Contrary to industry claims, GMOs do not have a long-term history of safe use, as they are subject to only short-term studies conducted by the companies that profit from them. In the 30 years since herbicide-tolerant and insect-resistant GMO crops entered the food supply, a substantial body of evidence has indicated their potential harm to human health. Credible studies that identify negative human health impacts have been actively discredited by agrochemical corporations.^29,30 Learn more about the industry's role in GMO testing.

In multiple animal studies, "first generation" herbicide-tolerant and insect-resistant GMOs have been linked to serious adverse effects, including organ abnormalities and cell and tissue damage, as well as gastric and uterine disease, stomach inflammation and kidney and liver damage, with potential outcomes including a rise in tumor incidence and increased mortality.^{31,32,33,34,35,36,37,38,39,40,41,42,43}

Additionally, herbicide-tolerant GMO crops have led to a dramatic increase in the use of accompanying herbicides.⁴⁴ Exposure to these herbicides is widespread and can be harmful to human health at very low levels.^45,46,47 Herbicide residue is linked to reproductive, developmental, neurological, metabolic, microbiome, digestive and urinary system damage, liver disease, GI tract damage, endocrine disruption, increased incidence of breast and other cancers, genotoxic effects and kidney disease.^{48,49,50,51,52,53,54,55,56,57,58}

Newer forms of genetic engineering include a wide range of organisms and potential food ingredients that are entering the food supply without regulation or safety testing.⁵⁹ While new genomic techniques such as gene editing are often described as a more precise method of creating GMOs, they can produce unexpected outcomes that are unlikely to occur with conventional methods, including off-target effects described by independent researchers as "chromosomal mayhem."^60,61,62,63 The instance of off-target effects is likely wildly undercounted.⁶⁴

With the expansion of biotechnology and the emergence of new genomic techniques, people encounter more GMOs with more complex genetic alterations from more food sources than ever before. 

GMO crops in products for human consumption are mostly low-nutrient additives in highly processed foods, providing little, if any, nutrition.¹⁹ The chemicals that accompany certain GMO crops can further deplete nutrients. For example, two common herbicides, glyphosate and glufosinate-ammonium, can act with soil microorganisms to reduce the crop's nutritional value.²⁰

One of the most commonly grown GMOs, corn, is a poor nutritional substitute for non-GMO and native maize varieties, containing lower levels of protein, fiber, antioxidants, and less of the beneficial nutrients crucial for childhood development.²¹

GMO crops can be engineered for increased nutritional value, but the efficacy of this type of intervention is unclear. For example, Golden Rice is a genetically modified rice designed to address Vitamin A Deficiency (VAD), a serious condition that can cause blindness or death.²² However, practical limitations could compromise Golden Rice's effectiveness as a VAD intervention: vitamin A is a fat-soluble nutrient, meaning the body cannot absorb it without fat in the diet, which populations affected with VAD do not typically have.²³ Also, the nutritional benefits of Golden Rice degrade rapidly during storage.²⁴ Golden Rice's efficacy is still unknown. Shortly after limited cultivation began in the Philippines, its approval was revoked over safety concerns.²⁵ In general, GMOs engineered to increase nutrients, alter flavor profiles or make healthy foods such as fruits and vegetables more convenient do nothing to address the root causes of hunger and malnutrition. Learn more about GMOs and feeding the world.

Alternatively, animal-free milk beverages made through genetic engineering may be marketed as "dairy-identical," but it is startlingly different from cow's milk.^26,27 Mass spectrometer analysis shows the product lacks many of the nutrients of cow's milk while containing compounds not present in cow's milk, including 92 compounds that could not be identified.²⁸

Industry-controlled media erroneously portray GMOs as part of the solution to global hunger.^1,2 Claims that accompanied the herbicide-tolerant and insect-resistant GMO crops that dominated the first generation of GMOs are now applied to recent GMOs made with new genomic techniques such as gene editing. However, GMOs have not meaningfully decreased hunger or malnutrition during the more than 30 years in the food supply.³ 

Most herbicide-tolerant and insect-resistant GMO crops end up in livestock feed and biofuels, not as food for humans.^4,5,6 Those used in food for human consumption are nutrient-poor but high in calories —  the raw materials for ultra-processed food.⁷ 

Multiple studies show GMO crops do not produce higher yields than non-GMO versions.^8,9,10,11  For example, EU countries that grow non-GMO crops under similar climatic conditions as US-based GMO farmers show similar or higher yields.^12,13 Meanwhile, industry-funded studies showing favorable GMO yields are generally small-scale trials or highly controlled conditions — environments that are not replicable or scalable.¹⁴

GMOs engineered to increase nutrients, alter flavor profiles or make healthier foods such as fruits and vegetables more convenient make up a small fraction of the GMOs on the market.¹⁵ These novel foods do nothing to address the root causes of hunger and malnutrition, such as lack of access and food waste, income inequality, armed conflict and trade policy. 

GMO developers use genetically engineered microorganisms to produce proteins, fats, vitamins and many other compounds through fermentation. Advocates consider this technology a saving grace for a growing population, declaring that "everyone on Earth could be handsomely fed, using a tiny fraction of its surface."¹⁶ However, their optimism ignores the high operating costs and practical limitations of this technology which compromise its usefulness as a potential climate solution.^17,18 Furthermore, the off-target effects and unexpected outcomes associated with new GMOs could potentially impact human health. Learn more about GMOs' impact on human health.