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Genetically Modified Soy: Cause for Concern?

Genetically Modified Soy: Cause for Concern?

In June of 2010, DuPont’s genetically modified (GM) soybean was approved by the US Dept of Agriculture for human consumption. The bean was engineered to contain high amounts of oleic acid and decreased polyunsaturated fat content. Polyunsaturated fat, when heated or processed, transforms into trans-fatty acids. It was one of the first foods that was modified for the benefit of human health.

Monsanto previously has engineered two varieties of soybeans that contain omega-3 fatty acid, but no trans fats. Gene splicing is used to engineer these soybeans. The expression of a gene in the fatty acid pathway is suppressed. Most of the North American soybeans already are genetically modified to resist pests. Most of the soy produced in the United States to date is used to feed livestock.

Potential benefits of the GM soybean
The American Heart Association has suggested that “soybean oil could be an effective alternative to fish oil as a source of heart-healthy omega-3 fatty acids.” Omega-3 eicosapentaenoic acid (EPA) levels were increased in the red blood cells of people consuming the GM soybeans to about the same levels found in people who consume fish oil. No hard proof exists to show that the oil from these soybeans will have the same impact on heart health as fish oil does.

Soybeans naturally produce oil that contains alpha-linoleic acid (ALA), an omega-3 fatty acid. The body converts stearidonic acid (SDA) into EPA, but does not efficiently convert ALA into EPA. Researchers have found that if you insert one gene from another plant and one gene from a fungus into a host soybean, the soybean is able to produce SDA, which is then converted to EPA (one of the heart healthy omega-3 fatty acids found in fish).

Eventually, it may become possible to engineer soybeans so that they contain plant stanols and sterols and/or become a more complete source of protein (increasing the content of methionine). Other targets for the genetic engineering of soybeans include increasing the amount of phosphorus absorbed from feed, leading to less waste matter production, and reducing groundwater contamination. Genes that lead to promotion of soy plant root nodules, which allow symbiotic bacteria to use atmospheric nitrogen, were identified. Researchers also are looking for a way to reduce stachyose, an oligosaccharide that humans and many animals cannot digest. This reduction would enhance the growth of domestic animals.

Potential safety concerns regarding GM soybeans and other foods
Few peer-reviewed studies exist on these GM foods and their effects on humans. Genetic modification often is equated with traditional crossbreeding by proponents of the technology, but the two are very different in actuality. A disruption may occur in the natural gene sequence when as isolated gene is spliced into another unrelated organism. The intended gene is combined with “promoter” DNA prior to insertion, which promotes its expression in the new host. This can cause the inserted gene to behave similar to an invading virus.

Just because no GM product was linked to a disease does not mean that these products are safe, and we may not know for decades what the true repercussions of developing and expanding on this technology are. The safety assessment of a GM food is directed by a comparison to its conventional form.

Factors taken into account include:

  • Identity
  • Source
  • Composition
  • Effects of processing and cooking
  • Transformation process
  • The recombinant DNA stability of insertion and potential for gene transfer
  • Protein expression product of the novel DNA
  • Effects on function
  • Potential toxicity
  • Potential allergenicity
  • Possible secondary effects from gene expression or disruption of the host DNA (composition of nutrients, endogenous toxicants, allergens, and physiologically active substances)
  • Potential intake and dietary impact of the introduction of the genetically modified food

Many people fear that use of these GM foods will lead to gradual organ and immune system deterioration. Data on the safety of these modified foods are limited. Unintended results could occur. As noted by the World Health Organization (WHO), “in achieving the objective of conferring a specific target trait (intended effect) to the host organism by the insertion of defined DNA sequences, additional traits could, theoretically, be acquired or existing traits lost (unintended effects)… Unintended effects may be due to factors such as random insertion events which might result in disruption of existing genes, modifications of protein expression or formation of new metabolites. The expression of enzymes at high levels may give rise to secondary biochemical effects, e.g. an altered metabolic flux resulting in changed metabolite patterns… In the future, genetic modifications of plants are likely to be more complex perhaps involving multiple between-species transfers and this may lead to an increased chance of unintended effects.”

