Tag Archives: Gretchen Mahler

Metal oxide nanoparticles and negative effects on gut health?

A May 4, 2023 Binghamton University news release by Jillian McCarthy (also on EurekAlert but published on May 9, 2023) announces the research, Note: A link has been removed,

Common food additives known as metal oxide nanoparticles may have negative effects on your gut health, according to new research from Binghamton University, State University of New York and Cornell University. 

Gretchen Mahler, professor of biomedical engineering and interim vice provost and dean of the Graduate School, worked in collaboration with Cornell researchers to study five of these nanoparticles. Their findings were recently published in the Journal of Antioxidants.

“They’re all actual food additives,” said Mahler. “Titanium dioxide tends to show up as a whitening and brightening agent. Silicon dioxide tends to be added to foods to prevent it from clumping. Iron oxide tends to be added to meats, for example, to keep that red color. And zinc oxide can be used as a preservative because it’s antimicrobial.” [emphases mine]

In order to test these nanoparticles, Mahler and Elad Tako, senior author and associate professor of food science in the College of Agriculture and Life Sciences at Cornell, used the intestinal tract of chickens. A chicken’s intestinal tract is comparable to a human’s; the microbiota that they have and the bacterial components have a lot of overlap with the microbiota that you see in the human digestive system, said Mahler. 

“We’ve been testing a series of nanomaterials here at Binghamton, and we’ve been looking at things like nutrient absorption, enzyme expression and some of the more subtle, functional markers,” said Mahler.

The doses of nanoparticles that were tested reflect what is typically consumed by humans. The nanoparticles were injected into the amniotic sac of broiler chicken eggs, which are specifically bred and raised for their meat. These chickens get larger faster, so the effects of the nanoparticles are more obvious earlier in development. The amniotic sac at a certain stage of development flows through the chicken intestine.

“When they hatched, we harvested tissue from the small intestine, the microbiota and the liver,” said Mahler. “We looked at gene expression, microbiota composition and the structure of the small intestine.”

The researchers found more negative effects with silicone dioxide and titanium dioxide. They also found that the nanoparticles had affected the functioning of the chicken’s intestinal lining (called the brush border membrane), the balance of bacteria in their intestinal tract and the chickens’ ability to absorb minerals.

The other nanoparticles had more neutral, or even positive, effects. Zinc oxide appeared to support intestinal development or compensatory mechanisms due to intestinal damage. Iron oxide could potentially be used for iron fortification, but with potential alterations in intestinal functionality and health.

Mahler doesn’t want to suggest that these nanoparticles need to be removed from our diets completely. Their research is meant to provide some information, and allow people to have a better understanding of what’s really in the food they consume.

“We’re eating these things, so it’s important to consider what some of the more subtle effects could be,” said Mahler. “We develop these gut models around this problem to try to understand it, and this collaboration, where we have these complementary methods to try to look at the problem, has been successful.”

Here’s a link to and a citation for the paper,

Food-Grade Metal Oxide Nanoparticles Exposure Alters Intestinal Microbial Populations, Brush Border Membrane Functionality and Morphology, In Vivo (Gallus gallus) by Jacquelyn Cheng, Nikolai Kolba, Alba García-Rodríguez, Cláudia N. H. Marques, Gretchen J. Mahler and Elad Tako. Antioxidants 2023, 12(2), 431, DOI: https://doi.org/10.3390/antiox12020431 Published online : 9 February 2023 (This article belongs to the Special Issue Dietary Supplements and Oxidative Stress)

This paper is open access.

Could engineered nanoparticles be behind rise in obesity and metabolic disorders?

The researchers haven’t published a study and they have used fruit flies as their testing mechanism (animal models) so, it’s a little difficult (futile) to analyze the work at this stage but it is intriguing. A June 9, 2015 news item on Azonano announces a research collaboration  designed to examine the impact engineered nanoparticles have on the gut and the gut microbiome,

Researchers at Binghamton University believe understanding nano particles’ ability to influence our metabolic processing may be integral to mediating metabolic disorders and obesity, both of which are on the rise and have been linked to processed foods.

Anthony Fiumera, associate professor of biological sciences, and Gretchen Mahler, assistant professor of biomedical engineering, are collaborating on a research project funded by a Binghamton University Transdisciplinary Areas of Excellence (TAE) grant to discover the role ingested nanoparticles play in the physiology and function of the gut and gut microbiome.

A June 8, 2015 Binghamton University news release, which originated the news item, describes the reasoning behind the research,

The gut microbiome is the population of microbes living within the human intestine, consisting of tens of trillions of microorganisms (including at least 1,000 different species of known bacteria). Nanoparticles, which are often added to processed foods to enhance texture and color, have been linked to changes in gut function. As processed foods become more common elements of our diet, there has been a significant increase in concentrations of these particles found in the human body.

