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Genetically modified foods: a taste of the future. (Advanced Practice).

Genetically modified (GM) foods have attracted intense media coverage in recent years. Depending on one's point of view, they have been hailed as "superfoods" or reviled as "frankenfoods." Yet, despite the controversy, GM foods have found their way onto American tables. In the United States, an estimated 60% of processed foods in supermarkets--from breakfast cereals to soft drinks--contain a GM ingredient, such as soy, corn, or canola. A few fresh vegetables have been genetically altered as well (Hopkin, 2001). As a result, most Americans have eaten GM foods, but many are not aware of it.

Genetic modification of foods offers many potential benefits for world agriculture, including the possibility of producing higher yields of more nutritious food in more environmentally sustainable ways (Huppatz & Fitzgerald, 2000). While consumption of GM foods has not produced any apparent short-term harmful effects, long-term effects are not yet known. Concerns about the safety of GM foods have been raised, as well as their ecologic and economic impact. By keeping informed of the latest information on GM foods, medical-surgical nurses can effectively teach patients about these foods and knowledgeably answer questions.

Basic Concepts of GM Foods

The technologies that genetically alter the organisms people eat were developed in the 1980s (Jacobson, 2000; Jones, 1999; Lewis, 2001). During the past 20 years, scientists have learned how to isolate genes from a living organism and transfer them to another organism, where they can function in their new host (Burke, 1998). The process of moving genes from one organism to another (for example, from bacteria to plants or from noncrop to crop plants) is known as recombinant DNA or gene technology. The newly created organism is said to be "genetically modified," "genetically engineered," or "transgenic" (U.S. Department of Energy Office of Science, 2001).

Farmers and plant breeders have been altering the genes of crop plants for centuries. However, genetic modification differs from conventional breeding in the precision of gene transfer (Halford & Shewry, 2000). Conventional breeding involves crossing genotypes that contain thousands of expressed genes, and selecting those offspring that combine the best features of the two parents (Halford & Shewry, 2000). A limitation of this approach is that it creates random assortments of genes. In addition, fertility barriers that allow only plants of the same, or closely related, species to be crossed limit conventional breeding. In contrast, genetic modification allows specific genes to be identified, isolated, copied, and introduced into other organisms in more direct and controlled ways (Jones, 1999). It is the ability to transfer genes between species that distinguishes this approach from conventional breeding.

Genetic modification of food is possible because the genes of all organisms comprise a universal chemical--DNA. Hence, the DNA from different organisms can be cut and joined together. In this process, DNA is isolated and treated with restriction enzymes, which are used to cut DNA at specific sequences and create fragments that have so-called "sticky ends." These sticky ends tend to adhere to each other through complementary base pairing, and the enzyme DNA ligase can then be used to rejoin the sugar-phosphate backbone of the two nucleic acid chains. The two DNA fragments joined by DNA ligase can be from the same or different organisms (Jones, 1999).

Bacteria are commonly used in the genetic modification of plants. Short loops of DNA found naturally in bacteria, known as plasmids, are cut with a restriction enzyme and mixed with the particular gene of interest (for example, a gene that produces insect resistance). DNA ligase is then used to "stitch" the gene of interest into the plasmid. This "recombinant" plasmid is mixed with bacteria which, under appropriate conditions, are capable of incorporating it. The bacterial cells are placed in culture and the plasmid is replicated during cell divisions, resulting in a bacterial culture that contains multiple copies of the plasmid and its inserted gene (Jones, 1999). To genetically modify plants, the plasmid is extracted from the bacteria, and the cloned gene is excised with a restriction enzyme. The particular gene can then be introduced into individual plant cells using a bacterial vector (which carries the gene into the bacteria cells).

Applications of Gene Technology in Food Production

Recombinant DNA technology offers a powerful new tool to assist plant breeders to produce crops with improved characteristics, such as insect resistance, disease resistance, herbicide tolerance, and climatic tolerance, as well as with enhanced consumer benefits, such as improved flavor and texture, longer shelf life, and added nutritional value (see Table 1). Work is also underway to identify and modify the genes for biologically active components of food crops, such as anti-nutrients (for example, trypsin inhibitors) and allergens (such as certain nut proteins), in hopes of developing foods that lack these undesirable components (Jones, 1999). Additionally, gene technology holds great promise to produce foods that can prevent illness and promote wellness (such as rice engineered with high levels of vitamin A and iron to alleviate nutritional deficiencies in developing countries; soybeans used for pharmaceutical production; and bananas that produce human vaccines against certain infectious diseases).

