isoflavone content of foods with soy additives
TRANSCRIPT
JOURNAL OFFOOD COMPOSITION
AND ANALYSIS
www.elsevier.com/locate/jfca
Journal of Food Composition and Analysis 18 (2005) 533–550
Original Article
Isoflavone content of foods with soy additives
Sabrina T. Umphress, Suzanne P. Murphy*, Adrian A. Franke, Laurie J. Custer,Carrie L. Blitz
Cancer Research Center of Hawaii, University of Hawaii, 1236 Lauhala Street, Suite 407, Honolulu 96813, USA
Received 13 June 2003; received in revised form 9 April 2004; accepted 16 April 2004
Abstract
The health effects of consumption of isoflavones from soy products are being actively investigated, yetfood composition tables often have incomplete values for commercial foods containing soy additives.Therefore, we analyzed 167 processed and fast foods with soy additives (e.g. isolated soy protein, soyprotein concentrate, soy flour, and hydrolyzed soy protein) for the isoflavones daidzein, glycitein, andgenistein. Total isoflavones were computed by adding these three isoflavones. Additionally, 12 traditionalsoybean products were analyzed, including soy flour and Asian condiments made from soybeans. Foodswere sampled from food stores and fast-food restaurants in Hawaii. Concentrations of total isoflavones,expressed as aglycones, ranged from not detected (ND, for 49 foods) to 149.9mg/100 g. Ranges within foodgroups were: bread and grain products (ND—93.9), gravies and sauces (ND—2.7), meat and poultryproducts (ND—15.9), meat substitutes (0.3–149.9), nutritional products (0.4–36.5), reduced fat peanutbutters (0.1–4.0), seafood products (ND—1.6), and soybean products (2.9–109.3). For 56 foods on our foodcomposition table, we calculated composite isoflavone values reflecting the mean of multiple brands and theproportion of brands containing soy additives. The resulting table now permits more accurate estimates oftotal isoflavone intakes by participants in our research studies.r 2004 Elsevier Inc. All rights reserved.
Keywords: Isoflavones; Daidzein; Glycitein; Genistein; Soy products; Soy additives
1. Introduction
Isoflavones are also known as phytoestrogens because they are found in plant foods (primarilysoy products) and appear to have estrogen-like activity. They are structurally similar to estrogen
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*Corresponding author. Tel.: +1-808-564-5861; fax: +1-808-586-2982.
E-mail address: [email protected] (S.P. Murphy).
0889-1575/$ - see front matter r 2004 Elsevier Inc. All rights reserved.
doi:10.1016/j.jfca.2004.04.008
and bind to estrogen receptors. Many potential health benefits of isoflavones in soy products havebeen investigated, including effects on cancer, vascular disease, osteoporosis, menopausalsymptoms, and cognitive function (Anderson and Garner, 1997; Sirtori, 2001). Because the datain humans are not conclusive for any of these possible benefits, it is important to continue toconduct studies relating isoflavones and soy foods in the diet to health outcomes. An accuratefood composition database is crucial for such studies.
Many laboratories have reported analytic values for isoflavones in soybeans and soybeanproducts and several compilations of these values are available (Reinli and Block, 1996; Pillowet al., 1999; USDA & Iowa State University, 2000; Murphy and Hendrich, 2002). However, thesefoods may not be the major source of isoflavones in the diets of non-Asian cultures. Horn-Rosset al. (2000b) demonstrated that baked products with added soy flour are a major source ofisoflavones in the diets of persons living in California. Although some isoflavone values havebeen published for foods containing soy additives (Dwyer et al., 1994; Murphy et al., 1999;Horn-Ross et al., 2000a; Murphy & Hendrich, 2002), the available information, in some cases,is for composites of foods or lacks detail which identifies the exact food analyzed. Thus, it isdifficult to incorporate these values into other food composition databases. Furthermore, valuesfor glycitein are often lacking, and thus values for total isoflavones in foods may beunderestimated.
The objectives of the current study were to: (1) Analyze the content of daidzein, glycitein, andgenistein in a variety of soy-containing foods available in Hawaii; (2) Investigate variability withinand between brands of the same products; and (3) Create composite values for the threeisoflavones, and for total isoflavones, that are appropriate for the foods on our food compositiontable.
2. Materials and methods
2.1. Collection and preparation of food samples
As reported by Horn-Ross et al. (2000a), soy flour and/or soy protein have been added to somebrands and varieties of breads, buns, English muffins, doughnuts, canned chilie’s, canned tunas,diet shakes and nutritional supplements, nutritional bars, and soy/‘‘veggie’’ burgers. To determinewhich foods in Hawaii contain such soy additives, dietitians canvassed grocery store chains andhealth food stores in the Honolulu area to check food label ingredient lists. Additionally, weobtained fast food ingredient information from company websites. A spreadsheet was developedlisting the names and brands of all foods in each category and the type of soy additive(s) present,if any. From this list, foods were purchased and analyzed if a soy additive appeared on the foodlabel. (See Table 1 for a complete list of the soy additives used in the analyzed foods.)
Where possible, we selected different brands of the same food for analysis. However, there oftenwere not multiple brands of a particular food containing a soy additive. To investigate withinbrand variability, an additional sample of some of the more commonly consumed baked goodswas collected from a different store later in the study.
Additionally, because soy flour and textured vegetable protein are the soy additives of choice inmany of the analyzed foods, two brands of soy flour and one brand of textured vegetable protein
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were also analyzed. We also analyzed fermented soybeans and three Asian sauces because thesefoods are commonly consumed in Hawaii.
Most foods, such as bread or canned chili, were ready to consume. Foods which requiredcooking (e.g. frozen beef patties) were prepared according to package directions. Foods inconcentrated form, such as dry gravy mixes, powdered soup bases, or condensed soups were notdiluted for analysis. Appropriate dilution factors were applied later to the results of the analyses.Foods were weighed and placed in two sealable plastic bags in 50-g aliquots each, and wherenecessary, cut into bite size pieces.
2.2. Extraction and analysis of isoflavones in foods
Food samples were frozen, lyophilized, and then kept in a desiccator. Prior to extraction, arepresentative sample of the dry food was ground to a fine powder with a mortar and pestle or in ablender. Depending on the expected level of isoflavones, either 0.2 or 1.0 g of the food wasextracted and analyzed as follows: after addition of 30mL 80% aqueous methanol the mixturewas vortexed for 30min followed by centrifugation for 5min at 1000 g. After removal of the clearsupernatant, the same extraction procedure was repeated for the residue. Additional repetitions ofthe residue extraction did not lead to significant isoflavone increases, and were therefore omitted.The organic portion of the combined supernatants was evaporated under reduced pressure at atemperature below 40�C.