Fiumera works in vivo with fruit flies while Mahler works in vitro using a 3-D cell-culture model of the gastrointestinal (GI) tract to understand how ingesting nanoparticles influences glucose processing and the gut microbiome. By using complementary research methods, the researchers have helped advance each other’s understanding of nanoparticles.

Using fruit flies, Fiumera looks at the effects of nanoparticles on development, physiology and biochemical composition, as well as the microbial community in the GI tract of the fly. The fly model offers two advantages: 1) research can be done on a wide range of traits that might be altered by changes in metabolism and 2) the metabolic processes within the fly are similar to those in humans. Fiumera also aims to investigate which genes are associated with responses to the nanoparticles, which ultimately may help us understand why individuals react differently to nanoparticles.

For this project, Mahler expanded her GI tract model to include a commensal intestinal bacterial species and used the model to determine a more detailed mechanism of the role of nanoparticle exposure on gut bacteria and intestinal function. Early results have shown that nanoparticle ingestion alters glucose absorption, and that the presence of beneficial gut bacteria eliminates these effects.

Mahler was already investigating nanoparticles when she reached out to Fiumera and proposed they combine their respective expertise. With the help of undergraduate students Gabriella Shull and John Fountain and graduate student Jonathan Richter, Fiumera and Mahler have begun to uncover some effects of ingesting nanoparticles. Since they are using realistic, low concentrations of nanoparticles, the effects are slight, but eventually may be additive.

The most interesting aspect of this research (to me) is the notion that the impact may be additive. In short, you might be able to tolerate a few more nanoparticles in your gut but as more engineered nanoparticles become part of our food and drink (including water) and your gut receives more and more that tolerance may no longer possible.

There is increasing concern about engineered nanoparticles as they cycle through environment and the US Environmental Protection Agency (EPA) funded a programed by Arizona State University (ASU), LCnano Network (part of the EPA’s larger Life Cycle of Nanomaterials project). You can find out more about the ASU program in my April 8, 2014 post (scroll down about 50% of the way).

Getting back to Binghamton, I look forward to hearing more about the research as it progresses.

Could nanoparticles in your mouthwash affect for your cells?

The first news item I’m going to highlight was posted on Nanowerk, March 8, 2012 and is focused on the use of silver nanoparticles in mouthwashes and dentures to prevent yeast infections,

Yeasts which cause hard-to-treat mouth infections are killed using silver nanoparticles in the laboratory, scientists have found. These yeast infections, caused by Candida albicans and Candida glabrata target the young, old and immuno-compromised. Professor Mariana Henriques, University of Minho [Portugal], and her colleagues hope to test silver nanoparticles in mouthwash and dentures as a potential preventative measure against these infections.

Professor Henriques and her team, who published their research in the Society for Applied Microbiology’s journal Letters in Applied Microbiology(“Silver nanoparticles: influence of stabilizing agent and diameter on antifungal activity against Candida albicans and Candida glabrata biofilms”), looked at the use of different sizes of silver nanoparticles to determine their anti-fungal properties …

The scientists used artificial biofilms in conditions which mimic those of saliva as closely as possible. They then added different sizes and concentrations of silver nanoparticles and found that different sizes of nanoparticles were equally effective at killing the yeasts. Due to the diversity of the sizes of nanoparticles demonstrating anti-fungal properties the researchers hope this will enable the nanoparticles to be used in many different applications.

Some researchers have expressed concerns around the safety of nanoparticle use but the authors stress this research is at an early stage and extensive safety trials will be carried out before any product reaches the market. [emphasis mine]

Following on the notion of safety and gargling silver nanoparticles, coincidentally, there was another news item also dated March 8, 2012 on Nanowerk, this one about the impact that nanoparticles may have on nutrient uptake,

Nanoparticles are everywhere. From cosmetics and clothes, to soda and snacks. But as versatile as they are, nanoparticles also have a downside, say researchers at Binghamton University and Cornell University in a recent paper published in the journal Nature Nanotechnology (“Oral exposure to polystyrene nanoparticles affects iron absorption”). These tiny particles, even in low doses, could have a big impact on our long-term health.

According to lead author of the article, Gretchen Mahler, assistant professor of bioengineering at 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’d get if you were taken a drug or supplement that included nanoparticles in some form. [e.g. silver nanoparticles in your mouthwash or on your dentures]

“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.”

As for why the researchers focused on iron and tested polystyrene nanoparticles (from the news item),

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 percent,” said Mahler. “But 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.”

While acute oral exposure caused disruptions to intestinal iron transport, chronic exposure caused a remodeling 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.

As to whether these changes are good or bad the researchers don’t speculate. They do have plans for more testing,

calcium,
copper,
zinc, and
fat-soluble vitamins A, D, E and K

They don’t mention any changes in the types of nanoparticles they might be testing in future.

In any event, our bodies have changed a lot over the centuries, you just have to visit a pyramid in Egypt or a museum that holds medieval armour to observe that humans were once much shorter than we are today.