Additional Background Information:

ASA Confirms the Natural Variability of Isoflavones in Soybeans

(Note: The following article is the subject of ASA's background
information. Please see additional articles that follow.)

Alterations in Clinically Important Phytoestrogens in Genetically Modified,
Herbicide-Tolerant Soybeans

(Copyright © Journal of Medicinal Food, (Vol 1., no. 4) in press, Maryanne Liebert Publishers)

Marc A. Lappé, Ph.D., Center for Ethics and Toxics, Gualala CA
E. Britt Bailey, M.A., Center for Ethics and Toxics, Gualala, CA
Chandra Childress, M.S., Children_s Hospital Medical Center, Cincinnati, OH
Kenneth D.R. Setchell, Ph.D., Children_s Hospital Medical Center, Cincinnati, OH

 Abstract

The growing clinical interest and use of soybean-based food products or extracts to increase dietary phytoestrogen intake makes the precise composition of the key biologically active ingredients of soybeans, notably genistin and daidzin of substantial medical interest. Conventional soybeans are increasingly being replaced by genetically modified varieties. We analyzed the phytoestrogen concentrations in two varieties of genetically modified herbicide tolerant soybeans and their isogenic conventional counterparts grown under similar conditions. An overall reduction in phytoestrogen levels of 12-14 percent was observed in the genetically altered soybean strains. Most of this reduction was attributable to reductions in genistin and to a lesser extent daidzin levels, which were significantly lower in modified compared to conventional soybeans in both strains. Significant sample to sample variability in these two phytoestrogens, but not glycitin, was evident in different batches of genetically altered soybeans. Given the high biological potency of isoflavones and their metabolic conversion products, these data suggest genetically modified soybeans may be less potent sources of clinically relevant phytoestrogens than their conventional precursors. These observations, if confirmed in other soybean varieties, heighten the importance of establishing baselines of expected isoflavone levels in transgenic and conventional soy products to ensure uniformity of clinical results. Disclosure of the origins and isoflavone composition of soy food products would be a valuable adjunct to clinical decision-making.

Copyright © Journal of Medicinal Food, (Vol 1., no. 4) in press, Maryanne Liebert Publishers.

ABSTRACT

One important aspect of the safety assessment of genetically engineered crops destined for food and feed uses is the characterization of the consumed portion of the crop. One crop currently under development, glyphosate-tolerant soybeans (GTS), was modified by the addition of a glyphosate-tolerance gene to a commercial soybean cultivar. The composition of seeds and selected processing fractions from two GTS lines, designate 40-3-2 and 61-67-1, was compared with that of the parental soybean cultivar, A5403. Nutrients measured in the soybean seeds included macronutrients by proximate analyses (protein, fat, fiber, ash, carbohydrates), amino acids and fatty acids. Antinutrients measured in either the seed or toasted meal were trypsin inhibitor, lectins, isoflavones, stachyose, raffinose and phytate. Proximate analyses were also performed on batches of defatted toasted meal, defatted nontoasted meal, protein isolate, and protein concentrate prepared from GTS and control soybean seeds. In addition, refined, bleached, deodorized oil was made, along with crude soybean lecithin, from GTS and control soybeans. The analytical results demonstrated that the GTS lines are equivalent to the parental, conventional soybean cultivar.

* Author to whom correspondence should be addressed [telephone 314/737-6386; email
stephen.r.padgette@monsanto.com

¥ Ralston Analytical Laboratories, St. Louis MO 63164

 © 1996 American Institute of Nutrition.

 Compositional Analysis of Glyphosate-tolerant Soybeans Treated with Glyphosate

ABSTRACT

The compositional analysis and safety assessment of glyphosate-tolerant soybeans (GTS) was previously described in the literature. These analyses were extensive and also addressed potential effects from the genetic change. Detailed compositional analyses established that the glyphosate-tolerant soybeans were comparable to the parental soybean line and to other conventional soybeans. Subsequently, two GTS lines, 40-3-2 and 61-67-1, were treated with commercial levels of glyphosate, the active ingredient in Roundup( herbicide. The composition of the seed from soybeans sprayed with glyphosate are compared to the non-sprayed parental control cultivar, A5403. The nutrients measured in the seed included protein, fat, ash, fiber, carbohydrates and amino acids. The level of isoflavones (also referred to as phytoestrogens) were also measured since these compounds are produced from the same pathway that was engineered for glyphosate tolerance. The analytical results from these studies demonstrate that the GTS soybeans treated with glyphosate are comparable to the parental soybean cultivar, A5403, and other conventional soybeans.

