GENETICALLY MODIFIED FOODS

-lakshmi

Genetically modified foods have become a controversial and current discussion among countries around the world. The article by Tom Nevin argues that the food production and distribution problems in Africa can be solved through genetically modified foods.

Genetic modification employs recombinant deoxyribonucleic acid (rDNA) technology to alter the genes of microorganisms, plants, and animals. Genetic modification is also called biotechnology, gene splicing, recombinant DNA technology, or genetic engineering.

Contemporary genetic modification was developed in the 1970s and essentially transfers genetic material from one organism to another. The modification of organisms has existed for centuries in the form of plant-breeding techniques (such as cross-fertilization) used to produce desired traits. With genetic modification, however, isolated genes are inserted into plants for a desired trait with a much quicker result than occurs when cross-breeding plants, which can take years. These isolated genes do not have to come from similar species in order to be functional; theoretically, genes can be transferred among all microorganisms, plants, and animals.

Examples of Genetically Modified Foods

Crops may be modified

· to increase resistance to pests and disease,

· increase adaptability to environmental conditions,

· improve flavor or nutritional profile,

· delay ripening, or

· increase shelf life.

Many common crops are genetically modified,

Corn, canola, flax, potatoes, tomatoes, squash, and soybeans.

· Corn and potatoes may be modified with a gene to produce an endotoxin that protects them against the corn-borer pest and the potato beetle, respectively.

· A soybean can be genetically modified with a gene from a bacterium to make it herbicide resistant. By inserting two genes from daffodil and one gene from a bacterium, rice can be enriched with beta-carotene.

In the early 1990s, genetically modified tomatoes (Flavr Savr by Calgene, Inc.) were deemed safe by the U.S., Canadian, and British governments and introduced into the market. These tomatoes were bred to stay firm after harvest so they could remain on the vine longer and ripen to full flavor. However, the tomatoes were so delicate that they were difficult to transport without damage, and the product was pulled from the market in 1997.

Recombinant bovine growth hormone (rBGH), also known as recombinant bovine somatotropin (rBST), is another example of a product that has not been very successful. In 1999 the United Nations Food Safety Agency unanimously declared the use of rBGH unsafe after confirming reports of excess levels of the naturally occurring insulin-like growth factor one (IGF-1), including its highly potent variants, in rBGH milk and concluding that these posed major risks of cancer.

Benefits of GM foods
There is a need to produce inexpensive, safe and nutritious foods to help feed the world’s growing population. Genetic modification may provide:

Better quality food
Higher nutritional yields
Inexpensive and nutritious food, like carrots with more antioxidants
Foods with a greater shelf life, like tomatoes that taste better and last longer
Food with medicinal benefits, such as edible vaccines - for example, bananas with bacterial or rotavirus antigens
Crops and produce that require less chemical application, such as herbicide resistant canola.

METHODS OF GENE TRANSFER

There are four primary methods of introducing an isolated gene into the host. These are:

1. Injection.

This is used primarily in animals. The new DNA is injected with a very small sharp needle into the nucleus of a single cell. This cell is usually a fertilised egg which can then be placed back in the female uterus where the injected cell is allowed to develop normally.

Unfortunately there is a high rate of failure when using this technique as cells infrequently take up and express the desired traits of the introduced DNA.

2. Biolistics.

Biolistics is used in the genetic modification of plants and involves shooting new genes into the potential host. Microscopic particles of gold or titanium are coated in the DNA sections which are to be introduced to the host. These are loaded into cartridges, similar to shotgun cartridges, which are then fired at the plant cells. The process relies on some of the microscopic particles entering this cell nuclei and their DNA coating combining with the plant chromosomes.

3. Vectors.

This method has the potential to be used in both plant and animal situations. It involves a bacteria or virus carrying a new gene into a cell. Using a modification of what is already happening in nature.

Example:

Common vectors in gene transfer between plants are Agrobacterium tumefaciens and Agrobacterium rhizogenes. These bacteria are usually found in the soil and if they infect plants will respectively cause galls or hairy roots through introducing some of their own DNA into the plant. The Agrobacterium transfer the DNA as a plasmid, a small circular piece of DNA, which is separate to the main bacterial chromosome. Genetic engineering makes use of this natural transfer of DNA through replacing a section of the bacteria's own DNA with a gene which scientists would like to introduce to a new host.

