Genetic Engineering: The Future of Foods?

Hawaiian farmers were in trouble. In the mid-1990s, an insect-borne virus--the papaya ring spot virus (PRSV)--threatened to decimate Hawaii's second-largest fruit crop. Plant breeders scrambled to produce a virus-resistant papaya. When traditional plant breeding methods failed, researchers turned to genetic engineering.

Years of research were finally met with success, and by spring of 1998, Hawaiian farmers were planting the seeds of PRSV-resistant papaya.

"The results were dramatic," says Dennis Gonsalves, Ph.D., a Cornell University plant pathologist who led the researchers' efforts to save the tropical delicacy and the livelihood of Hawaii's growers. "It was not a matter of increasing the yield, but a matter of whether they could grow it or not grow it."

Gonsalves' team of researchers from academia, industry, and government had isolated and copied a virus gene, then used a device called a gene gun to "shoot" the gene into the cells of the papaya plant. The virus gene in the plant works somewhat like immunization, but the mechanism of resistance is different, says Gonsalves, now director of the U.S. Department of Agriculture's Pacific Basin Agricultural Research Center in Hilo, Hawaii. "By integrating this virus gene into the chromosomes of the papaya, this made the papaya and subsequent generations resistant to the virus."

The rescue of the Hawaiian papaya industry is "a really satisfying story," says Gonsalves, and one that shows the difference that genetic engineering can make in people's lives.

But not all share Gonsalves' enthusiasm for genetically engineered foods. Although the newness of these foods may be wearing off, public concern about the safety and environmental impact of genetically engineered foods remains.

Some consumers and advocacy groups urge mandatory labeling that discloses the use of genetic engineering. Others advocate more stringent testing of these products before marketing. Still others want a ban on all genetically engineered foods.

"The Food and Drug Administration is confident that the genetically engineered food products on the U.S. market today are as safe as their conventionally bred counterparts, and the agency is prepared to meet the safety and regulatory challenges presented by new products as they emerge from the laboratory," says Commissioner of Food and Drugs Mark B. McClellan, M.D., Ph.D. "Genetically engineered foods must adhere to the same high standards of safety under the Federal Food, Drug, and Cosmetic Act that apply to more traditional food products," McClellan adds.

What Are Genetically Engineered Foods?

Genetically engineered foods are produced from crops whose genetic makeup has been altered through a process called recombinant DNA, or gene splicing, to give the plant a desirable trait. Genetically engineered foods are also known as biotech, bioengineered, and genetically modified, although "genetically modified" can also refer to foods from plants altered through other breeding methods, says James Maryanski, Ph.D., the FDA's food biotechnology coordinator. "Scientists and farmers have been genetically modifying plants for hundreds of years," he says. Hybrid corn and tangelos (hybrid of a tangerine and grapefruit), for example, are the result of genetic modification through traditional methods of plant breeding. And the many varieties of apples we eat today were produced through genetic modification.

Using traditional genetic modification methods, such as cross-fertilization, scientists can produce a desired trait, such as a hardier plant. But in doing so, they mix thousands of genes from several plants, requiring many attempts over many years to weed out the unwanted traits that occur.

Newer methods of genetic modification, in the form of genetic engineering, are more precise and predictable--and faster. By controlling the insertion of one or two genes into a plant, scientists can give it a specific new characteristic without transferring undesirable traits.

The first genetically engineered whole product--a tomato--went on the market in 1994. The FDA determined that the new tomato, which could be shipped vine-ripened without rotting rapidly, was as safe as other commercial tomatoes. Since then, more than 50 other genetically engineered foods have been determined by the agency to be as safe as their conventional counterparts.

The Grocery Manufacturers of America estimates that between 70 percent and 75 percent of all processed foods available in U.S. grocery stores may contain ingredients from genetically engineered plants. Breads, cereal, frozen pizzas, hot dogs and soda are just a few of them.

