Since thousands of years humans have bred and domesticated animals and plants to enhance a particular trait. This had led to lineages of organisms that are genetically modified from the original species. With the advent of modern techniques, the genetic modification of organisms and foods has become possible within very limited period of time.

Genetically Modified Foods (GMF) are derived from organisms whose genetic material has been modified in such a way that it does not occur naturally. Genetically modified food has foreign genes inserted into their genetic codes. This is called as Genetic Engineering which can be done with plants, animals and any organisms. Genetically modified plants are used throughout the world as food crops, and offer best prospect of increasing food supply. Such plants has greater tolerance to stress, tolerance to herbicides, higher yeilds per acre, reduction of natural plant toxins, and better nutritional quality. 

The main objective of developing plants based on genetically modified organisms was to improve the crop protection through introduction of resistance  against plant diseases caused by insects or viruses or through increased tolerance to herbicides. Insect, virus and herbicide resistance are acheived by incorporation of either gene from certain viruses or introduction of certain bacteria which causes diseases in plants. Generally traditional food is considered as safe food and have been consumed for many years. Genetically modified foods are regulated by Food and Drug Administration.

Sources of genetically modified foods

Mainly the genetically modified plants are corns, cotton, canola, soyabean, tomatoes, potatoes, etc. As per FDA, such foods are as nutritious as food from traditionally bred plants. 

Risk of GM foods on human health

• Genetic changes in GM foods are harmful and toxic to human health.
• Genetically modified foods are likely to show allergic reactions.
• According to research, consumption of disease resistant crops may promote human viruses and other diseases and eating these crops may suppress the body's natural defense against viruses.
• Other GM foods like milk with injected growth hormones is highly riskier and may cause breast, lung, colon and other cancers. 
• Pregnant women eating GM foods may endanger their offspring by harming the normal fetal development and thus these gene expressions are passed to future generations.

Some benefits of genetically modified foods

• Tastier and bmore nutritious food
• Less use of pesticides
• Faster growing plants and animals
• Medicinal foods that could be used as vaccines or other medications.
• Increased supply of food with reduced cost.

Genetically Modified Foods are considered to be safe as there are no reports of illnesses or diseases. However to ensure the food safety adequate testing is required.