4. Protoplast transformation.

This is also commonly used in plants. The cellulose in the plant wall is dissolved away using enzymes leaving a protoplast. DNA can then be added to the protoplast which are then cultured on a growth media. This encourages the protoplast to regrow cell walls and eventually grow into a transgenic plant.

POTENTIAL BENEFITS OF GENE TECHNOLOGY

As previously mentioned the incentives for modifying organisms and especially food genetically, come in four main categories: better health, better products, better for the environment and better business.

Better Health

Genetically modified food has great potential as a relatively cheap source of human therapeutics, especially for the worlds poorer countries. Example:Researchers say that a banana or any fruit that is eaten raw could be genetically engineered to vaccinate against a wide range of diseases, providing a cheap source of protection. Food is also being modified to increase its nutritional value through altering the vitamin, mineral, carbohydrate, protein and fat profiles.

Better Products

Aside from health benefits, food can be improved through making the process of producing them easier for the farmer or grower. This improvement comes about through providing the plant with pest and disease resistance or increasing crop tolerance to a wider range of climates, or making the food more attractive to the consumer.Example:Crops are difficult to raise for different reasons, for example strawberries are not very frost hardy which makes them difficult to grow in certain climates. However a few years ago researchers discovered that the Arctic flounder produces an anti freeze to protect itself in Arctic waters. Research is now underway to introduce the anti freeze gene into fruits and vegetables like strawberries and soya beans which can be damaged or destroyed by frost. In the same way a gene from the common soil bacterium Bacillus thuringiensis, which is well known for its insecticidal properties can be incorporated into crops to make them more resistant to an insect attack.

From the consumers point of view food can be made more attractive in many ways. Possible examples include apples which don't go brown after a few minutes when you cut or bite into them, or onions that don't make your eyes water. Genetic engineering has also provided the possibility of raising crops with less use of chemical protectants such as herbicides and fungicides. This means less residue on the crops which is also makes this type of product more attractive to the consumer.

Better For The Environment

Growing genetically modified crops resistant to pests or diseases could reduce the reliance of agriculture on chemical sprays. While this makes the crop easier and cheaper to grow for the farmer, it also means that other indirect costs of spraying are eliminated, eg. knocking out all the beneficial insects and vertebrates through the use of chemical pesticides. Such resistance provides a good marketing opportunity whereby New Zealand may be able to enhance its "clean green" image.

The development of herbicide resistant crops generally involves transferring genes with resistance to environmentally friendly herbicides such as Glyphosate (Round Up). This allows growers to spray such herbicides without damaging the crop plant.

Safety of Genetically Modified Foods

Biotechnology has moved at such a rapid pace that the safety of genetically modified foods has become a concern. At this time, there are no long-term, large-scale tests to prove their safety—or lack thereof. Unforeseen consequences may arise from widespread genetic modification of the food supply, including:

•Allergic reaction. If a gene producing a protein that causes an allergic reaction is engineered into corn, for example, an individual who is allergic to that protein may experience an allergic reaction to the corn. Despite the fact that food-regulating agencies require companies to report whether altered food contains any suspect proteins, unknown allergens could potentially slip through the system.
Increased toxicity. Genetic modification may enhance natural plant toxins in unexpected ways. When a gene is switched on, besides having the desired effect, it may also stimulate the production of natural toxins.
Resistance to antibiotics. As part of the genetic modification of organisms, marker genes are used to determine if the desired gene has been successfully embedded. Marker genes typically provide resistance to antibiotics. Even though marker genes are genetically scrambled before use to reduce the potential for this danger, their use could contribute to the growing problem of antibiotic resistance.
Herbicide-resistant weeds. Once modified crops are planted, genes may travel via airborne, waterborne, or animal-borne seeds and pollen to weedy relatives, creating "superweeds" that are able to resist herbicides.
Harm to other organisms. Nontargeted species may inadvertently be harmed by a genetically modified plant producing endotoxins intended for a specific pest.