The residual solution was incubated at 39�C overnight after addition of 0.5mL beta-glucosidase (1mg/mL in 0.2M sodium acetate buffer pH 5) and 100mL arylsulfatase in order tohydrolyze the conjugated isoflavones to their aglycones. We decided in this study to applyenzymatic instead of acid hydrolysis because the former method gave a shorter turn-around timeand achieved similar results. Four-methyl umbelliferone sulfate (0.25mg/mL in 0.2M sodiumacetate buffer pH 5), formononetin (1mg/mL dissolved in methanol), and flavone (1200 ppmdissolved in methanol) were added as internal standards to test hydrolysis efficiency and analyteloss. The analytes were extracted 2 times with 3mL diethylether. Shortly before high pressureliquid chromatography (HPLC) analysis was performed, the ether phases were dried by a streamof dry nitrogen and redissolved in 500mL acetonitrile and 500 mL sodium acetate buffer (0.2M,pH5).
HPLC photo-diode array-electrospray mass spectrometry (HPLC/PDA/ESI-MS) was carriedout as reported previously, except for the use of a model ‘‘LCQ Advantage’’ mass spectrometerequipped with an orthogonal electrospray ionization unit (Thermo Finnigan Corp., San Jose, CA)(Franke et al., 2002). In brief, 10mL were injected onto a Hydrobond PS C18 pre-column(25� 3.2mm i.d.; 5 mm) coupled to a Hydrobond PS C18 analytical column (100� 3.0mm i.d.;5mM) and eluted with 0.2mL/min of methanol in water (% vol/vol) as follows: 25–95% linearlyin 30min, at 95% for 4.5min, 95–25% linearly in 0.5min, and at 25% for 5min prior tosubsequent injection. PDA detection was performed during the entire run at 220–400 nm.Quantitation by PDA was performed for foods above 0.04mg/100 g (total isoflavone levels) byexternal calibration using peak areas obtained by monitoring at 260 nm after adjusting for aninternal standard (flavone). Highly linear PDA calibration curves were obtained from all threeisoflavone standards in the range 1–200mM with r2>0.988 when monitored at 260 nm. The limitof quantitation at a signal-to-noise ratio of 3 for daidzein, glycitein, genistein, and total
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STable 1
Daidzein, glycitein, genistein, and total isoflavone content (mg/100 g) of analyzed foodsa,b
Food USDAc
Code
Water
(%)
Daidzein
(mg/100 g)
Glycitein
(mg/100 g)
Genistein
(mg/100 g)
Total IFL
(mg/100 g)
Soy Additived
Bread and grain products
Bread crumbs; Contadina Bread Crumbs, Italian Style 18376 0 0.0 0.0 0.0 0.0 SF
Bread crumbs; Progresso Bread Crumbs, Plain 18079 0 0.4 0.0 0.3 0.7 SF
Bread, cinnamon roll; McDonald’s Cinnamon Rolls 18356 16 4.4 0.7 0.9 6.0 SF
Bread, cinnamon roll; Svenhard’s 4 Cinnamon Rolls 18356 14 0.6 0.1 0.6 1.4 SF
Bread, cinnamon roll; Svenhard’s Viking Size Cinnamon
Bun
18356 19 0.8 0.1 0.7 1.6 SF
Bread, French; Star Markets French Breade 18029 32 0.0 0.0 0.0 0.0 SF
Bread, mixed-grain; Country Hearth 12 Grain Bread 18035 30 0.4 0.0 0.3 0.7 SF
Bread, mixed-grain; Country Hearth 12 Grain Bread 18035 30 0.4 0.0 0.3 0.8 SF
Bread, mixed-grain; Milton’s 99% Fat Free Healthy Multi-
Grain Bread
18035 32 0.0 0.0 0.0 0.0 SF
Bread, sweet; King’s Hawaiian Hawaiian Sweet Bread none 27 0.5 0.0 0.5 1.0 DSF
Bread, sweet; King’s Hawaiian Hawaiian Sweet Rolls none 27 0.5 0.1 0.5 1.1 DSF
Bread, taro; Taro Brand Taro Rolls none 33 0.5 0.1 0.4 1.0 SF
Bread, taro; Taro Brand Taro Rolls none 30 0.4 0.0 0.3 0.8 SF
Bread, wheat; Love’s Golden Wheat Breade 18064 31 0.0 0.0 0.0 0.0 SF
Bread, wheat; Times King Wheat Bread 18064 33 0.0 0.0 0.0 0.0 SF
Bread, white; Holsum Sandwich White Enriched Bread 18069 35 0.0 0.0 0.0 0.0 SF
Bread, white; Love’s Kid’s Choice White Bread 18069 40 0.0 0.0 0.0 0.0 SFib
Bread, white; Love’s Sandwich White Bread 18069 33 0.6 0.1 0.4 1.1 SF
Bread, white; Love’s Sandwich White Bread 18069 34 1.0 0.1 0.8 1.9 SF
Bread, white; Star Markets White Butter Top Bread 18069 38 0.0 0.0 0.0 0.0 SF
Bread, white; Times King White Bread 18069 34 0.0 0.0 0.0 0.0 SF
Cake, snack; Hostess Cup Cakes none 19 0.0 0.0 0.0 0.0 SPI
Cake, snack; Hostess Ding Dongs 18606 7 0.0 0.0 0.0 0.0 SPI
Cake, snack; Hostess HoHos none 14 0.5 0.0 0.5 1.0 SPI
Cake, snack; Hostess Twinkies none 19 0.0 0.0 0.0 0.0 SPI
Cake, snack; Tastykake Bakery Fresh Iced Cupcakes none 13 0.0 0.0 0.1 0.1 SPI
Cereal; Harmony Vanilla Almond Oat 08398 2 1.4 0.2 1.9 3.6 SPI
Cereal; Kashi Go Lean 08393 1 8.4 1.4 7.7 17.4 SP, SG
Cereal; Kashi Good Friends 08390 0 0.0 0.0 0.0 0.0 SPC
Cereal; Kellogg’s Smart Start Soy Protein Cereal 08385 0 41.9 10.2 41.9 93.9 S, SPC, TSP
Doughnuts, cake; Country Hearth Sugared Donuts 18250 19 1.8 0.3 1.7 3.8 SF
Doughnuts, cake; Country Hearth Sugared Donuts 18250 19 2.0 0.2 1.7 3.9 SF
Doughnuts, cake; Hostess Chocolate Frosted Donettes 18249 10 2.1 0.2 1.8 4.1 SF
Doughnuts, cake; Hostess Chocolate Frosted Donettes 18249 9 1.7 0.2 1.5 3.3 SF
Doughnuts, cake; Hostess Powdered Donettes 18250 0 2.6 0.3 2.3 5.1 SF
Doughnuts, cake; Hostess Powdered Donettes 18250 10 1.8 0.2 1.6 3.7 SF
Doughnuts, cake; Love’s 12 Finer Donuts 18250 14 4.1 0.5 3.6 8.2 SF
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SDoughnuts, cake; Love’s Old Fashioned Donut, Powdered
