Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: thedoc on 12/07/2013 02:30:01
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Michael Veiga asked the Naked Scientists:
I know it's been estimated that the human body re-generates itself almost completely every 7 odd years or so (except, I hear, the brain which remains as it is - I never followed on with Biology).
If the adage that "You are what you eat" applies and if one were to *only* eat genetically modified foods for a period of 7 years, would that person's body be considered to be genetically modified as well by the end of the 7 years and what would the health implications of that be?
Many thanks for the feedback and awesome radio shows (http://www.thenakedscientists.com/HTML/podcasts/) (Radio 702)
Michael Veiga
Johannesburg
What do you think?
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Your body breaks down food into small units as part of digestion - individual amino acids, fats and sugars.
Your body then reassembles these small units into proteins, fats and sugars that make part of your body, based on the instructions already existing in your DNA.
So even if the food had been genetically modified to include proteins or sugars from a different species, they are still composed of the same basic units, and your body will still build them up into the same human proteins. So eating this kind of genetically modified food would not turn you into a "genetically modified human".
The major risks with genetically modified plants, animals and foods have to do with:
- The environment: Will these genetically modified varieties take over the ecosystem and displace the natural varieties?
- New Compounds: Is there a significant amount of a new substance in the plant which is not already "generally recognised as safe"? (eg because people are already eating large amounts of it in a different type of plant)
- Poisons: Will the previously-edible food now contain poisons which will kill or injure those eating it? (eg an apple expressing snake venom)
- Carcinogens: Some types of poisons can damage your DNA and cause cancer
In a sense, food-delivered carcinogens can modify your genes, in addition to the natural carcinogens such as radiation from rocks, carcinogens in existing foods and housing materials, plus artificial sources like cigarette smoke, X-Rays and chemicals in the environment. But carcinogens usually modify DNA in a way which causes random and destructive changes in random cells - not something that you would say turned you into a genetically modified human.
The challenge of regulating genetic engineering is to carefully evaluate any genuinely new substances, as these may interfere with your digestive system, or may include basic units which are not found in nature, and could potentially be poisons or carcinogens in your body.
Even if there are no genuinely new substances, testing must ensure that the introduced genes do not increase the level of poisons or carcinogens in edible parts of the plant, but only introduce characteristics which are helpful for humans (eg vitamins in golden rice) or good for the plant (eg drought tolerance or disease resistance).
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We normally eat all sorts of hybrids, from grapefruit to mule meat, yet nobody worries until the hybridisation is carried out purposively. I wonder why?
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We normally eat all sorts of hybrids, from grapefruit to mule meat, yet nobody worries until the hybridisation is carried out purposively. I wonder why?
Not only that but since everything we eat usually has DNA in it why aren't they also worried they'll turn into whatever animal they are eating, say a cow, or pig, or celery?
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The major exception is viruses - eg if you eat some Norovirus, a lot of cells in your gut will turn into Norovirus.
Fortunately, most people can clear this nasty little virus in a few days.