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Your Immune System

Microbes and You: Unlocking the Power of Probiotics

Illustration of a variety of microbes
Illustration of a variety of microbes

Dr. Colin Hill

Professor of Microbiology, University College Cork

Desiree Nielsen

Registered Dietitian

Your immune system is a complex system made up of many cells and a surprising number of bacteria and other microorganisms. On the brink of cold and flu season, we’re all focused on ensuring that our immune systems are as strong as possible, and, with 70 to 80 percent of immune cells residing in the gut, we know that actively managing our gut microbiome is essential to ensuring good health.

The science is clear that the bacteria living in the gut can be both detrimental or beneficial depending on the specific strains and the delicate balance maintained between them. “We’ve accepted for hundreds of years that bacteria can dramatically affect health,” says Dr. Colin Hill, Professor of Microbiology at the University College Cork in Ireland. “It’s not such a leap to go from knowing that bacteria can interact with the human body in a negative way to believing that they can also interact with the body in a positive way.”

Choosing the right probiotic for the job

Probiotics can help support healthy gut flora by increasing the population of good bacteria. The big problem, however, is that probiotics aren’t always labelled in a way that makes their scientifically-proven benefits clear. Not all probiotics are created equally, and it’s very important to select the right one for your needs.

“People ask, ‘Do probiotics work?’ And the answer is yes,” says Dr. Hill. “But you have to take the right ones. It’s like asking, ‘Do pills work?’ Yes, of course. We know that pills can treat a headache, but that doesn’t mean you just grab the nearest pill off a shelf and then get disappointed when it doesn’t cure your headache.”

Not all probiotics are created equally, and its very important to select the right one for your needs.

Further, because the microbiome is ever-changing, it’s important to realize that probiotics aren’t fire-and-forget, the way some small molecule drugs are. “Unlike pharmaceuticals, a probiotic isn’t necessarily something you take once and then symptoms magically disappear,” says Desiree Nielsen, a registered dietitian. “It’s something you take on a regular basis to improve the resilience of your gut health.”

Trust your gut to help your immune system

Though it may seem strange at first to think of the gut as a primary player in the immune system, it’s important to remember that not only is our gut one of our most significant membranes for interaction with the outside world, it also evolved in a world where microbes were ubiquitous.

“Our immune systems speak the same chemical language as microbes, and the largest part of the immune system is in the gut,” says Dr. Hill. “Our immune systems have evolved to recognize, interact with, and respond to our gut microbiome. What we try to do with probiotics is identify and introduce bacteria that elicit a positive health response.”

The gut does more than we give it credit for

We tend to think of the gut as primarily a digestive organ, but its role goes far beyond that. Because of the interplay between gut flora and immune cells, what’s going on in the digestive tract can play an important role in inducing or amplifying immune response throughout the body. “Many people aren’t aware of how much goes on in the gut beyond digestion,” says Nielsen. “When your gut is healthy and strong, it keeps you safe from outside pathogens that could harm you.”

We live in an ever-changing microbe-rich environment. And, as one of our most significant interfaces with the outside world, we depend on our guts to provide a robust barrier against microbial illness. Fortunately, the microbiome is particularly well-adapted to do so.

“Remember that we evolved into a world that was already full of microbes,” says Dr. Hill. “Microbes have been here for three billion years. Humans have only been here for a few hundred thousand. We evolved into a microbial world, so it’s not surprising that we’re adapted to expect to encounter microbes.”

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