Sugar
18250 21 4.7 0.5 4.4 9.6 SF
Doughnuts, cake; Safeway Bakery Old Fashion Cake
Donut, Glazed
18250 13 0.5 0.1 0.5 1.1 SF
Doughnuts, yeast; Safeway Bakery, Glazed 18255 18 0.3 0.0 0.2 0.6 SF
English muffins; Golden Cr"eme English Muffins 18258 45 0.0 0.0 0.0 0.1 SF
English muffins; Thomas’ English Muffins 18639 46 0.5 0.0 0.4 0.9 SF
Rolls; Love’s Dinner Rolls 18342 29 0.0 0.0 0.0 0.0 SF
Stuffing mix; Safeway Turkey Flavor Stuffing Mix 18081 3 0.1 0.0 0.2 0.3 HSP, SF
Stuffing mix; Stove Top Stuffing Mix for Turkey 18567 2 0.3 0.0 0.2 0.5 HSP, SF
Gravies and sauces
Gravy, canned; Boston Market Roasted Turkey Gravy 06125 90 0.3 0.1 0.3 0.7 SF
Gravy, canned; Franco-American Chicken Gravy 06119 86 0.0 0.0 0.0 0.0 HSP
Gravy, canned; Franco-American Mushroom Gravy 06121 91 0.0 0.0 0.0 0.0 HSP
Gravy, canned; Heinz Home Style Roasted Turkey Gravy 06125 90 0.0 0.0 0.0 0.0 SPI
Gravy, mix; Knorr Gravy Classics, Classic Brown
Gravy Mix
06118 0 0.0 0.0 0.0 0.0 HSP
Gravy, mix; Knorr Gravy Classics, Mushroom Brown
Gravy Mix
06122 0 0.0 0.0 0.0 0.0 HSP
Gravy, mix; Lawry’s Brown Gravy Mix 06118 0 0.0 0.0 0.0 0.0 HSP
Gravy, mix; McCormick Brown Gravy Mix 06118 0 0.0 0.0 0.0 0.0 HSP
Gravy, mix; McCormick Mushroom Gravy Mixe 06122 0 0.0 0.0 0.0 0.0 HSP
Sauce mix; Betty Crocker Hamburger Helper Salisbury 22700 0 0.1 0.0 0.1 0.2 HSP
Sauce mix; Betty Crocker Hamburger Helper Three Cheese 22700 0 0.1 0.0 0.1 0.2 SF
Sauce mix; Betty Crocker Scalloped 100% Real Potatoese 11386 0 0.2 0.0 0.2 0.5 HSP
Sauce mix; Betty Crocker Tuna helper creamy pastae none 0 0.0 0.0 0.0 0.0 HSP
Sauce mix; Rice A Roni Beef Flavor none 0 0.0 0.0 0.0 0.0 HSP
Sauce mix; Rice A Roni Chicken Flavor none 0 1.4 0.2 1.1 2.7 SF
Sauce mix; Safeway Scalloped Potatoes 11386 0 0.1 0.0 0.3 0.4 HSP, SF
Sauce; Lea & Perrins Worcestershire Sauce none 72 0.1 0.0 0.0 0.2 HSP
Meat and poultry products
Beef patties, frozen; May’s Teriyaki Beef Patties 23501 42 3.4 0.5 3.1 6.9 TSF, S
Chicken patties, frozen; Banquet Grilled Breast Patties
Glazed Chicken
none 70 0.2 0.0 0.3 0.5 SPC, HSP
Chicken patties, frozen; Fast Fixin Chicken Breast Patties none 52 0.3 0.0 0.3 0.6 SPC
Chicken strips, frozen; Armour Homestyle Chicken Breast
Strips
none 47 0.3 0.0 0.3 0.7 TSPC, SPC
Chicken strips, frozen; Armour Homestyle Chicken Breast
Strips
none 34 0.1 0.0 0.2 0.4 TSPC, SPC
Chili, canned; Dennison’s Chunky Chili con Carne with
Beans
22904 70 0.0 0.0 0.1 0.1 SPC
Chili, canned; Dennison’s No Bean Chili con Carne none 74 0.1 0.0 0.4 0.5 SPC
Chili, canned; Dennison’s Original Chili con Carne with
Beans
22904 63 0.8 0.1 0.7 1.7 SF, SPC
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Chili, canned; Hormel Chili No Beans 22705 76 1.7 0.3 1.7 3.6 TVP, HSP
Chili, canned; Hormel Chili Turkey No Beans none 85 1.2 0.2 1.2 2.5 TVP, HSP
Chili, canned; Hormel Chili Vegetarian With Beans 99%
Fat Freee22720 78 1.9 0.2 1.2 3.3 TVP, HSP
Chili, canned; Nalley Original chili Con Carne With Beanse 22513 68 3.4 0.4 2.4 6.1 TVP, HSP
Chili, canned; Nalley Real Hearty Chili con Carne with
Beans
22513 71 0.8 0.1 0.9 1.8 TVP
Fast food; Jack in the Box Monster Taco, Beef Filling none 55 2.6 0.2 13.1 15.9 TVP, SG, HSP
Fast food; Pizza Hut Beef Topping none 47 0.2 0.0 0.3 0.5 TSPC, SPC, HSP
Fast food; Pizza Hut Pork Topping none 43 0.1 0.0 0.1 0.2 TSPC, SPC, HSP
Fast food; Subway Chicken Teriyaki Strips none 64 0.0 0.0 0.0 0.0 SPC, SS, S
Fast food; Subway Meatballs none 57 3.0 0.3 2.7 6.0 SPC
Frankfurter; Armour, Quarter Pound Beef Franks 07022 49 1.0 0.1 0.8 1.9 SF
Frankfurter; Ball Park, Fat Free, Beef Franks none 67 0.6 0.1 1.0 1.7 SPI, SPC
Frankfurter; Ball Park, Fat Free, Franks Made with Beef &
Pork, Turkey
none 69 0.0 0.0 0.0 0.1 SPC
Frankfurter; Ball Park, Lite Franks Made with Pork &
Chicken
none 57 0.0 0.0 0.1 0.1 SPC
Frankfurter; Redondo’s Hawaiian Winners 07023 52 0.1 0.0 0.1 0.3 SPC
Ravioli, canned; Chef Boyardee Beef Ravioli in Tomato &
Meat Sauce
22515 80 0.5 0.1 0.4 1.0 TVP
Ravioli, canned; Franco-American Beef Ravioli in
Meat Sauce
none 71 0.0 0.0 0.0 0.0 TSPC
Ravioli, canned; Safeway Beef Ravioli in Tomato &
Meat Sauce
none 80 0.6 0.1 0.6 1.2 TVP
Ravioli, canned; Springfield Beef Ravioli in Tomato &
Meat Sauce
none 74 0.6 0.1 0.5 1.1 TVP, SP
Sausage, canned; Hormel Vienna Sausage 07083 61 0.0 0.0 0.0 0.0 HSP
Sausage; Jimmy Dean Heat ‘N Serve Sausage Links 07065 39 0.3 0.0 0.5 0.8 SPI
Sausage; Swift Premium Brown ‘N Serve Original Fully
Cooked Sausage
07065 48 0.2 0.0 0.3 0.6 SPC
Spaghetti, canned; Chef Boyardee Spaghetti & Meatballs in
Tomato Sauce
22518 78 0.0 0.0 0.0 0.0 SPC, HSP
Spaghetti, canned; Franco-American Spaghettios Meatballs
A to Z’s
none 76 0.2 0.0 0.3 0.6 SPI
Meat substitutes
Bacon bits; Betty Crocker Baco’s 16104 2 93.9 10.0 45.9 149.9 DSF, SS, HSP
Bacon bits; McCormick Bac’n Piecese 16104 4 49.6 7.5 45.7 102.8 TSF, HSP
Boca Burgers All American Classic none 62 0.5 0.1 0.5 1.1 SPC, SS
Boca Burgers Original Vegane none 64 0.7 0.1 0.6 1.4 SPC, HSP, SS
Table 1 (continued)
Food USDAc
Code
Water
(%)
Daidzein
(mg/100 g)
Glycitein
(mg/100 g)
Genistein
(mg/100 g)
Total IFL
(mg/100 g)
Soy AdditivedS
.T.
