American
Soybean
Association
Wednesday, 23 June 1999ASA Confirms The Natural Variability Of Isoflavones In Soybeans
The American Soybean Association (ASA) is providing this information to
journalists and broadcasters as background material in advance of a study to be published
in the Journal of Medicinal Foods. A recently posted abstract of a study (Lappe,
et. al.) to be published in the Journal of Medicinal Foods (Vol. 1, No. 4) claims
that Roundup Ready® soybeans may have reduced levels of isoflavones. The
authors further claim the implications are meaningful since isoflavones are potentially
beneficial nutritional components in soybeans.
As a soybean organization responsible for the collection and
dissemination of accurate information about soybeans and their uses, ASA believes it is
important to inform you that the isoflavone content of soybeans between and within
varieties does vary, so that people don’t over interpret the results of this study. ASA believes the Lappe study confirms what soybean experts already know
well—that isoflavone components in soybeans are highly variable and well
characterized in scientific literature. This natural variability is similar to the
variability of micro-nutrients in any crop, and is greatly influenced by environmental
factors. ASA has confidence in the regulatory reviews of Roundup Ready soybeans conducted
by U.S. and global regulatory agencies and the underlying scientific studies that found
equivalence in isoflavone content between Roundup Ready soybeans and conventional
soybeans. EQUIVALENCY A study published in 1996 in the respected Journal of Nutrition
(Padgette, et. al.) found that the isoflavone content of conventional soybeans versus
Roundup Ready soybeans is comparable. Roundup Ready soybeans are widely characterized as the most studied
soybean ever grown by farmers, and were reviewed for equivalency by the U. S. Food &
Drug Administration and other global agencies around the world. Over 400 individual
components were analyzed in all – including isoflavone values – and the values
all were well within a predictable range of variability for soybeans. VARIABILITY According to Dr. Stephen Barnes, professor of pharmacology and
toxicology at the University of Alabama-Birmingham, "The data analyzed by authors
Lappe, et al. are well within the range of variability of isoflavones exhibited in any
soybean variety." Such variability of isoflavone content is common in soybeans due to
individual varietal influences and environmental factors such as weather, soil, etc. Dr.
Clare Hasler, Executive Director of the Functional Foods Health Program at the University
of Illinois Urbana-Champaign, and a member of the Journal of Medicinal Foods’
editorial review board, also expressed concern about the Lappe paper. "Concluding that the results of the Lappe paper are biologically
relevant would be inappropriate and misleading since the scientific literature clearly
suggests that isoflavone amounts in soybeans can vary as much as 300 percent or
more," Dr. Hasler stated. Global experts in soy production and nutrition technology such as Dr.
Stephen Barnes and Dr. Clare Hasler also have confirmed that variability of isoflavones in
soybeans, whether conventional or Roundup Ready, are well established and within the
typical range one would expect to see. ENVIRONMENTAL Recent research being prepared for publication by the University of
Illinois shows that numerous environmental factors, such as weather during the growing
season, and even the slope of the field where the soybeans are grown, can lead to
variability in the isoflavone content of soybeans. "Variability is due to the varietal component and the
environmental component," said Dr. Don Bullock, Associate Professor of Biometry, at
the University of Illinois at Urbana-Champaign. "Right now, the environmental effect
is far greater than the varietal effect." BENEFITS According to Dr. Hasler, the hundreds of studies conducted on soy and
soyfoods have pointed to significant health benefits. "This is a truly exciting time to be in the field of functional
foods," said Dr. Hasler. "We’ve known for a long time that soy is a good
source of nutrition, and now we’re seeing promising results in the use of soy to
prevent or treat a variety of diseases." Seed technologies, such as Roundup Ready, have been embraced by farmers
because these products offer the potential to reduce input costs, and provide increased
production flexibility in conservation tillage practices. Work also is under way to
produce soybeans with output traits that will directly benefit consumers. ASA is a national, not-for-profit, grassroots membership organization
with 31,440 members, affiliate offices in 26 states, and overseas marketing offices in 13
countries. The Association develops and implements policies to increase the profitability
of its members and the entire soybean industry. For more information contact these soybean experts: Stephen Censky, Chief Executive Officer Dr. Clare Hasler, Executive Director, Functional Foods for Health
Program Dr. Stephen Barnes, Professor of Pharmacology and Toxicology Dr. Don Bullock, Associate Professor of Biometry Dr. Patricia Murphy, Food Science and Human Nutrition Department Dr. Pamela White, Food Science and Human Nutrition Department Access this release at http://www.oilseeds.org/
KEY SCIENTIFIC LITERATURE Research data demonstrates that Roundup Ready soybeans and conventional soybeans are
substantially equivalent in composition, safety and nutritional value. RESOURCES Composition studies show that isoflavone (also called phytoestrogen) levels are
equivalent in Roundup Ready and conventional soybeans. Both Roundup Ready and conventional
soybeans show a very wide range of phytoestrogen levels (5-6 fold) when grown under
different environmental conditions. Padgette, S.R. et al. (1996). The composition of glyphosate-tolerant soybean seeds is
equivalent to that of conventional soybeans. Journal of Nutrition 126:702-716 Data from 1992 and 1993 unsprayed Roundup Ready soybean and parental line (A5403) -
9 locations, isoflavone analysis of whole grain and toasted meal showed wide variability
(5-6 fold) but no significant difference between Roundup Ready soy and the parental line. The levels of isoflavones in Roundup Ready soybeans and conventional soybeans are
the same, even when Roundup is applied. Taylor N.B., R.L. Fuchs, J. McDonald, A.R. Shariff and S.R. Padgette. (1999).