** Ralston Analytical Laboratories, St. Louis, MO.

 Manuscript was submitted to
Journal of Agricultural and Food Chemistry
on January 18, 1999.

Soybeans in American Agriculture

Beginning over 3,500 years ago, the soybean was first cultivated in Asia and transformed from its wild state into a staple agricultural crop. A legume (related to crops such as peas, lentils and alfalfa), soybeans today are the leading global source of protein and oil. Soybeans account for 54% of the world oilseed production, with 47% of global soybeans being grown in the U.S.

The U.S. is the world’s leading soybean producer, growing a record 2,727 billion bushels harvested in 1997 – the highest production level in history. Grown in over 29 states, the value of the U.S. soybean crop reached a record high of $17,589 million in 1997 on an average price paid to U.S. farmers of $6.45 per bushel ($237 per metric ton). Europe is the principal market for U.S. whole soybeans export, while Japan is the largest single country customer.

Soybean Composition:

Like protein found in animal products, soybean protein is "complete" – meaning that it contains all eight essential amino acids needed for human health. Soybeans are the only vegetable food that contain protein makeup which is considered to be nutritionally complete. Soybeans also serve as an important source of nutrition in animal feed. Soybean seed is processed into a variety of protein fractions used for human consumption. Soybean food products include baked goods, confections, meat products, textured foods and nutritional supplements. Soybeans are also an important source of dietary fiber and contain a relatively high oil content. Soybean oil is used extensively in the fod industry in products such as cooking oil and salad dressing. Lecithin, extracted from soybean oil, is a natural emulsifier and lubricant used in everything from pharmaceuticals to protective coatings.

Soybean Health Benefits

In recent years, researchers, nutritionists and physicians have recognized the significant health and nutritional benefits of a diet containing soybean based food products. Researchers are studying soybeans for their potential to lower cholesterol, fight cancer and build healthy bones. Indeed, the U.S. Food and Drug Administration is expected to put soy products on the short list of foods shown to actually lower the risk of heart disease (the others included fiber-containing fruits, vegetables, whole grains and psyllium seed husk).

The best available evidence, accumulated over the last 25 years, indicates soy’s ability to lower cholesterol. Studies show that eating as little as 47g (about 1.5 oz.) of soy can lower total cholesterol levels an average of 9% and low density lipoprotein (LDL) 13%. A 1% drop in total cholesterol translates into a 2% drop in the risk of developing heart disease. According to the American Heart Association, recent studies suggest that the isoflavones (also referred to as phytoestrogens) present in soybeans may contribute to cholesterol lowering and other positive cardiovascular effects.

For example, incidence of certain chronic heart conditions and diseases are significantly lower in populations, such as the Japanese, that consume large quantities of foods known to contain isoflavones.

In particular, the isoflavone genistein has been shown clinically to have a weak "estrogenic" effects. Genistein (and phytoestrogens in general) are believed to hold potential for reducing the risk of breast and prostate cancer; increasing bone density postmenopausal women; and, reducing premenopaual symptoms (hotflashes, cramping, etc.).

Roundup Ready Soybeans

In 1996, Monsanto commercially introduced Roundup Ready Soybeans in the United States. This soybean, genetically modified to tolerate Roundup herbicide, was approved by the United States Department of Agriculture and completed the Food and Drug Administration review process in 1994. The Roundup Ready trait enables the plant to withstand the application of Roundup – a broad spectrum, environmentally friendly herbicide used by farmers to control weeds. Through traditional breeding methods, this trait has been transferred to hundreds of other soybean varieties.

Roundup Ready soybeans have been shown to be the same as conventional soybeans in over 400 seed and processed fraction composition qualities, and confirmed as safe and nutritious in a series of animal feeding studies.

Today, Roundup Ready soybean varieties are approved for use in food, feed or food processing in the European Union, Canada, Mexico, Argentina, Japan, Denmark, Switzerland and Brazil. In the United States in 1999, Roundup Ready soybeans are planted on nearly half the total soybean acres planted. Growers choosing to plant Roundup Ready soybeans experience better weed control and crop safety which leads to lower production costs. Roundup Ready soybeans also enable growers to use conservation tillage practices which have significant water quality and environmental benefits.

Click here to close this window when finished.