Typically, when a new crop is created, whether by traditional methods or genetic modification, breeders conduct field testing for several seasons to make sure only desirable changes occur. Appearance, growth characteristics, and taste of the food are checked, and analytical tests to determine changes in nutrients and safety are performed

EFFECTS OF GENETICALLY MODIFIED ORGANISMS

There are two diametrically opposed factions involved in this debate. Where possible balanced arguments have been presented.

Remember that the process of genetic modification has gone on for years through traditional plant and animal breeding techniques. The new genetic modification techniques can speed this up significantly. However because genetic engineering allows the transfer of a gene from any source, transgenic manipulations create safety, environmental, social and ethical concerns for many people.

Effects On People:Nutritional value of food

Genetically modifying foods can alter their nutritional value. This can have undesirable as well as beneficial effects. For example, researchers recently inserted a gene from a Brazil nut into soybean to try and improve its nutritional quality. However, in their testing, they found that the protein produced was the one responsible for the allergenicity of Brazil nuts. This allergenicity was also transferred to the soybeans. As a consequence, this soybean has never been marketed.

The nutritional value of food could also be diminished by inserted genes interrupting the function of other genes in a genetically modified plant. However, these should normally be detected during the experimental stage and/or testing.

Effects of marker genes

During genetic transformation not all cells will undergo the desired modification and it is therefore necessary to select those that have been changed. To do this a marker gene may be inserted along with the desired gene into the plant. A marker gene may confer resistance to specific antibiotics so that when these antibiotics are added to the growth medium, only those cells with the desired modification will grow.

Ethical considerations

Given genes can be transferred from any organism to another, some ethical considerations arise. For example when eating a vegetable will a vegetarian be concerned to learn that their broccoli contains DNA copied from a pig gene? If it were to contain copies of a human gene does this mean that the person eating it is a cannibal?

Effects In Agriculture:Use of herbicides and pesticide resistant genes

Tolerance of crops to herbicides, insects and pests and adverse climatic conditions are the most hotly researched characteristics of crops at present. However potential dangers are seen in a number of areas.

1. Pests and diseases can develop tolerance to the genetically conferred pest and disease resistance factors in the crop as a result of high selection pressure. This may mean that resistance

2. The genetically modified crop may interbreed with closely related weed type species, thus making these weeds difficult to control with some specific herbicides.

3. It is also thought that the genetically modified crop itself may become a weed in its own right due to its resistance to chemicals and potentially wide range of climate tolerance if it was allowed to escape the confines of the paddock.

Long term risks

Long term consequences cannot be completely predicted. While risk assessment can be a relatively comprehensive process, commercial needs also push towards GMO's available being released as quickly as possible.

Nuclear technology has had some ghastly health consequences for those working with it, with problems ranging from development of cancer to birth defects. Those problems arose due to a lack of knowledge at the time of the long term effects these technologies could have on the people and the environment.

What foods can you create by genetic modification?
Sweet corn, rice, tomatoes and rape plants are just some examples of the many food products that have already been genetically modified. Many more are on the way. Scientists worldwide are working on the development of a variety of different genetically modified crops.

Not all corn, rice, tomato and rape plants are genetically modified. Yet, genetically modified (GM) crops may be found in different places around the world. However GM rice and tomatoes have not yet been approved for sale Europe.

Genetic modification is complex and takes many years. It is not yet possible to genetically modify everything. Here are 4 examples of the most well known genetically modified crops

Which genetically modified foods are sold now - and where are they grown? In Europe today 3 genetically modified crops are permitted (June 2002). These are:

Soya beans - resistant to crop spray
Sweet corn - resistant to crop spray and produce insecticide
Rape plants - resistant to crop spray and does not produce pollen (therefore it cannot pollinate other plants)

All 3 plants have been approved for import and food produce manufacture. Sweet corn and rape plants are also approved for cultivation.

Genetically modified chicory lettuce is also approved for cultivation. But the lettuce is solely used in processing work and not as food produce.

4 examples of genetically modified crops
Pesticide resistant rape plants
Scientists have transferred a gene to the rape plant which enables the plant to resist a certain pesticide.

Advantages:

The farmer can grow a larger crop because it is easier to fight pests.
In some cases the farmer can use a more environmentally friendly crop spray.
The farmer can also protect the environment by using less crop spray.

