Genetically modified foods have been altered to develop potentially desirable qualities, such as the ability to grow year-round, be pest-resistant or have enhanced taste or added nutritional value.
Genetically modified foods are produced using gene splicing (recombining the DNA of two different organisms). This involves taking a gene (or genes) from one organism and placing it in another. Gene splicing is an improvement over the more time-consuming traditional genetic modification techniques, such as plant grafting (attaching a portion of one plant to another) and hybridization (sometimes called cross-breeding), in which two different plants are bred to produce offspring with qualities of both parent plants. These methods also resulted in the transmission of undesirable traits as well as desirable traits.
The first genetically modified foods focused on making plants easier and cheaper to produce. This resulted in plants that were more pest- and disease-resistant and able to withstand the use of herbicides. Later, genetically modified foods focused on traits beneficial to the consumer, such as enhanced nutritional value and improved appearance and taste. More recent genetic modification has focused on the potential pharmaceutical and environmental uses of genetically modified plants. Genetically modified foods are relatively new, first becoming available in the 1990s. To date, the U.S. Food and Drug Administration (FDA) has approved over 50 genetically modified foods.
Genetically modified foods may provide potential benefits such as reduced production costs, improved availability and the use of fewer chemicals (e.g., pesticides) during production. However, a number of concerns have also been raised regarding genetically modified foods, including the potential for introduced allergens, adverse long-term health effects as well as environmental and ethical concerns.
Genetically modified foods are regulated by the FDA, U.S. Department of Agriculture (USDA) and Environmental Protection Agency (EPA). The FDA is responsible for ensuring genetically modified foods are safe for human consumption. The USDA is responsible for ensuring genetically modified plants are safe to grow and do not harm other plants or the environment. The EPA is responsible for ensuring genetically modified foods are safe for humans, animals and the environment. While these agencies act independently, they have a close working relationship since many products come under the review of all three.
The FDA does not require genetically modified foods be identified on product labels, as long as they are “substantially equivalent” to their conventional counterparts. This means they should have the same nutritional value, allergens, and nearly the same composition and characteristics of their counterparts. However, in many other parts of the world (e.g., the European Union, Japan), all genetically modified foods must identified as such on their labels. Because of this, exports of genetically modified foods from the United States to these countries have been banned.
The FDA has determined that genetically modified foods are as safe as their conventional counterparts and pose no risks that their conventional counterparts do not. The American Dietetic Association supports this determination.
About genetically modified foods
Genetically modified foods, which are also called genetically engineered foods, biotech foods and bioengineered foods, are produced by recombining DNA of two different organisms (gene splicing). This is a process to remove a gene or genes from one organism and place them into the DNA of another to introduce new traits to the second organism. This can help make crops more resistant to certain pests and herbicides.
DNA contains the genetic blueprint for all life forms. Specific parts of DNA contain the codes, or genes, necessary to produce proteins. These proteins contribute to the creation of a specific trait by stimulating biochemical reactions or by acting as structural or storage units of a cell.
Traditional genetic modification techniques include plant grafting (attaching a portion of one plant to another) and hybridization (sometimes called cross-breeding), in which two different plants are bred to produce offspring with qualities of both parent plants.
These traditional methods have been used for hundreds of years to introduce a desired trait from one plant into another. However, traditional techniques have limitations. They introduce thousands of genes, instead of just one or a few particular genes. This can have unpredictable results. The new plant is likely to have as many undesirable new traits as desirable ones. The process of producing a plant with the desired trait(s) and few or no undesired traits involves a great deal of trial and error and can take a long time. Generally, only plants that are closely related can be used.
On the other hand, gene splicing allows scientists to introduce just the desired gene or genes into the target plant. Thus, the likelihood of introducing undesirable new traits may be reduced. In addition, gene splicing does not require that only closely related plants be used. Genes from nearly any type of organism may be used, including genes from bacteria and insects, and vertebrates such as fish or mammals.
Reasons foods may be genetically modified include:
To grow year-round
To be more resistant to pests and adverse weather conditions such as drought
To tolerate herbicides for more effective weed control
To increase appearance, nutritional content and storage capacity
To resist plant diseases
Genetically modified foods are relatively new, first becoming available in the 1990s. The first genetically modified whole food was a tomato introduced in 1994. It was designed to ripen more slowly, remain on the vine for longer periods of time and stay fresh longer after ripening than other tomatoes. The U.S. Food and Drug Administration (FDA) determined that this genetically modified tomato was as safe for consumption as traditionally grown tomatoes. Since then, the FDA has approved over 50 additional genetically modified foods.
