You’ve probably heard that GMO (genetically modified) foods are potentially unsafe, and that many other countries have banned them altogether. Are they over-reacting, or are we in the United States not paying enough attention to what’s really going on?
When you consider genetic modifications which allow literally tons of pesticides and herbicides to be added to our food supply (like Round-Up Ready corn and soy, which tolerate large doses of glyphosate), the safety issue is glaringly obvious. (Over 80% of GMO plants are engineered to resist herbicides. Use of herbicides in the US has gone up accordingly, ending up in our environment and in our bodies.)
But what about tomatoes that are altered to withstand shipment without bruising? Or perhaps an apple that doesn’t turn brown after slicing? They look the same. They taste the same. How can these GMO foods possibly be bad for us?
Let’s start with how GMO foods are made. The most common method uses a small piece of circular DNA from a bacteria called Agrobacterium tumefaciens. Almost all bacteria have these circular pieces of DNA, called plasmids, which often contain ‘special’ genes that are separate from the chromosome. Agrobacterium has a very unusual plasmid that has the ability to enter a plant cell and ‘inject’ bacterial DNA directly into the cell’s chromosomes. In nature, this causes Crown Gall disease, where infected plant tissues overgrow into a tumor-like gall.
Scientists have learned to use this natural ‘gene-injector’ to add new genes to plants. They simply remove the tumor-causing gene from the Agrobacterium plasmid, and replace it with another gene, leaving the rest of the ‘injecting’ machinery intact, then mix it with a number of single plant cells. Some of these cells will take up the plasmid and it will become incorporated into their DNA, giving them a new gene. Unlike other genes, which have a ‘switch’ that turns them on and off according to the plant’s needs, the new gene has a permanent ‘on switch’ attached. This means that this gene will always be ‘on’ in a GMO plant (so that it continuously produces a pesticide, or a protein that inhibits spoilage, etc.).
Why is it important for genes to have a switch? Let’s use the example of the potato. Every single cell in the potato plant has a gene that allows it to make solanine, a toxin that can be fatal to humans in large amounts. Production of solanine is normally turned off in the tubers, the part of the plant we eat. When the tuber comes in contact with sunlight, the gene switches on in those cells, which is why we’re told not to eat green potatoes. We rely on this gene being always ‘off’ in potato tubers, making them safe to eat.
In GMO foods, a new gene and switch have been inserted randomly into the plant’s genome by the Agrobacterium plasmid. Depending where it ends up, it could potentially disrupt any number of genes, turn them on or off, or alter the amount of protein they are making. If the thousands of genes in a plant working together in balance are like an intricate spider web that has been woven over millennia, randomly inserting a new gene can be like a fly getting caught: part of the web is going to get mucked up. Which part, exactly? We have no good way of knowing.
There can be huge and unpredictable changes in a plant’s native genome. Genes can be deleted, mutated, or permanently change the amount of protein they make. Plants can make larger amounts of an existing allergen or toxin, or begin producing a new or slightly different one. There is no way to control these changes, or even test for all of the possible new or different proteins that a plant might produce.
There have been numerous studies in animals on the health effects of a GMO diet, and nearly all showed adverse effects. Various results indicate that consumption of GMOs can result in reproductive failure, organ damage, and inflammation. The accumulation of large amounts of herbicide residues and their break-down products in heavily sprayed GMO crops (at least 86% more spray than non-GMO) may also lead to increased allergies and health problems.
There is a protein in natural soybeans that is similar to an allergy-causing protein in peanuts. GMO soy was introduced in 1996. Peanut allergies in the US doubled between 1997 and 2002.
As of 2014 in the US, GMO ingredients are in as much as 80% of conventional processed foods. This includes corn syrup in candy, canola and cottonseed oil in snack foods, and soy lecithin, among many other common ingredients.
For more info and studies: