Fruits and vegetables have been genetically modified since the mid-1990s. The genetic modification started with tomatoes, and then slowly permeated animals like cattle, dairy, and other edible plants.

Often, crops are genetically modified to improve their durability or their ability to grow under adverse conditions like poor weather. Plants can also be modified to naturally avert insects who may eat them before they can be harvested and sold to consumers. While these modifications are useful and protect farmer's crops and guarantee consumers particular fruits and vegetables regardless of natural hindrances, could they cause harm to humans?

Plants are often genetically modified to make a molecule called endotoxin. This toxin keeps pests from attacking a plant and eating it before it's ready to harvest. However, in a new study where mice were fed endotoxin, researchers found that even the smallest, and once deemed safe, doses of the toxin appeared to cause harmful immune reactions. The researchers looked at the mouse's immune responses, discovering that many changes occurred to only its blood but no other organ.

Researchers looked at immune reactions in the exposed mice after one, three, and seven days. They found that after one day, the mouse's blood contained many inflammation-inducing molecules. These inflammatory molecules were not localized to anywhere in particular, indicating that the blood was rejecting the toxin and the immune system was sending out molecules to mark it for immune attack. By the third day, the level of inflammatory agents in the blood had significantly increased, further indicating that the toxin was creating a negative effect in the mice, even at a small dose.

In terms of the blood itself, many adverse changes were observed as well. After three days, there was a significant reduction in red blood cell counts and hemoglobin in the blood. This led to hypochromia, or some loss of the red color of blood, because without enough red blood cells and hemoglobin, there cannot be enough oxygen in the blood - as a result, deoxygenated blood is very dark and nearly brown, while oxygenated blood is bright red. Between days three and seven, hemoglobin levels in the mice decreased by fivefold.

A lack of hemoglobin and red blood cells in the blood can have grim consequences. Anemia, a blood disorder in which organs like the heart do not get enough oxygen, is rooted in the blood's inability to hang onto oxygen. Oxygen does not float freely in the blood, but rather must bind to hemoglobin molecules that are located on red blood cells. Hemoglobin has a high affinity to bind the oxygen and help it stay in the bloodstream. Without hemoglobin or red blood cells, the blood begins to lack oxygen. This is a problem, as a lack of oxygen in the body can be fatal.

Anemia is characterized by fatigue, pale skin, shortness of breath and poor circulation, as a lack of oxygen throughout the body is detrimental. Anemia, according to the Centers for Disease Control and Prevention, kills close to 5,000 people each year.

The Mayo Clinic recommends eating an iron-rich diet or taking multivitamins to help reverse the effects of anemia. However, if genetically modified foods have toxins in them that are attacking our body's essential mechanisms, perhaps it is better to eat genetically modified foods with caution. The researchers conclude that the toxic effects of endotoxins increase over time. While the mechanism by which the toxins are creating blood disorders like anemia are not yet known, the fact that they can negatively alter blood so that it no longer performs its function is alarming.

Source: Poletto-Mezzomo B, Miranda-Vilela AL, de Souza-Freire I, et al. Hematotoxicity of Bacillus thuringiensis as Spore-crystal Strains Cry1Aa, Cry1Ab, Cry1Ac or Cry2Aa in Swiss Albino Mice. Journal of Hematology and Thromboembolic Diseases. 2013.