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dC
om
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an
dA
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18
(2
00
5)
53
3–
55
0538
ARTIC
LEIN
PRES
SCasbah Original Perfect Burger Mix none 0 11.2 1.2 12.4 24.8 TSF
Fantastic Nature’s Burger Mix none 0 2.6 0.6 2.0 5.2 TSF, SS
Gardenburger Originale none 60 0.2 0.0 0.1 0.3 SPC
Morningstar Farms Breakfast Patties 22122 46 2.0 0.3 2.3 4.6 TVP, HS
Morningstar Farms Breakfast Strips 16104 39 1.6 0.2 2.7 4.5 TSPC, SPI, S
Morningstar Farms Chik Patties none 55 1.8 0.4 2.2 4.4 TVP, HSP
Morningstar Farms Garden Veggie Patties 22118 57 0.8 0.2 1.1 2.2 TVP, SS, S, SPI
Morningstar Farms Grillers Original Veggie Burgers none 48 1.7 0.3 1.7 3.7 TVP, S
Morningstar Farms Harvest Burgers none 63 1.3 0.2 1.9 3.4 SPC, SPI, HSP
Morningstar Farms Low Fat Veggie Dog 22119 49 0.4 0.0 0.6 1.0 HSP, SPI, SFib
Nutritional bars
Balance Oasis Chocolate Peanut Crisp Flavor none 4 4.6 0.7 6.9 12.2 SPI
Balance Yogurt Honey Peanut Flavor none 5 11.8 1.2 13.6 26.6 SPI, S
Cliff Bar Crunchy Peanut Butter Flavor none 5 13.3 0.6 13.0 26.9 SPI, SF, S
Cliff Luna Nuts Over Chocolate Flavor none 3 8.1 1.2 8.4 17.7 SPI, SF, SPI
Ensure Chocolate Maple Nut none 6 2.8 0.6 5.1 8.5 SPI
Ensure Cookies ‘n Cream none 5 2.3 0.5 4.4 7.3 SPI
Slim Fast Meal-On-The-Go Milk Chocolate Peanut
Flavored
none 5 3.5 0.4 4.6 8.4 SPI
Slim Fast Meal-On-The-Go Oatmeal Raisin Flavored none 9 2.3 0.2 4.0 6.4 SPI
Tiger’s Milk Protein Rich none 4 4.9 0.7 5.9 11.5 SPI
Nutritional beverages
Ensure Plus Strawberry Flavor none 69 0.3 0.0 0.5 0.8 SPI
Ensure Plus Vanilla Flavor none 68 0.1 0.0 0.2 0.4 SPI
Ensure Strawberry Flavor none 77 0.2 0.0 0.4 0.7 SPI
Ensure Vanilla Flavor none 78 0.3 0.0 0.4 0.8 SPI
Glucerna Strawberry Flavor none 79 0.3 0.1 0.4 0.7 SPI, SFib
Glucerna Vanilla Flavor none 79 0.5 0.1 0.8 1.4 SPI, SFib
Ultra Slim Fast Chocolate Royale Flavored powder none 0 2.8 0.4 4.8 8.1 SPI, SFib
Ultra Slim Fast French Vanilla Flavored powder none 0 3.2 0.5 5.3 9.0 SPI, SFib
Ultra Slim Fast with Soy Protein Chocolate Delite Flavor
powder
none 0 12.9 2.5 21.1 36.5 SPI, SFib
Peanut butters, Reduced fat
Skippy Reduced Fat Creamy Peanut Butter Spread none 0 0.0 0.0 0.0 0.1 SP
Best Yet Reduced Fat Creamy Peanut Butter Spread none 0 1.5 0.1 0.7 2.3 SP
Jif Reduced Fat Creamy peanut butter spread none 0 2.2 0.1 1.6 4.0 SP
Safeway Reduced Fat Creamy Peanut Butter Spread none 0 1.5 0.1 0.4 2.0 SP
Seafood products
Crab, imitation; Kanimi Imitation Crabmeat 15138 73 0.0 0.0 0.0 0.0 HSP
Crab, imitation; Okuhara Surimi Seafood Imitation
Crabmeat Sticks
15138 72 0.1 0.0 0.1 0.2 SPI
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Tuna, canned; Bumble Bee Chunk Light Tuna in
Vegetable Oil
15119 72 0.0 0.0 0.0 0.0 HSP
Tuna, canned; Bumble Bee Chunk Light Tuna in Water 15121 79 0.1 0.0 0.0 0.1 VB
Tuna, canned; Bumble Bee Solid White Albacore in
Vegetable oil
15124 70 0.6 0.1 0.9 1.6 HSP
Tuna, canned; Bumble Bee Solid White Albacore in Water 15126 69 0.2 0.0 0.3 0.5 HSP
Tuna, canned; Chicken of the Sea Chunk Light Tuna in
Canola Oil
15119 70 0.0 0.0 0.0 0.0 HSP
Tuna, canned; Chicken of the Sea Chunk Light Tuna in
Spring Water
15121 78 0.0 0.0 0.0 0.0 HSP
Tuna, canned; Chicken of the Sea Albacore in Canola Oil 15124 68 0.1 0.0 0.0 0.1 HSP
Tuna, canned; Chicken of the Sea Albacore in Spring Water 15126 71 0.0 0.0 0.1 0.1 HSP
Tuna, canned; Coral Hawaiian Chunk Light Tuna in Oil 15119 76 0.0 0.0 0.0 0.0 HSP
Tuna, canned; Coral Hawaiian Chunk Light Tuna in Oil 15119 75 0.0 0.0 0.0 0.0 VB
Tuna, canned; Coral Hawaiian Chunk Light Tuna in Water 15121 75 0.0 0.0 0.0 0.0 VB
Tuna, canned; Coral Hawaiian Chunk Light Tuna in Water 15121 76 0.0 0.0 0.0 0.0 HSP
Tuna, canned; StarKist Chunk Light Tuna in Spring Water 15121 75 0.0 0.0 0.0 0.0 VB
Snacks
Chips, potato; Maui Kettle Style Potato Chips Sweet
Maui Onion
none 0 0.0 0.0 0.0 0.0 HSP
Chips, potato; Ruffles Flavor Rush Big BBQ & Cheddar none 0 0.0 0.0 0.0 0.0 SF, HSP, SS
Chips, potato; Thin & Crispy Sweet Maui Onion Flavor none 0 0.0 0.0 0.0 0.0 HSP
Chips; Sun Chips none 0 0.1 0.0 0.0 0.1 HSP