According to the U.S. Department of Agriculture(USDA), genetically modified crops made up 40 percent of corn and 81 percent of soybeans grown in the United States in 2003. Genetically modified plants are usually used to make the ingredients (e.g., oils, flour, cornmeal) for a variety of processed foods such as breads, cereals, corn chips, hot dogs and soda. These plants may also be used as animal feed or for non-food purposes (e.g., fabric).
Proponents are constantly looking for new ways to use genetic foods. For example, plans were recently announced to plant the first commercial crop of genetically modified potatoes. These potatoes have been modified so they can be used in the production of papers and adhesives and are not intended to be used as food.
Types and differences of genetically modified foods
Genetically modified foods may differ, depending on the desirable traits they are designed to include. There have been three major movements involving genetically modified foods.
The first genetically modified foods focused on making plants easier and cheaper to produce. Desirable traits for these purposes include:
Pest resistance. Many plants have been genetically altered to produce a chemical that is toxic to certain pests (e.g., insects, fungi) but harmless to humans. Crops that have been altered in this way include corn, soybeans, canola, apples and wheat.
Herbicide tolerance. Plants have also been genetically altered to be able to better withstand herbicides. This allows farmers to kill weeds without harming the crop. Foods that have been modified in this way include soybeans, corn, sugar beets, alfalfa, canola, wheat, lettuce and rice.
Disease resistance. Plants have also been genetically modified to resist certain diseases. Crops modified in this way include corn, bananas and papayas.
Increased production. Some plants have been genetically altered to produce higher crop yields under specific environmental conditions.
Later, genetically modified foods focused on potential benefits to the consumer. Many of these foods may not be available or approved for human consumption. Desired traits for these purposes include:
Enhanced health and nutritional value. Several different plants have been genetically modified to include additional nutrients. For example, rice has been developed with added beta-carotene, and soybeans that contain higher levels of protein are being developed. Genetic modification is also being used to reduce the amounts of saturated fats in cooking oils and to reduce the absorption of oil in potatoes. In addition, early results on the development of a reduced-allergen soybean appear promising.
Improved appearance or taste. Genetic modification may make foods look better, taste better and stay fresh longer. This includes citrus fruits with less bitterness, tomatoes with more flavor, and other fruits and vegetables with improved shelf life.
Increased adaptability to environmental conditions. Rice has been genetically modified to grow in harsh conditions, such as drought, cold temperatures or in salty soil. This type of modification may also be used for corn, wheat and other cereals.
Other benefits. Genetical modification is being explored for other benefits to consumers (e.g., beans that cause less flatulence).
More recently, genetically modified foods are being designed to focus on pharmaceutical and environmental benefits. These foods are still in the developmental stage. Desirable traits for these purposes include:
Potential pharmaceutical use. Genetically modified plants (e.g., fruits, vegetables) may be able to produce proteins that may function as edible medications or vaccines. Potential vaccines under development include those for measles, Hepatitis B, Norwalk virus, diarrhea and cholera. Medications that may be available in genetically modified foods include antibiotics, anticoagulants, blood substitutes and hormones.
Potential environmental use. Genetically modified plants may be able to aid the environment in a number of ways. Plants may be modified to reduce the spread of mosquito-borne malaria. Plants may be modified to absorb certain toxic or hazardous substances in the soil or water. Genetic modification may also help protect nonfood plants (e.g., trees) from diseases.
Benefits and concerns
Genetically modified (GM) foods may provide a number of potential benefits, including:
Reduced costs. Traits that make crops easier and cheaper to produce have the potential to reduce consumer costs as well, making food cheaper. This may also be of benefit to developing countries.
Improved availability. Crops that stay fresher longer may improve food selection year-round. For example, fruits may be able to maintain freshness in seasons when they would not normally be available.
Fewer chemicals. Improved pest resistance by genetically modified foods may help reduce the amount of chemicals used on farms.
