Nutrigenomics

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Description

A genetically modified food is a food product derived in whole or part from a genetically modified organism (GMO) such as a crop plant, animal or microbe such as yeast. Genetically modified foods have been available since the 1990s. The principal ingredients of GM foods currently available are derived from genetically modified soybean, maize and canola.

Some governments have a very strong mutual disagreement over the labelling and traceability requirements for GM food products. For example the European Union and Japan require labelling and traceability while regulatory agencies in the United States do not believe these requirements are necessary.

Background

Genetic engineering or genetic modification (GM) refers to technologies that allow single genes to be inserted or altered in living organisms such as animals, plants, or bacteria. Biotechnology, a more general term, refers to using living organisms or their components, such as enzymes, to make products that include wine, cheese, beer, and yogurt. Combining genes from different organisms is known as recombinant DNA technology, and the resulting organism is said to be "genetically modified," "genetically engineered," or "transgenic." Genetic engineering may more correctly be termed genetic re-contextualisation where genes can be transferred to new contexts in order to generate new characteristics. GM products (current or in the pipeline) include medicines (e.g. insulin, vaccines), foods and food ingredients, feeds, and fibers.

Locating genes for important traits such as those conferring insect resistance or desired nutrients has until recently been one of the most limiting steps for the use of genetic engineering for developing new or improved products for humankind. Genome sequencing and discovery programs for hundreds of different organisms are now generating detailed maps along with data analysis technologies to understand and use them.

Development and application

The origins of genetic engineering represent a series of sequential scientific advances from the Nobel prize-winning discovery of DNA to the production of the first recombinant E .coli bacteria.

The first commercially grown genetically modified food crop was a tomato created by Calgene called the FlavrSavr (1). Calgene submitted it to the U.S. Food and Drug Administration (FDA) for assessment in 1992; following the FDA's determination that the FlavrSavr was, in fact, a tomato, did not constitute a health hazard, and did not need to be labeled to indicate it was genetically modified, Calgene released it into the market in 1994, where it met with little public comment. Considered to have a poor flavor, it never sold well and was off the market by 1997. However, it had improved solids contents which made it an attractive new variety for canned tomatoes.

Transgenic crops are grown commercially or in field trials in over 40 countries and on 6 continents. In 2000, about 109.2 million acres (442,000 km) were planted with transgenic crops, the principal ones being herbicide- and insecticide-resistant soybeans, corn, cotton, and canola. Other crops grown commercially or field-tested are a sweet potato resistant to a US strain of a virus that affects one out of the more than 89 different varieties of sweet potato grown in Africa, rice with increased iron and vitamins such as golden rice, and a variety of plants able to survive extreme weather.

Between 1996 and 2001, the total surface area of land cultivated with GMOs had increased by a factor of 30, from 17,000 km (4.2 million acres) to 520,000 km (128 million acres). The value for 2002 was 145 million acres (587,000 km) and for 2003 was 167 million acres (676,000 km). Soybean crop represented 63% of total surface in 2001, maize 19%, cotton 13% and canola 5%. In 2004, the value was about 200 million acres (809,000 km) of which 2/3 were in the United States.

Four countries represent 99% of total GM surface in 2001: United States (68%), Argentina (22%), Canada (6%) and China (3%). It is estimated that 70% of products on U.S. grocery shelves include GM ingredients. In particular, Bt corn is widely grown, as are soybeans genetically designed to tolerate glyphosate herbicides.

The US Agriculture Department estimated that 38 percent of the 79 million acres (320,000 km) of corn planted in 2003 will be genetically engineered varieties as well as 80% of the 73.2 million acres (296,000 km) soybeans. The Grocery Manufacturers of America estimate that 75% of all processed foods in the U.S. contain a GM ingredient.

Future envisaged applications of GMOs include bananas that produce human vaccines against infectious diseases such as Hepatitis B, fish that mature more quickly, fruit and nut trees that yield years earlier, and plants that produce new plastics with unique properties. The next decade may see exponential progress in GM product development as researchers gain increasing access to genomic resources that are applicable to organisms beyond the scope of individual projects.

Benefits and risks

The majority of commercially available crops have an agronomic advantage like herbicide tolerance or insect resistance. These traits offer major benefits to the farmer. However, there are indirect benefits to the consumer from these traits: GM crops have been shown to contribute to significantly reduced greenhouse gas emissions from agricultural practices. This reduction results from decreased fuel use, about 1.8 billion liters in the past nine years, and additional soil carbon sequestration because of reduced ploughing or improved conservation tillage associated with biotech crops. In 2004, this reduction was equivalent to eliminating more than 10 billion kg of carbon dioxide from the atmosphere. (2)

Controversies surrounding GM foods and crops commonly focus on human and environmental safety, labeling and consumer choice, intellectual property rights, ethics, food security, poverty reduction, and environmental conservation.

Controversies over risks

Although no major health hazards have come to light since GM food was introduced 10 years ago, some fear for the long term health risks which GM could pose, or that the risks of GM have not yet been adequately investigated.

