GMO (genetically modified organisms) refers to crops, such as soybeans, corn, and cotton, whose genome has been modified in the lab to provide some advantage, such as herbicide resistance, improved nutrition, resistance to insect pests, improved yield, or reduced water needs. When GMO food crops were first introduced in 1996, there was perfectly understandable concern that there might be some health consequences from eating foods made with GMO ingredients. However, since then many studies and a lot of real-world experience has shown these worries to be unfounded. Hundreds of millions of people have eaten an untold number of meals containing GMO ingredients, and there has not been a single documented case of anyone’s health suffering as a result – NOT A SINGLE CASE! As a result of this and other evidence, dozens of scientific organizations have declared GMO food to be as safe as any other food – these organizations include the French Academy of Sciences, the World Health Organization, the European Commission, the Royal Society, and the U.S. National Academy of Sciences.
Yet, opposition to GMO foods on health grounds remains widespread. It’s hard to figure out why, other than the all-too-common human propensity to ignore facts and believe what feels good (or what fits in with their conspiracy theories, such as the hare-brained idea that the above-listed scientific societies are in the pay of Monsanto). The opposition is also fueled by charismatic hucksters such as Vandana Shiva who travel around spreading lies and distortions about GMO food and making up “facts” as it suits them. Unfortunately there seems no end of gullible people ready to swallow this nonsense (for example, GMO foods cause autism, Alzheimer’s, suicide of farmers, cancer, allergies, and so on.). There is no evidence for any of these claims.
This is not to say that there are no legitimate concerns related to GMO crops, such as industrial farming, monoculture, corporate ownership of seeds, and loss of genetic diversity. There is also growing concern over the heavy use of the herbicide Roundup (a GMO crop that is Roundup-resistant allows the herbicide to be sprayed freely to kill weeds). The ingredients in Roundup have been linked to cancer in a recent World Health Organization report, and the product has been banned in many countries, but not the U.S. These are separate issues, however, unrelated to the (nonexistent) health risks of eating GMO food.
Update: While GMO foods seem to present no health dangers, a new report (October 2016) indicates that they are not bringing about the predicted benefits of higher yields and lowered pesticide use. Comparing the US and Canada, where GMO crops are widely used, with western Europe, where they are banned, no yield benefits from GMO crops were seen. Insecticide use in the US/Canada has decreased, but it has decreased even faster in France. And while herbicide use in the US/Canada has shot up, it has decreased in Europe. So, the “great promises” of the GMO revolution have yet to be realized, except perhaps for seed and herbicide manufacturers’ bottom lines.