The first commercial application of gene technology in crop plants occurred in the early 1990s, and involved modifying plants for resistance to disease and insects or improving plant production systems. Since that time, GM crops have been introduced at a rapid pace in the United States. In 2001, over 65% of the soybeans and over 25% of the corn grown in this country were genetically modified (Pew Initiative on Food and Biotechnology, 2002). While soybeans, cotton, corn, and canola remain the most common transgenic crops in the world, the number of transgenic products has now increased to over 50, involving 13 separate crops (Huppatz & Fitzgerald, 2000). Over the next 2 decades, it is predicted that gene technology will reach every type of agricultural crop in the world, although this will depend upon a high level of consumer acceptance and confidence about the safety of GM foods (Huppatz & Fitzgerald, 2000). While genetically modified animals are currently not approved for consumption in the United States, fast-growing genetically engineered salmon, trout, and other fish are in development.

Safety Implications Of GM Foods

In the United States, the Food and Drug Administration (FDA) is responsible for ensuring the safety and accurate labeling of foods, including those derived from GM plants. The FDA's current safety assessment approach has been voluntary, and although GM food consumption has not caused any known health problems, the FDA plans to develop a mandatory system in the near future (Gasson & Burke, 2001; Taylor & Hefle, 2001). Public health concerns surrounding GM foods include the potential for direct adverse effects from food consumption, the unintended introduction of allergens into the food, transfer of antibiotic resistance markers, and the potential impact on the environment (see Table 2).

Because products derived from gene technology ultimately result in the introduction of new proteins, the potential allergenicity of these novel proteins must be determined. The FDA requires labeling of all GM foods that are potentially allergenic (Taylor & Hefle, 2001).

Another safety issue involves the practice of using antibiotic resistance as a marker to measure the success of a genetic modification. Antibiotic resistance is tagged onto the genetic modification, so that cells that contain the new gene are also antibiotic resistant (Leeder, 2000). A commonly used antibiotic resistance marker is the neomycin phosphotransferase 2 (npt II) gene, which confers resistance to the antibiotics kanamycin and neomycin (Gasson & Burke, 2001). Although studies have suggested that the presence of this antibiotic-resistance gene in any crop will have a negligible impact on food safety (Gasson & Burke, 2001; Huppatz & Fitzgerald, 2000), there is concern that these genes have the potential to compromise the therapeutic value of antibiotics in humans and animals.

Aside from their potential human health impact, GM foods also pose certain environmental risks (see Table 2). Among the environmental risks associated with GM crops are the possibility that: (a) superweeds could arise if herbicide-resistant genes find their way into weeds; (b) desirable insects, such as the monarch butterfly, could be harmed by insecticides built into many GM crops; and (c) crops could fail if insects and weeds develop resistance to built-in insecticides and herbicides. Additional concerns are the unknown effects of GM crops on other organisms (such as soil microbes), and the potential loss of flora and fauna biodiversity.

Nursing Considerations

Given the safety issues, it is important that nurses know about GM foods and their implications for consumer health and safety. Numerous reliable Web sites are available to assist nurses to remain up-to-date on the latest information on GM foods (see Table 3). The introduction of GM foods not only raises concern among persons with severe allergies, but also among vegetarians and persons of various ethnic-cultural backgrounds (for example, Moslems, Jews) who may wish to avoid foods containing genes or gene products derived from animals. Other individuals may be concerned about the potential for GM crops to create environmental problems or believe that it is unethical to transfer genes between different species.

The nurse may be the first person that patients consult for information and advice about the health and safety issues surrounding GM foods. Since food allergies are a key issue with GM food, pertinent nursing interventions include: (a) taking a careful history of actual and potential food allergies, (b) discussing appropriate avoidance strategies, (c) teaching patients to recognize early signs of an allergic reaction, and (d) providing emergency plans and medications as appropriate in case of accidental ingestion. Other nursing interventions are ensuring that patients and their families are given ample opportunity to discuss concerns about GM foods and to have their questions answered in a sensitive, informed, supportive, and unbiased manner. In addition, nurses can help identify reliable resources where patients can obtain additional information about GM foods, technologies, and associated issues. A sample patient information sheet is provided in Table 4.

