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It's a popular public sentiment that - GM foods like tomatoes (flavr savr) will affect our health.. Is there any logical scientific explanation behind this?

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    $\begingroup$ I don't see a personal health question here. The question might not be very profound otherwise though. $\endgroup$ – Chris Nov 10 '14 at 6:51
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    $\begingroup$ this q. is legitimate...slightly debatable...but not at all a personal medical q.... $\endgroup$ – souvik bhattacharya Nov 10 '14 at 7:43
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    $\begingroup$ I agree with the above comments. However, I think this question would be a better fit on skeptics.SE. By doing a simple search for "GMO" on skeptics.SE you will get several interesting hits. The question might be considered as a duplicate of other questions on skeptics.SE. I would tend to think this question should be answered following these guidelines $\endgroup$ – Remi.b Nov 10 '14 at 13:30
  • $\begingroup$ Would improving health count? If GMOs provide larger yields or better nutrient content with less dependence on pesticides or herbicides those would all be good things. Most of the questions I see about GMO only ask about potential negative outcomes. $\endgroup$ – user137 Nov 10 '14 at 17:12
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It's a popular public sentiment that - GM foods like tomatoes (flavr savr) will affect our health.. Is there any logical scientific explanation behind this?

GM organisms can have different genes and gene expression than natural ones, so they can create more protein or different proteins. Proteins can be toxic, can cause allergy and can catalyze reactions which can lead to toxic products.

To create a GM plant you need dollar millions, so it is not a cheap business. The GMO food regulations are very strict (at least in the EU), so it is unlikely that you will eat a GMO which contains toxic compounds.

Whereas food safety organizations find nothing inherently unsafe in the process of genetic engineering, they note that new plant characteristics developed in the next wave of agricultural biotechnology could present new risks. At the same time, future generations of biotechnology may well provide food products with higher vitamin or protein content and lower allergenicity, yielding benefits to food consumers.

Despite all the effort to make GMO foods safe, there are issues:

Pesticides associated to genetically modified foods (PAGMF), are engineered to tolerate herbicides such as glyphosate (GLYP) and gluphosinate (GLUF) or insecticides such as the bacterial toxin bacillus thuringiensis (Bt). The aim of this study was to evaluate the correlation between maternal and fetal exposure, and to determine exposure levels of GLYP and its metabolite aminomethyl phosphoric acid (AMPA), GLUF and its metabolite 3-methylphosphinicopropionic acid (3-MPPA) and Cry1Ab protein (a Bt toxin) in Eastern Townships of Quebec, Canada. Blood of thirty pregnant women (PW) and thirty-nine nonpregnant women (NPW) were studied. Serum GLYP and GLUF were detected in NPW and not detected in PW. Serum 3-MPPA and CryAb1 toxin were detected in PW, their fetuses and NPW. This is the first study to reveal the presence of circulating PAGMF in women with and without pregnancy, paving the way for a new field in reproductive toxicology including nutrition and utero-placental toxicities.

The study of combined effects of pesticides represents a challenge for toxicology. In the case of the new growing generation of genetically modified (GM) plants with stacked traits, glyphosate-based herbicides (like Roundup) residues are present in the Roundup-tolerant edible plants (especially corns) and mixed with modified Bt insecticidal toxins that are produced by the GM plants themselves. The potential side effects of these combined pesticides on human cells are investigated in this work. Here we have tested for the very first time Cry1Ab and Cry1Ac Bt toxins (10?ppb to 100?ppm) on the human embryonic kidney cell line 293, as well as their combined actions with Roundup, within 24?h, on three biomarkers of cell death: measurements of mitochondrial succinate dehydrogenase, adenylate kinase release by membrane alterations and caspase 3/7 inductions. Cry1Ab caused cell death from 100?ppm. For Cry1Ac, under such conditions, no effects were detected. The Roundup tested alone from 1 to 20 000?ppm is necrotic and apoptotic from 50?ppm, far below agricultural dilutions (50% lethal concentration 57.5?ppm). The only measured significant combined effect was that Cry1Ab and Cry1Ac reduced caspases 3/7 activations induced by Roundup; this could delay the activation of apoptosis. There was the same tendency for the other markers. In these results, we argue that modified Bt toxins are not inert on nontarget human cells, and that they can present combined side-effects with other residues of pesticides specific to GM plants.

Though GM crops promises to meet the world's food need and eliminate the world hunger and starvation, the potent harmful effects cannot be overlooked and these need to be taken seriously. The long term impact on the society cannot be overruled as it includes the health risk of all the people involved be it producers (farmers) or the consumers along with the scientists who are working in the laboratory. Hence, it is the need of the hour to reach and try for sustainable development that meets the needs of humans and the balance of nature maintained.

I think it is the same story as by food, pharma and plastic industry. The billion dollar profit can be more important than the consequences. Btw. if you check a regular food, which you can buy in the shop, you will find a lot of unhealthy components e.g. trans fatty acids, omega-6 fatty acids, fungicide remnants, etc... which can affect your health as well.

My conclusion is that in most of the cases it is safe, however in rare cases it might have a mild harmful effect. To filter out those cases and their causes we need further studies and better regulation.

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Genetic engineering is a technology not a trait.

In general, genetic engineering and genome editing are as safe as conventional breeding and mutagenesis (introducing thousands of random mutations by radiation or chemicals to speed up the breeding process).

The safety of the resulting product depends on what has been changed or how the crops are used. You can obtain unsafe products from conventional breeding, as shows the popular example of the Lenape potato (Wikipedia), which was bred for specific traits while unintentionally increasing its solanine content to dangerous levels.

The same goes for GMOs. Glyphosate resistant crops will increase the glyphosate level in the plant and favor unsustainable farming practices like large mono-cultures and a lack of crop rotation with potential risks for the environment or even human health. On the other hand, Bt-crops have been shown to reduce pesticide use and can therefore be beneficial for health and nature.

Your tomato example is not that much related to farming. The aim was to improve shelf life, which could help to reduce food waste. Similar products are non-browning apples (Arctic Apples). Usually, they work by blocking the activity of an enzyme that normally would degrade the fruit. Of course, there are debates if the enzyme is needed for important processes in the plant and if it would have any negative effects on the healthiness of the product. But usually nothing significant is found.

Furthermore, genetic engineering can also make products healthier by introducing positive traits like increasing vitamin or healthier fatty acids.

Again, the safety of the product depends on specific changes and not on how these changes have been achieved. If we could have all these products with conventional breeding, we would do it. And we probably could, it just takes ages. So, all "negative impacts" of GMOs should really be discussed as "Do we want/need this trait and what are the effects?" and not as "Was it created by genetic engineering?".

Finally, GMOs are the best tested products on the market. While we know very well, what has been modified in these plants, we have no idea which genes have been changed in mutagenesis products. And because of strict regulations and research, approved products can generally be considered to be safe to consume. So far, there is no recorded case of someone having serious health issues from consuming GM-food, while people are dying from their self-grown zucchini (I'm not kidding).

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