Snack mix; Chex Mix Traditional 19033 0 0.0 0.0 0.0 0.0 HSP
Snack mix; Gardetto’s Snakens Original Recipe Snack Mix none 0 0.0 0.0 0.0 0.0 SF
Soups, Soup bases
Soup base; Sapporo Ichiban, Japanese Style Noodles &
Beef Flavored-Soup
06581 0 0.2 0.0 0.1 0.3 HSP, SS
Soup base; Sapporo Ichiban, Japanese Style Noodles &
Chicken Flavored-Soup
06581 0 0.0 0.0 0.0 0.0 HSP
Soup base; Top Ramen, Beef Flavore 06581 0 0.4 0.0 0.1 0.5 HSP, SS
Soup base; Top Ramen, Chicken Flavor 06581 0 0.0 0.0 0.3 0.4 HSP, SS
Soup, bouillon, dry; Herb Ox Beef Flavor Bouillon 06075 0 0.0 0.0 0.0 0.1 HSP
Soup, bouillon, dry; Best Yet Beef Flavor Granulated
Bouillon
06075 0 0.0 0.0 0.0 0.1 HSP
Soup; Campbell’s Condensed Cream of Mushroom Soup 06043 82 0.0 0.0 0.0 0.0 SPC
Soup; Campbell’s Condensed Soup Vegetable Beefe 06071 85 0.0 0.0 0.0 0.0 HSP
Soup; Campbell’s Condensed Soup 98% Fat Free Cream of
Chicken
none 77 0.0 0.0 0.1 0.1 SPC, SPI
Table 1 (continued)
Food USDAc
Code
Water
(%)
Daidzein
(mg/100 g)
Glycitein
(mg/100 g)
Genistein
(mg/100 g)
Total IFL
(mg/100 g)
Soy AdditivedS
.T.
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/J
ou
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18
(2
00
5)
53
3–
55
0540
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SSoup; Campbell’s Condensed Soup Homestyle Chicken
Noodle
06059 77 0.0 0.0 0.0 0.0 SPI
Soup; Progresso Turkey Noodle Soup 06465 78 0.0 0.0 0.0 0.0 SPI
Soup; Safeway Chicken Broth 06413 97 0.0 0.0 0.0 0.0 HSP
Soup; Safeway Chicken Broth, Fat Free, Reduced Sodium none 98 0.0 0.0 0.0 0.0 HSP
Soup; Safeway New England Clam Chowder 06205 76 0.0 0.0 0.0 0.0 SPI
Soup; Swanson Chicken Broth, 99% Fat Free none 98 0.0 0.0 0.0 0.0 HSP
Ramen; Nissin Cup Noodles Beef Flavor 06582 0 1.4 0.2 1.1 2.7 TSP, SS, HS
Soybean products
Frozen dessert; Glace Soymilk Frozen Dessert Whole Soy
Swiss Chocolate
none 0 7.0 0.9 6.2 14.0 SM
Frozen dessert; Tofutti Nondairy Original Premium Frozen
Dessert
none 0 1.1 0.1 1.7 2.9 SP, T
Sauce, hoisin; Lee Kum Kee Hoisin Sauce 06175 29 2.2 0.2 1.7 4.1 FS, FB
Sauce, hoisin; Wing Hoisin Sauce 06175 25 10.0 0.9 4.8 15.7 S
Sauce, kochujang; Koha Ko-Chu-Jang (Hot Bean Paste) none 23 6.6 1.1 6.0 13.7 S
Soy beans, fermented; Family Salted Black Beans none 27 32.9 9.2 21.6 63.6 FS
Soy flour; Arrowhead Mills Whole Grain Soy Flour 16115 0 47.6 7.3 51.4 106.2 SF
Soy flour; Arrowhead Mills Whole Grain Soy Flour 16115 0 45.6 13.6 50.1 109.3 SF
Soy flour; Bob’s Red Mill Stone Ground Whole Grain
Soy Flour
16115 0 45.8 9.8 46.3 102.0 SF
Soy flour; Bob’s Red Mill Stone Ground Whole Grain
Soy Flour
16115 0 44.2 10.7 50.6 105.5 SF
Textured vegetable protein; Bob’s Red Mill Textured
Vegetable Protein
none 0 48.2 10.6 46.9 105.8 SF
Textured vegetable protein; Hawaiian Healthy Gourmet
Soy Ground Beef
none 2 34.5 3.9 33.5 71.9 SF
aLimit of detection: 0.014 for daidzein, 0.014 for glycitein, 0.015 for genistein, and 0.043 for total isoflavones (mg/100 g). Values less than 0.05 are
considered insignificant and are rounded to 0.0 in the table. Therefore, some zero values are above the detection limit.bValues are for foods as purchased except for frozen beef patties and frozen chicken strips, which were cooked prior to analysis.cUSDA code may not be exact match.dSoy Additive Key.
SF = Soy Flour; DSF = Defatted Soy Flour; SFib = Soy Fiber; SPI = Soy Protein Isolate; SP = Soy Protein; SG = Soy Grits; SPC = Soy
Protein Concentrate; S = Soy; TSP = Texturized Soy Protein; HSP = Hydrolyzed Soy Protein; TSF = Textured Soy Flour; TSPC = Textured Soy
Protein Concentrate; TVP = Textured Vegetable Protein; SS = Soy Sauce; HS = Hydrolyzed Soy; VB = Vegetable Broth (includes Soy); SM =
Soy Milk; T = Tofu; FS = Fermented Soy; FB = Fermented Bean Curd.eValues for these foods are the mean of duplicate analyses; except for these foods, values in the table represent a single analysis.
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isoflavones was 0.014mg/100 g, 0.014mg/100 g, 0.015mg/100 g, and 0.043mg/100 g, respectively.Final levels were adjusted for water content and are given for each food as purchased. Totalisoflavones were computed by adding the three individual isoflavones.
