Global food security is now attracting more attention from the public, people are paying more attention on choosing healthier food . Therefore, people would like to gain more knowledge to distinguish whether a food production is healthy or not. However, according to the research [2–3], as technology advances, the concept of natural food, organic food or transgenic food appears, people feel confused about these foods and cannot tell which to choose. Thus, an argument about the choice of food appears to the society. [Image2]
What is natural food?
As a matter of fact, there is no specific definition for natural food. To sum up the descriptions in many articles, natural foods are often assumed to be foods that are not processed, do not contain particular additives such as antibiotics, sweeteners, food colours, or flavourings that were not originally in the food . In brief, natural food is the food staying in the original condition, without any transformed.[Image3]
A large amount of people believe that natural food is the best choice to their health, it is pure without any pollutions or chemical fertilizers, contain all nutrition inside, which is do good to our health. However, ‘nature’ in food not always a good thing. For example, raw milk can be seen as natural food which can provide full of nutrition benefits, but raw milk can harbour dangerous microorganisms, such as Salmonella, E. coli, and Listeria, which can pose serious health risks to our body.  Except that, the natural vegetables, fruits, fish or other meat also have potential risk, such as harmful bacteria, virus, or heavy metal elements because of the environmental pollution.
What is organic food?
Organic food is the food which produced by methods that abide by the standards of organic farming, which keep away the harmful influential factors from plants or animals. Organizations regulating organic products may restrict the use of certain pesticides and fertilizers in farming while slightly processing inspection by people in order to ensure the quality which do good to people’s health . [Image4 ]
Therefore, organic foods are usually checked but not processed using irradiation, industrial solvents or synthetic food additives, meanwhile, the process does not destroy the nutritional content of food. In terms of milk issue, firstly, people organically feed cows to make them healthier. After that, pasteurizing milk killed harmful bacteria and keep drinker safer while does not cause allergic reactions or reduce milk’s nutritional [Image5]value. Since 2000, the organic food market has been growing all over the world, with yearly growth rates of about 10%. [8,9] Consumers buy such food because they expect that it is healthier than food from non-organic production and because of environmental concerns. 
What is Genetically modified food?
Genetically modified (GM) foods are foods derived from organisms whose genetic material (DNA) has been modified in a way that does not occur naturally, e.g. through the introduction of a gene from a different organism.  There are several reasons to explain why people are keen on the research and development of genetically modified foods, one is to relieve the pressure of food shortage, the others are expected to extend the preservation time for transporting and storage , through the introduction of resistance to plant diseases or of increased tolerance of herbicides, to reducing its allergenic potential, etc . However, even until now we still cannot make sure whether genetically modified food have hidden trouble or not. Although the products we bought from markets are mostly genetically modified and few people got ill with it, we still worry about it. Some research even proved that it might threats our health. [Image6]
What affect food security?
1.Immature GM technology poses a potential threat to GM foods’ safety.
2.Environmental pollution is biggest threat to food security:
- water pollution will lead to soil pollution, for example, the heavy metal elements in water will influence both aquatic organisms and plants in soil, which will indirectly do harm to human’s health.
- the air pollution will cause climate change, reduce the production of food then lead to a famine[Image8]
- Unscientific use of pesticides will directly do harm to our body. It will become a chronic poison if people cannot effectively clean the food.
4.Unscientific collocation foods may cause chemical reactions between foods which will lead to food poisoning. Moreover, some cooking method will cause the lost of food’s nutrition, which may make us nutritionally unbalanced.
- Before scientists figure out the problem of GM food, the potential hazards of GM food will continue to threaten our health.
what should we do?
After analyzing the reason that influencing food security, we need to find out solutions according to these problems. We cannot determine good or bad among natural food and other types of food so far, what we can do is to reduce the potential risks of foods.
- To improve the quality of natural food, we have to reduce to environmental pollution, which is a vicious circle not only affect the food security, but also do harm to ecological balance. Factories have to reduce the amount of exhaust emissions to the atmosphere and rivers, while citizens have to reduce the domestic waste. In addition, governments should organize groups to governance these polluted area.
- To reduce the potential risk of GM food, the only thing we can do is to gain more knowledge and keep on researching, find out the best way to modify food. 
- What’s more, no matter which type of food we chose to eat, we should pay more attention to the food collocation. It is the easiest thing to avoid so far while also the most direct factor that affect our body.
- In addition, cooking method is also an important way to maintain nutrition and help to keep fit. Different cooking method saved food’s nutrition to different degree. There might be millions of cooking methods around the world. For instance, salad seems a healthy diet to get balanced nutrition. In contrast, foods like chips, burgers and fried chickens are in high calories and low nutrition, which we need to try to avoid. Vegetable soup also seems a good choice to intake nutrition, at the same time, it has low calories and do good to our stomach.[Image9,10,11]