Your Guide to Your Gut: Why Probiotics Really Matter | Physician's Choice

A Guide to Your Gut: Why Probiotics Really Matter

November 18, 2019 16 min read

Woman making a heart with her hands next to her stomach

Your gut health is driven by the world of bacteria you carry inside of your body. The composition of that bacteria can vary, depending on what you take in each day, and that composition (also often referred to as your microbiome) matters. 

Those lacking diversity of bacterial strains in their microbiome, or those harboring an excess of harmful bacteria, can be at risk for a remarkable number of health issues that others don't face.

Meet the live creatures in your gut

The foundation of the gut biome begins at birth, say researchers writing in the journal Gastroenterology and Hepatology. As babies move through the birth canal, they absorb bacteria from their mom's body. Babies who breastfeed take in even more bacteria. These cells move from the digestive tract to the gut, where they begin to grow and multiply once they arrive.

While babies and their moms may have very similar gut bacteria, things begin to change as those babies grow. Bacteria are living organisms, and they rely on food to thrive. Bacteria cells that do not get the right type of food may die off, while cells that get the right kind of nutrition may begin to thrive.

We also live in a world filled with germs and bacteria. Microbes are on almost everything, including the foods we eat and the surfaces we touch. That environment can influence the bacteria within the gut.

Some medications can also play a role in gut bacteria diversity. Antibiotics, for example, may kill off entire colonies of bacteria. That's true whether you take the pills to treat illness or whether you eat meat treated with antibiotics.

Everyone has a slightly different gut biome, and researchers with the American Gut Project say there is no ideal biome defined quite yet. Those researchers are attempting to determine the specific mix of bacteria that is most closely linked with optimal physical and mental health, but their work isn't done.

Other researchers have examined how some types of gut bacteria contribute to common illnesses, and that research might compel you to think about what you can do to support your own gut.

Your gut is your second brain

When you think of thoughts and emotions, you likely think of your brain. However, gut health also has a lot to do with mental health. Research suggests that the makeup of the gut can influence how we feel about almost everything.

In a study profiled by The Atlantic, researchers performed a series of anxiety tests on mice. Researchers gave one group of mice a common antidepressant and gave the other group a specific strain of gut bacteria thought to reduce anxiety. 

The two groups of mice had the same reaction to the stress test, suggesting this type of bacteria is at least as effective as medications in reducing anxiety symptoms.

Studies like this are important as they demonstrate just how much the colonies living in our digestive tracts impact what is happening in our minds. If we can amend what is living in the gut, perhaps we can improve what happens in the mind. 

Additional research highlighted by Scientific American suggests that the gut and the brain communicate clearly and often. Sometimes, researchers say, that communication has to do with food cravings.

Bacterial cells have preferred types of food. Some thrive on glucose, while others prefer proteins. The bacteria are adept at knowing what will help to keep them alive and thriving. 

Research suggests bacterial cells can call to the brain and spark cravings for the foods they like best. It can become a self-perpetuating cycle, researchers say. People with specific strains of bacteria will crave foods that support that bacteria. In fulfilling those cravings, they create a medium in which that bacteria thrives, and they (perhaps) alienate other strains in the process.

Similarly, some types of gut bacteria are associated with body size. In a study highlighted by Scientific American, researchers collected intestinal samples from women who were obese and women who were not. Those samples were transplanted into mice, and those with the obese samples gained weight while the others did not. Of note, the mice were in different cages, but they ate the same type of diet

When researchers repeated the experiment, they placed both groups of mice into the same cage. This time, all of the mice remained thin. Researchers say the mice with the obese sample picked up lean microbes from their neighbors, which helped them keep the weight off.

Humans aren't mice, and most of the studies that explore the link between the brain and the gut have involved rodents. More human studies are required before we can understand just how this works and what it means. But these results do seem to suggest that gut health and mental health are closely linked.

Top 5 probiotic benefits including digestive health, immune health, weight loss, inflammatory support, and certain allergies

Your gut is part of your immune system

Just as gut health can impact the way you think, the way you eat, and the way you handle emotional triggers, it can also play a role in your ability to fight off illness and disease.

Researchers at Johns Hopkins University point out that many of the cells lining your digestive tract secrete antibodies. These are the substances that help your body identify and fight invaders—a key part of the immune system that originates within the gut.