Reduced allergens. Genetic modification may be able to remove the protein in certain foods (e.g., peanuts, wheat, soy) that can cause allergies. This could allow people who are allergic to these foods to safely eat them.
Pharmaceutical use. The potential to develop vaccines, antibiotics and other medications in genetically modified foods could reduce the production cost of pharmaceuticals. This could also increase the accessibility of medications in developing countries, where the storage and administration needs of conventional medications (e.g., refrigeration, needle sterilization) limit their availability.
A number of concerns have also been raised regarding genetically modified foods. These include:
Introduced allergens. There is some concern that certain genes used in genetically modified foods may produce new allergenic proteins. This could potentially cause a person with an allergy to these proteins to have an allergic reaction to foods they otherwise could eat. In addition, allergens present in genetically modified foods may expose susceptible people to low levels of these allergens over time that could result in the development of allergies.
Current testing methods cannot identify unknown allergens that may develop in genetically modified foods. Companies that use known allergens when producing a genetically modified food must demonstrate to the Food and Drug Administration that the allergens do not cause reactions. Otherwise, the allergen must be identified on the food label.
Recently, researchers at Michigan State University announced the possible discovery of an animal model to test whether or not genetically modified foods can cause allergic reactions in people. The Environmental Protection Agency gave the researchers a $447,000 grant to help determine whether or not this test is effective.
Potential long-term effects. Because the technology involved in genetic modification is still young, some concern exists regarding possible long-term effects of eating genetically altered foods. There are few clinical studies involving human or animal subjects regarding possible health risks of consuming these foods, so potential long-term effects are not clear. It is also unknown whether genetically modified foods may contribute to the development of antibiotic-resistant strains of bacteria.
Environmental concerns. There are concerns about the environmental impact of genetically modified crops. Specifically, that genetically modified crops may cross-breed with traditional or wild plants, or that modified crops may spread beyond controlled areas to become “super weeds.” For example, genetically modified canola pollen can easily be transported by the wind to grow in unintended areas, where it may negatively impact other plants in the area.
Ethical concerns. Because genetic modification involves manipulation of an organism’s DNA, there are ethical concerns about the appropriateness of the technique. These concerns are heightened when considering genetic modification of nonplant sources of food, such as animals.
Other concerns. Concern has been raised about the possibility that genetically modified foods not approved for human consumption may become mingled with their conventional counterparts and used in food production. This occurred when genetically modified corn approved only for animal consumption and industrial use was found in commercial corn taco shells.
Global concerns with genetically modified foods
Most genetically modified foods available on the market in the United States are considered by the Food and Drug Administration(FDA) to be “substantially equivalent” to their conventionally produced counterparts. This means that the genetically modified food contains the same nutritional value, allergens, and nearly the same composition and other characteristics as the conventional crop. In the United States, genetically modified foods that are substantially equivalent to their conventional counterparts are not required to be labeled or otherwise identified as genetically modified products.
However, in many other parts of the world (e.g., the European Union, Japan), all genetically modified foods must be identified as such on their labels. Because of this, exports of genetically modified foods from the United States to these countries have been banned.
The United States remains the largest producer of genetically modified foods, according to the American Dietetic Association. However, countries such as China and many developing nations are using genetic modification techniques as well.
Food labels and genetically modified foods
The U.S. Food and Drug Administration (FDA) does not require genetically modified foods to be identified as such on their labels, as long as they are “substantially equivalent” to their conventionally produced counterparts. This means they should have the same nutritional value, allergens, and nearly the same composition and characteristics of their counterparts. Whether labeled or not, most corn and soybean products grown in the United States have been genetically modified.
Some organizations argue that this is a violation of a consumer’s right to information about a food being purchased. Regulatory initiatives are under way that would require food manufacturers to clearly identify the presence of genetically modified ingredients on product labels. It is believed that this would help people with food allergies avoid potentially dangerous foods. It would also identify products that involve genetic modification so consumers could make informed purchase decisions.
If genetically modified foods are not substantially equivalent to their conventional counterparts, the FDA requires they be identified as genetically modified on their labels. This could be required in cases of genetically modified foods that have different nutritional properties, allergens or other characteristics (e.g., handling, storage or cooking requirements) than their conventional counterparts. These labels must specify the precise difference in the genetically modified food.