Soybean oil, cottonseed oil and corn syrup are ingredients used extensively in processed foods. Soybeans, cotton and corn dominate the 100 million acres of genetically engineered crops that were planted in the United States in 2003, according to the U.S. Department of Agriculture (USDA). Through genetic engineering, these plants have been made to ward off pests and to tolerate herbicides used to kill weeds. Other crops, such as squash, potatoes, and papaya, have been engineered to resist plant diseases.

Safety of Genetically Engineered Foods

Genetically engineered plants are regulated by three government agencies: the FDA, the USDA, and the Environmental Protection Agency (EPA). The FDA ensures that foods made from these plants are safe for humans and animals to eat, the USDA makes sure the plants are safe to grow, and the EPA ensures that pesticides introduced into the plants are safe for human and animal consumption and for the environment. While these agencies act independently, they have a close working relationship since many products come under the review of all three.

The Federal Food, Drug, and Cosmetic Act (FD&C Act) gives the FDA authority to regulate foods for humans and animals, including foods derived from bioengineered plants. Under the act, companies have a legal obligation to ensure that any food they sell meets the safety standards of the law. The safety standards apply equally to conventional food and genetically engineered food. If a food does not meet the safety standards, the FDA has the authority to take it off the market.

Bioengineered foods do not pose any risks for consumers that are different from conventional foods, says Maryanski. "We make sure there are no hazards, such as an unexpected allergen or poisonous substance in the food, or that the food is not changed in some way that would affect its nutritional value."

The FDA's efforts to ensure the safety of bioengineered foods include publishing rigorous safety testing guidelines, establishing a consultation process with industry, and seeking the expertise of scientists outside the agency.

In 1992, the FDA published a policy statement and testing guidelines for foods developed using all methods of plant breeding, including the use of genetic engineering. These guidelines explain the types of food safety questions that developers should address in evaluating the safety of all plant-derived foods.

In 1994, the FDA set up a consultation process to assist developers in meeting the safety standards set forth in its guidelines. FDA scientists advise companies on the tests needed to assess the safety of new foods. After testing is completed, companies send safety and nutritional information to the FDA for the agency's scientific evaluation.

Although consultation is voluntary on the part of developers, the legal requirements that the foods have to meet are not. Some consumer advocates and scientists have urged the FDA to make the consultation process mandatory, but the agency believes that companies are cooperating within the voluntary system.

"This current process is working very well and fully protects public health," says McClellan. "To the best of our knowledge, all bioengineered foods on the market have been evaluated by FDA through the current consultation process." This includes genetically engineered foods produced by companies outside the United States and marketed here.

In July 2003, the Codex Alimentarius Commission adopted international guidelines for biotech food safety that are consistent with the FDA's approach. Codex, an entity established by the World Health Organization and the Food and Agriculture Organization of the United Nations, is the highest international body on food standards.

Several private and government organizations have studied the safety of genetically engineered foods. In a study released in 2000, a committee of the National Academy of Sciences (NAS) concluded, "The committee is not aware of any evidence that foods on the market are unsafe to eat as a result of genetic modification." This conclusion was echoed in a report published by the Government Accounting Office in 2002. On the animal side, the international Organization for Economic Cooperation and Development published a consensus document in 2003. It noted that there is no evidence to date from animal feeding studies with bioengineered plants that the performance of animals differed in any respect from those fed the non-bioengineered counterpart.

Labeling

The FDA has received many inquiries about the labeling of genetically engineered foods. Some consumer advocates and organizations, such as the Union of Concerned Scientists, urge the FDA to require labeling to identify which foods are genetically engineered.

Under the FD&C Act, Congress has provided the FDA a limited basis on which to require labeling. Generally, there must be something tangibly different about the food product--not the process by which it's made--for the FDA to require labeling.

"The FDA has no information that the use of biotechnology creates a class of food that is different in quality, safety or any other attribute from food developed using conventional breeding techniques," says Maryanski. He adds that disclosure of genetic engineering techniques is not required on the label, just as identification of conventional breeding techniques is not required--for example, "hybrid corn" can just be called "corn."