Quality of the arguments

In a recent article in the New York Review of Books ("Genes in the Food," June 21, 2001), Harvard biologist Richard Lewontin, a frequent critic of the political and scientific establishments, professes to be less concerned about his allergic reactions to GM food than about his "allergies to the quality of arguments about GM food."

And in the spirit of fairness, he provides examples of woefully flawed arguments on both sides of the debate. He marvels that the same people who rave about the dangers of GM food express no concern over the large number of diabetics taking twice-a-day doses of genetically engineered insulin. He also wonders why a physicist chooses to base her argument on Hindu scripture rather than rigorous analysis. He then chastises the proponents of GM food who celebrate the benefits of Vitamin A golden rice to the malnourished residents of developing countries, when they should know that the rice is actually rich in beta carotene, which is converted to vitamin A only when consumed by an otherwise well-nourished person. Golden rice alone will be of little value to the world's malnourished. And he points out that the purported precision of genetic engineering is exaggerated, because although it is possible to transfer a specific gene into a crop species, it is not possible to control the effect that process will have on regulatory genes.(3)

Dangerous Potatoes?

In August 1998 widespread concern, especially in Europe, was sparked by remarks by nutrition researcher, Dr Arpad Pusztai, regarding some of his research into the safety of GM foods.

Pusztai claimed his experiments showed that rats fed on genetically modified potatoes had suffered serious damage to their immune systems and shown stunted growth. He was criticized by leading British politicians, the majority of scientific peers with expertise in the area and by the GM companies because he announced his preliminary results in a television interview before the publication of the results in a scientific journal. When his studies were finally published (4) no evidence of stunted growth or damage to immune system was substantiated. The Royal Society's review of the Pusztai data was published 1 June 1999 and led to the conclusion that the study "is flawed in many aspects of design, execution, and analysis and that no conclusion should be drawn from it" Royal Society Report.

Dangerous Corn?

Another controversy recently arose around biotech company Monsanto's data on a 90-Day Rat Feeding Study on a strain of GM corn. In May 2005, critics of GM foods pointed to differences in kidney size and blood composition found in this study, suggesting that the observed differences called into question the regulatory doctrine of substantial equivalence - that GM food with similar proteins and toxins is deemed no different than conventional food, without further investigation of the effects of any other differences. Some argued that this study suggested human health might be affected by eating GM food.

However, the European Food safety authority has examined the Monsanto data and concluded that the observed small numerical decrease in rat kidney weights were not biologically meaningful, and the weights were well within the normal range of kidney weights for control animals. There were no corresponding microscopic findings in the relevant organ systems, and all blood chemistry and organ weight values fell within the "normal range of historical control values" for rats. Thus, the experts concluded that there were no effects on the functioning of kidneys in rats fed a diet of GM corn.(5)

New Allergens

GMOs that induce allergies have been produced in the laboratory. In 1993 Pioneer Hi-Bred International developed a soybean variety with an added gene from the Brazil nut.(6) This gene increased the levels of methionine, an amino acid commonly added to poultry feed, in the GM soybean. However, a preliminary Pioneer funded study by the University of Nebraska indicated that the added gene could cause allergic reactions in humans. The completed study, published in the New England Journal of Medicine (7), later confirmed the preliminary results. Pioneer discontinued further development of the GM soybean and had all material related to the modified soybeans destroyed. While this study indicates the possible risks of GM foods, some point out it establishes the commitment the developmental community has toward consumer safety as well as the competence of current safeguards. A similar result was published in November 2005, when a pest resistant field pea developed by the Australian CSIRO for use as a pasture crop was shown to cause an allergic reaction in mice. The immunologist who tested the pea noted that the episode illustrated the need for each new GM food to be very carefully evaluated for potential health effects.[6]

Environmental and Ecological impacts

As discussed above there is some evidence for positive impacts of the planting of GM crops on reduced green house gas emissions and pesticide loads in the environment. However, there has been controversy over the results of a farm-scale trial in the United Kingdom comparing the impact of GM crops and conventional crops on farmland biodiversity. Some claimed that the results showed that GM crops had a significant negative impact on wildlife.

Others pointed out that the studies showed that using herbicide resistant GM crops allowed better weed control and that under such conditions there were fewer weeds and fewer weed seeds. This result was then extrapolated to suggest that GM crops would have significant impact on the wildlife that might rely on farm weeds. In July 2005 the same British scientists showed that transfer of a herbicide-resistance gene from GM oilseed rape to a wild cousin, charlock, and wild turnips was possible.

rBGH (Bovine somatotropin

rBGH, a genetically engineered version of bovine somatotropin, is a hormone used to increase the production of milk in cows. Although it is used in the United States, it is banned in Canada, the EU, and Australia. rBGH is a frequent target of anti-GMO groups, who claim that there is evidence of an increased risk of disease in consumers of milk from rbST-injected cows.

Links

• Council for Responsible Genetics
• Scanned in Alternative Report by A. Pusztai (Rowett Research Institute)
• Slightly Breathless Discussion on Thorkild's Lectin Site

Attribution

• This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Genetically Modified Food".