Disadvantages:

Genes from the genetically modified rape crop could be transferred to the pests. The pests then become resistant to the crop spray and the crop spraying becomes useless.
Rape plants can pollinate weeds .Corn, soya beans and sugar cane have also been genetically modified .

Insecticide sweet corn
Scientists have genetically modified sweet corn so that it produces a poison which kills harmful insects. This means the farmer no longer needs to fight insects with insecticides. The genetically modified corn is called Bt-corn, because the insect-killing gene in the plant comes from the bacteria Bacillus thuringiensis.

Advantages:

The farmer no longer has to use insecticide to kill insects, so the surrounding environment is no longer exposed to large amounts of harmful insecticide.
The farmer no longer needs to walk around with a drum of toxic spray wearing a mask and protective clothing.

Disadvantages:

This type of genetically modified corn will poison the insects over a longer period than the farmer who would spray the crops once or twice. In this way the insects can become accustomed (or resistant) to the poison. If that happens both crop spraying and the use of genetically modified Bt-corn become ineffective.
A variety of insects are at risk of being killed. It might be predatory insects that eat the harmful ones or, perhaps attractive insects such as butterflies. Cotton and potatoes are other examples of plants that scientists have , genetically modified to produce insecticide.

Golden rice
Golden rice is genetically modified rice that now contains a large amount of A-vitamins. Or more correctly, the rice contains the element beta-carotene which is converted in the body into Vitamin-A

Beta-carotene gives carrots their orange colour and is the reason why genetically modified rice is golden. For the golden rice to make beta-carotene three new genes are implanted: two from daffodils and the third from a bacterium.

Advantages:

The rice can be considered a particular advantage to poor people in underdeveloped countries. They eat only an extremely limited diet lacking in the essential bodily vitamins. The consequences of this restricted diet causes many people to die or become blind. This is particularly true in areas of Asia, where most of the population live on rice from morning to evening.

Disadvantages:

Critics fear that poor people in underdeveloped countries are becoming too dependent on the rich. By making the plants sterile these large companies can prevent farmers from growing plant-seed for the following year - forcing them to buy new rice from the companies.
Some opposers of genetic modification see the "golden rice" as a method of making genetic engineering more widely accepted. Opponents fear that companies will go on to develop other genetically modified plants from which they can make a profit. A situation could develop where the large companies own the rights to all the good crops.

Long-lasting tomatoes
Long-lasting, genetically modified tomatoes came on to the market in 1994 and were the first genetically modified food available to consumers. The genetically modified tomato produces less of the substance that causes tomatoes to rot, so remains firm and fresh for a long timE

.Strawberries, pineapples, sweet peppers and bananas have all been genetically modified by scientists to remain fresh for longer.

http://www.bionetonline.org/English/Content/ff_cont3.html

HOW IS SAFETY ASSESSED?

Safety assessment of GMO's is based on the principle of "Substantial Equivalence" which is promoted by the OECD, FAO and WHO. Substantial equivalence compares the GMF to the food from which it was derived (the parent). This is a comparative approach leading to one of three results.

1. The product is substantially equivalent to the parent

2. The product is substantially equivalent to the parent except for defined differences

3. The product is not substantially equivalent to the parent

This approach gives a guide as to how in depth any safety assessment must be. It is not an assessment in itself. Depending on the extent of the difference between the GMO and its parent, the product then undergoes an evaluation looking at the following areas.

1. General safety.

- Sources of genetic material.

- Fate of introduced proteins during processing and/or digestion.

- Presence of allergens and/or enhanced levels of natural toxicants or anti-nutritive factors.

2. Toxicology.

- Any changes in levels of pre-existing natural toxicants as a consequence of genetic modification.

- Toxic screening of any new or substantially modified components.

3. Nutrition.

- Any change in nutritional composition especially in key elements which have significant impacts on the whole diet.

- Any changes in bioavailability of nutritional components.

Genetically modified carrots provide more calcium for osteoporosis patients

A specially developed carrot has been produced to help people absorb more calcium. Researchers studied the calcium intake of humans who ate the carrot and found a net increase in calcium absorption. Adding this carrot to the diet can help prevent such diseases as osteoporosis.

The study conducted by researchers at Baylor College of Medicine in Houston and the Vegetable and Fruit Improvement Center at Texas A&M University, and the report appears in the Proceedings of the National Academy of Sciences.