Quantitation by mass spectrometry was performed for foods with a total isoflavoneconcentration below 0.04mg/100 g. However, for the purpose of quantifying intakes, levelsbelow 0.05mg/100 g were considered insignificant and are not reported here. These data may beobtained from the authors.
All samples showed complete hydrolysis to umbelliferone from its sulfate, indicating sufficientremoval of methanol thereby suggesting that the activity of the enzymes required for hydrolysis ofanalytes was not impaired (Franke et al., 1998; Horn-Ross et al., 2000a). The addition ofarylsulfatase improved recovery of analytes confirming the glucosidase activity of this enzymepreparation as was shown previously for glucuronidase and glucuronidase/sulfatase mixtures(Goodman et al., 1998; Andlauer et al., 2000). Higher enzyme specificity can be achieved by usingmore highly purified enzyme preparations (Fanti et al., 2003).
Replicate analyses (n=12) of a soy protein powder used as an external standard to test inter-assay variability showed excellent precision with inter-assay coefficients of variation of 3.9%,3.9%, 3.0%, and 4.5% for daidzein (mean 34.48mg/100 g), glycitein (mean 6.18mg/100 g),genistein (mean 56.37mg/100 g) and total isoflavones (mean 97.03mg/100 g), respectively.Replicate analyses of 12 different (wet) foods with mean levels for daidzein, glycitein, genistein,and total isoflavones of 5.47mg/100 g (range 0.01–49.6mg/100 g), 0.80mg/100 g (range 0.01–7.5mg/100 g), 5.11mg/100 g (range 0.01–45.7mg/100 g), and 11.38mg/100 g (range 0.04–102.8mg/100 g) showed mean inter-assay coefficients of variations of 9%, 10%, 12%, and 6%,respectively.
3. Results
Table 1 shows the aglycone concentrations (mg/100 g) of daidzein, glycitein, genistein, and totalisoflavones in the foods analyzed. Values are for foods as purchased, except for frozen beef pattiesand frozen chicken strips, which were cooked according to manufacturer directions prior toanalysis. The soy additive, as listed on the food label, is also shown. Of the 179 foods analyzed, 47contained no detectable level of daidzein, 65 contained no detectable level of glycitein, and 49contained no detectable level of genistein or total isoflavones. Breadcrumbs, white and wheatbreads, snack cakes, highly flavored potato chips, snack mixes, imitation crabmeat, cannedsausage, gravies, sauce mixes for pasta and rice mixes, canned soups, dry soup bases, canned pastaproducts, hot dogs, and canned tunas contained very low or undetectable levels of isoflavones.The concentration of total isoflavones in the sampled foods ranged from not detected (ND) to149.9mg/100 g. Highest concentrations of total isoflavones were found in imitation bacon bits:102.8–149.9mg/100 g. Isoflavone-fortified cereals had total isoflavone concentrations rangingfrom ND to 93.9mg/100 g. Nutritional beverage products contained total isoflavone concentra-tions of 0.4–36.5mg/100 g, while nutritional bars contained 6.4–26.9mg/100 g. Meat substitutes,such as meatless burgers or burger mixes, yielded 0.3–24.8mg/100 g of total isoflavones. Fast foodmeats exhibited total isoflavone concentrations from ND to 15.9mg/100 g. Baked goods, such asdoughnuts and cinnamon rolls, contained modest total isoflavone levels, of 0.6–9.6mg/100 g.
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Frozen teriyaki beef patties, canned chili products, and reduced fat peanut butters contained lowlevels of total isoflavones, of 0.1–6.9mg/100 g.
From the 179 analyzed foods, daidzein, glycitein, genistein, and total isoflavone values werecalculated for 56 food composites for inclusion in our food composition tables. The results areshown in Table 2. The food name as used in our food composition table is listed. The daidzein,glycitein, genistein, and total isoflavone values presented are averaged values of the analyzedindividual foods comprising the composite. The ratio represents the number of brands containinga soy additive to the total number of brands we found of a particular food, and is to be applied tothe respective values listed. Additionally, the proportion, which is the percentage the analyzedfood contributes to the ready-to-consume food item on our database, is also to be applied to therespective values listed. Neither of these factors has been applied to the data in Table 2, as otherusers may wish to derive different values for the ratios and proportions.
4. Discussion
Many studies have reported isoflavone concentrations of soy-based foods, but few havepresented values for foods in which a soy product is merely an ingredient. As can be seen in Table1, manufacturers incorporate several different soy additives into a wide variety of foods. Thewidespread use of these soy additives in foods makes this a previously unsuspected source ofisoflavones. Horn-Ross et al. (2000a) reported daidzein and genistein values for various foodswith added soy flour or soy protein, but many of the values are for food composites. Lack ofdetails on the foods in each composite makes it difficult to use these values in other foodcomposition tables. In contrast, our analyses provide concentrations of daidzein, glycitein,genistein, and total isoflavones for specific brands of foods. We also provide calculated compositevalues to illustrate the steps that might be used to incorporate these data into a food compositiontable, although other database developers may choose to use different procedures.
In general, the soy products used as additives in the foods we investigated are very concentratedsources of daidzein, glycitein, and genistein. Thus, these ingredients have the potential to increaseisoflavone levels in nontraditional soy-containing foods, depending on the amount used in thefood. Table 1 shows that no correlation exists between the type of soy additive and the level ofisoflavones found in a food, with the exception of hydrolyzed soy protein. When hydrolyzed soyprotein, a flavor enhancer, is the sole soy additive, isoflavones are usually undetectable or presentonly in trace amounts. Although the position of the soy additive on the product’s ingredient labelmight be an indicator of the level of isoflavones in the food item, we did not find that thisinformation could be used reliably to determine actual amounts present in the food. However, ageneral trend toward higher isoflavone concentrations can be seen when the soy additive is amongthe first three ingredients.
