Are GMO foods safe to eat?

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Yes, within the available evidence: a major 2016 review compared commercially available foods from genetically engineered (GMO) crops with their conventional counterparts. It found no substantiated evidence that foods from the GMO crops examined were less safe than foods from crops bred in the usual ways. But subtle or delayed health effects can be hard to detect, and some farming problems, including resistant weeds and insects, are real.

Why people believe it

In 2014, the World Health Organization (WHO) described the first GMO foods on the European market as not significantly cheaper and no better tasting for consumers. It described no apparent benefit in how long food keeps, either. It said unrelated food scares in the second half of the 1990s had weakened trust that European food supplies were safe. Those scares had also affected discussions about whether GMO foods were acceptable. Consumers also questioned assessments of long-term health and environmental risks. Consumer organisations debated possible allergic reactions.

The authors of a 2015 discussion paper argued that independent GMO safety research faced two limits. They cited a lack of funding independent of ownership interests and restricted access to research materials. They also argued that the available evidence did not support conclusive claims that GMOs as a whole were safe or unsafe. These are reasonable questions to bring to the evidence.

“Eating it harms your body”

The US National Academies' 2016 review examined almost 900 research and other publications. It focused on corn, soybean and cotton. For health, it compared what foods contain, animal tests, farm animal health and patterns of human illness over time. Together, these showed no differences pointing to a higher human health risk from the engineered foods examined. These foods were commercially available, and the comparison was with equivalent conventional foods.

“We don't know the long-term effects”

The review had limits. It lacked long-term studies comparing illness cases with comparison groups, called controls. It acknowledged several sources of bias in the population data it used. It also said internationally accepted animal-testing methods for engineered foods used small groups that could miss real differences. Despite imperfect study designs, it judged the combined experimental evidence sufficient to reach a conclusion. It concluded that animals were not harmed by eating food from engineered crops. It still warned that subtle effects of any new food might go undetected or develop over time. This applied to engineered foods and other new foods alike.

“It could cause allergies”

WHO says safety assessments generally focus on several issues, including possible allergic reactions and toxicity, meaning the ability to poison. Others include nutrition and unintended effects of inserting genes. The European Food Safety Authority (EFSA) describes assessing whether the new protein or the whole GMO plant could cause allergies. It also describes comparing nutritional value with a matching conventional food. Those checks sit alongside the review's finding that no differences had been found pointing to a higher health risk in the foods examined.

“But the farming causes problems”

Some concerns have evidence behind them. Where planting herbicide-resistant crops led to heavy reliance on glyphosate weedkiller, some weeds evolved resistance to glyphosate. Some target insects also evolved damaging resistance to Bt, a feature that helps crops resist insects. This happened where methods for managing resistance were not followed. Yet Bt crops generally reduced use of insecticides (products that kill insects) and yield losses compared with non-Bt varieties. The result depends on the crop feature and farming practice.

Official positions, with dates

WHO, 1 May 2014: foods then on the international market had passed safety assessments and were unlikely to pose human-health risks. It recommended continuing safety assessments based on Codex Alimentarius principles, or food-safety guidelines. Where appropriate, it also recommended adequate checks after sale.

EFSA, 2 August 2017: its explainer describes safety checks before EU approval to import or grow the crops.

US FDA, pages current 5 March 2024 and 12 May 2023: its Plant Biotechnology Consultation Program for food from new GMOs is voluntary. All foods from new plant varieties must meet the same legal requirements, whatever the breeding method.

What people also ask

Are GMOs harmful to the body?

The National Academies found no substantiated evidence that the engineered foods it examined were less safe than conventional foods. That conclusion comes with limits on detecting subtle or delayed effects.

What are some dangers of GMOs?

WHO says safety assessments generally consider potential allergy, the ability to poison and unintended effects of inserting genes. Resistant weeds and insects are documented farming problems under the conditions described above.

Is there a downside to GMOs?

Beyond health, the review found non-engineered crop varieties were becoming less available where engineered crops were widely used. This finding covered the US and Brazil. Non-engineered varieties had not disappeared, and the pace of the trend was uncertain.

What are the benefits of GMO crops?

The review found generally favourable economic results for farmers adopting engineered soybean, cotton and corn. Results varied with pests, farming practices and infrastructure, meaning the systems and facilities farming depends on. Protecting harvests is different from raising potential yield, the amount a crop could produce. Engineered crops already commercialised by the 2016 review could protect yields where they had been introduced. But their potential yield did not exceed that of their conventional counterparts.

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