Now it is safe to consume fish-based diets, as a new study demonstrates how a ‘Probiotic’ removes methylmercury from the intestines while leaving the beneficial nutritional bacteria behind.

Fish, as a primary source of protein and healthful fats, constitutes a vital part of the diet for over three billion individuals across the globe. In particular, dietary regimens such as the Mediterranean and Nordic ones place a premium on fish.

However, the accumulating environmental pollutants, which include cancer-causing heavy metals, are a significant concern as they are absorbed along the food chain.

Take, for instance, Mercury. Its release from industrial operations like coal combustion finds its way into our water bodies where microorganisms convert it into methylmercury.

This compound then becomes part of the diet of plankton, which is consumed by shrimp, leading to the accumulation of methylmercury in shrimp tissues. As we progress further up the food chain, this toxic compound continues to accumulate in increasing amounts. This phenomenon is referred to as biomagnification.

A recent scientific breakthrough suggests a potential solution to this issue.

A pioneering study conducted by researchers at Pennsylvania State University posits that the manipulation of gut microbiota in humans might prove efficacious in impeding the absorption of deleterious metals like mercury, while simultaneously facilitating the absorption of nutritionally essential metals such as iron.

The research findings were unveiled at the annual American Society for Microbiology’s ASM Microbe 2023 conference.

Methylmercury, a neurotoxin, poses significant risks, emphasized Daniela Betancurt-Anzola, a graduate student at Penn State who spearheaded this study. The toxin exerts harmful effects on neurological development during gestation and early childhood, especially in populations heavily dependent on fish-based diets. Although fish and shellfish are the main sources of methylmercury exposure, other sources do exist.

“It accumulates in living things, in plants and fish,” she adds. “We eat those things, and it accumulates in us.”

Mercury-blocking Probiotics

Betancurt-Anzola and her team first looked at the genomes of tens of thousands of gut bacteria, focusing on genetic factors that affect how well bacteria can interact with metals. She noted that many genes are known to be associated with metal resistance, but that this study narrowed down on those that allow bacteria to metabolize mercury into less deadly forms.

The team used metagenomic sequencing to look at how bacteria in both humans and mice reacted to mercury. This helped them figure out how these genes work and how they affect the host. Lastly, the researchers used what they had learned to make a probiotic that removes a dangerous type of mercury that is often eaten by people. They modified strains of the lactic acid bacterium Lacticaseibacillus by inserting genes from Bacillus megaterium, which is resistant to methylmercury.

“It’s a perfect probiotic for this because we have previously shown it works in humans, and now we are engineering it to make it even better,” Betancurt-Anzola comments. “It is inside the gut, it grabs the methylmercury, then it goes out.”  

She said that although her team is now studying the effects of mercury on gut microorganisms, future work will expand to include other metals. Their final goal is to come up with ways to get rid of dangerous metals like mercury and make it easier for the body to absorb the metals it needs.

“We are interested in studying how the entire microbial community reacts to different metals,” Betancurt-Anzola adds.

Image Credit: Getty