It is impossible to test for all potential negative results. When low glutelin rice was created to improve rice storage proteins for commercial sake brewing, it was found that the decrease in glutelin levels correlated with an unintended increase in prolamins. This proved that a targeted change in the level of one protein can cause unintended effects on other proteins. This change would not affect the GM rice’s industrial use, but could affect nutritional quality and allergenic potential. GM soy with increased lysine showed an unexpected decrease in oil content. GM “golden rice” unexpectedly accumulated xanthophylls.

Standard traditional nutritional analyses would not find the changes to both the low glutelin rice and the golden rice. Even the National Food Processors Associations became very concerned when ProdiGene mistakenly contaminated soybeans intended for human consumption with an experimental corn intended for pharmaceutical production. Food companies also are scared that minute amounts of a pharmaceutical could contaminate their products. In 1989, genetically engineered tryptophan produced toxic contaminants. Unfortunately, by the time that it was recalled by the US Food and Drug Administration, 37 Americans had died, 1500 were permanently disabled, and 5000 developed eosinophila-myalgia syndrome.

Specific concerns about GM food and allergenicity
A major area of consternation among opponents is allergenicity. Some proteins that are added to the GM foods are new to human consumption and could potentially become identified as “foreign” in the human body, leading to an allergic reaction. Proteins in GM food are compared to the sequences of protein in known allergens. Currently, significance sequence similarity is determined if is a match of at least eight contiguous, identical amino acids occurs. This is based upon the minimum peptide length for a T cell-binding epitope (a group of amino acids in protein that can bind to either T cells or IgE antibodies).

If no allergic potential is found, the food is then tested for the protein’s stability during digestion, which also could indicate potential allergenicity. The use of digestive stability for determination of allergenicity is useful, but novel proteins could exist that are stable to digestion and yet will not become allergens. However, opponents claim that even more allergies could exist that are not yet classified, that the test for protein stability during digestion only identifies a specific allergen that interacts with specific intestinal cells, that transferred genes from a source of unknown allergen could occur, or that the process of genetic modification could result in the creation of a new allergen or expression of a minor allergen.

The allergy assessment developed by the International Food Biotechnology Council and the Allergy and Immunology Institute of the International Life Sciences Institute in 1996 was widely adopted by the agricultural biotechnology industry. This strategy focuses on the source of the gene, the sequence homology of the newly introduced protein to known allergens, the immunochemical binding of the newly introduced protein with IgE from the blood serum of individuals with known allergies to the source of the transferred genetic material, and the physicochemical properties of the newly introduced protein. If the GM food contains genes from sources with known allergenic effects, you must assume that the novel gene product is allergenic unless proven otherwise.

In 1996, soybeans engineered to include protein-rich genes from the Brazil nut also contained the allergenic properties of the Brazil nut, but animal studies had not revealed this. Luckily, release was stopped prior to its entering the market. In July 1999, a study of Ohio crop pickers and handlers found that Bacillus thuringiensis (Bt) “can provoke immunological changes indicative of a developing allergy. With long-term exposure, affected individuals may develop asthma or other serious allergic reactions.” Bt is a bacterium spliced into millions of acres of corn, potatoes, and cotton. This led to fear that perhaps it was dangerous even if you did not consume the food.

Scary animal studies and GM foods
Recently, Russian biologists discovered that hamsters fed Monsanto’s GM soy for 2 years over three generations led to infertility, as well as slower growth and higher mortality in their pups. Some of the third-generation hamsters also were found to have hair growing inside of their mouths. The hamsters were divided into four groups—no soy, non-GM soy, some GM soy, and higher doses of GM soy. Each group contained five pairs of hamsters, and each pair had seven or eight litters, resulting in the study of 140 animals. New pairs were then taken from each group, which produced another 39 litters. Fifty-two pups were born to the control group, and 78 were born to the non-GM soy group. In the GM soy group, only 40 pups were born, and 10 of these (25%) died. This was a fivefold higher rate of mortality than in the control group. In the high-GM soy group, only one female gave birth. She had 16 pups, and about 20% died. In the third generation, many of the animals were sterile. While this study is not conclusive, it does give one pause when considering the potential adverse effects of changing the genetic makeup of our food. The GM soybeans also contain much higher levels of herbicide, which could account for some of the problems found in the animals consuming these products.

