Microplastics are harming gut health: study

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A new study about microplastics harming the gut biome of seabirds warns that humans should be wary of a similar health concern.

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The study, published this week in Nature Ecology and Evolution, involved an international team of scientists, including Jennifer Provencher, a research scientist with Environment and Climate Change Canada.

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It found microplastics — small plastic particles less than five millimeters in length — in the digestive tract of seabirds altered the microbiome of the gut, increasing the presence of pathogens and antibiotic-resistant microbes, while decreasing the beneficial bacteria found in the intestines.

To understand how species are affected by diets contaminated with microplastics, the scientists examined the gut microbiome of two seabird species, the northern fulmar and the Cory’s shearwater.

Provencher, who plans to study the effects of microplastics in seabirds along the BC coast for her next project, said the amount of plastic found in seabirds is disturbing.

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“When we examine the birds, even before I open the stomach, I can hold it in my hand, and I can feel the plastic inside them,” he said. “These birds have very high levels of plastic.”

The scientists compared the microbes in birds with no plastic in their stomachs to birds with lots of plastic. Provencher said while they are not certain why the gut microbiome is changing, they do have a couple of theories.

“One way that could be happening is that there are microbes living on the plastics, and those are actually being carried into the stomachs of the birds,” said Provencher.

“The microbes living on plastics may actually compete with the microbes that are already in the stomach. And the presence of the plastics actually might affect the microbes because they have contaminants or additives on them. Those chemicals that are in the plastics may be leaching out and potentially harming the beneficial bacteria.”

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She added that the more microplastics found in the bird’s gut, the fewer commensal bacteria could be detected. Commensal bacteria, or good bacteria, supply their host with essential nutrients and help defend the host against pathogens, according to the study. A lack of these bacteria can lead to disease.

The study, led by researchers in Germany and at Canada’s McGill University, says that while this research involves animals in the wild, humans should take note because they also ingest microplastics from the environment and through food.

Provencher said many of his colleagues who work on human health issues are very keen to study this more in the human context, or in relation to animals that humans consume.

“If we don’t have the beneficial bacteria, it can affect your digestive system, and how well we take nutrients, it can affect our immune system. And so anything that alters your gut biota can have negative effects. And that certainly does have implications for both animals who ingest and accumulate those plastics as well as a human,” he said.

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Some species of seabirds — such as petrels — have been found with more plastic in their bellies than other types of seabirds like seagulls, which have the ability to break it down in their stomachs better, she added.

Gloria Fackelmann, who conducted the study as part of her doctoral thesis at the institute of evolutionary ecology and conservation genomics at Ulm University in Germany, said up until now there has been little research on whether the amounts of microplastics present in the natural environment hurt gut microbial health.

Provencher has some upcoming similar projects on the BC coast, studying how and where shorebirds are exposed to plastics. She will be studying birds on Vancouver Island and at Haida Gwaii.

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