Is GM corn toxic?

According to Vendomois et al, 2009:

these data highlight signs of hepatorenal toxicity, possibly due to the new pesticides specific to each GM corn.

Monsanto, fomous for its Round Up lawsuit, the manufacturer of two of the studied strains of GM corn, responded, dismissing the article, particularly by criticizing the statistical methods used. Is Monsanto’s criticism valid?

Have their been additional studies done that either support or refute the claim that genetically-modified corn has toxic effects?

Answer:

The simple answer is no.

GM corn has the BT gene that allows lower use of pesticides due to increased or the RR gene that allows the use of glyphosate for weed control. Neither of these alterations have any impacts upon the production of sugars or proteins in the plant. http://www.ca.uky.edu/entomology/entfacts/ef130.asp

The problem that can arise is from the pesticides that are now used on the crops and the timing of their application. These pesticides are known to harm mammals and if the dose is high enough can cause problems. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2793308/

Generally though, because you are removing pests and weeds the plants tend to be healthier so they are less impacted by pathogens, thus better for consumption. http://www.acsh.org/factsfears/newsID.962/news_detail.asp

There is an issue with using corn as a feed supplement in animals though. Corn is not a complete food source and is generally low in protein, especially tryptophan. This means that a feed mix is required, not just straight corn meal. http://www.ag.ndsu.edu/pubs/ansci/beef/as1238w.htm

Another issue is that corn can cause Pellagra. This is due to the niacin and B12 being bound in the corn starches and not being released in normal digestion. Tryptophan is also low in corn and can cause Pellagra.

So the problems often cited with GM corn are actually just problems with corn itself. Neither are harmful, if used correctly in a balanced diet, but pesticide residues are of concern. For more see this: http://onlinelibrary.wiley.com/doi/10.1046/j.0960-7412.2002.001607.x/full

Another point that should be made is that the paper cited is from a notorious “research” group who produce shoddy science in order to further their biased agenda against GM technology. The big problem with the paper is that it uses the wrong sort of analysis and the data has already been analysed by two other papers and found to say the opposite of what this paper says. Essentially, if you do a statistical test with a 95% confidence margin, you are saying that you have one chance in twenty of being wrong because of natural variability. So if you measure 20 variables with separate tests, you are likely to have one be a false positive result. Measure 40 with separate tests, 2 false positives. This is what the research group did, set up the stats to generate lots of false positives, instead of analysing the data correctly with tests that account for this problem. It should be noted that this is a common problem/tactic with anti-GM research papers.

Additional question: The ACSH source claims Studies Indicate GM Crops Are Safer and Healthier, but last time ACSH reported their funding, they were co-funded by what are now GMO companies. Currently they are not open about their funding at all. Therefore, their independence cannot be established. Can you back up the claim by research where all funding sources are open and independent? – gerrit

Reply: Of course there is plenty of independent data. gmopundit.blogspot.com/ has an entire series devoted to the safety studies of GM crops. The highly respected journal Nature had an entire edition devoted to the topic. But that is beside the point, the underlying mechanism of the Bt is not one that works on humans (it is even sprayed on organic farms). We don’t have an alkaline stomach to activate the chemical (ditto some insects it doesn’t impact either) which means it can’t do anything. So the concerns are completely misplaced.

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Can we grow enough crops to feed all people on Earth?

Vegetarianism is heavily promoted. But let’s say all people on Earth stop eating animal products. Can we grow enough crops so all people on the Earth are provided with enough healthy, nutritious food?

The question is of course very theoretical, but without discussing future possibilities to cultivate deserts and oceans, is there enough space to grow enough crops?

Answer:

This question is a very contentious one as it relies upon a lot of variables that are largely poorly understood.

The first part is arable land mass. Currently animal production is focussed on either high value grazing areas or low value extensive areas. Extensive grazing areas cannot be cropped. That area of production would have to be made up by increased crop production in other areas. 56% of Australia is extensive agriculture, worldwide it is ~5,000,000,000 hectares. That is a large amount of low production land to make up for.

Simply put, we can increase food availability (in terms of calories, protein and critical nutrients) by shifting crop production away from livestock feed, bioenergy crops and other non-food applications….. But even small changes in diet (for example, shifting grain-fed beef consumption to poultry, pork or pasture-fed beef) and bioenergy policy (for example, not using food crops as biofuel feedstocks) could enhance food availability and reduce the environmental impacts of agriculture.

Also, the areas quoted vary so much, because the figures are not fully understood. Cropping land is rarely cropped every year, instead rotated or rested at intervals, dependant upon crop type, soil type and amount of water/rainfall. Some countries just don’t have accurate records.

The second part is feed conversion. There are methods, such as mixed enterprise systems (crops plus grazing) and of course feedlotting that use grain feeding. The feedlotting is what people refer to the most, not understanding that cattle have a much higher energy conversion rate for vegetable matter than humans (being ruminants) and are not regularly fed for their entire lives. Thus grazing remains a large part of production.

Humans also preferentially eat higher protein foods like meat (see rise in meat demands from Asia with increasing wealth). This is because it is more calorically and nutritionally dense as a food, which is linked to satiety.

The third part is grain types. Most grains that are fed to animals are what is referred to in the grains industry as “feed grains”. These are generally lower quality grains that are unsuitable for human food production. Some of the grains used cannot be eaten by humans (e.g. lupins have high alkaloid levels that give both a bitter taste and become toxic when consumed regularly). Obviously the category of feed grain varies from “could be used” through to “cannot be used” for humans. This is once again a shorfall in the production required to replace meat in the diet. Remembering that feed crops are often grown where human crops cannot be grown, or not grown regularly (e.g. see wheat classes and agronomy).

Conclusion: These factors combine to create quite a different picture than what is normally presented in the “can we grow enough crops to replace meat eating” discussion. There would be less land available for cropping than is available for producing a mixed diet. There would be crops produced that would not be suitable for human consumption. We would also need slightly higher production or quality of crops to make up the energy conversion gap. This all makes for a large hole in the argument. There is nothing wrong with a vegetarian diet, nor an omnivorous one for that matter, but the environmental argument is not black and white and cannot be used as grounds for switching diets.

References:

Info on ME and DE for humans: http://fao.org/DOCREP/006/Y5022E/y5022e04.htm

This paper covers come of the conversion ratios for different animals that are grain fed (Cattle 7:1, Pigs 4:1, Chicken 2:1): http://ncbi.nlm.nih.gov/pmc/articles/PMC1240832

Another reference for the protein claims:http://sciencedirect.com/science/article/pii/S0301622699000196