9 mg/d) and 2007–2010 (200.1 mg/d), with tea being the top food source of flavonoids. However, intake of anthocyanidins increased during this period, mainly due to greater consumption of berries and wine, which was consistent with the increase in per capita consumption of these foods based on USDA food availability data.
Electronic supplementary material The online version of this article (doi:10.1007/s00394-015-0942-x) contains supplementary material, which is available to authorized users. * Ock K. Chun [email protected] 1
Department of Nutritional Sciences, University of Connecticut, 3624 Horsebarn Road Extension Unit 4017, Storrs, CT 06269‑4017, USA
2
BOM Research Institute, Seoul National University, 599 Gwanak‑ro, Gwanak‑gu, Seoul 151‑742, Korea
Conclusions The results of this study provide updated information on flavonoid intake and food contributors and warrant further studies on the health implications of flavonoid intake. Keywords Diet · Flavonoid · Food sources · USDA flavonoid database · NHANES
Introduction Accumulating evidence suggests that greater intake of dietary flavonoids may reduce the risk of some chronic diseases, particularly cardiovascular disease and certain types of cancer [1–5]. Flavonoids are polyphenolic compounds commonly distributed in plant-based foods. Despite growing evidence for the health effects of dietary flavonoids, estimates of flavonoid intake in studies have relied on incomplete and independently developed databases or data based on published reports of the flavonoid content of foods [6–9], which exhibit considerable variation depending on the dietary database available, types of flavonoids included, and methods used for estimation [10–16]. While these studies have provided estimates of flavonoid intake, comprehensive databases and validated methods are essential to accurately estimate flavonoid intake and allow for comparisons among studies and over time. The United States Department of Agriculture (USDA) has released and updated flavonoid databases for foods that are commonly consumed in the USA and reported to be rich in flavonoids [17–23]. Although these databases are still unlikely to be representative of all foods consumed [24–27], they have facilitated research on estimating flavonoid intake and its association with health outcomes in the USA [16, 28, 29] and foreign countries [25, 30, 31].
13
Our research group has estimated the flavonoid intake of a representative sample of US adults by developing an investigative research tool by which we could expand the number of foods covered by the USDA flavonoid database [16]. This method has been validated by comparing the isoflavone intakes of US adults with their urinary isoflavone metabolites in the NHANES 1999–2002 [32]. As the food consumption patterns of the US population have changed over time and the USDA databases have been expanded, it is timely to determine whether the intake of flavonoids in the US diet has changed over the past decade. In this study, we implemented an updated method to expand the USDA flavonoid database, estimated the total and individual flavonoid intake of US adults and in sociodemographic subgroups, and documented changes in the intake and major food sources of flavonoids by comparing NHANES 1999–2002 and NHANES 2007–2010.
Methods Source of dietary flavonoid databases This study used the USDA Databases for the Flavonoid Content of Selected Foods, version 3.1 [17], containing values for 506 food items of 26 dietary flavonoid compounds classified by flavonoid subclasses: flavonols, flavones, flavanones, flavan-3-ols, and anthocyanidins; and the USDA Database for the Isoflavone Content of Selected Foods, version 2.0, containing values for individual isoflavone compounds for 557 foods [18]. These two databases were combined to a single database of 31 flavonoids: flavonols (isorhamnetin, kaempferol, myricetin, quercetin), flavones (apigenin, luteolin), flavanones (eriodictyol, hesperetin, naringenin), flavan-3-ols [(+)-catechin, (+)-gallocatechin, (−)-epicatechin, (−)-epigallocatechin, (−)-epicatechin 3-gallate, (−)-epigallocatechin 3-gallate, theaflavin, theaflavin 3-gallate, theaflavin 3′-gallate, theaflavin 3,3′-digallate, thearubigins], anthocyanidins (cyanidin, delphinidin, malvidin, pelargonidin, peonidin, petunidin), and isoflavones (daidzein, genistein, glycitein, biochanin A, formononetin). The flavonoid contents in USDA databases are expressed as aglycone. Expansion of the flavonoid database 551 out of 900 food items in the combined flavonoid database were matched to the food items consumed in the NHANES 2007–2010 by the USDA Food and Nutrient Database for Dietary Studies (FNDDS), version 5.0 [33]. Consequently, the number of food items covered by the
