First, some background on Bt toxins before I answer your question directly.
The Bt toxin is so named because it comes from the bacterium Bacillus thuringiensis. Farmers have used spray formulations of this bacterium on their crops since the 1920s as a means to control certain insect pests. It has been widely used in the Americas, Europe and Asia, and it is one of the pesticides allowed for use in organic farming.
In determining the safety, it is important to understand how Bt proteins work. When consumed by insects, the toxin first has to become soluble in the insect gut, which has low acid levels. It then has to be activated by enzymes in the gut. Once activated, the Bt toxin binds to highly specific sites in the insect gut. These binding sites allow the Bt toxins to form pores in the gut cells leadings to death of the cells and eventually the insect. The guts of humans and other mammals are different from the susceptible insects in several ways making them unsusceptible to the Bt toxins. For one, the human gut is a high in acid and therefore the Bt toxin can’t become soluble or activated. Second, the human gut lacks the specific receptors needed to bind the Bt toxin. Without binding, pores are not formed.
In the 1970s, the US Environmental Protection Agency registered the first formulation of Bt sprays as a pesticide. Based on the safety studies, EPA determined that the Bt toxin is nontoxic to humans and other nontarget animals and no restrictions needed to be placed on the amount of Bt spray used on crops. EPA also determined that food sprayed with Bt pesticides could be consumed immediately after spraying.
In the mid 1990s, the EPA registered the first GMO plants that produced the same Bt toxins found in the Bt sprays. Like for the Bt sprays, EPA determined that Bt toxins produced in GMOs are safe for human consumption. There have been many animal toxicology studies where test animals were fed Bt spray formulation, Bt toxins purified from spray formulation, Bt toxins from GMOs, as well as the GMO itself. As expected based on the biology of the Bt toxins, no adverse effects have been observed in these studies when consumed greatly in excess of what humans might ever encounter. Nor were there any changes observed in the gut of test animals that were examined under a microscope. So, to answer your question directly, your assumption is not valid. All evidence supports the conclusion that consumption of GMOs that produce Bt toxins will not increase the porosity of your intestines nor increase the adsorption of any supplements you might take.
Also, as you mentioned that you use dietary supplements, you might be interested to know that safety testing is not required by FDA for these products. Per the FDA’s website, the safety of dietary supplements is evaluated through research and adverse event monitoring in people using them after they are already on the market. This is in stark contrast to the large volume of safety studies conducted on Bt toxins before they are approved for use in GM crops. http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm047470.htm
I have included some references if you would like additional safety on Bt toxins.
- Frederiksen, K., Rosenquist, H., Jørgensen, K., and Wilcks, A. 2006. Occurrence of Natural Bacillus thuringiensis Contaminants and Residues of Bacillus thuringiensis-Based Insecticides on Fresh Fruits and Vegetables. Appl. Environ. Microbiol., 72(5), 34353440.
- WHO. IPCS., 1999. International Programme on Chemical Safety - Environmental Health Criteria 217: Bacillus thuringiensis. Geneva, Switzerland.
- OECD, 2007. Consensus document on safety information on transgenic plants expressing Bacillus Thuringiensis - derived insect control proteins. in Joint Meeting of the Chemicals Committee and the Working Party on Chemicals, Pesticides and Biotechnology, Paris, France.
- Betz, F., Hammond, B.G., and Fuchs, R.L., Safety and advantages of Bacillus thuringiensis-protected plants to control insect pests, Regul. Toxicol. Pharmacol., 32, 156, 2000.
- Hammond, BG, Koch, MS. (2012) A review of the food safety of Bt crops. In: Sansinenea, E. (Ed.), Bacillus thuringiensis Biotechnology. New York, NY: Springer, 305-325.