Yes GMO's can put vitamins into foods that don't have any but if you are eating real fruit and vegetables and eating a variety of them then we don't need to put in say vitamin C into a potato. Another issue is that GMO companies like Monsanto are putting chemicals into crops that we as humans eat and other animals eat as well. They put them into the DNA of the plants so that if a bug eats the plant it will be poisoned. This isn't like spray on chemicals that you can just wash off, this is in the DNA of the plants. If bugs die from them by eating a leaf, what happens to us if we eat the whole plant over and over and over. Studies show that it increases cancer cells, dulls your immune system, and probably does a whole that more to your body. The FDA or whatever the health/food department is called allows Monsanto to produce these foods and sell these foods to us without even having tests first. Another thing is because the plants are stronger the bugs are getting stronger so they can survive, now normal spray on pesticide doesn't even work because of these new bugs that are being called "super bugs". I think everyone should research both sides and they will see that we need to stop them.
Because of our meddling, we have created great things like crops resistant to certain diseases. The cost comes though when we do not know what all these modifications do when it comes to people ingesting them. We can also see some bad from the Africanized honey bees, aka killer bees. The intentions were ultimately good, but disaster was the ultimate outcome.
I think that it is safe to say that GMOs are indeed a threat to the environment. We still do not fully understand what it is when we are modifying food in this manner, and we cannot predict what exactly will happen down the road if we keep doing this.
All of the changes made in GMOs are possible out of luck. They are all intended to improve our food and no matter how stupid you may think the people doing the research are the fact is that they are actually quite smart. All of the food we eat has some genetic differences and though GMOs have more GMOs are made and the gene changes are done with more care. Even if they hurt the environment, which there is no evidence for, they almost certainly help the human race which is the overall goal of all of this. Saving animals is nice but if it is advantageous to humans and there are no likely side effects humans should always come first.
I think genetically modified organisms have improved our crops and ability to survive. They will also offer us new ways to cure and help those that are ill and who know what other possibility. That being said, which is why I am on the fence with this one, we just wont know the long term impact these actions will have. I am hopeful that we will be able to fix any mistakes we have before they negatively effect the environment.
I don't think that there is any reason to think that GMOs are anymore of threat to the world than anything else that we happen to be doing currently. What we are doing is making things better for ourselves through science, and there is nothing wrong with that I say.