The gut can also regulate inflammation within the body. Specific cells within the gut can trigger a complex reaction that can result in local tissue swelling. That swelling means the immune system is awake and active, and it isn't always positive.

When something benign triggers the immune system, such as food moving through the digestive tract, its efforts are distracted from fighting off serious threats like infections. When this happens, there can be no energy left to fight off a genuine threat.

The right gut biome can help reduce inflammation throughout the body, making the body more capable of fighting off infections. And that has clear implications for women.

Gut health and women

Women have a special reason to pay attention to gut health. Feeding the gut with the right kind of bacteria can help prevent urinary tract infections (UTIs), which is important as standard methods to treat UTIs (like antibiotics) could make poor gut health even worse.

UTIs arise when naturally occurring bacteria (either on our bodies or in the environment) invades the urinary tract. Since a woman's anatomy leaves very little distance between the outside world and the warmth of the urinary tract, UTIs are common in women.

In the journal American Family Physician, researchers note that women who have one UTI have a 50% chance of getting another at some point in life.

UTIs are best treated with antibiotics, researchers say, and they should be treated early. An infection that begins in the bladder can move to the kidneys, causing life-threatening complications. Antibiotics typically work quickly to resolve the infection, which helps protect the kidneys.

Women who have recurring UTIs may be advised to take antibiotics for months or even years. This preventive antibiotic regimen is meant to protect the urinary tract, so women don't get potentially life-altering infections on a frequent basis.

Unfortunately, antibiotics are also known to kill beneficial bacteria within the gut. Recurrent use leads to urinary tracts nearly void of all bacteria. It's quite possible that women who take antibiotics for chronic UTI symptoms are at a greater risk for future infections, as they lose vital immune protection from the gut. 

Research profiled in Live Science suggests that probiotic therapy could help women prevent recurring UTIs. Here, researchers split women with frequent UTIs into two groups. One received a probiotic, and one did not. Of those who got the probiotic, only seven experienced a recurrent UTI; 13 had another in the control group.

We'll move into the demonstrated benefits of probiotic supplements in a bit. But it's important for women who experience recurring UTIs to know about this link between the gut and urinary health.

To promote urinary tract health, Physician's Choice Women's Probiotic contains D-Mannose and clinically proven ProCran™. ProCran™ is a patented and potent cranberry juice extract shown to prevent UTIs.

Probiotics and antibiotics

In an average year, there are 154 million prescriptions written for antibiotics, according to the U.S. Centers for Disease Control. Antibiotics can be life-saving medications when people are dealing with serious infections. But they can decimate the environment of the microbiome.

Antibiotics don't always discriminate between good bacteria and bad bacteria. And since they're typically taken internally, antibiotics have the power to move through the entire body quite rapidly. That means antibiotics can move into the gut, and once there, kill off all healthy bacteria inside the gut. This can lead to disastrous complications.

In a study published in the journal Expert Review of Anti-Infective Therapy, researchers reported that diarrhea takes hold in up to 39% of those who take antibiotics. A severe form of diarrhea, clostridium-difficile diarrhea, takes hold in about 10–25% percent of these cases.

Diarrhea can quickly lead to dehydration, particularly if it continues for an extended period of time. For those on antibiotics, diarrhea can persist until the course of therapy is complete. That means some people could deal with diarrhea for weeks.

Probiotics, filled with healthy bacteria, are tailor-made to help recolonize the body with beneficial bacteria. Probiotic therapy will not counteract the work done by antibiotics; instead, it replenishes the gut with healthy bacteria. Though the antibiotics may kill off all bacteria, the probiotic doses will continue to replace what has been lost.*

Eating to help your gut

The foods you eat can have a considerable influence on gut health. This is especially true for people who choose to eat plant-heavy diets. 

In New Atlas, researchers reported that people who ate 30 or more different types of plants each week had more diverse gut bacteria than people who ate ten or fewer different kinds of plants each week.

Researchers aren't entirely sure why varied plant-eating is so vital to gut health, though fiber is likely a key player. It could also be that people who eat so many plants eat very little meat, so they're not exposed to antibiotics riding in the meats they eat.

A researcher quoted in The Guardian also suggests that plants support the gut because they encourage the proliferation of healthy bacteria. The human gut is not designed to break down plant material, so it relies on bacteria to do the work. The more plants you eat, the more nutrition these healthy bacteria can get.

