January 12, 2021 10 min read

We’ll start off with a truism: the human body is a very complex system filled with more complex systems, mechanisms, and tiny living things—all of which we’ll be touching on down below.

And speaking of touching, did you know there’s a ballpark number of 5 million bacteria on each of your hands? Some of them living symbiotically, others potentially pathogenic. The human body is in itself a world of organisms that interact both with one another and with the earth they inhabit (i.e. every surface of your body).

By now most people know that yogurt is healthy because it provides some of the “helpful” versions of the microbes that live in your gut. And with our constantly evolving understanding of what makes us, “us,” these microbes are beginning to play a larger part in our understanding of how everything works.

One of the ways that bacteria affect us is through the function of our immune system.

Another complex mechanism that helps us avoid and fight off illness, our colony of tiny organisms, and the immune system are very interwoven. And while common understanding has often cited the usefulness of probiotics in maintaining a healthy immune function, things are more complicated than they first appeared—as is usually the case.

Gut Biome

First Thing’s First—What are Probiotics?

Inside of your gut, there are an estimated 100 trillion microorganisms, living their lives. And that’s just in your intestines. Which begs the question—what are they and what are they up to?

These tiny microbes are either bacteria, viruses, parasites, or fungi, and they can either be beneficial for us, harmful, or simply neutral. What we want to focus on is the beneficial bacteria (the pro-biotics, if you will), since that’s what can help us resist infections and maintain overall health.

A commonly cited claim in popular science has been that these microorganisms outnumber our bodies’ cells by 10 to 1. While the claim might be a fun fact to pull out at parties, it’s based on a napkin calculation from a study in the 70s—so not exactly a hard, scientific fact. Nevertheless, modern estimations place the ratio at 3:1 of microbes to cells, or 1:1. Still a surprising amount, but not so dramatic.

These trillions upon trillions of microbes make up your microbiome—your own little community of organisms. And to add to that, every person’s microbiome is unique. Even twins have different microorganisms with different proportions.

“Probiotics” are the beneficial bacteria that mainly live on your skin, lungs, urinary tract, vagina, mouth—and most importantly for our purposes—the gut.

So, How Do They Work?

The main role that good bacteria plays in our bodies is that of regulating and balancing our health.

When bad bacteria enter our body, the good bacteria can fight them off, for example. A big thing that good bacteria do is control inflammation, which also supports your immune system. They also help create vitamins, help your body digest food, and support the cells that line your gut. All of these functions play into both digestive and immune health.

The point with probiotics is to maintain a healthy balance of them within your body. That’s why probiotic foods such as yogurt are often a good idea to eat while taking antibiotics since the antibiotics kill both the good and the bad bacteria. With probiotics foods and supplements, you’re replacing that population with good bacteria.

Maintaining a good balance of microbes inside your body is one of the best ways to ensure a healthy life, but what exactly are the benefits of probiotics on your health?

Fermented food

Probiotics and Gut Health

While the emphasis in recent years has been on taking probiotics orally—either through food or through supplements—good bacteria is something that plays a role from the moment we’re born.

Take, for example, the fact that babies born through C-section lack several bacteria when compared to babies who are born the conventional way. It’s also been shown that there’s a connection between C-section babies, the lack of this bacteria, and a higher chance of developing allergies, having less optimal immune systems, and a lower level of gut microbiota.

However, lifestyle is usually the most important aspect when looking at our gut health.

For example, stress, antibiotics, drugs, lack of sleep, and poor diet choices all play a part in destroying a healthy balance of gut microorganisms. A holistic approach to the issue is necessary for optimal gut health to be achieved.

When the digestive system is healthy with a good balance of bacteria, it can be expected to effectively filter out things that can damage your health. Things such as bad bacteria and toxins are either stopped or mitigated from causing you harm.

Practically speaking, this plays out by aiding against diarrhea (both antibiotic-associated and infectious), inflammatory bowel disease, irritable bowel syndrome, and even improving symptoms in people with ulcerative colitis. And in premature infants, they’ve been shown to reduce the risk of severe and fatal necrotizing enterocolitis by 50%.

It is, however, important to keep in mind that a lot of this is preliminary research.

