One main safety concern is the introduction of toxic or allergenic proteins. There is the possibility for new toxic compounds being formed in the food supply. However, toxic components associated with foods are well known and are tested for before the release of any genetically modified food. For this, feeding studies to assess this toxicity if any needs to be conducted.
Allergenicity is another important issue. As allergens are proteins, there is a possibility for introduction of allergens when introducing new genes into an organism. An example of a this problem was the transformation of soybean with a introduction of gene encoding a Brazil nut protein to enhance the amino acid profile of the soybean. This transformation was effective at enhancing the sulfur-containing amino acids in soybean. However, it was discovered that this protein from the Brazil nut was allergenic.
It is pointed out that if genetic manipulations are done to enhance oil composition, the protein does not become a component of the resultant oil. Also, if a food is processed by heat, thermal denaturation of proteins alters the enzyme activity and protein structure in a way that might make these concerns less of an issue. Foods are by nature composed of DNA and Human consumption of DNA of all species has occurred safely over the years. Even human DNA is consumed, as it is a component of cells shed from the nasopharynx and the gastrointestinal tract. The fact that DNA is degraded by nucleases in the digestive tract should make the origin of the DNA of minor concern.