Compositional analysis of glyphosate-tolerant soybeans treated with glyphosate. Submitted
Journal of Agricultural and Food Chemistry
Data from the 1993 sprayed glyphosate-tolerant (Roundup Ready) soybean and
unsprayed parental control (A5403) - 4 locations, isoflavone (6 components) analysis of
whole grain. Study confirms that the application of glyphosate on Roundup Ready
soybeans does not effect the levels of isoflavones or other nutritional factors. Site to site variability in isoflavone levels was high with data varying 4-7
fold, with no significant differences between Roundup Ready soybean
and the parental line. 2. Isoflavone levels vary widely between soybean varieties and in soybeans grown
under different environmental conditions. RESOURCES A single soybean variety contained isoflavone (phytoestrogen) levels that varied 3
fold from year to year. A 2-5 fold variation was observed between 11 US and Japanese
varieties. Wang, H. and P.A. Murphy. (1994). Isoflavone composition of American and
Japanese soybeans in Iowa: Effects of variety, crop year, and location. J. Agric.
Food Chem. 42:1674-1677. Isoflavone (12 components) levels measured in whole seed. Using a single variety
over three years, total isoflavones were significantly different (varied 3-fold) from year
to year. Analysis on 8 conventional US varieties and 3 Japanese varieties found wide
variation (2-5 fold) in isoflavone levels that were significantly different between
varieties. Brazilian conventional soybean varieties showed wide variability between varieties
and differed significantly between years. The variability observed was 3-8 fold. Carrao-Panizzi, M. and Kitamura, K. (1995). Isoflavone content in Brazilian soybean
cultivars. Breeding Science 45:295-300. 22 conventional Brazilian soybean cultivars were analyzed for isoflavone content
(2 components) over 2 years. Isoflavone content was significantly different among
cultivars and between years and varied widely (3-8 fold). Total isoflavone levels varied 2-3 fold between 4 soybean varieties. This
variability was attributed to climatic and environmental factors. Eldridge, A. C. and Kwolek, W. F. (1983). Soybean isoflavones: Effect of environment
and variety on composition. Journal of Agriculture Food Chem. 31:394-396. Total isoflavone (6 components) in whole beans was analyzed across 4 varieties
and across two years. Values varied widely from variety to variety (2-3 fold) and there
were also significant differences (3-5 fold) when the same variety is grown in different
locations. "Significant variation among years suggests that unknown climatic and
environmental factors contribute to variation in isoflavones". Additional supporting literature. Fukutake, M., Takahashi, M., Ishida, K., Kawamura, H., Sugimura, T. and Wakabayashi, K.
(1996). Quantification of genistein and genistin in soybeans and soybean products. Food
and Chemical Toxicology 34:457-461. Choi, J-S., C., Kwon,T-W. and Kim, J-S. (1996). Isoflavone contents in some varieties
of soybean. Foods and Biotechnology 5:167-169. Naim, M., Gestetner, B., Zilkah, S., Birk, Y. and Bondi, A. (1976). Soybean
isoflavones, characterization, determination, and antifungal activity. Agric. Food
Chem. 22:806-810.
3. Isoflavone variability is also observed in processed soy food products. A database is available that reports the isoflavone levels in food and food
products. Isoflavones vary significantly in foods and food products. USDA-Iowa State University Database on the Isoflavone Content of Foods - 1999 Web address: http://www.nal.usda.gov/fnic/foodcomp/Data/isoflav/isoflav.html
A comprehensive database and analysis of isoflavone levels in the major food sources
(legumes species and processed products) of phytoestrogens in human diet. Includes data
reported from references with means, ranges, and statistics. Isoflavone variation of US
commodity soybean showed ranges of 3.5 fold for genistein, 3.8 fold for diadzein and 3.3
fold for total isoflavone. Murphy, P.A., Barua, K. and Song, T. Soy isoflavones in foods: Database development.
In: American Chemical Society Symposium Series: Functional Foods: Overview and Diseases
Prevention, ed. T.Shibamoto. In press. Describes justification for, data compilation, variability, utility, interpretation
and quality control of the database. Isoflavone levels vary by food product, sometimes as high as in whole bean and
sometimes below limit of detection due to losses during processing. Fukutake, M., Takahashi, M., Ishida, K., Kawamura, H., Sugimura, T. and Wakabayashi, K.