Any significant differences between the bioengineered food and its conventional counterpart do have to be disclosed in labeling. These would include differences in nutritional properties, the presence of an allergen that consumers would not expect in the food, or any property that would require different handling, storage, cooking or preservation. For example, when a manufacturer produced a line of soybeans whose oil had higher levels of oleic acid than found in conventional soybean oil, the FDA agreed to naming the product "high-oleic soybean oil" to distinguish it from traditional soybean oil. The high-oleic oil can be used in frying without the need for the chemical process of hydrogenation, which produces trans fat.

Food processors may voluntarily label either the presence or absence of a genetically engineered food in their products as long as the information is truthful and not misleading to consumers. The FDA has produced guidance to the industry for this type of labeling.

Future Foods and Regulatory Challenges

The first generation of genetically engineered crops was developed primarily to benefit the growers. Plants were created to resist pests and diseases and to tolerate herbicides used to kill weeds. Scientists see the next generation of genetically engineered products benefiting consumers directly. They are adding nutrients to foods to help prevent diseases, reducing allergens and toxins, and making foods tastier.

Using the tools of biotechnology, researchers are working to reduce the bitterness in citrus fruits, reduce saturated fats in cooking oils, produce more flavorful tomatoes, and even lessen the gassiness caused by beans. Grains, fruits and vegetables that contain more nutrients and potatoes that absorb less oil when made into chips and french fries are also in the development pipeline.

As the tools and techniques used in biotechnology become more complex and a broader range of plants are researched for a wider variety of uses, the FDA must prepare for the safety and regulatory challenges that novel genetically engineered foods may present.

One of these challenges is evaluating food for its potential to cause allergic reactions. People who have food allergies are usually allergic to specific proteins in foods.

FDA biochemical engineer Tong-Jen Fu, Ph.D., is analyzing methods currently used by scientists to determine the allergenic potential of new proteins that may be introduced in food. "The only way people can avoid allergic reactions to food is to avoid eating those offending foods," says Fu. "But we know that there is some possibility that a new protein in food may be an allergen for some individuals. So it is important to have sound scientific methods for assessing whether a new protein will be an allergen."

Fu is analyzing a current test that assumes a correlation between digestive stability and allergenic potential. Using simulated gastric and intestinal fluids, she has found that this correlation isn't always present. Fu's work is improving the FDA's knowledge about proteins and their likelihood of being allergens, which ultimately will help agency regulators determine if a food is safe.

To further assure that the FDA has the best scientific knowledge available to assess the safety of genetically engineered foods, the agency has increased the number of staff experts in plant genetics, molecular biology, immunology, and agricultural biotechnology.

In addition to its own scientists who evaluate safety data, the FDA looks to outside experts, such as the NAS, for advice on food safety assessments. In response to public concerns about the unknown long-term effects of consuming genetically engineered foods, the FDA, USDA and EPA requested assistance from the NAS. The NAS is currently conducting a study to assess the potential for unintended health effects resulting from genetically engineered foods.

"We have no reason to believe there are any adverse effects from the long-term use of these foods," says Maryanski, "but we've asked the NAS to look into it as part of our continuing effort to make sure that our decisions are based on the best science available today."

The FDA has added members with agricultural biotech expertise to its advisory committees that address scientific questions related to bioengineered foods and animal feeds. These committees also include consumer representatives.

"The FDA will continue to reach out to the public to help consumers understand the scientific issues and the agency's policies regarding genetically engineered food," says McClellan. "FDA, in cooperation with USDA and EPA, will continue its oversight of new and emerging food biotechnology products and will be vigilant in ensuring the safety and integrity of the food supply."

A Look Into the Biotech Laboratory

Scientists are developing new varieties of crops that can withstand harsh growing conditions.

Ray Wu, Ph.D., a genetic engineering pioneer and molecular biologist at Cornell University in Ithaca, N.Y., has added two genes from the E. coli bacteria to rice plants, making them tolerant to drought, cold temperatures and salty soil. The genes produce trehalose, a naturally occurring sugar found in a variety of organisms, including bacteria, that protects them from environmental stresses.

The rice plants grew successfully in the greenhouse and are ready for field testing, says Wu. He predicts that in about five years, the plants can be growing in farmers' fields.