Not only that, but most of this research has been done with very specific probiotic strains—something that we’ll touch on further down below.

What matters is that probiotics are absolutely essential for not only maintaining our health but also ensuring that we’re performing at optimal levels. Keeping a healthy balance of good bacteria can’t be overemphasized when considering your overall health. But what about the other health claims probiotics? Specifically, when it comes to the immune system.

Probiotics and the Immune System

We’ve already touched on one way that probiotics help support the immune system. By maintaining a healthy gut microbiome, the bad bacteria is effectively counteracted by the good bacteria. When it comes down to avoiding certain digestive diseases and illnesses, probiotics are extremely beneficial.

But their use as immune-boosting agents goes even further than that

Certain strains of probiotics have been shown to boost the production of antibodies that fight pathogens inside the body. Furthermore, there’s also evidence that suggests that they promote the activity of immune cells such as T cells and natural killer cells.

However, the relationship between the digestive tract and the immune system is also moderated by a healthy gut microbiome.

The Intestinal Barrier and the Immune System

The intestinal barrier is much like what it sounds like—composed of cells of mucus, epithelial cells, and immunoglobulin, and antimicrobial peptides (along with other immune cells).

This barrier is what allows these two systems to “talk” with one another and maintain a relationship. This is also the barrier that keeps the probiotics where they’re supposed to be—in the intestine. But it’s also what keeps harmful bacteria out while allowing nutrients to pass through.

Keeping this layer healthy means having a healthy gut microbiome, which helps to protect and strengthen several types of immune cells.

Responding to Pathogens and Inhibiting their Growth

A symbiosis occurs as well with the gut bacteria creating an inhospitable environment for pathogens in the intestines. In turn, the immune system protects the good bacteria by combatting these pathogens and keeping inflammatory responses at bay to other substances we consume (i.e. food).

This last point is important because inappropriate immune function to non-harmful things can be the cause of several illnesses, including celiac disease and allergies. With a healthy gut microbiome, this inappropriate immune response is mitigated.

Furthermore, healthy bacteria also create short-chain fatty acids (SCFAs) as a by-product in the gut. These SCFAs effectively lower the pH levels of the intestine, which helps to inhibit pathogenic bacteria from gaining a foothold. This kind of innate immunity is our front-line defense against attackers, and maintaining its health is one of the most important things we can do to prevent from falling sick.

Through various direct and indirect pathways, some of which were outlined above, the health of gut bacteria can be seen to play a key role in the overall health of our bodies. And so, it seems to follow that the “more” probiotics we have, the better we’re off for it—right?

Fermented Sourdough

Probiotics with a Grain of Salt

While the science continues to suggest that gut health is essential for the function of our immune systems, it doesn’t paint a full picture just yet.

Part of the reason is that studies are usually done with single strains of probiotics with predefined endpoints, in terms of where the study is going. While these studies continue to suggest, they’re stringent and we shouldn’t jump the gun on many of their conclusions.

The variety of probiotics is one key aspect to keep in mind, even when buying consumer products. Some strains are advertised on the packaging, while others might not be. And even if you get the one you want, sticking to a single strain of probiotic isn’t good in terms of maintaining a diverse microbiome as well as a populous one.

Some of the most commonly found strains include:

  • Lactobacillus (including lactobacillus acidophilus and lactobacillus rhamnosus)
  • Bifidobacteria
  • Saccharomyces boulardii
  • Enterococcus faecium
  • Streptococcus thermophilus
  • Leuconostoc

And the thing with some supplements and probiotic-rich foods is that often times the specific strains of bacteria aren’t outlined.

Some of the above are good for preventing diarrhea, others might be good for your skin, or maybe even be able to prevent constipation—and certain probiotics haven’t even been shown to have specific benefits. So, even if you’re inclined to get your gut health up to speed, it might be best to eat more natural probiotic foods, unless you know exactly what you’re after.

And why natural? They’re more likely to house an array of different strains, so you get a healthy dose of variety rather than a single strain that you might not even need. While the science is placing a greater emphasis on gut health, we’re still not sure exactly how everything interacts (especially when it comes to the immune system).

Which begs the question, can probiotics be taken safely by everyone?

Probiotics for All?