Some companies identify the presence or absence of genetically modified ingredients on product labels, even if not required to do so by the FDA. In general, the FDA discourages the terms “GMO” or “genetically modified” on food labels. Technically, it could be argued that all foods have been genetically modified, whether by traditional means (e.g., hybridization) or through gene splicing (recombining DNA of two different organisms), what is typically thought of as genetic modification. Thus, the FDA prefers the term “genetically engineered.”
Organic foods may not include any genetically modified ingredients.
Regulations and oversight
Crops that have been genetically modified are regulated by the U.S. Food and Drug Administration (FDA), U.S. Department of Agriculture (USDA) and Environmental Protection Agency (EPA).
The FDA is responsible for making sure that genetically modified foods are safe for human consumption. The agency has developed a policy statement and testing guidelines for these foods, as well as a consultation process to ensure that the guidelines are followed. FDA advisory committees are responsible for raising and addressing specific scientific questions about safety and other issues regarding genetically modified foods.
The FDA must approve a genetically modified food before it can be released for consumer purchase and consumption. These foods must meet the same safety standards as conventional foods. The FDA also ensures that no substantial differences, such as unexpected allergens or changes in nutritional value, exist in these foods. When differences exist, they must be properly identified on product labels or they will not be allowed to enter the United States market.
The USDA is responsible for making sure that genetically modified plants are safe to grow and do not harm other plants or the environment. USDA regulations on genetically modified plants involve inspections and compliance enforcement.
The EPA is responsible for making sure genetically modified plants are safe for humans, animals and the environment. This agency often focuses of the safety of genetically modified traits, such as plants modified to be more pest-resistant by producing substances toxic to insects.
Internationally, the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) have developed recommendations for genetic modification research and production. Recommendations differ, depending on whether potential allergens are involved, such as:
Genetically modified foods that contain known allergens. The FAO and WHO define any genetically modified foods that contain a known allergen as likely to be allergenic. They recommend the development of such products be stopped and the food refused entry into the marketplace.
Genetically modified foods not known to contain allergens. The FAO and WHO recommend detailed testing of genetically modified foods to determine whether any similarities exist to known allergens. If similarities are found, additional testing is recommended to determine whether people with known allergies show symptoms to the similar substance.
Once a genetically modified food product reaches the market, the FAO and WHO recommend that a self–reporting system be put in place to monitor any adverse health effects caused by consuming the genetically modified food. However, genetically modified ingredients or foods may be difficult to monitor (and any side effects tracked) if they are not required to be identified as such on their labels.
The FAO and WHO have no regulatory power over the research, development, distribution or monitoring of genetically modified foods. Compliance with their recommendations by agricultural producers or marketers is voluntary.
FDA health claims for genetically modified foods
The Food and Drug Administration (FDA) has determined that genetically modified foods currently available in the United States market are as safe as their conventional counterparts. These genetically modified foods have been found to pose no risks that their conventional counterparts do not. The FDA and other government agencies continue to monitor and regulate new genetically modified foods as they become available.
The FDA, U.S. Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) requested assistance from the National Academy of Sciences (NAS) to evaluate the safety of genetically modified foods. In response, the NAS conducted a study in 2000 to investigate potential concerns, including long-term health effects. This study did not find any health or safety hazards as a result of the consumption of genetically modified foods.
The American Dietetic Association (ADA) supports the FDA’s determination of the safety of genetically modified foods. The ADA encourages the availability of these foods and the continued education of consumers about the foods and technology used to produce them.
Questions for your doctor
Preparing questions in advance can help patients to have more meaningful discussions with health professionals regarding their conditions and concerns. Patients may wish to ask their doctor or registered dietitian the following questions related to genetically modified foods:
Do you consider genetically modified foods to be safe overall?
Do genetically modified foods pose a threat to me, considering my food allergies?
Do you know of any genetically modified foods that may let me eat foods that I could not otherwise eat because of my food allergies?
What brands of foods contain genetically modified ingredients?
Could genetically modified foods cause any interactions with my medications?
Are genetically modified foods from other countries as safe as those produced in the United States?
How long will a particular variety of genetically modified food remain fresh and safe to eat?
Could added nutrients in genetically modified foods help my nutritional deficiency?
Are organic foods a safe option if I want to avoid genetically modified foods?
