Genetically modified foods: a taste of the future. (Advanced Practice).
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.
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.
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
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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: email@example.com; Fax: (603) 643-3169.
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|Author:||Lessick, Mira; Keithley, Joyce; Swanson, Barbara; Lemon, Betty|
|Date:||Oct 1, 2002|
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