According to Gretchen Mahler of Binghamton University much of the existing research on the safety of nanoparticles has been on the direct health effects. But what Mahler, Michael L. Shuler of Cornell University and a team of researchers really wanted to know was what happens when someone gets constant exposure in small doses – the kind you would get if you were taken a drug or supplement that included nanoparticles in some form.
"We thought that the best way to measure the more subtle effects of this kind of intake was to monitor the reaction of intestinal cells," said Mahler. "And we did this in two ways – in vitro, through human intestinal-lining cells that we had cultured in the lab, and in vivo, through the intestinal linings of live chickens. Both sets of results pointed to the same thing – that exposure to nanoparticles influences the absorption of nutrients into the bloodstream."
The uptake of iron, an essential nutrient, was of particular interest due to the way it is absorbed and processed through the intestines. The way Mahler and the team tested this was to use polystyrene nanoparticles because of its easily traceable fluorescent properties.
"What we found was that for brief exposures, iron absorption dropped by about 50 per cent," said Mahler. "But when we extended that period of time, absorption actually increased by about 200 per cent. It was very clear – nanoparticles definitely affects iron uptake and transport."
While acute oral exposure caused disruptions to intestinal iron transport, chronic exposure caused a remodelling of the intestinal villi – the tiny, finger-like projections that are vital to the intestine's ability to absorb nutrients – making them larger and broader, thus allowing iron to enter the bloodstream much faster.
"The intestinal cells are a gateway that ingested nanoparticles must go through to get to the body," said Mahler. "We monitored iron absorption both in vivo and in vitro and found that the polystyrene nanoparticles affected the absorption process and caused a physiological response."
The next step for Mahler and the team is to take a look at whether similar disruptions in nutrient absorption could be possible in other inorganic elements such as calcium, copper and zinc. Also on the research agenda is the reaction of other nutrients such as fat-soluble vitamins A, D, E and K. And chickens and their intestines will definitely be part of this next phase of the study.
MEDICA.de; Source: Binghamton University