Plants aren't the only foods that fortify the gut. Fermented foods, like tempeh and miso, are filled with bacteria. Those cells help to transform raw materials into the tasty, tangy products we eat. 

People who eat these fermented foods are ingesting that bacteria directly. The same goes for yogurt and kefir, which also have bacteria built right in. Adding these items to your meals is a great way to get a load of bacteria into the body very quickly.

Infographic of probiotic food sources

Supplements can also help

Taking in 30 or more different types of fruits and vegetables can be daunting—and some people don't appreciate the tang of foods like kefir. Fortunately, probiotic supplements can help to fill the gap.

Probiotic supplements are loaded with bacteria targeted to help improve overall gut health. Most come in pill form, so you can easily take them with a meal.

Since bacteria are living organisms that need food to thrive, the benefits of probiotics will not persist from temporary supplementation. As Harvard Medical School points out, people need to keep taking probiotics to reap ongoing benefits. 

In addition, probiotics come in many formulations. A formulation that works perfectly for one person might not work as well for someone else. Experts writing in Healthline recommend looking for probiotics designed to address specific concerns rather than probiotics for general health and wellness. Reaching for that targeted product can help ensure each dose has the right mix of bacteria to fit your needs.

Finally, The Daily Beast points out that the U.S. Food and Drug Administration does not regulate probiotics, so it can be difficult for consumers to know that the products they take do what they say they do. Thankfully, third-party laboratories can test samples of probiotic pills for purity, strength, and quality. This testing helps consumers know they're getting the most out of their supplements.

Beneficial probiotic strains

A "probiotic" is defined as a live microorganism administered to bring about some kind of positive health change. In most cases, the live microorganisms we're talking about when discussing probiotics are bacterial cells.

Research published in the International Journal of Environmental Research and Public Health points out that the human body contains at least ten times more bacterial cells than human cells. In this way, we can begin to view our bodies as more than just human—bringing along a flourishing ecosystem of microbes along with us. 

But the bacteria we take in when we consume probiotics are made to survive—and proliferate—within the gut. Each probiotic strain works a little differently. It's important to know what each strain can do so you can make an informed choice as a consumer.

Here are the strains typically included in probiotic products:

  • Bifidobacterium bifidum. A healthy human gut contains many B. bifidum cells. Researchers identified this bacterium more than 60 years ago, and it's been the focus of hundreds of research papers. In The Microbiota in Gastrointestinal Pathophysiology, researchers found that B. bifidum was effective in treating inflammatory bowel disease and ulcerative colitis. Researchers suggest that this bacterium can colonize the gut and smooth out inflamed gut tissue. That could help reduce symptoms such as pain, bloating, and urgency.
  • Bifidobacterium longum. This bacteria is common in the microbiome of breastfed babies. The strain helps babies digest their mother's milk, and it tends to die out as babies grow out of breastfeeding. Supplementation with B. longum could be beneficial for people dealing with diarrhea. For example, in a study in the journal Alimentary Pharmacology and Therapeutics, researchers found that B. longum helped the immune system fight against pathogens that led to diarrhea. The bacterium also appeared to make the gut less susceptible to attack from diarrhea-causing bacteria.
  • Bifidobacterium breve. This is another form of bacteria that's common in a healthy gut. While we typically talk about a bacteria's ability to help slow down the digestive tract so diarrhea won't take hold, B. breve is a little different. In a study in Nutrition Journal, researchers found that this particular bacterium could regulate the work of the colon. That means people dealing with constipation may find relief with this probiotic. People with irritable bowel syndrome (IBS-C) may appreciate this aspect of B. breve, as it could help them overcome a constipation episode.
  • Bifidobacterium infantis. As the name implies, this is a type of bacteria common among babies. Movement through the birth canal and breastfeedings help moms pass this bacteria on to their babies. B. infantis typically helps a baby ingest breast milk, but the benefits to adults are also vast. In a study in the journal Gut Microbes, researchers found that this bacterium reduced inflammation markers in people with inflammatory bowel disease. In a second study profiled in the journal Clinical Gastroenterology and Hepatology, researchers found that B. infantis helped people overcome the pain, bloating, and constipation caused by irritable bowel disorder. Those who took the supplement had significantly fewer symptoms than did those who got a placebo instead.
  • Lactobacillus casei. Cheese-lovers owe a debt of gratitude to this bacterium. It's common in cow's milk, and its work is responsible for cheese, yogurt, and other fermented foods we eat. This bacterium can also do wonders within the human gut. Research suggests that this bacterium interacts with the human immune system, helping people fight against invaders that can make them ill.* For example, in a study in the European Journal of Clinical Nutrition, researchers found that giving this bacterium to healthy people changed the composition of the intestinal microflora, and bacteria levels dropped significantly. In a second study in the journal Applied and Environmental Microbiology, researchers found that L. casei could inhibit the growth of the bacteria Helicobacter pylori. This is a crucial finding, as H. pylori has been implicated in the development of ulcers. With supplementation, those painful ulcers could go away.
  • Lactobacillus acidophilus. This bacterium is found not only in the gut, but also in the mouth and the vagina. Since it is part of the healthy vaginal microflora, it's not surprising that this bacterium is often found in women's probiotic products. Keeping vaginal bacteria balanced can help women avoid painful urinary tract infections, yeast infections, and other similar bacterial infections. Studies, including this one from the American Journal of Gastroenterology, suggest that L. acidophilus can reduce diarrhea caused by antibiotic use.
  • Lactobacillus bulgaricus. This bacteria is found in both human bacterial tracts and in dairy products like milk and cheese. Unfortunately, just drinking milk is typically not enough if the amount of L. bulgaricus in your gut is low. This bacterial strain digests milk, so it can help people dealing with diarrhea due to lactose intolerance. It can also be helpful for people with inflammatory bowel conditions caused by bacteria. L. bulgaricus is competitive, and it will fight other bacteria for resources. Adding it to the gut could keep other bacteria from growing.
  • Lactobacillus brevis. If you've ever sipped spoiled beer or wine, you know how powerful L. brevis can be. This bacterium powerhouse feeds on sugars, and it can zap sweet tastes from fluids in mere minutes. In the gut, L. brevis can reduce inflammation, including inflammation in the mouth, according to a study in the Journal of Periodontal Research.
  • Lactobacillus rhamnosus. At one point, researchers thought L. rhamnosus was the same as L. casei. After multiple studies, experts discovered that these are two very different bacteria that do different things in the human body. L. rhamnosus is commonly found in probiotic products, for a good reason. As a study in the journal Microbial Cell Factories points out, L. rhamnosus can persist in the human gut for about a week after supplementation, which means it keeps working long after people take their pills. It can also reduce the impact of nasty germs inside the human body, reducing the risk of diarrhea, bacterial vaginosis, and more.
  • Bacillus subtilis. This bacterium is prominent in the human gut, but it's also found in the soil we walk on. Gardeners might take in this soil when they touch their mouths with dirty gloves, and farmers might breathe in spores when they walk through their fields. Supplements that contain B. subtilis can be beneficial for boosting the immune system. Research published in the journal Molecular Microbiology suggests that B. subtilis can produce more than two dozen different types of antibiotics.
  • Bacillus coagulans. This is considered one of our most beneficial bacterial strains. Medline suggests that it has been used to treat diarrhea, irritable bowel syndrome, inflammatory bowel disease, stomach ulcers, and respiratory infections.
  • Saccharomyces boulardii. This is a member of the yeast family, and research published in the journal Therapeutic Advances in Gastroenterology suggests that many of its benefits can be traced to the power of yeast. It can inhibit the growth of bacteria in the gut, help the gut's immune system, and stimulate healthy cell growth. It's been used to treat a variety of conditions, from diarrhea to constipation to ulcers.

How do probiotics work?

The human gut is home to about 100 trillion bacteria, according to Harvard Medical School. These small systems have the potential to help us tackle every day, life-saving tasks. Some help us break down foods, such as starches and milk. Others produce vitamins and hormones, so we have the nourishment we need to stay strong and healthy. And still, others help fend off invading bacteria species we might ingest.

Probiotic supplements contain helpful bacteria. These bacterial strains are similar to those seen within a healthy adult's gut, but others are seen only in infants.

Probiotics are taken orally, and they must survive the stomach's acidic environment to move down to the intestines. Once there, they can begin to colonize.

For people with decimated gut bacteria levels due to disease or antibiotic use, the bacteria in probiotics can forge new colonies within the intestine. Those with an imbalance of gut bacteria— meaning they have too many cells within the intestine that cause harm—probiotic bacteria can wage war with the unhealthy bacteria, resulting in a more optimal gut biome.

