Genetic Modification of Food Crops and Their Effects on Human Health


Controversy has arisen around the possibility of labeling genetically modified food products. Non-governmental organizations (NGO's), like Greenpeace andFriends-of-the-Earth, have called for labels on GM foods to give consumers the right to chose to consume these products. They point out that GM technology has not been proved safe for humans. However, microbial contamination of foods may, in fact, be a greater food safety concern than GM content (Huffman 2004).

Labeling has its drawbacks (See Economic Efficiency) and some people believe they would be ineffective and the effect on the economy and consumer choice are potentially negative (Huffman 2004). The process is associated with real costs that will get passed on to the consumer. Currently, the federal government only requires labeling for products that possess distinctive characteristics different from the non-GM food (Huffman 2004). However, only the company itself is responsible for segregating the two types of crops and reporting the presence or absence of genetically modified organisms in their products. The European Union adopted food labels in 1997 (Huffman 2004). See Economic Efficiency for more information on this decision.

The WHO has identified potential health risks associated with genetically modified organisms. Allergenicity, gene transfer and out-crossing are the three main human health concerns. To avoid allergenicity, protein products from allergenic plants are not transferred unless the transferred protein can be proven to be non-allergenic(WHO 2010). This may mean that scientists may be able to create non-allergenic foodstuffs. In other words, the reaction-causing protein in peanuts could be removed.

Gene transfer of GM plant genes into the human body or bacteria in the human body is unprecedented and could have possible adverse affects on human health. This would also be particularly potent if antibiotic resistant genes, used in the bacteria used in modification were transferred. Probability is low, but with many people and many GM crops a FAO/WHO expert panel has recommended the use of technology without antibiotic resistance genes (WHO 2010).

Outcrossing is the movement of genes from GM plants into conventional crops or related species in the wild. This has ramifications on both human health and the environment. This concern is also related to the mixing of of conventional seeds and GM crops, which could potentially have an effect on food safety and food security. This is very real risk, in fact GM maize approved for feed use only was found in maize products marked for human consumption in the United States of America (WHO 2010). Strategies exist that hope to reduce mixing, including separation of fields. 

Food Safety Concerns

The USDA, for the most part, allows individual companies to police themselves. That is to say, engineered crops that are not significantly different from their regular counterparts need not see careful investigation. To date, no serious food safety concerns have risen as a result of GM. Salmonella and E. coli outbreaks, and the like, are not a result of genetic modification, per se. But this is not to to say that there are no food safety concerns. In November 2009, Monsanto pulled two of their GM corn varieties. Monsanto informed the European Food Safety Autority (EFSA) that it no longer wishes to pursue approval of maize LY038 and MON810, designed to accelerate the growth rate of animals. It is said that they did this after a request from European regulators for additional research and safety data (John, 2009). Both Monsanto and the EFSA have no mention of this on their website. Scientists in New Zealand scrutinized the corn varieties, that were approved in 2005 in the United States for cultivation, animal feed, and human use (John, 2009). Concerns are linked to toxins and possible allergies and cancer links. Test plantings occurred in the USA, but no commercialization has appeared to have occurred. Monsanto is alleged to have failed to test cooked corn, the whole GM plant and not just the food. They also did not test by mixing GM strains and only used short feeding trials, among other concerns (John, 2009).

The Italian government's Institute on Food and Nutrition completed a study that observed significant disturbances in the "immune system of young and old mice that have been fed the GM maize MON 810" (ISIS 08). The Austrian government showed that GM Maize reduces fertility and deregulatory genes in mice. Mice have long been studied to predict effects on humans. The study in Italy was performed on GM maize with the toxin Cry1Ab, which is used as a pesticide. Diets used in testing contained 50% MON 180 and non-GM maize (ISIS 08). There was no difference in mean body weight or food consumed among the mice (ISIS 08). However, the number of T and B cells and of other immune system proteins were different in the gut, spleen and blood (ISIS 08). The cytokines involved in allergic responses were all increased in concentration in the blood. A resistance to this change was observed after a certain number of days, in the young mice tested (ISIS 08).

Antibiotic Resistance

Antibiotic resistance is another closely related human health concern. Marker genes bearing antibiotic resistance are used in the target organism. This method helps prove modified genes were indeed transferred. There are concerns that breeding this antibiotic resistance into widely consumed crops may have unintended consequences for the environment and for humans and animals consuming the crops (Uzogara 2000). According to a recent report from the British Medical Association antibiotic resistant marker genes in certain crops could be transferred to disease causing microbes in the gut of humans or animals consuming GM foods. (E. coli is a microbe in the cow's intestine that when ingested by humans causes a devastating illness). This development could result in antibiotic resistant microbes in the population, and "contribute to the growing health problem of antibiotic resistance (Uzogara 2000).

