In the new study published in the Journal of Organic Systems, Australian and U.S. researchers found pigs fed genetically engineered feed were much more likely to suffer from severe stomach inflammation and heavier uteri, a condition that could signal endometrial cancer, endometriosis, abnormal thickening, or gynecological polyps, all things that could affect fertility. “Clearly, issues are raised in this pig study that need to be followed up, especially since in the U.S., we don’t require safety assessments before [GE crops] come onto the market,” says Michael Hansen, PhD, chief scientist at Consumers Union. The GE feed used in the study included ingredients like corn, which is genetically engineered to produce pesticides within the plant or to withstand heavy sprayings of glyphosate, the main ingredient in Roundup. Some corn is genetically manipulated to produce pesticides internally and also withstand chemical spraying. Researchers also used GE soy developed for glyphosate dousing, another go-to ingredient for livestock feed (and processed people foods.) More From Prevention: The Gateway GMO Food? Long-term feeding studies like the recent pig study—they fed pigs on this diet about 5 months under real-world conditions until slaughter—are also rare. In America, the FDA doesn’t require studies investigating potential health impacts of GE ingredients to humans before genetically engineered crops can enter the market, and seed companies who own patents on GE technology must approve researchers’ requests to study their seeds, something critics say greatly stifles research. “If the company decides they don’t like your research, then it doesn’t get approved. That’s not the way you do science,” Hansen says. “Imagine where we’d be if we let the tobacco industry decide which studies could have been done on tobacco and its safety.” This rare feeding study found the uterus weight of GE-fed pigs was 25% higher than non-GE-fed pigs; GE-fed pigs also showed severe stomach inflammation at a rate of 2.6 times that of non-GE-fed pigs. It’s important to note, though, that even pigs on the non-GE diet experienced moderate stomach inflammation, a side-effect scientists say needs to be studied further. Using pigs in the experiment serves two purposes. According to Hansen, commercial pig farmers are trying to figure out what’s causing emerging health problems in pigs. The physiology of pigs is the closest to human physiology of vertebrate animals, too. “The findings here are of particular significance for potential impacts on human health,” explains Warren Porter, PhD, professor of zoology and environmental toxicology at the University of Wisconsin, Madison. The study stirred up more questions, too. Researchers didn’t examine the large and small intestines, but Porter says future research should focus on those organs to evaluate the gut microflora of animals fed GE versus non-GE feeds. Gut bacteria levels can have very important impacts on immune function and should ultimately be evaluated in long-term feeding studies before the government releases these crops into the food chain, Porter says. A 2012 study published in the journal Current Microbiology raises gut and immune system concerns, too. In that study, German researchers found glyphosate, the active ingredient in Roundup, kills off beneficial bacteria, allowing more resistant, pathogenic germs to colonize in the gut. Warren notes that on Wisconsin dairy farms, the lifespan of organically fed cows is often up to three times longer than the lifespan of GE-fed cows, with the literature suggesting another link to GE-foods and immune system problems. More from Prevention: The Latest Science On Roundup “It is important to remember that if immune function is being affected by GMO crops, it is also highly likely that endocrine and neurological functions are also being impacted because those three systems interact with each other in multiple, intricate ways,” Porter says. Hormonal changes in the endocrine system could also affect developmental processes of fetuses in pregnant females, he adds. Hormones are extremely sensitive to even tiny doses of chemicals, meaning there could be very broad impacts of feeding GE ingredients on fetal development, Warren adds. “The public should be aware of the multiple connections between organ systems in normal bodily function when considering consumption of GMO foods,” Porter says. “These intricate interconnections between gut function, immune health, and the health of the rest of the body also elevates the need for labeling of GMO foods for human consumption and for domestic animal production.” To avoid GMOs in your diet, eat organic, Non-GMO Project Verified, and 100-percent grass-fed foods. If you don’t want to wait for the federal government to make GMO labeling mandatory, consider starting at the state level. In June 2013, both Connecticut and Maine passed GMO labeling laws. More from Prevention: First State of GMO-Labeling?