Prebiotics vs. probiotics: What's the difference?

All probiotics are bacteria, and the human gut is a perfect environment for these cells. The spaces they colonize are dark and warm, so they're an ideal place for bacteria to grow and thrive.

But bacteria also need food to grow. Without the right kind of nutrition, these cells won't have the energy to replicate. That's where prebiotics come in. These are substances probiotics feed on for sustenance and growth.

Good sources of prebiotics include:

  • Bananas
  • Apples
  • Leek
  • Cooked oats
  • Garlic
  • Greens, including seaweed and dandelion
  • Onion
Bulbs of garlic, a prebiotic food source

If you're taking a probiotic supplement, adding these prebiotic foods to your diet can help you ensure that you're making the most of your investment. Physician's Choice probiotic products contain a blend of prebiotics with ingredients that help probiotic organisms thrive.

Pros and cons of probiotic supplements

Probiotics are available in a variety of forms, including drinks, foods, and pills. Some forms of probiotics are even available through transplantation. 

For many people, using probiotic supplements in pill form is the most reasonable and efficient way to support their gut health. But there are pros and cons to supplementation that comes in a pill.

Probiotic pill pro: Taste

Probiotic foods are often fermented. A sugary substance, such as milk or cheese, is injected with bacteria. Those cells feast on the sugars in the food, and when the colonies grow big enough, that food is considered a probiotic source.

While this is a natural way to ingest a probiotic, the taste can be an issue for some. Fermented foods tend to be tangy, tart, and a little fizzy. Some people can't get used to the taste, so they avoid the foods that can help them.

Probiotic pills don't come with an unusual taste (or any at all). The active cells are encased in a coating that stays in place until the pill reaches the stomach. That means people who are averse to fermented flavors may be able to stick with therapy a little longer.

Probiotic pill pro: Convenience

Probiotic foods can be expensive, and as a result, some people opt to make their own fermented foods at home. This can be incredibly time-consuming—and it isn't always safe.

Mother Nature Network reports that kombucha typically takes days to brew, and those who do so need to ensure that the pH level remains at 2.5 to 3 before taking a sip. Brewers must also worry about dangerous mold spores infecting their brews.

People who make yogurts and kefir at home deal with the same concerns. If their milk batches grow too warm, the products will clump, clot, and be unsafe to consume. If the milk is too cold, the fermentation will never take hold.

Probiotic pills come with none of these concerns. All the production happens within a factory, and the product is ready to consume right when it's delivered. Those who struggle with preparing probiotic foods might find this very appealing indeed.

Probiotic pill con: Adjustment periods

Most probiotic pills contain several bacterial strains, and each dose delivers real power. That means the cells packed within each pill may fight for space within the gut, producing uncomfortable (but temporary) symptoms.

The Cleveland Clinic reports that people taking probiotics may experience gas, bloating, and stomach discomfort for the first few days of supplementation. These symptoms tend to fade with time.

Since foods that naturally contain probiotics contain smaller amounts of probiotics, they may not require this kind of adjustment.

Probiotic pill con: Need to work with a reputable source

Probiotics are considered supplements, not medications. That means they're not regulated as tightly by the U.S. Food and Drug Administration. Probiotic manufacturers may make claims about the types of bacterium included, and they may identify how many bacterial cells are in each dose. But the reality may be quite different.

That's why it's so vital to check for third-party testing of purity and potency. That testing can help ensure the label accurately describes the product included inside the bottle.

At Physician's Choice, we test our probiotics in a laboratory for both strength and purity, so you can trust that you're getting a powerful product that contains the active ingredients we cite on the label. We also encase our probiotics in an acid-resistant capsule that protects the ingredients as they move through the harsh environment of the stomach. That means you'll have more helpful bacteria reaching your intestines and helping your gut.*


Not all probiotics are the same, but there is a lot of research backing the importance of probiotic supplements and gut health. While scientists are still answering some of the exact "why" questions, we do have strong evidence that gut health is vital to our well-being. We also know well-designed probiotics have real power to impact our health for the better. 

Taking a trusted, effective probiotic with a clinically proven prebiotic blend and other science-backed ingredients is an easy way to help restore the balance in your gut biome and help you feel your best every day.

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