Allergenicity from GM Foods

Another potential risk of genetically modified organisms is that a transfer of allergenic properties of the donor source to a recipient plant or animals may occur. Microorganisms with unknown or untested allergenic potential are used. Genes from non-food sources could trigger reactions or exacerbate existing ones. The Pure Food Campaign is an advocacy group interested in this topic. Pioneer Hibred International incorporated Brazil nut genes into soybeans to increase protein content of anima (Uzogara 2000). This modification caused allergic reactions to consumers allergic to the Brazil Nut and was recalled (Uzogara 2000). The FDA does not require food companies to demonstrate the potential allergens are not contained in any of their modified foods. The FDA and EPA require companies to report presence of problem proteins; there is a concern unknown allergens could be released into the market undetected (Uzogara 2000). Efforts, nonetheless, are underway in the production of allergen free rice and peanuts. 

Improvement by Genetic Modification of Nutritional Value of Food

In a scientific article soon to be released, scientists in Kyoto, Japan have been working on improving the nutritional value of rice. An important grain for countless consumers worldwide, this improvement may have important nutritional benefits for rice consumers. They altered a beta subunit  in rice with strong phagocytosis-stimulating activity, which is the uptake of nutrients from the grain in the digestive system.

Recently, GM soy containing omega-3 oils has been approved by the US Food and drug Administration. Companies can begin testing it in products such as margarine. Omega 3-fatty acids have been shown to decrease heart attack and stroke risk by 36%. Lack of omega-3 in the diet is the sixth leading cause of preventable deaths in the US, according to a Harvard School of Public Health study. GM canola plants that produce similar oils has been developed. Some plants naturally produce ALA (alpha-linolenic acid), a omega-3 fatty acid. But only a small fraction can be used by the body. Because fish are the principal source of omega-3 afatty acids, this development could have positive affects on fish stocks. The need for overfishing could be drastically reduced by this development. (Coghlan 2009)

Nutrients and health benefits have been implemented by genetic modification. Genetic engineering can be used to "increase levels in food of minerals and naturally occurring anti-oxidant vitamins (carotenoids, flavonoids, vitamins A, C, and E)" (Uzogara 2000). In other words, humans could soon become much more efficient at getting all the vitamins and minerals they need, now without supplements. These compounds have been shown to slow or shut down biological oxidation, a reaction that promotes cancer growth and development, heart disease, and blindess (Uzogara 2000). Biotechnology could place vital nutrients into stable flood plants, especially potent in areas of the world fighting nutrient deficiencies, like Africa (Uzogara 2000).

Protein quality and carbohydrate content can also be increased by genetic modification. This could mean improved essential amino acid content of crops, like increases in methionine and lysine. Efforts are underway to remove the beany flavor of soybeans through the removal of lipoxygenases (Uzogara 2000). Tomatoes that can more easily be made into pastes and sauce have been produced. Potatoes can be engineered to be made more useful for making French Fries. Monsanto has done this through the insertion of a starch producing gene from bacteria into the potato plant (Uzogara 2000). 

Crops in developing countries have been engineered to help improve nutritional content. Cassava has been recently bioengineered to have higher nutrient value and the destructive mosaic virus (Uzogara 2000). Rice has been modified to make a vitamin A precursor and to accumulate much more iron. Work is also being done to produce insulin in plants. Insulin would then be ingested by diabetics in the food they eat (Uzogara 2000). 

Edible Vaccines and Drugs

 Soon, one may see bananas that produce human vaccines against infectious diseases such as hepatitis B, fruit tress that yield sooner, and plants that produce "new plastics with unique properties." (Human Genome Project). Tropical crops eaten raw, like the banana, have been "bioengineered to produce proteins that can be used against hepatitis, rabies, dysentry, cholera, diarrhea, or other gut infections prevalent in developing countries" (Uzogara 2000). The amazing ramifications of this development are readily apparent; these foods can be distributed at low cost in places where resources and medical infrastructure are lacking.

"20 QUESTIONS ON GENETICALLY MODIFIED (GM) FOODS." World Health Organization (WHO). 2010. 17 April 2010. <>

Coughlan, A. "US FDA says omega-3 oils from GM soya are safe to eat." 2009. 17 April 2010. <

Ho, MW. "GM Maize Disturbs Immune System of Young and Old Mice" 2008. Institute of Science in Society. 19 Nov 2008. 17 April 2010. < System.php>

Huffman, Wallace. "Production, Identity Preservation, and Labeling in a Marketplace with Genetically Modified and Non-Genetically Modified Foods." 2004.  Plant Physiology. 134:3-10

John, Brian. "Monsanto pulls GM corn amid serious food safety concerns." 9 Nov. 2009. GM Free Cymru. 17 April 2010. <>

"Sustainable Agriculture and Genetic Engineering." 2009. Greenpeace. 17 April 2010. <>

 Uzogara, SG. "The impact of genetic modification of human foods in the 21st century." 2000. Biotechnology Advances. 18 (3): 179-206.  

“What are Genetically Modified (GM) Foods?" Human Genome Project, US Department of Energy Office of Science. 5 Nov 2008. 17 April 2010 < 


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