GMOs and Health – The effects of GMO Ingestion on The Human Body
While genetic engineering of food crops has been ongoing for 15 years, it is currently experiencing a major boom with the potential for widespread worldwide application. Yet, few people understand how a GMO food could really be so much different than a non-GMO food in regard to health and disease effects.
Effects of GMO ingestion:
Ingesting GMOs can affect both the microbiome and human cells. The microbiome is the microorganism population which lives on and in the human body. Most of it exists in or on the mouth, nose, stomach, intestines, and skin. The gut microbiome has received considerable attention due to its apparently profound effect on the immune system, not to mention its effect on food digestion. The gut microbiome is involved in determining the risk of autoimmune diseases, allergic diseases, cardiovascular disease, and some infectious diseases like osteomyelitis. The microbiome can get out of balance (called dysbiosis) and produce severe diseases such as Clostridium difficile overgrowth and more mild disorders like small bowel bacterial overgrowth and irritable bowel syndrome. The bottom line is that a balanced microbiome is critical for health and we are just now beginning to appreciate how serious the consequences of dysbiosis may be.
Several studies have shown that the organisms (mostly bacteria) of the microbiome can take up genes from GMO foods. “Conjugation”, or gene transfer, is a common trick used by bacteria to evolve and adapt. This is one mechanism by which antibiotic resistance perpetuates. The consequences of GMO gene transfer to intestinal bacteria involve the expression of the gene and/or insertional mutagenesis. The frequency with which these consequences will occur is not known, but they will occur to some degree at least.
Intestinal bacteria which begin to express the GMO gene will then be producing the same active proteins which define the GMO. For example, intestinal bacteria could start producing the Bacillus thuringiensis (Bt) pesticidal toxin that has been inserted into potatoes, corn, and soybeans. The exact effect of this toxin on humans, if any, is not well established but it has been found in a study of Canadian women, including pregnant women and their fetuses.
Insertional mutagenesis refers to the gene inserting itself into another coding gene and, thus, causing a gene mutation by disrupting the code. This may produce more severe results as it is a well known mechanism by which viruses may cause cancer, cell death, or cellular dysfunction.
These same mechanisms, gene transfer and insertional mutagenesis, can affect human cells just the same. While intestinal cells are likely to be the most affected, GMO genes which pass into the blood intact may affect just about any cell and tissue in the body. It is quite possible that GMO foods are regularly resulting in the genetic modification of the humans consuming them! There are many unknowns here and I suspect that there remains a lot to be discovered, but we should not let the absence of evidence be mistaken for the evidence of absent harm. We should, instead, demand more information and more research!
Effects of GMO associated pesticide exposure and ingestion:
Another route of possible harms from GMO foods comes from the exposure to and ingestion of GMO associated pesticides. The most successful GMO crops have been the “Roundup Ready” or glyphosate resistant varieties of corn, soybean, and cotton. The same genes have been inserted into alfalfa, wheat, and canola (rapeseed) but these have not yet been widely introduced. The result of glyphosate resistance is that glyphosate can then be applied without discrimination to area or dose. In the past, the use of a pesticide like glyphosate to control weeds had to be balanced with the cost of losing crop due to inadvertently heavy crop exposure.
Glyphosate spraying has dramatically increased with the introduction of glyphosate resistant crops. This logically increases the risk for excessive occupational exposure, the magnitude of environmental contamination with glyphosate, and the direct and indirect exposures to the general public and consumers of GMO foods (including livestock). Presumably, the glyphosate residue on (and inside… it can’t be washed out) glyphosate resistant food products is higher than that on non-resistant varieties, but data supporting this is scarce. I’ve failed to find any study which quantifies and contrasts the amount of pesticide residue between GMO and non-GMO foods. More research is needed, but again we can’t assume that the absence of evidence is evidence of absence. It is simply unknown if there are any differences, but assuming so is a very logical assumption.