One of the difficulties in selecting foods for analysis is deciding how to perform the sampling.For foods with added soy products, we first considered foods previously identified as having soyadditives. After reviewing hundreds of food labels in several grocery store chains and health foodstores in Honolulu, we also identified and analyzed additional soy-containing foods, such as fastfood meats, frozen chicken breast products, sausages, canned ravioli and spaghetti, reduced fatpeanut butters, breakfast cereals, cinnamon rolls, Hawaiian sweet bread, Oriental ramen soup
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Table 2
Averaged isoflavone levels in analyzed foods (mg/100 g)
Food description on database Daidzein
(mg/100 g)
Glycitein
(mg/100 g)
Genistein
(mg/100 g)
Total IFL
(mg/100 g)
Ratioa Proportionb
Bacon bits, imitation 71.8 8.8 45.8 126.3 1
Bread crumbs, dry 0.2 0.0 0.1 0.3 3/5
Bread, French 0.0 0.0 0.0 0.0 1/4
Bread, mixed grain 0.2 0.0 0.2 0.4 4/5
Bread, Hawaiian sweet 0.5 0.0 0.5 1.0 1/6
Bread, taro 0.4 0.0 0.4 0.9 1/3
Bread, wheat 0.0 0.0 0.0 0.0 2/4
Bread, white, enriched 0.2 0.0 0.1 0.3 4/6
Chicken breast, frozen, patties or strips 0.2 0.0 0.3 0.6 1
Chili, con carne, no beans, canned 0.9 0.2 1.0 2.1 2/3
Chili, con carne, with beans, canned 1.2 0.2 1.0 2.4 2/4
Chili, vegetarian, canned 1.9 0.2 1.2 3.3 1/3
Chips, potato, specialty-flavored 0.0 0.0 0.0 0.0 1
Crab, imitation, made from surimi 0.0 0.0 0.1 0.1 2/4
Doughnuts, cake-type, sugared or glazed 2.2 0.3 2.0 4.4 1
Doughnuts, yeast-type, sugared or glazed 0.3 0.0 0.2 0.6 3/4
English muffins, plain 0.3 0.0 0.2 0.5 2/6
Flour, soybean 45.8 10.4 49.6 105.8 1
Gravy, brown 0.0 0.0 0.0 0.1 7/8
Hamburger Helper with pasta 0.1 0.0 0.1 0.2 1 5%
Jack in the Box Monster Taco 0.6 0.0 3.0 3.6 1 23%
Meatless Burger Mix, Casbah Original Perfect Burger 11.2 1.2 12.4 24.8 1 44%
Meatless Burger Mix, Fantastic Nature’s Burger 2.6 0.6 2.0 5.2 1 44%
Meatless Burger, ‘‘garden’’ type burgers 0.5 0.1 0.6 1.2 1
Meatless Burger, Boca Burger products 0.6 0.1 0.6 1.3 1
Meatless Burger, Morningstar Farms products 1.5 0.2 1.8 3.6 1
Nutritional bar 6.0 0.7 7.3 13.9 1
Nutritional beverage, Ensure 0.3 0.1 0.5 0.9 1
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SNutritional beverage, Ensure Plus 0.2 0.0 0.3 0.6 1
Nutritional beverage, Ultra Slim Fast, powder 6.3 1.1 10.4 17.9 1
Peanut butter, reduced fat 1.3 0.1 0.7 2.1 1
Potatoes, scalloped, prepared from dry mix 0.2 0.0 0.2 0.4 1 4%
Ravioli, beef in tomato and meat sauce, canned 0.4 0.0 0.4 0.8 1
Rice-A-Roni 0.7 0.1 0.5 1.4 1 2%
Rolls and buns, dinner 0.0 0.0 0.0 0.0 1/4
Rolls, cinnamon, with frosting 2.6 0.4 0.7 3.7 1/2
Sauce, hoisin, ready to serve 6.1 0.6 3.3 9.9 1
Sausage, frankfurter, beef 1.0 0.1 0.8 1.9 2/3
Sausage, frankfurter, beef and pork 0.1 0.0 0.1 0.3 2/3
Sausage, frankfurter, beef and pork, low fat 0.2 0.0 0.4 0.6 3/4
Sausage, smoked link 0.2 0.0 0.4 0.7 2/3
Snack cake, cupcake, chocolate with cream filling 0.0 0.0 0.0 0.1 1
Snack mix 0.0 0.0 0.0 0.0 1
Soup, bouillon 0.0 0.0 0.0 0.1 1 3%
Soup, chicken broth 0.0 0.0 0.0 0.0 1
Soup, Cup Noodles 1.4 0.2 1.1 2.7 1 29%
Soup, oriental broth with noodles (e.g. ramen, saimin) 0.2 0.0 0.1 0.3 1 1%
Spaghetti and meatballs, canned 0.1 0.0 0.2 0.3 1
Stuffing, bread, prepared from dry mix 0.2 0.0 0.2 0.4 1 27%
Textured vegetable protein 41.4 7.3 40.2 88.8 1
Tofu frozen dessert 4.0 0.5 3.9 8.5 1
Tuna helper creamy pasta 0.0 0.0 0.0 0.0 1 6%
Tuna, light meat, canned in oil, drained 0.0 0.0 0.0 0.0 1
Tuna, light meat, canned in water, drained 0.0 0.0 0.0 0.0 1
Tuna, white, canned in oil, drained 0.3 0.1 0.4 0.8 1
Tuna, white, canned in water, drained 0.1 0.0 0.2 0.3 1
aRatio represents the number of brands containing a soy additive to the total number of brands of a food and is to be applied to the averaged
analytic values listed on the same row.bProportion is the percentage of the analyzed food, which is an ingredient in the food on the food composition database, and is to be multiplied by
the averaged analytic values listed on the same row in order to obtain concentrations of isoflavones in the food as found on the database. When not
listed, the proportion is 100%.
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bases, and sauce mixes for skillet dinners and sides, as well as locally-produced hot dogs, frozenteriyaki beef patties, imitation crab, and taro bread. We also selected the following traditionalsoy-based foods for analysis because they are commonly consumed in Hawaii and/or are soyadditives which can be used as ingredients in a food composition database: soy flour, texturedvegetable protein, imitation bacon, hoisin sauce, Korean hot bean paste (kochujang), fermentedsoy beans (tau si), and soy-based frozen desserts.
From our investigation of food labels, we also found that the soy additives used in a particularproduct vary from brand to brand. Therefore, where possible, we selected different brands of thesame food for analysis, in order to investigate brand-to-brand variability. Indeed, our analysesclearly show that isoflavone concentrations of a particular food vary greatly from brand to brand.
Additionally, we wanted to investigate within brand variability, especially for baked goods. Atdifferent times and from different stores, we purchased two samples of 12 commercial products.For four of the samples (Country Hearth 12 Grain Bread, Country Hearth Sugared Donuts,Arrowhead Mills Whole Grain Soy Flour and Bob’s Red Mill Stone Ground Whole Grain SoyFlour), the total isoflavone coefficient of variation (CV) between samples was low (2–6%). Foranother five of the samples (Hostess Frosted Donettes, Love’s Donuts, Svenhard’s CinnamonRolls, King’s Hawaiian Sweet Bread, and Taro Brand Taro Rolls), the total isoflavone CV rangedfrom 11–15%. The CV was 24–39% for the remaining three samples (Hostess Powdered Donettes,Love’s Sandwich White Bread, and Armour Homestyle Chicken Breast Strips). For these last twofoods, mean total isoflavone concentrations were very low (1.5mg/100 g and 0.5mg/100 g,respectively), so a small variation in levels yielded a relatively large CV. It is unclear whataccounts for the variability seen within these brands, but it is likely that manufacturersperiodically adjust product formulations. If we had collected multiple samples of the same foodover a longer time period, it is possible that the variability would increase for many of the sampledproducts.