A 100-g portion is a rich source of vitamin A (5-10 mg carotene); provides 2.5 g of dietary fibre and supplies 35 kcal (145 kJ) generally.

""These carrots were grown in carefully monitored and controlled environments," said Hirschi. "Much more research needs to be conducted before this would be available to consumers."

- Baylor College of Medicine

Source: Baylor College of Medicine, USA

(Published at www.healthnewstrack.com on January 17, 2008)

Currently, toxicity in food is tested by chemical analysis of macro/micro nutrients and known toxins. Better diagnostic methods are needed, such as mRNA fingerprinting, proteomics and secondary metabolite profiling.

Safety tests on commercial GM crops

GM tomatoes: The first and only safety evaluation of a GM crop, the FLAVR SAVR^TM tomato, was commissioned by Calgene, as required by the FDA. This GM tomato was produced by inserting kan^r genes into a tomato by an 'antisense' GM method. The results claim there were no significant alterations in total protein, vitamins and mineral contents and in toxic glycoalkaloids.⁹ Therefore, the GM and parent tomatoes were deemed to be "substantially equivalent."

GM maize: Two lines of Chardon LL herbicide-resistant GM maize expressing the gene of Phosphinothricin Acetyltransferase Enzyme (PAT-PROTEIN) before and after ensiling showed significant differences in fat and carbohydrate contents compared with non-GM maize and were therefore substantially different. Toxicity tests were only performed with the PAT-PROTEIN even though with this the unpredictable effects of the gene transfer or the vector or gene insertion could not be demonstrated or excluded.

Compositional studies

GM soybeans: To make soybeans herbicide resistant, the gene of 5-enolpyruvylshikimate-3-phosphate synthase from Agrobacterium was used. Safety tests claim the GM variety to be "substantially equivalent" to conventional soybeans.

GM potatoes: There is only one peer-reviewed publication on GM potatoes that express the soybean glycinin gene. However, the expression level was very low and no improvements in the protein content or amino acid profile were obtained.

GM rice: The kind that expresses soybean glycinin gene (40-50 mg glycinin/g protein) has been developed and is claimed to contain 20% more protein. However, the increased protein content was probably due to a decrease in moisture rather than true increase in protein putting a question mark over the significance of this GM crop.

Conclusion

Genetically-modified foods have the potential to solve many of the world's hunger and

malnutrition problems, and to help protect and preserve the environment by increasing

yield and reducing reliance upon chemical pesticides and herbicides. Yet there are many

challenges ahead for governments, especially in the areas of safety testing, regulation,

international policy and food labeling. Many people feel that genetic engineering is the

inevitable wave of the future and that we cannot afford to ignore a technology that has

such enormous potential benefits. However, we must proceed with caution to avoid causing

unintended harm to human health and the environment as a result of our enthusiasm

for this powerful technology.

JOURNAL ARTICLES:

The Plant Journal

Volume 27 Issue 6 Page 503-528, September 2001

Assessment of the food safety issues related to genetically modified foods

Harry A. Kuiper Gijs A. Kleter, Hub P. J. M. Noteborn and Esther J. Kok.National Institute for Quality Control of Agricultural Products (RIKILT), Wageningen University and Research Centre, PO Box 230, NL 6700 AE Wageningen, the Netherlands

Abstract

Summary

. Substantial equivalence is a starting point in the safety evaluation, rather than an endpoint of the assessment. Consensus on practical application of the principle should be further elaborated. Experiences with the safety testing of newly inserted proteins and of whole genetically modified foods are reviewed, and limitations of current test methodologies are discussed. The development and validation of new profiling methods such as DNA microarray technology, proteomics, and metabolomics for the identification and characterization of unintended effects, which may occur as a result of the genetic modification, is recommended. The assessment of the allergenicity of newly inserted proteins and of marker genes is discussed. An issue that will gain importance in the near future is that of post-marketing surveillance of the foods derived from genetically modified crops. It is concluded, among others that, that application of the principle of substantial equivalence has proven adequate, and that no alternative adequate safety assessment strategies are available.

