Nutrition-wise blog

Genetically modified foods — Why the controversy?

By Katherine Zeratsky, R.D., L.D. May 20, 2016

Genetically modified organisms (GMOs) are plants, animals or microorganisms that have had their genetic material altered in a way that doesn't occur naturally.

The purpose of genetically altering, also called genetically engineering, plants is to improve their durability, such as through drought tolerance or disease resistance, or their nutritional value. These changes are aimed at increasing yield and lowering costs.

Farmers have long sought to breed better plants. Traditionally this has involved repeatedly cross-pollinating plants to create an offspring with the desired combination of traits. This process introduces a number of genes into the plant, including some that may have unwanted traits.

Genetic engineering isolates the gene for the desired trait, adds it to a single plant cell in a lab, and generates a new plant from that cell. By introducing only one gene, scientists hope to avoid transferring unwanted traits from other genes.

According to the Food and Drug Administration (FDA), foods from GM plant varieties marketed to date are as safe as comparable non-GM foods.

However, GM foods are controversial. The main topics of debate include:

  • Allergenicity. It's possible to transfer a gene from an allergenic plant to a non-allergenic plant. The Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) have developed protocols for testing GM foods. To date, no allergic effects have been found in GM foods currently on the market.
  • Gene transfer. The risk that genes from a GM food will be transferred to the cells of the body or bacteria in the gastrointestinal tract is considered low. However, there's concern about the transfer of antibiotic resistance genes and effects on human health.
  • Outcrossing. When genes from GM plants spread to conventional plants, it's called outcrossing. The effects of introducing engineered genes into wild populations are concerning, as are the possible effects on food safety and security. For this reason, several countries have adopted strategies to keep GM crops separate from conventional crops.

The FAO and the WHO have developed safety guidelines for GM foods. These rules aren't binding but are part of the World Trade Organization's agreement between trading partners to align safety assessments of GM foods traded between countries.

In the U.S. the FDA regulates the safety of food for humans and animals, including foods from GM plants. The FDA encourages developers of GM plants to consult the agency before marketing their products. During this process, the food developer conducts a safety assessment that is submitted to the FDA for evaluation.

Concerned groups question the validity of assessments of GMOs with regard to human health and environmental safety, particularly with respect to long-term effects. Additionally, some groups are calling for labels on GM foods to help consumers make more informed purchasing decisions.

Do you favor one side of the debate? Do you see benefits? Do you have concerns? Or are you on the fence?

Originally published Dec. 2, 2015

May 20, 2016