Humans consume 100 trillion nanoparticles a day, according to the press release for a new study on nanoparticle influence on nutrient absorption. As the uses for nanotechnology become more widespread, from sunscreens to socks, we are just starting to learn about the possible effects these miniscule under-regulated particles may have on our health.
A new study shines light on perhaps the scariest news yet: nanoparticles can change the rate at which nutrients are absorbed. If nutrient absorption is affected, it means that toxin absorption could also be affected. In even more disturbing findings, the study shows that nanoparticles caused "remodelling of the intestinal villi" -- changes in the intestinal linings which are critical for passing nutrients from ingested foods through to the bloodstream.
Nanoparticles as Popeye's Kryptonite
Although it has since been shown that Popeye's predilection for spinach is based on an error (spinach has no higher iron content than any other leafy, green vegetable), Popeye was the poster child for for the energy depletion caused by iron deficiency. When Popeye popped a can of spinach, he came roaring back to life.
The first thing researchers from Binghamton University and Cornell University noticed: brief exposure to low levels of 50nm carboxylated polystyrene, chosen because its fluorescent properties make it easy to track, caused iron absorption in the intestine to drop off by 50%.
Or Popeye's Superfriend?But a strange thing happened when exposure to the nanoparticles continued for longer: "when we extended that period of time, absorption actually increased by about 200 percent. It was very clear -- nanoparticles definitely affects iron uptake and transport," explains Gretchen Mahler, assistant professor of bioengineering at Binghamton University, and lead author of the report in Nature Nanotechnology.
In fact, chronic exposure to the nanoparticle polystyrene caused physiological changes of the villi, small fingers in the intestinal wall that provide a large surface area through which nutrients can be absorbed. Villi became larger and broader, which allowed the iron to enter the bloodstream at a much faster rate.
Beyond IronThe scientists behind this study plan to extend their research to other minerals such as calcium, copper, or zinc and to fat-soluble vitamins like A, D, E and K.
But this study raises perhaps equally important questions: first, how do nanoparticles affect the absorption of toxins? Faster absorption rates could mean that household products which are not fatal to children who accidentally consume them now to become deadly when nanoparticles enter the mix.
Also, if chronic exposure to nanoparticles changes our intestines so that more surface area is available for absorption, will toxins that are currently excreted cause more damage to organs after distribution through the blood, or faster accumulation in body fat? Will bioaccumulation of toxins in our food chain accelerate?
The research provides some breakthrough tools for studying these questions. Again from the press release: "With so many nanomaterials under development and with so much yet to be learned about nanoparticle toxicity and potential human tissue reactivity, Mahler and the team are hoping that their work, particularly the in vitro model, will provide an effective low-cost screening tool."
We hope so too.