Food Safety Focus (35th Issue, June 2009) – Food Safety Platform

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Food Safety Focus (35th Issue, June 2009) – Food Safety Platform

Genetically Modified Food – An Overview

Reported by Ms. Shuk-man CHOW, Scientific Officer,
Risk Assessment Section, Centre for Food Safety

In previous series, we have introduced information on possible hazards in food. From this issue, we will move to a new series on the safety of foods that are derived from or have been treated with certain kind of technology, as well as foods that are produced under specific agricultural practice. The first one that we are going to introduce is genetically modified (GM) food derived from modern biotechnology.

The term"biotechnology"may sound like modern. In fact, humans have utilised primitive forms of biotechnology (the use of living things to create products) for thousands of years ever since the transition from hunter-gatherer to farmer. Rather than just gathering foods from the wild, humans began to selectively breed plants and animals with desired characteristics (e.g. high yield) and cross breed them to create new varieties. Although ancient farmers did not understand the mechanism behind the processes, they applied such breeding techniques over generations to obtain crops and animals that could match and grow better under local conditions.

Genetic Engineering and GM Food

With increased understanding of genetics and advances in science, we are now able to transfer genes between totally unrelated species and specifically modify the genetic make-up of different organisms in a faster and more precise manner. GM organisms can be applied directly for food use (e.g. GM tomato) or to produce products used as food additives or processing aids (e.g. aspartame, an artificial sweetener, produced by GM bacteria is used in soft drinks).

Potential Benefits of GM Food/Crops

Many of the GM foods are actually still under development, but some, like herbicide tolerant and insect resistant crops are already widely commercialised. Scientists envisage the development of GM crops has the potential to i) reduce production cost and increase yield, ii) provide pest resistance to crops and reduce the use of pesticide, iii) produce food with enhanced nutrition, iv) improve flavour and texture of produce, and v) mitigate allergen level.

Concerns over GM Food/Crops

Although the use of genetic engineering has the potential to provide us with food of better quality, risks associated with the consumption of GM crops continue to attract attention.

  1. Unintended effects altering the allergenicity and toxicity of GM crops
    Allergenicity and toxicity are two unintended effects envisioned. First, the random insertion of the transgene into the host plant genome during genetic engineering might change the expression of host genes which in turn affects the normal metabolism and level of endogenous toxins or allergens in the transgenic plant. Secondly, insertion of transgene has the potential to create additional new proteins that might be toxic or allergic to susceptible individuals.
  2. Transfer of antibiotic resistance gene to bacteria in gut
    Antibiotic resistance genes are commonly used for the identification of successfully transformed plant cells during the development of GM crops. There are concerns that bacteria in the gut of human might become antibiotic resistant through the uptake of the resistance gene from the DNA spilling out of the digested GM plant before the DNA is completely degraded.
  3. Outcrossing
    Outcrossing describes the movement of genes from GM plants into conventional crops or related species in the wild, as well as the mixing of seeds derived from conventional crops with those grown using GM crops. Such crossing has an indirect effect on food safety where crops not yet approved for food use may unintentionally mix with their conventional counterparts that pose risks for human consumption.

To address issues surrounding the safety of GM foods, national authorities of GM food producing countries have put in place safety assessment schemes to ensure newly developed GM organisms are suitable for human consumption before they are approved for food use.

In view of the concerns over the safety of food derived from genetic engineering, in the coming two issues, we will discuss in detail the potential risks associated with GM food and their possible remedies.

Besides food safety concerns, GM food may also have environmental and social concerns. Relevant information can be found at


Antibiotic resistance gene A gene which confers resistance to antibiotics. It is used for the selection of transformed cells during the process of genetic engineering.
Gene A gene is a unit of hereditary material, which carries the required information necessary to produce a protein(s) that determines the characteristics of an organism.
Genetic engineering A technique which enables direct manipulation of genes of organisms.
Genetically modified food Any food which is, or is derived from, genetically modified organisms.
Genome A complete set of chromosomes found in nucleus of a given species which contains the entire genetic materials.
Transgene The gene of interest to be introduced into the host organism.