In recent years, there are often some misuse of food additives, excessive pesticide residues, heavy metal contamination and other food safety incidents, resulting in a number of people began to reject all “artificial” production of food, the pursuit of “pure natural”. They believe that all industrially produced things are bad, including genetically modified crops, which are contrary to the “natural principle”. In fact, the pursuit of pure “natural food” is simply unable to meet the basic needs of human social development. Moreover, the lack of necessary food safety supervision in small-scale food processing makes it easier for harmful substances to grow, such as peanuts and corn, which can be contaminated by mold and produce highly toxic aflatoxins and fumonisins if not properly preserved. Transgenic technology is a brand new technology, and the potential risk exists in theory in case someone intentionally or unintentionally transfers a gene that expresses toxic substances or allergens into a crop, which will cause harm to human health. Therefore, when the development of GMO technology began in the 1970s and 1980s, the safety of GMOs was a major concern. Scientists have also made a point of emphasizing the need for greater control of the potential risks of GM technology research and application. However, risk is not a realistic, already existing hazard or danger, but the possibility of some kind of loss occurring in a specific environment and within a specific time period. Subsequently, countries around the world have established their own evaluation systems to fully justify and test the GM products to be marketed. Although the modes and procedures of safety evaluation vary from country to country, the general evaluation principles and technical methods are still developed according to the standards of the Codex Alimentarius Commission. The scientific procedures proposed by the International Codex Alimentarius Commission in 1997 for evaluating the potential side effects of additives, contaminants, toxicants and pathogenic bacteria in food, beverages and feeds on humans or animals have now become the basis for countries around the world to develop risk-based evaluation standards and management practices, carry out risk-based food evaluations and exchange risk-based information. Food is digested into small molecules in order to be absorbed by the human body The use of genetically modified plants as food raises concerns about human consumption as ingredients and processed products (cooking oil, etc.) on the one hand, and meat, eggs, milk, etc. produced after being used as animal feed on the other. In fact, after humans eat food, large molecules such as starch, nucleic acids, proteins and fats in food need to be turned into small molecules (e.g. glucose, nucleotides, amino acids, fatty acids, etc.) by the action of digestive enzymes in the digestive tract before they can be absorbed by the body. Saliva is secreted in the mouth, and saliva contains amylase, which can hydrolyze the starchy substances in food into small molecules. We often say “chew slowly”, which means to bite the food sufficiently, and let the amylase fully mixed with the food. The food enters the stomach along the esophagus, where there is strongly acidic stomach acid and pepsin, and the small intestine, where there is pancreatic juice secreted by the pancreas and pancreatic protease. Protein is continuously opened up in its original long chain-like structure by the action of pepsin and thereafter trypsin, and finally broken down into small molecules of amino acids in order to be absorbed as nutrients by the small intestinal wall. In the in vitro experiments, according to the requirements, the GM food must be completely digested and broken down within 10 minutes, otherwise it will not pass. Therefore, GM foods that pass the safety evaluation do not linger and accumulate in the body. Since the proteins in the food do not change the genes of the reproductive cells, if a person eats it and it causes a health hazard, it will only be effective for him/her and will not show the hazard until 3 generations later. The DNA in food that is exposed in the digestive tract is broken down into small molecules such as nucleotides that are absorbed and used by the body, and no longer functions as DNA, much less is inserted into the genome of germ cells to affect future generations. Schematic diagram of the human body’s protein digestion process Almost all foods contain protein and DNA, both non-GMO and GMO foods. Of course, there is a slight difference between GM and non-GM foods: generally GM crops add functional genes, such as Bt genes in insect-resistant crops, so GM foods may contain small amounts of Bt proteins. So some people say, “Can people eat crops that don’t even eat pests?” In fact, such a question would be raised because of a lack of understanding of the mechanism of action of biopesticides. Human and other vertebrates (birds, fish, livestock) gastric juice pH between 1.5 to 2.5, a strongly acidic environment, and contains pepsin. In contrast, Bt protein can only be activated in an alkaline environment, so it is quickly broken down into amino acids by digestive enzymes after entering the digestive tract of humans and other vertebrates. Therefore, even if people and other vertebrates eat the Bt insecticide protein expressed in insect-resistant transgenic crops, they will not be poisoned. In fact, Bt biopesticides have long been in use, and even in the natural environment, people are exposed to Bt insecticidal proteins, and these do not have toxic effects on humans. When describing GM foods as being as safe to eat as non-GM foods, authorities will say that they are “substantially equivalent”. For example, a Bt insect-resistant GM crop is equivalent to a regular crop, Bt gene DNA and Bt protein. The DNA is generally considered a safe component and does not need to be tested separately. Therefore, it is only necessary to confirm that the Bt protein is non-toxic to consider the Bt insect resistant GM crops and common crops to be substantially equivalent. Does the safety of GM foods need to be tested over several generations? Some people believe that to promote GM food, the first thing to do is to ensure the absolute safety of GM food. Even if they are safe to eat now, how can we know that they are not harmful if they are not tested for more than a decade or even several generations? At first glance, this statement seems to have some truth, because the safety or otherwise needs to be tested over a long period of time. But scientifically speaking, this view is problematic in terms of thinking and perception. First, what is a safe food? According to China’s “Food Safety Law”, safe food includes three elements: non-toxic, harmless; meet the nutritional requirements that should be in place; and does not cause any acute, subacute or chronic harm to human health. From a legal point of view, food that has passed the food safety risk assessment and obtained a marketing permit is safe. The current evaluation of the safety of genetically modified foods for consumption includes nutritional, toxicological and allergenic evaluation experiments, which are themselves a distillation of hundreds of years of food and drug safety issues and are sufficient to exclude all potential hazards that may arise. In addition, due to the demands of public opinion, three generations of experimental animal reproduction have been included, which can predict the safety risks of the offspring of experimental animals to a considerable extent. Of course, if we must ask what “absolute safety”, “absolutely no problem”, there is no experiment can prove. However, there is no “absolutely safe” food in the world? In traditional food, betel nut and red meat are first-class carcinogens; traditional breeding methods such as mutagenesis and hybridization, the genetic changes are far more uncontrollable than genetic modification. From the present perspective, only scientific methods can effectively assess which foods are relatively safe and which are relatively unsafe, and subjective speculation is not helpful for empirical evidence. Second, the development and application of GM technology has a long history and large-scale practice. With hundreds of millions of hectares of land planted with GM crops, hundreds of millions of tons of GM products entering the international market, and billions of people consuming GM foods each year, no real scientific evidence of safety concerns has been found. Henry Miller, a physician and molecular biologist who founded the FDA’s Office of Biotechnology, said, “In the United States, more than 80 percent of processed foods contain genetically modified ingredients. In North America alone, consumers have used more than 3 trillion servings of foods containing GMOs and have not found a single documented adverse reaction.” Third, there are those who recognize that GM research can move forward, but then argue that the promotion of GM crops should be decades away. This argument ignores the fact that agricultural science research is not a masculine endeavor, but rather an industry that requires significant investment of resources and the collection of lucrative returns. China has invested a lot of research funds in the field of GM, and if the results are just papers and reports without being transformed into productivity, it will greatly dampen the enthusiasm of researchers and affect the incentive of commercial companies to invest. Until today, our GM-related articles are “Why we need GM”, “GMOs everywhere (above)”, “GMOs everywhere (below)”, and this article. “, and this article. We hope that through the related science popularization, we can slightly reduce readers’ distrust and fear of GM technology. As science and technology progress and human society evolve, we can learn more about genetic modification.