Titanium oxide (TiO2) is a common food additive that is generally recognized as safe by the U.S. Food and Drug Administration. The compound is an inert and insoluble material that is commonly used for white pigmentation in food, cosmetics, personal care products and common household items. In food industry, titanium dioxide is used in certain chocolate products to give a smooth texture; in donuts, candy and gums to provide color; and in skimmed milks for a brighter, more opaque appearance. A 2012 Arizona State University study tested 89 common food products including gum, Twinkies, and mayonnaise and found that they all contained titanium dioxide. About five percent of products in that study contained titanium dioxide as nanoparticles.
There have been numerous studies on how titanium oxide nanoparticles affects digestive tract, but none looking at a low concentration that is comparable to food consumption exposure level. Researchers from Binghamton University, State University of New York, recently studied food consumption concentration level with two exposure models: acute exposure and chronic exposure. In the acute exposure, a small intestinal cell culture is exposed to one meal’s worth of titanium dioxide nanoparticles over four hours; in the chronic exposure, the small intestinal cell culture is exposed to three meal’s worth of titanium dioxide nanoparticles over five days.
The study showed that the ability of small intestine cells to absorb nutrients and act as a barrier to pathogens is “significantly decreased” after chronic exposure to nanoparticles of titanium dioxide. Specifically, it is noted that the chronic titanium dioxide nanoparticles exposure diminished the microvilli, the absorptive projections on the surface of intestinal cells. With fewer microvilli, the intestinal barrier was weakened, reactive oxygen species (ROS) generation, pro-inflammatory signaling, and intestinal alkaline phosphatase activity all increased while the absorptions of nutrients such as Iron, zinc, and fatty acid transport were significantly decreased. Researchers also observed the altered expression of nutrient transporter protein gene, suggesting that cells for regulating the transport/absorption mechanisms have been disturbed by nanoparticle ingestion. Overall, the study shows that intestinal epithelial cells’ function are negatively affected by exposure to titanium dioxide nanoparticles commonly ingested from food causing increased systematic inflammation, reduced digestive enzymatic activity, and reduced nutrient absorption.
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Dr. Connie Wan
Zhongyuan Guo, Nicole J. Martucci, Fabiola Moreno-Olivas, Elad Tako, Gretchen J. Mahler. Titanium dioxide nanoparticle ingestion alters nutrient absorption in an in vitro model of the small intestine. NanoImpact, 2017; 5: 70 DOI: 10.1016/j.impact.2017.01.002