Wu explains that the two E. coli genes in the rice will not harm consumers. "E. coli contains thousands of genes," says Wu. "We are only taking two particular genes that we know will not produce toxic products." As an added precaution, Wu used a "promoter" to control the expression of the E. coli genes to direct the plant to make trehalose in specific parts, such as the non-edible leaf. Also tested was a second promoter, which serves as an "on-off switch" so that trehalose is made only in response to an environmental stress.

Although rice is a relatively minor crop in the United States, it is a staple in many developing parts of the world, says Wu. And scientists can use the same procedure of inserting genes and a promoter to create biotech wheat, corn and other cereal plants that can withstand harsh conditions. "The world population continues to increase at an explosive rate, our arable land is deteriorating, fresh water is becoming scarce, and increasing environmental stresses will pose ever more serious threats to global agricultural production and food security in future years," says Wu. "Anything we can do to help crop plants cope with environmental stresses will also raise the quality and quantity of food for those who need it most."

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One concern about genetic engineering is that scientists might unknowingly create or enhance a food allergen. But researchers are hoping that this powerful technology can be used to eliminate or reduce allergens, such as those found in peanuts, wheat and soy.

Experts estimate that 8 percent of children 6 years old and younger and 1 to 2 percent of adults have food allergies, which can cause severe, and sometimes life-threatening, reactions.

Early attempts to eliminate a food allergen have yielded promising results. In 2002, researchers genetically engineered soy to eliminate expression of a common soy protein. Soy allergies are particularly common in infants and young children, according to the National Institute of Allergy and Infectious Diseases. It's difficult to avoid eating soy because of its wide use in many processed foods, including infant formula, cereals, and salad dressings.

Using a "gene silencing" technique, researchers were able to "knock out" a gene that makes a protein called P34, which is thought to trigger most allergic reactions to soy. Tests on blood from people allergic to soy showed no antibody response to the plant with the knocked-out gene, indicating that the allergen could not be detected. The plant's characteristics were also analyzed. "We see no change in the pattern of growth, productivity, or protein composition," says Eliot Herman, Ph.D., lead researcher on this project and molecular biologist at the U.S. Department of Agriculture's Agricultural Research Service.

The work is not done yet, cautions Herman. "There are up to 15 different proteins in soybeans that people are allergic to," he says. "The major one, P34, is responsible for 75 percent of the allergic reactions. How much do you have to get rid of to not trigger an allergic response at all? This is what we need to find out."

Herman sees the benefit of genetically engineered soy in both human food and animal feed. "Baby pigs are similar to baby humans in their reaction to soybeans," he says. "They have gastric distress too." Herman's team is studying the reaction of piglets to the genetically engineered soy, and these studies may pave the way to human clinical trials.

'Pharm' Factories of the Future

Plants may become miniature "factories" for pharmaceuticals through genetic engineering. Scientists are growing plants that produce antibodies to help fight cancer, heart disease and tooth decay. And researchers are experimenting with growing fruits and vegetables that contain vaccines for measles, hepatitis B, Norwalk virus, diarrhea, cholera and more.

These edible vaccines could be pureed into an applesauce-like consistency and fed to children and adults alike. They could be produced in larger quantities and at less expense than current vaccines, although they will have to be grown and handled under strict conditions imposed by the U.S. Department of Agriculture (USDA) aimed at ensuring that they do not inadvertently enter the food supply.

The Food and Drug Administration regulates pharmaceuticals, whether they are manufactured in traditional factories or in crops in the field, to ensure their safety, purity and potency. The FDA and the USDA have jointly published draft guidance specifically addressing the use of bioengineered plants to produce pharmaceutical products.

The FDA is also part of a White House National Economic Council working group that is addressing the regulation of genetically engineered crops to ensure there are no gaps in protecting human health and the environment.

For More Information

FDA's food biotechnology Web site
www.cfsan.fda.gov/~lrd/biotechm.html

List of bioengineered foods that have completed FDA consultation
www.cfsan.fda.gov/~lrd/biocon.htm