Summary

Technologies for genetically modifying foods hold great promise for meeting important public health challenges. Yet, like all new technologies, they also carry certain risks. Foods produced through gene technology are already on supermarket shelves and have been subjected to rigorous safety testing; and many more GM foods are currently under development (Biotechnology Industry Organization, 2002).

While controversies surround the development of GM foods, it should be remembered that DNA has always been a part of our daily diet. We consume millions of copies of many thousands of genes on a daily basis (Jones, 1999). Consider, for example, the genes of tomatoes, peppers, and lettuce in a salad, or the genes of the many micro-organisms that we breath and swallow. As frontline providers of health care, it is important that nurses be well informed about the development and implications of GM foods. With their expertise in patient education, nurses can communicate the benefits and risks of GM foods in a manner that promotes informed decisions by patients regarding GM foods.
Table 1.
Examples of Genetically Modified Crops

         Altered Plant                         Advantage

* Delayed softening and improved   Extended shelf life and enhanced
    ripening of tomatoes             flavor
* Herbicide-resistant cotton       Reduces use of toxic herbicides
* Canola oil enriched with high    Improved health attributes
    levels of oleic acid             (potential cardiovascular health
* Rice with beta-carotene and        benefit)
    extra iron
* Virus-resistant squash and       Added nutritional value
    papaya
* Bananas resistant to fungal      Can resist viral infection
    infection
* Delayed ripening bananas and     Extended shelf life
    pineapples
* Elongated sweet pepper           Improved flavor, easier to slice
* High-starch potatoes             Absorb less oil on frying
* Insecticide-resistant cotton     Reduces use of toxic insecticides
* Sweet peas and peppers           Retain sweetness longer
* Insect-resistant corn            Can resist certain insects
* Herbicide-resistant soybeans     Possible use of smaller amounts of
                                     toxic herbicides
* Weather-hardy strawberries       Survive freezing and thawing

Modified from: Lewis, R. (2001).

Table 2.
Potential Benefits and Risks of GM Foods

Benefits

* Increased nutritional qualities (e.g., added vitamins, minerals,
  iron, and nutrients that protect against certain diseases)

* Reduced or eliminated natural toxicants (e.g., glycoalkaloids in
  potatoes) or allergens (e.g., allergenic proteins in nuts)

* Resistance to insects, diseases, herbicides, and environmental
  extremes

* Improved keeping and processing qualities (e.g., delayed fruit
  ripening to extend shelf life)

* Production of pharmaceuticals and edible vaccines

* Enhanced taste and quality of food materials

* Control of crop traits important for harvesting and processing
  (e.g., plant height, seed size and number)

* Development of new products (e.g., biodegradable plastics)

Risks

* Possible direct adverse effects from food consumption

* Unintended introduction of allergens or naturally occurring
  toxins in food

* Transfer of antibiotic resistance markers

* Reduction of biodiversity

* Unintended transfer of transgenes beyond GM plants to other species,
  harming them or making them toxic or allergenic

* Unknown effects on other organisms (e.g., soil microbes)

* Over time, insects and weeds may evolve tolerance to built in
  insecticides and herbicides, respectively

* Possible escape of genes from GM crops to weedy plant relatives,
  creating superweeds

* Unexpected results from combinations of genes from different species

Table 3.
Examples of Web-Site Resources for GM Foods and Technologies

* U.S. Department of Energy Office of Science, Office of Biological and
  Environmental Research, Human Genome Program. Genetically modified
  foods and organisms
  http://www.ornl.gov/hgmis/elsi/gmfood.html

* Northern Lights Special Edition: Genetically modified foods
  http://special.northernlight.com/gmfoods/

* SCOPE GM Food Forum
  http://scope.educ.washington.edu/gmfood/index.php

* Information Systems for Biotechnology
  http://www.isb.vt.edu/indexmain.cfm

* Pew Initiative on Food and Biotechnology
  http://pewagbiotech.org

* AgBiotechNet, Genetically modified foods
  http://www.agbiotechnet.com/topics/Database/GMFood/GMFood.asp

Table 4.
Sample Patient Information Sheet: Genetically Modified Foods

What Are Genetically Modified Foods?

Genetically modified (GM) foods are foods that have had their genetic
makeup changed. GM foods are also known as superfoods, frankenfoods,
genetically engineered foods, and transgenic foods. Processed foods
such as salad dressings, chips, and cookies often contain a genetically
modified food product like canola oil.