Another difficulty in adding values to a food composition table is determining the procedure forresolving variability. What is the best way to combine replicate analyses (within samplevariability), different brands (between brand variability), and duplicate samples (within brandvariability)? Coefficients of variation were low for replicate analyses of the same sample (9–12%for the individual isoflavones and 6% for total isoflavones). Thus, we used the mean of thesereplicate analyses. Variability was considerably higher between brands of the same food product.Thus, for isoflavone values, brand specificity and product identity are clearly important, but mostfood composition tables do not carry the same degree of brand specificity as these analyses. Wherepossible, we preserved brand identity by matching an analyzed food to its identical food in ourfood composition database. When this was not possible because we do not carry the analyzedbrand on our database, we averaged the isoflavone values of different brands of the same food,thereby creating a composite. In addition, we applied a ratio to the composite values to accountfor brands that do not contain soy additives (and therefore are not expected to contain significantisoflavone levels), and applied a proportion for foods that were analyzed in undiluted form orwere part of a mixture. For example, two different brands of breadcrumbs were analyzed, so thefirst step was to average their two sets of isoflavone values. Of the five brands of breadcrumbs wefound on store shelves in Hawaii, only 3 contained a soy additive; hence we will multiply theaveraged values by 3/5 to obtain the final values for our food composition table. FantasticNature’s Burger, a meatless dry burger mix, illustrates the use of a proportion. The values
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presented in Table 2 are the concentrations of the dried mix, as purchased. When reconstitutingthe mix with water, according to the package instructions, the dry mix constitutes 44% of theprepared burger before cooking. Thus, we will multiply the isoflavone values of the dry mix by0.44 to give appropriate values for the ready-to-cook burger. Note that moisture changes duringcooking were not included in the proportion because our food composition table automaticallyapplies them during recipe calculations.
When comparing published values for isoflavones, it is important to know if the data are for theconjugated or the aglycone forms. We chose to hydrolyze the isoflavonoids to their aglyconeforms in order to simplify the HPLC analysis and to increase the likelihood of detecting theanalytes. While conjugated forms may be below the detection limit for some foods, hydrolysis tothe aglycones can yield levels that are above the detection limit (Franke et al., 1994).
Daidzein and genistein values of the foods with soy additives that were analyzed for this studyare compared to those found in other publications in Table 3. For most foods, differences weresmall. Larger differences may be due to differences in product sampling, as well as the variation inisoflavone concentrations across and within brands. When comparing isoflavone values fornutritional bars, ours are higher than those presented by Horn-Ross et al. (2000a) and Pillow et al.(1999), reflecting a recent trend by manufacturers to increase the soy protein fortification of theseproducts, in response to the research on the health benefits of phytoestrogens. Most likely, theproducts sampled in previous studies contained less soy additives than those sampled in our study.Murphy and Hendrich (2002) reported 2.2mg/100 g of total isoflavones in canned tuna withhydrolyzed soy protein, which supports the data in Table 3 showing that isoflavone levels are lowin this product. Their values for doughnuts (8.5–10mg/100 g) are higher than the values in Table3, but similar to those shown in Table 1 for the doughnut samples from Love’s Bakery.
We also compared isoflavone concentrations of soy flour analyzed in this study to mean valuesfrom three other studies (Pillow et al., 1999; USDA and Iowa State University, 2000; Liggins et al.,2002). Our values were lower (44.2–47.6mg/100 g for daidzein and 46.3–51.4mg/100 g forgenistein), but they are within the range of the USDA-Iowa isoflavone database values (USDAand Iowa State University, 2000): 1.7–123.3 and 2.8–144.0mg/100 g (textured soy flour), 22.6–93.9and 46.5–100.5mg/100 g (defatted soy flour), and 18.2–130.9 and 6.4–145.2mg/100 g (full-fat soyflour) for daidzein and genistein, respectively. Variable isoflavone concentrations exist in soybeanand soybean products, because they are affected by environmental, genetic, harvesting, andprocessing conditions (Tsukamoto et al., 1995; Wang and Murphy, 1996). For example, Murphyand Hendrich (2002) reported a large range for total isoflavones in hydrolyzed soy proteinsamples, from 12.7 to 162.1mg/100 g. However, we found little variation in total isoflavonesacross two different brands of soy flour, or across samples of the same brand purchased at twodifferent stores (CV of 2.0% and 2.4%). It is possible that the lower values for the soy flourspurchased in Hawaii indicate a reduced isoflavone content due to consistent differences in one ormore of these conditions.
5. Conclusions
Foods with added soy products often contain significant levels of isoflavones. When consumedregularly, they can provide an important source of isoflavones in the diet. Because many effects of
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Table 3
Comparison of daidzein and genistein concentration of foods with soy additives (mg/100 g)
This publication Horn-Ross et al.a Liggins et al.b Pillow et al.c USDAd
Food Daidzein Genistein Daidzein Genistein Daidzein Genistein Daidzein Genistein Daidzein Genistein
Bread, English muffins 0.26 0.21 0.18 0.23
Bread, white 0.16 0.13 0.61 0.83 0.14 0.16
Bread, whole grain 0.20 0.16 0.16 0.14 0.37 0.46
Canned chilli 1.24 1.06 0.54 0.71 1.37 1.87
Canned tuna 0.09 0.11 0.41 0.73
Doughnuts 1.86 1.67 1.97 3.21
Imitation bacon 71.78 45.78 53.03 70.43
Nutritional bars 5.97 7.32 1.80 3.27 0.05 0.08
Nutritional beverages 0.56 0.91 0.09 0.15 2.58 6.39
Soy/veggie burgers 1.40 1.56 3.05 2.02 4.90 13.90
Textured vegetable
protein
41.39 40.18 47.85 66.00 59.62 78.90
Yogurt, frozen
non-dairy (Tofutti)
1.07 1.71 0.30 1.80
aHorn-Ross et al. (2000a).bLiggins et al. (2002).cPillow et al. (1999).dUSDA and Iowa State University (2000).
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isoflavones on health have been proposed, researchers are actively examining associationsbetween dietary intakes of soy products and various health outcomes. However, at least in USpopulations, accurate estimates of total isoflavone intake depend on food composition tableswhich reflect isoflavones in all foods, not just in foods which have been traditionally consideredsources of these compounds. Because the use and level of soy additives can vary widely amongsimilar food products, even greater accuracy could be achieved by carrying brand-specific entrieson the food composition table, and by collecting correspondingly specific food intake data. Fornutrition monitoring at the national level, our estimates of isoflavones in food products sold inHawaii should be extended to other geographic locations.
Acknowledgements
Support for this work was provided by a Cancer Center Support Grant, NIH # 2P30 CA 71789.We thank Donna Lyn MT Au and Naomi Stephens for assistance in sample collection, andDouglas M. Crowley for assistance in sample preparation and extraction.
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