(1996). Quantification of genistein and genistin in soybeans and soybean products. Food
and Chemical Toxicology 34:457-461. Describes levels of the phytoestrogens genistein and genistin in soybean, soy nuts,
soy powder, soy mil, and tofu. Levels of genistein and genistin ranged from 4.6-18.2 and
200.6-968.1 ug/g food weight in soybean, soy nuts, soy powder and from 1.9-13.9,
94.8-137.7 ug/g food weight in soy milk and tofu. Studies show that significant isoflavone losses occur during processing of soybeans. Wang, C., Ma, Q., Pagadala, S., Sherrad, MS. and Krishnan, PG. (1998). Changes of
isoflavones during processing of soy protein isolates. Am. Oil Chemists Society
75:337-341. Mass balance changes during processing. Describes losses of isoflavone during
different steps of processing of soybeans into soy protein isolates. Study revealed that
only 26% of total isoflavone remained in final processing step. Wang, H-J. and Murphy, P. A. (1996). Mass balance study of isoflavones during soybean
processing. Agric. Food Chem. 44:2377-2383. Mass balance changes during processing. Describes losses of isoflavone during
different steps of processing of soybeans tempe, soy milk, tofu and protein isolate. Wang, H-J. and Murphy, P. A. (1994). Isoflavone content in
commercial soybean foods. Agric. Food Chem. 42:1666-1673. Concentration of isoflavone was analyzed in 29 commercial soy foods. High protein
soy ingredients had isoflavone levels similar to that to unprocessed beans. EXPERTS Dr. Clare Hasler* Executive Director Functional Foods for Health Program University of Illinois at Urbana-Chaqmpaign 103 Agricultural Bioprocess Lab. (M/C 640) 1302 West Pennsylvania Ave. Urbana, IL 61801 217-333-6363 217-333-7386 fax Dr. Clare Hasler is the Executive Director of Functional Foods for Health (FFH), a
joint program of the University of Illinois at Chicago and the University of Illinois at
Urbana-Champaign, dedicated to the improvement of human health through multi-disciplinary
research, education and communication focused on the identification of safe and
efficacious foods and other physiologically active natural products which may reduce
chronic disease risk or promote optimal health. Her research has dealt with the health
benefits obtained from consumption of soy protein products. Dr. Hasler was a recipient of
the 1997 Illinois Soybean Association's Friend of Agriculture Award.
Dr. Patricia Murphy* Professor, Food Science and Human Nutrition Iowa State University, 2312 Food Science Building, Ames, Iowa 44011-1061 Phone 515-294-1970 Fax 515-294-8181 Dr. Patricia Murphy has been studying and testing isoflavones for nearly 20 years and
has been in the forefront of understanding the role isoflavones have in human health. She
is the developer of the U.S. Department of Agriculture and Iowa State University
Isoflavone Database, an authoritative database of the isoflavone content of human foods
which will help scientists pinpoint which estrogen-like compounds -- isoflavones -- in soy
foods may be responsible for a lower risk of cancer, especially breast cancer. A recipient
of the Iowa State Board of Regents Faculty Excellence Award.
Dr. Stephen Barnes* Professor, Department of Biochemistry and Pharmacology Department of Pharmacology, University of Alabama at Birmingham, Volker Hall, Rm G010
UAB Station, Birmingham, Alabama 35294 Phone 205-934-7117 Fax 205-934-8240 Dr. Barnes is a recognized expert in the field of isoflavone analyticals and the role
these compounds play in preventing cancer. Trained in London, England, he joined the Mayo
Clinic in Rochester, Minnesota in 1975. He has been at the University of
Alabama-Birmingham since 1977 and is a Professor in the Departments of Pharmacology &
Toxicology and Biochemistry & Molecular Genetics. He is also the Director of the
Comprehensive Cancer Center Mass Spectrometry Shared Facility. Dr. Pam White* Department of Food Science Human Nutrition Iowa State University Ames, Iowa Phone 515-294-9688 Fax 515-294-8181 Dr. Pam White is a leading researcher in the area of the functional
properties of foods, including soybean, corn and oats. Dr. White is former chair of the
Department of Food Science at Iowa State University.
The American Soybean Association, (800) 688-7692, scensky@soy.org
The University of Illinois at Urbana-Champaign, (217) 333-6364, c-hasler@uiuc.edu
The University of Alabama at Birmingham, (205) 934-7117, Stephen.Barnes@pharmtox.uab.edu
The University of Illinois at Urbana-Champaign, (217) 244-8221, dbullock@uiuc.edu
Iowa State University, (515) 294-1970, pmurphy@iastate.edu
Iowa State University, (515) 294-9688, pjwhite@iastate.edu
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