Are GM Foods Safe to Eat?

GM foods are not known to cause any health problems. GM foods are
regulated by the Food and Drug Administration (FDA) on a voluntary
basis. Food labels are required on foods that have been genetically
modified to contain common food allergens, such as peanuts, eggs,
wheat, and shellfish. Be sure to let your health care provider know if
you have any food allergies.

What Are the Potential Benefits and Risks of GM Foods?

Some of the benefits of GM foods are better flavor, greater freshness,
and healthier nutrition content such as less fat or more vitamins.
Food allergies are the major risk associated with eating GM foods.

What Are Some Examples of GM Foods with Potential Health
Benefits?

* Tomatoes with increased amounts of tycopene, a cancer-fighting
  antioxidant

* Canola or sunflower oil with lower amounts of trans-fatty acids to
  promote a healthy heart

* Soybeans with reduced amounts of saturated fats

* Potatoes with a higher starch content, which absorb less oil during
  frying

What Are Some Reliable Internet Resources?

* Pew Initiative on Food and Biotechnology
  http://pewagbiotech.org

* Scope GM Food Forum
  http://scope.educ.washington.edu/gmfood/

* New York Times on the Web. Genetically modified organisms
  http://www.nytimes.com/library/national/science/health/gm-index.html

* University of Nebraska--Lincoln. Safety of genetically engineered
  foods http://agbiosafety.unl.edu


References

Biotechnology Industry Organization. (2002). Agricultural biotech products on the market. Retrieved July 26, 2001, from http://www.bio.org/er/agri_products.asp

Burke, D. (1998). Why all the fuss about genetically modified food? Much depends on who benefits. British Medical Journal, 316, 1845-1846.

Gasson, M., & Burke, D. (2001). Scientific perspectives on regulating the safety of genetically modified foods. Nature Reviews Genetics, 2(3), 217-222.

Halford, N.G., & Shewry, P.R. (2000). Genetically modified crops: Methodology, benefits, regulation and public concerns. British Medical Bulletin, 56, 62-73.

Hopkin, K. (2001, April). The risks on the table. Scientific American, pp. 60-61.

Huppatz, J.L., & Fitzgerald, P.A. (2000). Genetically modified food: To grow or not to grow? Medical Journal of Australia, 172, 170-173.

Jacobson, M. (2000). The genetically modified food fight. Western Journal of Medicine, 172, 220-221.

Jones, L. (1999). Science, medicine, and the future: Genetically modified foods. British Medical Journal, 318, 581-584.

Leeder, S.R. (2000). Genetically modified foods--food for thought. Medical Journal of Australia, 172, 173-174.

Lewis, R. (2001). Human genetics: Concepts and applications (4th ed.). New York: McGraw-Hill.

Pew Initiative on Food and Biotechnology. (2002). Genetically modified crops in the United States. Retrieved July 26, 2002, from http://pewag.biotech.org

Taylor, S.L., & Hefle, S.L (2001). Will genetically modified foods be allergenic? Journal of Allergy and Clinical Immunology, 107, 765-771.

U.S. Department of Energy Office of Science, Office of Biological and Environmental Research, Human Genome Program. (2001). What are genetically modified (GM) foods? Retrieved December 10, 2001, from http://www.omi.gov/hgmis/elsi/gmfood.html

Mira Lessick, PhD, RN, is an Associate Professor, University of Toledo, College of Health and Human Services, Toledo, OH.

Joyce Keithley, DNSc, RN, FAAN, is a Professor, Rush University College of Nursing, Chicago, IL.

Barbara Swanson, DNSc, RN, is an Associate Professor, Rush University College of Nursing, Chicago, IL.

Betty Lemon, MSN, RN,C, CNN, CSN, is an Assistant Professor, University of Toledo, College of Health and Human Services, Toledo, OH.

Note: This article was developed by members of the International Society of Nurses in Genetics, Inc. For more information on ISONG visit their Web site at http://www.isong.org or contact Executive Director Eileen Rawnsley, BSN, RN, CGC, at 7 Haskins Road, Hanover, NH 03755; email: erawn@valley.net; Fax: (603) 643-3169.
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Author:Lessick, Mira; Keithley, Joyce; Swanson, Barbara; Lemon, Betty
Publication:MedSurg Nursing
Geographic Code:1USA
Date:Oct 1, 2002
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