When it comes to healthy individuals, probiotics are never generally a bad idea. Sure, some people might be gassier afterward and in rare cases, a rash might develop, but these side effects aren’t serious and they can be easily reversed by stopping the ingestion of probiotics.

The story does get more complicated with people who are ill or immunocompromised, however.

While certain strains of probiotics have been shown to be good for several digestive tract conditions such as celiac disease, there are some which increase intestinal permeability (such as Chron’s and colitis). This is not a good thing when it comes to probiotic bacteria since it means that it can travel into the lining of the gut, potentially creating an inflammatory response from the immune cells. And an inflamed intestine is one of the last things you need if you’re already sick.

Immunocompromised individuals might also want to stay away from probiotics.

While it is impossible to make a generalizable statement about how all immunocompromised people should stay away from probiotics since that covers such a vast range of conditions, there have been some studies showing severe side effects for those who are critically ill, recovering from surgery, or young, sick children.

Those who are receiving certain cancer therapies might also want to stay away from probiotics. A study found that in a group of individuals receiving immunotherapy, those that took probiotic supplements were measurably less likely to respond to the therapy.

As it stands, the risk of probiotics isn’t high by any means, but it also shouldn’t be treated as a cure-all or an immune system booster. This is especially true for those who might be at risk from more severe side effects.

Ferment

Where to Get Your Probiotics

However, if you don’t fall into any of the at-risk groups, including probiotics in your diet can be a good way of maintaining a healthy lifestyle and gut microbiome. So, where do we get these little organisms from?

The most well-known is yogurt. There are several consumer yogurts that market themselves as good sources of probiotics, usually containing Lactobacillus strains. Along with yogurt, there’s kefir—a fermented milk drink that’s both rich in probiotics and yeast.

Foods such as cottage cheese, kombucha, tempeh, miso, sourdough bread, sauerkraut, kimchi, and pickles are all good sources of probiotics as well. Pretty much all fermented food and a lot of dairy products that are fermented as well. Watch out for foods that are labeled with “live and active cultures.”

This last point is important, especially for processed foods. Yogurt for example is first pasteurized after fermenting, and then the bacterial cultures are added in an inactive state. The thinking is that these cultures will pass through your digestive tract, “warm-up,” and then activate once they get to your intestines.

Knowing What to Buy

There are some criteria that companies must follow when presenting their product as a source of probiotics. The bare minimum is that the food is proven to have fermentation microbes and at a high enough concentration. If no health claim is made, the probiotic simply needs to be of a space species.

If, however, health claims are included on the product the requirements a bit more stringent.

For one, the strain must be defined. The delivery of an adequate amount of live microorganisms at the end of shelf life must also be shown, along with scientific evidence that shows that the strains do actually have health benefits. 

Prebiotics for Digestive Health

Another way to support your gut microbiome is by eating plenty of prebiotics.

These are the supports of the probiotics. Since they’re non-digestible carbohydrates, prebiotics pass through you and act as food for the microorganisms living in your gut. The thinking is that prebiotics can selectively stimulate the activity of certain strains of microbes which can help your body achieve optimal health.

Most of these prebiotics are oligosaccharides—compounds that are resistant to your digestive enzymes. While supplements exist, they can also be obtained from foods such as artichoke, asparagus, bananas, barley, garlic, milk, onion, and honey.

Eating enough (and a wide enough variety) of plant fibers is also a good way to foster a healthy culture of gastrointestinal bacteria.

Supplementation and Holistic Wellness

Another way to boost your gut health is by taking supplements. There are, however, several things to watch out for.

One thing to consider is that probiotics are considered dietary supplements and not drugs, which means that the FDA doesn’t monitor its manufacturing. If you’re to go down the probiotic supplement route, it’s best to ensure you’re getting a high-quality product.

However, no supplement will ever completely support a healthy body.

Probiotics—and the foods and supplements they come in—are just one ingredient that’ll support your body. Sure, they’re an important ingredient, but it’s going to take a holistic approach to achieve holistic wellbeing.

Health needs to be built on the foundation of a good diet, regular exercise, and plenty of sleep. Without these foundational principles of living a healthy life, probiotics aren’t going to be able to push you over the finish line when it comes to combating and avoiding sickness.

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