How Do Small Particles in Our Food Affect Our Gut Bacteria?
New research on nanoparticles found in the food products we consume has provided new information about their effects on gut bacteria.
Researchers from the Mainz University Medical Center in Germany and colleagues from other centers in Germany, Austria and the United States discovered that ultra-small particles can bind bacteria.
In a paper now published in the NPJ Journal of Food, the authors describe how attaching to nanoparticles can alter the life cycle of gut bacteria and their interactions with the body.
The results should be beneficial to both the pharmaceutical and food industries. For example, they could lead to research on the use of nanoparticles in probiotics.
An example of this is scientists’ observations that synthetic nanoparticles can prevent transmission of Helicobacter pylori (a type of bacteria found in the stomach).
H. pylori is a bacterium that grows on the lining of the human stomach. It attracts the attention of many scientists because of its complex relationship with cancer.
“Before our work,” says Roland H. Stauber, professor in the Department of Otorhinolaryngology and Head and Neck Surgery at Mainz University Medical Center, no one looked at whether the nanoadditives directly affect the gastrointestinal flora. ”
The Use of Nanoparticles Is Increasing Rapidly
Nanotechnology manipulates materials on the nanometer scale, the same scale as atoms and molecules. A nanometer is one billionth of a metre, so there are 25.4 million of them in 1 inch.
In their work history, Prof. Stauber et al describe how the use of nanoparticles is increasing rapidly in many fields. These range from medicine to agriculture, the manufacture of personal care products and food processing.
For example, the food industry uses synthetic nanoparticles to lighten and color foods, impart nutrients and prevent infection.
All of these can “go into the human gut,” he says, “as part of food and drink that the gut can feed on.”
Nanoparticles are interesting not only because they are very small, but also because the materials containing them have unique properties at the nanoscale.
Compared to larger particles derived from the same materials, nanoparticles have a much larger surface area for their size, have “greater Brownian motion,” and can overcome biological barriers. These barriers include the mucus layer that lines tissues such as the gut.
For these reasons, their fate in the human gut is likely to differ drastically from their larger-scale counterparts derived from the same materials.
According to the study authors, “It is therefore important to ensure that any nano-enabled food ingredient is safe for use in food.”
Human Gut and Microbiome
The human intestine, or gastrointestinal tract, digests about 60 metric tons of food in an average lifetime. Over thousands of years, the human gut and the huge colonies of microbes that invade it have developed a relationship that is both complex and mutually beneficial.
As the partnership evolved, gut microbes have played an important role in human health and disease.
Gout microorganisms contain more bacteria; it also includes single-celled organisms called fungi, viruses, and protozoa.
Scientists use the term gut microbiome to denote the sum total of the trillions of genomes of microorganisms found in the gut.
The 3 million genes in the gut microbiome outnumber the 23,000 in the human genome. They also produce thousands of small molecules that perform many functions in the human host.
In this way, gut bacteria help digest food, harvest energy, control immunity and protect against pathogens.
However, imbalances in the gut microbiome can impair these critical functions to trigger or protect against disease.
Studies have linked an imbalance in the microbiome to cardiovascular disease, allergies, cancer, obesity, and psychiatric conditions.
All Nanoparticles Bind to Gut Bacteria
Stauber and colleagues conducted experiments in which they could examine the effects of a wide variety of synthetic nanoparticles.
These experiments simulate the journeys different particles can make as they pass through different parts of the gut and encounter various bacteria.
The main conclusion was that “currently used or potential future nanosized food additives” demonstrated the ability to bind to bacteria in the gut.
The nanoparticles bind to all kinds of bacteria, including the “probiotic” strains that can grow in dairy products like yogurt.
While all the synthetic nanoparticles they tested were bound to bacteria, the researchers noticed differences in their binding properties.
When attached to nanoparticles, the bacteria changed their behavior in some ways that could be beneficial and invariably.
One potential outcome that could be beneficial is the inhibition of infections, for example H. pylori. The team made this discovery while experimenting with silica nanoparticles in cell cultures.
However, a potentially troubling possibility that has arisen in other experiments is that binding to nanoparticles may make some unfriendly bacteria less visible to the immune system. Such a result may increase inflammatory responses, for example.
An important point the authors make is that food also contains naturally occurring nanoparticles – some of which can enter food during preparation.
The team also conducted experiments with natural nanoparticles and were surprised to find similar results to experiments with synthetic nanoparticles.
“It was surprising that we isolated naturally occurring nanoparticles from foods like beer, which also showed similar effects.”
Roland H. Stauber
Healthline, Nanoparticles in food can alter the behavior of gut bacteria, 2019