The world population is expected to increase to 9.9 billion by the year 2050, meaning humans need to produce 60% more food within that same timescale. Achieving this goal is challenging, not least because it needs to be accomplished with less land and water, within an increasingly warmer climate. Conventional farming methods can no longer keep up with the global demand for food production so genetically modified (GM) crops could provide a way to secure a future for agricultural production. Genetic modification of plants involves altering their DNA, giving them new or different characteristics. A meta-analysis of GM crops illustrates that GM technology adoption has reduced chemical pesticide use by 37%, increased crop yields by 22%, and increased farmer profits by 68%. Yet its adoption throughout the world is not consistent. While the US and many countries in South America rely on GM crops, there is a hesitance towards their use in Europe. While there are many reasons for its lack of acceptance (different food safety regulations and large costs/development time), a lot of the opposition has stemmed from the uncertain effects of GM crops on human health. While there is evidence of GM crops providing health benefits, the scarcity and contradictory nature of GM scientific evidence has prevented any conclusive and reliable claims of safety or lack of safety. This has made it challenging to objectively state that GM foods are healthier for the consumer.
Changing the crop
Genetically modifying a food crop has naturally led to skepticism about its health risks amongst the general public. For many, this stems from the belief that GM crops may contain allergens that were absent from the ‘natural’ type. One example of this is the ‘Starlink’ maize, which had been approved for animal feed and industrial use in 1998 in the US. It wasn’t approved for human consumption owing to the possibility of it being allergenic to humans, but when it was recalled worldwide in 2000 (due to the detection of residues of the Cry protein in food products), this naturally added to a growing distrust of GM crops. What needs to be remembered is that there will always be an allergenic risk, for every food product, they just need to be suitably labelled. One of the most robust safety assessments we have is to compare the potential differences between genetically modified food and its counterpart. Research on papayas proves that there was a compositional similarity between the transgenic papayas with the delayed ripening trait and its non-transgenic control. So if there’s little difference, why is there opposition? Well, these experiments should alleviate concerns about the health risks of GM crops, however, there is influential research that complicates this viewpoint. A study in 2012 claimed that rats that digested Roundup-ready crops (herbicide-resistant crops) were 3 times more likely to die and more rapidly than the controls. Yet a review of the data led to this study being retracted and alternative research on GM crops found there was no difference and deemed it to be safe. These back-and-forth arguments are characteristic of the GM health debate – many studies that claim GM crops have adverse effects on humans are often later assessed as having a high risk of bias and small sample size.
So where do the claims of improved health come from?
GM crops inherently require fewer pesticides and herbicides. The use of GM cotton (known as Bt cotton) in India showed that there was a reduction in cases of pesticide poisoning by 2.4–9 million cases per year. In addition, a 21-year meta-analysis of GM maize showed that it had lower concentrations of mycotoxins, which are both toxic and carcinogenic to humans. So could its adoption reduce cancer rates? We can further increase the nutritional value of many crops through the insertion or silencing of genes. Carrots expressing the Arabidopsis H+/Ca2+ transporter CAX1 (Cation Exchanger 1) contained up to 50% more calcium than plants transformed with control vectors. Perhaps the most famous example comes from the increased production of beta-carotene in rice (commonly known as golden rice). Beta-carotene is an essential component for vitamin A production and so around 2 decades ago, it was released for humanitarian purposes to many countries in Africa where vitamin A deficiency was rife. We should note that this strengthens corporations’ grip over rice and agriculture in lower socio-economic countries, making us question the impacts of allowing companies to have this monopoly over the GM market. While unlikely, GMOs could be clandestinely manipulated to create damage and have adverse health effects – perhaps creating a new platform for bioterrorism. We must also consider mental health. Higher and more stable yields, provided by GM crops, may result in a higher quality of life for both the consumer and farmer. The mitigation of abiotic stressors and the increased resilience of crops give a more certain future for our food production in the face of climate change. This will have a positive effect on the mental well-being of the consumer and farmer. However, one study in India found that the failure of the establishment of Bt cotton actually resulted in increased suicide rates among farmers – although this link has not been explicitly demonstrated with a sufficiently robust analysis.
Gene transfer
One of the biggest concerns stems from gene transfer. GM crops often contain a promoter to regulate the spatial and temporal expression pattern of the transgene. Research suggested that these promoters increase the tendency for DNA to recombine, increasing the likelihood of its incorporation into our own genes. This could have uncertain health consequences, as the introduction of foreign genes into the human DNA may be detrimental to essential body functions. This must not be taken at face value as follow-up research clarifies that the overall conclusions were sweeping and not representative of the data. Overall the risk of gene transfer is low, although there has also been evidence to suggest gene transfer could occur with the selectable markers used in GM. Therefore, there have been recent efforts to develop marker-free transgenic crops, resulting in food products that have no DNA-associated health risks.
Using GM to tackle diseases
There is evidence to suggest that GM crops could be beneficial for human health, within the realm of modern medicine. Antibodies are expensive to produce and often come from animals or animal cell cultures. Plants are a cheap way of creating complex molecules and so can be used as ‘bio-factories’ for the production of pharmaceutical proteins and plant-specific metabolites. As many vaccines are often proteins, these proteins can be expressed within the plant, producing an edible plant-based vaccine – there is research to suggest plants could be utilised to hold a vaccine for Alzheimer’s, as well as, COVID. As mentioned previously, antibiotic markers are consistently used to identify transformed cells when creating GM crops. Their extensive use in agriculture may result in an increased incidence of resistance, entering us into a post-antibiotic era where drugs might not be able to treat even the simplest of infections. Therefore, this must be taken into consideration, otherwise, the pharmaceutical benefits generated by GM crops could be null and void.
Conclusion
It seems GM crops provide clear health benefits to the consumer, both physically and mentally. An increase in yield, nutrition, and its potential for tackling diseases, gives support to the consumption of transgenic crops. Based on the research and evidence available it appears that GM crops pose no significant health risk to the consumer. Despite this, contention over the topic has likely arisen due to a lack of awareness about how our food production system has evolved. Opposition to GM can easily spread, as when the stakes are perceived to be so high (such as a risk to human health), ideological coherence often outweighs empirical evidence and logical consistency. Therefore, the scientific community needs to adequately address public concerns about GM foods and communicate that even if they pose a small health risk, they must be balanced against the enormous benefits of this technology and weighed against alternative options.
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