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Monday, March 26, 2012

Nanoparticles affect iron absorption…maybe

Nanoparticles are almost ubiquitous in medicines and cosmetics.  I recently posted a diagram detailing their myriad uses.  But are they safe?  This is a question that Michael Shuler from Cornell University, Gretchen Mahler from Binghamton University and their colleagues set out to answer.  They found that nanoparticles do affect iron absorption, but that the body can probably compensate for this.

Nanoparticles are simply teeny tiny particles.  They vary in size and construction, depending on what they’re being used for.  For this study, the researchers added both 50 nanometer (nm) in diameter and 200 nm particles of different types and dosages to intestinal epithelial cell cultures.  They also fed 50 nm particles to live chickens. In each case, the number of nanoparticles was calculated to yield a dosage similar to what a person would ingest with a pill, which would be over a trillion.

The test tube studies showed that the addition of nanoparticles did affect how readily intestinal cells could take up iron and how easily they could pass it on (which would be to the bloodstream in a living animal). However, different types and concentrations of nanoparticles affected iron absorption in different ways, sometimes increasing absorption and sometimes decreasing it.

This figure shows 50 nm carboxylated polystyrene nanoparticles (green) interacting with a cell culture model of the intestinal epithelium (red). Oral exposure to these particles was shown to affect iron transport.
Credit: Nature Nanotechnology

Tests were also done with two groups of chickens.  The chronic exposure group was fed 50 nm particles every day for two weeks.  The acute exposure group was only fed the nanoparticles on sampling day.  When analyzed, the acute group had far less iron absorption than controls, but the chronic group had far more iron adsorption. Further examination showed that the chronically exposed chickens actually had many more villi in their intestines. 

So what does all this mean?  Clearly nanoparticles are having an effect on chickens, and by extension, almost certainly on humans as well.  It’s interesting that the body seems able to compensate for exposure to the nanoparticles.  You’d almost wonder if doctors should administer nanoparticles as a cure for anemia or malnutrition, if it will increase the number of villi in our intestines.