Are genetically modified foods safe for human consumption? Yes, but ...
Yes
When we read about healthy eating, we are often told to stick to organic foods, and to avoid genetically modified, or "GM", ones. As GM foods are not produced naturally, and usually involve the addition of new genetic materials, many nutrition experts say they can have a negative impact on human health.
Common fears about GM foods include the belief that they can cause enlarged organs, and even cancer.
According to dietitian Daphne Wu, the three main health issues summarised by the World Health Organisation with regards to GM foods are the potential to provoke an allergic reaction, gene transfer, and outcrossing.
"The first is concerned with the transfer of genes from commonly allergenic organisms to non-allergenic organisms," says Wu. "The second issue relates to the transfer of modified genes which may be antibiotic-resistant, to human cells or gut microflora. This can adversely affect human health.
"Finally, the outcrossing of genes from GM plants into conventional crops in the wild may have an impact on food safety and security," says Wu.
Most GM foods on the market are GM crops, which commonly include soya beans, corn, cotton and canola.
Sally Poon, a dietitian from Private Dietitian, says that GM crops were developed to enhance crop protection and increase yield. Their genes were modified to make the plants herbicide tolerant and insect resistant, for example.
GM foods with modified nutritional content are also available. For example, scientists can modify the fatty acid content of soya beans to provide a stable vegetable oil suitable for frying. This negates the need for hydrogenation, so reduces the formation of trans fats due to partial hydrogenation.
In addition, GM crops with various characteristics can be combined using conventional crossing to generate advanced lines with multiple characteristics.
As different GM foods contain different genes inserted in different ways, the risks and safety of GM foods should be considered individually, says Wu. So it is not possible to make general statements about the health risks of all GM foods.
Despite the controversies surrounding GM foods, Poon says that, so far, they seem to be safe for human consumption, at least in the short term. She notes, for example, that the probability of the transfer of antibiotic resistant genes is low.
"But as a precautionary measure, some international organisations recommend the production of GM foods without antibiotic-resistant genes, which are commonly used for the identification of transformed cells during the development of GM crops," Poon says.
"Furthermore, no incident related to the allergic effect of commercialised GM food has been identified so far," she says.
According to the Food Safety Focus report by the Centre for Food Safety Hong Kong, countries that produce GM foods for the international market have systems in place to regulate the safety of exports.
Because of an increase in the variety of GM foods, there have been proposals to introduce a pre-market safety assessment scheme in Hong Kong.
As for the long-term health risks of GM foods, experts agree that more research needs to be done. Previous studies have been criticised by scientists and national food safety authorities for being flawed in their design, result analysis and interpretation. As a result, these studies have led to invalid or misleading conclusions.
"As any kind of food can be unhealthy if consumed in excess, and there is a chance you could overdose on micronutrients like vitamins and minerals, I recommend eating GM foods in moderation," says Wu. "It's always important to eat a variety of foods to achieve a balanced diet."
Poon agrees. "Well-balanced eating is the key to health," she says.