Screening of transgenic proteins expressed in transgenic food crops for the presence of short amino acid sequences identical to potential, IgE – binding linear epitopes of allergens

Gijs A Kleter Ad ACM Peijnenburg

RIKILT Institute of Food Safety, P.O. Box 230, NL 6700 AE Wageningen, The Netherlands



Published:	12 December 2002

Abstract

Transgenic proteins expressed by genetically modified food crops are evaluated for their potential allergenic properties prior to marketing, among others by identification of short identical amino acid sequences that occur both in the transgenic protein and allergenic proteins. A strategy is proposed, in which the positive outcomes of the sequence comparison with a minimal length of six amino acids are further screened for the presence of potential linear IgE-epitopes. This double track approach involves the use of literature data on IgE-epitopes and an antigenicity prediction algorithm.

Results

Thirty-three transgenic proteins have been screened for identities of at least six contiguous amino acids shared with allergenic proteins. Twenty-two transgenic proteins showed positive results of six- or seven-contiguous amino acids length. Only a limited number of identical stretches shared by transgenic proteins (papaya ringspot virus coat protein, acetolactate synthase GH50, and glyphosate oxidoreductase) and allergenic proteins could be identified as (part of) potential linear epitopes.

Environ Health Perspect. 2003 June; 111(8): 1114–1121.

Research Article

Clinical and laboratory investigation of allergy to genetically modified foods.

Jonathan A Bernstein, I Leonard Bernstein, Luca Bucchini, Lynn R Goldman, Robert G Hamilton, Samuel Lehrer, Carol Rubin, and Hugh A Sampson

Department of Medicine, University of Cincinnati, Cincinnati, Ohio, USA.

Abstract

Genetic engineering facilitates the transfer of genes among organisms. Generally, only minute amounts of a specific protein need to be expressed to obtain the desired trait. Food allergy affects only individuals with an abnormal immunologic response to food--6% of children and 1.5-2% of adults in the United States. Not all diseases caused by food allergy are mediated by IgE. A number of expert committees have advised the U.S. government and international organizations on risk assessment for allergenicity of food proteins. These committees have created decision trees largely based on assessment of IgE-mediated food allergenicity. Difficulties include the limited availability of allergen-specific IgE antisera from allergic persons as validated source material, the utility of specific IgE assays, limited characterization of food proteins, cross-reactivity between food and other allergens, and modifications of food proteins by processing. StarLink was a corn variety modified to produce a (Italic)Bacillus thuringiensis(/Italic) (Bt) endotoxin, Cry9C. The Centers for Disease Control and Prevention investigated 51 reports of possible adverse reactions to corn that occurred after the announcement that StarLink, allowed for animal feed, was found in the human food supply. Allergic reactions were not confirmed, but tools for postmarket assessment were limited.

esearch Section

Substantial equivalence of antinutrients and inherent plant toxins in genetically modified novel foods

W. K. Novak and A. G. Haslberger ^*
Institute for Nutritional Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
Accepted 22 January 2000. Available online 25 May 2000.

Abstract

For a safety evaluation of foodstuff derived from genetically modified crops, the concept of the substantial equivalence of modified organisms with their parental lines is used following an environmental safety evaluation. To assess the potential pleiotropic effect of genetic modifications on constituents of modified crops data from US and EC documents were investigated with regard to inherent plant toxins and antinutrients. Analysed were documents of rape (glucosinolates, phytate), maize (phytate), tomato (tomatine, solanine, chaconine, lectins, oxalate), potato (solanine, chaconine, protease-inhibitors, phenols) and soybean (protease-inhibitors, lectins, isoflavones, phytate). The results presented indicate that the concept of the substantial equivalence is useful for the risk assessment of genetically modified organisms (GMOs) used for novel foods but possible environmental influences on constituents of modified crops need more attention.

Bibliography

Institute of Food Technologists (2000). "Genetically Modified Organisms: A Backgrounder." Food Technology 54:42–45.

International Food Information Council (2000). Food Biotechnology: A Communications Guide to Improving Understanding. Washington, DC: Author

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2. www.naturopathy-uk.com | info@naturopathy-uk.com

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4. http://www.foei.org/

5. http://www.guardian.co.uk/

6. http://www.percyschmeiser.com/

7. http://www.biointegrity.org/health-risks/health-risks-ge-foods.htm

8. http://www.geneticengineering.org/dna7/default.htm