In 2005, Irina Ermakova, also with the Russian National Academy of Science, found that more than half of baby rats from mothers fed GM soy died in the first 3 weeks of life. The non-genetically modified organism (non-GMO) soy group had a mortality rate of 10%. The babies in the GM group also were smaller and sterile. When the male rats were fed GM soy, their testicles turned dark blue.

Other scientists have found that:

  • GM soy caused testicle changes and damaged young sperm cells in mice
  • Mice had fewer babies when fed GM corn
  • Cows and pigs became sterile and some pigs had false pregnancies or gave birth to bags of water when they consumed GM corn feed
  • Rats raised on corncob bedding made from GM corn neither bred nor exhibited reproductive behavior, and had higher rates of breast and prostate cancer cell cultures
  • Buffalo consuming GM cottonseed suffered from infertility, frequent abortions, premature deliveries, prolapsed uteruses, and mysterious deaths

Labeling of GM foods
Only genetically modified foods that differ substantially from their nongenetically modified equivalents need to have special labels. Therefore, the new high-oleic soy would need special labeling. However, defining “substantially different” is always up for debate. The products of animals fed the GM soybeans, such as eggs or milk, would not need this labeling. Mandatory labeling systems in Europe have led to manufacturers sourcing GE (genetically engineered)-free products rather than having to label their product as containing GE ingredients.

Consumers want mandatory labeling because of a variety of reasons, including to:

  • Address fears of safety
  • Comply with religious dietary laws
  • Make food choices consistent with individual dietary preferences
  • Choose whether or not to consume GE foods

This allowance for personal choice is really what the argument is all about.


References and recommended readings

Damery P, D’Adamo N, Graham M, Hoffman M, Riedl J. The debate on labeling genetically modified food.
Available at: http://www.public.iastate.edu/~ethics/LabelGMFood.pdf.
Accessed June 14, 2011.

Food and Agriculture Organization of the United Nations, World Health Organization. Safety Aspects of Genetically Modifiable Food of Plant Origin: Report of a Joint FAO/WHO Expert Consultation on Foods Derived From Biotechnology.
Available at: http://www.biotech-info.net/FAO-WHO_safety_GMO.pdf.
Accessed June 14, 2011.

Good R, Hasslberger S. Genetically modified soy in Russia.
Available at: http://www.biotech-weblog.com/50226711/genetically_modified_soy_in_russia.php.
Accessed June 14, 2011.

Jacobson M. The genetically modified food fight: higher levels of testing are needed for crops that have an increased potential for harm. West J Med [serial online]. 2000;172:220-221.
Available at: http://www.cspinet.org/reports/oped220.pdf.
Accessed June 14, 2011.

Jacobson MF, Jaffe G. Who’s watching what you eat?
Available at: http://www.cspinet.org/biotech/pdtake.html.
Accessed June 14, 2011.

Jaffe GA. Labeling genetically modified food: communicating or creating confusion?
Available at: http://www.cspinet.org/biotech/pew-forum.html.
Accessed June 14, 2011.

Lilyquist K. GM high-oleic soy—despite concerns, it may soon be available for human consumption. Today’s Dietitian [serial online]. 2010;12:42.
Available at: http://www.todaysdietitian.com/newarchives/121610p42.shtml.
Accessed June 14, 2011.

Smith J. Genetically modified soy linked to sterility, infant mortality in hamsters.
Available at: http://www.huffingtonpost.com/jeffrey-smith/genetically-modified-soy_b_544575.html.
Accessed June 14, 2011.


Review Date 7/11



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