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Nutrition 3701



Lecture 3701-lecture 26 


10 November 2010                   


Genetically modified organisms (GMOs)


Foods that have had their genomes modified so as to increase their resistance to disease, competing plants,  drought or insects


- can also be used to increase components of food –increased amounts of the 6 nutrient classes









Specific carbohydrates, lipids, proteins, vitamins, minerals


-can be used to improve appearance  or taste of food

                        Eg softening enzyme in tomatoes- blocked by antisense technology


What would be the advantages of genetic engineering?


Engineer strains of organisms that have been engineered to produce substances that occur in nature in small amounts or not at all


Bacteria –production of rennin-used to curdle milk to make cheese- rennin comes from lining of calves stomachs- but this is expensive- so put rennin gene in bacteria and this produces the rennin in large scale amounts and fairly cheaply


Cotton plants and other plants that produce its own herbicide-

Limitations :      include a lack of control of pests not killed by the plant herbicide

                                                            High cost of transgenic plants

                                                            Development of resistance by pests


Growth enhancing gene in salmon- market ready faster


Creation of pharmaceutical producing plants and animals

                        Nourishment and drugs vaccines all from plants and animals


Economical way of producing food, drugs and vaccines for isolated villages for example


Rice and beta carotene- gene for beta-carotene put in rice so that people can avoid blindness (remember that vitamin A is derived from beta carotene and that vitamin A is responsible for maintaining tissue quality- in the case of vitamin A deficiency it is the cornea( piece of clear tissue on the front of the eye that loses function due to tissue damage to the cornea brought on by the deficiency of vitamin A)


Issues of nutrients and safety


This is the focus of the debate between organic and genetically modified foods



                Organic camp says that there products are safer (the all-natural argument) and that they contain more nutrients than                   conventional foods because organic compost fertilizes plants with more vitamins and trace minerals than those                   provided by synthetic chemical fertilizers


However plants do not take up vitamins from either compost or other fertilizers-rather through their roots they absorb only water  and elements making vitamins in the tissues of the plants


Trace minerals do get into plants and trace minerals are richer in organic compost compared to synthetic fertilizers


As to nutrient content of organic foods versus conventional foods only trace amounts of extra nutrients and the extra amounts were not significant to human health


        GMOs also do not have significant greater nutrient value than either organic or conventional foods-therefore there is no              health advantage


However can supplement or add additional vitamins minerals, proteins, carbohydrates and lipids into various products by virtue of genetic modification- leads to elimination of human error_how


Pesticides also occur in organic foods- drifted over from fields sprayed with pesticides


                                    -pesticide residue limits are set well below threat to human health so organic people do not really have                                              an argument about the risk of pesticides

                        -washing of foods dramatically lowers the risk of pesticides

                                    -plant pesticides are denatured in the human body and therefore bioengineering is alright-but what                                          about allergy or intolerance?





Potential risks for GMOs


Unforeseen events- are the central issue with GMOs- this is why the Europeans refer to them as Frankenstein foods or Frankenfoods



                        Creation of unique proteins never encountered by human body


                        Ethical and moral issues-playing God


Imperfect technology- If a disease producing organism is used to donate genetic material to a rDNA food then it must be shown that this is not a problem-ie no dangerous characteristic comes from the disease producing organism has also entered the food




                        Environmental concerns

                        Genetic pollution

outcrossing to non GMO plants


But this can be overcome by terminator technology where offspring of outcrossed plants automatically die- such terminator technology  prevents GMO genome from getting in to weeds  and also does not allow farmers to save fertile seeds from their own harvests from year to year- thus poor substistence farmers would be hardest hit by all this


One alternative possibility would be to genetically modify only genes of structures (eg chloroplasts whose genetic material passes through female liness- remember only male genes are carried in the pollen


Possibly other animals may be affected by dining on transgenic plants

                        Crop vulnerability-outcrossing

                        Loss of gene pool-variabilty is reduced

                        Profit motive-companies are just in this for the money

Unproven safety- DNA- fear of incorporation into our genome

Increased allergens-new proteins being formed

                        Decreased nutrients-long storage will decrease nutrients

No product tracking- who knows where things come from-no labeling and identification to source

                        Over use of herbicides-to combat herbicide resistance of GMOs

                        Increased consumption of pesticides- cannot wash-off pesticides

Lack of oversight-no one is regulating the industry and concerned about the consumer


Risks of organic foods


                        unpasteurised organic juices milk or cheeses

                        tend to spoil faster- no preservatives


Benefits of GMOs



Safety-GMOs are only modified in a minor way


Boost economy


Ethical and moral issues-benefits of feeding more people- Bumper crops on far fewer acres with less erosion and use of water and use of pesticides and herbicides


Genetic engineering could save rainforest-less acreage needed to supply a living to farmers

Genetic improvements are more likely to benefit than harm

Improved crop resistance-disease, drought, plant competitors, and insects

Gene pool preserved- in laboratories

Control of allergens-most allergens are known and no new ones are being created in GMOs

Increased nutrients – eg beta carotene in rice

Excellent product tracking-easy to regulate

Conservative use of herbicides-not trying to overcome GMO herbicide capability

Reduced  use of pesticides-pesticide resistance built in

Sufficient regulation and rapid response-good tracking and regulations laid down-