13
Eur J Nutr
database is a small fraction of the total number of foods actually consumed by the US population. To overcome this limitation, the database was expanded as described in the previous publication [16]. Briefly, flavonoid values were assigned the same food code as food items that were similar in preparation or processing, but were not included in the original flavonoid or isoflavone databases (e.g., baked, boiled, chopped, cooked, drained, frozen, toasted, steamed, stewed, french-fried, strained, heated, prepared, homeprepared, oven heated, poached, bottled, canned, sliced, minced, salted, kernels, pickled, pitted, fat-free, fortified with calcium, sulfured, sweetened, vitamin and mineral fortified, flavor-added, low sodium, low calorie, nonfat, low fat and vacuum pack). Because certain methods of food processing may greatly affect flavonoid content, flavonoid values were not assigned to similar food items for foods with versus without skin or peel, different color, mature or immature, spear, cultivar and seasoned [34–36], or if processing of foods included the addition of ascorbic acid, syrup, water, or lemon; enrichment; physical processing that influences density (diluted, dried, powdered, concentrated, flour, dehydrated) [37, 38]; and chemical processing that changes physical and chemical properties (with alkali, brown, granules, flakes, puffs, blanched) [39]. Since flavonoid values are only available for brewed coffee in USDA flavonoid database, flavonoid values of brewed coffee were used for brewed espresso, instant coffee, and coffee/ cocoa mix. This might result in an underestimation of flavonoid intake from instant coffee since instant coffee has higher flavonoid content compared to brewed coffee [40]. However, the proportion of instant coffee consumption is much lower compared to brewed coffee consumption in NHANES 2007–2010 (brewed coffee consumers 42.4 %, instant coffee consumers 10.7 %, and both brewed coffee and instant coffee consumers 5.5 %). FNDDS was used to assign flavonoid values to the ingredients of complex food items in NHANES. The flavonoid contents of these food ingredients were summed to derive an estimate of the flavonoid contents of complex foods that were not originally available in the flavonoid database, thereby expanding the number of foods covered by the flavonoid database. The flavonoid content of foods was further adjusted for retention factor, moisture, and fat content [33]. Using this method, the final version of the flavonoid database included 1185 food items by increasing the proportion of major food sources having flavonoid composition data from 36 to 67 %. This method has significantly improved the coverage of the flavonoid database for flavonoid-rich food groups, such as fruits, fruit juices, vegetables, beverages, and legumes [16]. The remaining missing values for flavonoids in databases after expansion were assigned to 0.
Eur J Nutr
Estimation of dietary flavonoid intake Dietary flavonoid intake was estimated by combining the expanded flavonoid database with the food consumption data of the NHANES 1999–2002 (n = 8833) [41, 42] and 2007–2010 (n = 9801), excluding pregnant or breastfeeding women and those with dietary recalls coded as unreliable or incomplete. The daily intake of individual flavonoids was calculated by summing individual flavonoid intakes from all foods reported in 24-h dietary recalls. Total flavonoid intake was determined by summing the daily intake of individual flavonoids. For dietary data from NHANES 2007–2010, mean daily intake was calculated from 2 days of dietary recall data [43, 44]. Using data from dietary recalls, daily flavonoid intake was estimated for US adults aged 19 years and older and by gender, age, ethnicity, poverty status, physical activity, smoking status, alcohol intake, and supplement use. Alcohol consumption was defined as consumption of at least 12 alcoholic drinks per year based on “The National Survey on Drug Use and Health” [45]. Positive smoking status was defined as smoking 100 cigarettes per year with current smokers defined as those who had not quit and former smokers as those who had reported quitting by the time of interview. Poverty income ratio (PIR) was classified into
