It’s difficult to walk through the aisles of grocery stores nowadays without coming across a slew of products containing “probiotics,” boasting labels that claim to help with everything from obesity to depression, from the common cold to indigestion. Probiotics have risen in popularity recently as some recent discoveries have turned our attention to the human gut microbiome, and revolutionized our opinions on bacteria.
It has become clear that the 39 trillion or so bacteria that reside in our stomach, gastrointestinal tract, and colon are critical to keeping us alive and healthy, regulating our immune systems and protecting us from a world full of pathogens. This rainforest-like ecosystem of bacteria helps break down our food, produces compounds that ward off invaders, and has a huge effect on how we think and feel by producing compounds like serotonin (responsible for feelings of happiness in the brain) and vitamins like K and B12.
As the importance of this micro-world of bacteria has been recognized in maintaining our wellbeing, naturally, supplements have been developed to try and improve it.
Probiotics are composed of live cultures of “friendly” bacteria that aim to boost the health of our gut microbiome. We see them in dietary supplements and in a variety of foods and drinks, including juices, fermented dairy products like yogurt, cereals, protein powders and fermented drinks like kombucha. The companies selling these products claim a host of benefits from taking these supplements, even referring to probiotics as a ‘miracle cure’.
These claims have allowed probiotics to become one of the most common dietary supplements taken in the world: currently, more than 3.9 million Americans consume some form of prebiotic or probiotic supplement, and 60% of healthcare providers prescribe probiotics as a form of treatment for various conditions. Astonishingly, as of 2018 the global probiotics market exceeds $49 billion, and it is expected to reach $64 billion by 2022.
Unfortunately, most of the statements about probiotics that are driving this craze are unproven; most of the existing research on probiotics actually suggests that it might not carry any benefits for healthy people at all.
In this article, we will address some of the myths surrounding probiotics, and share some insights gathered from rigorous scientific studies about how they work, what they’re good for, and when you should consider taking them. Probiotics supplements aren’t useless, but they definitely aren’t all they’re cracked up to be… before you spend the money on the next batch of supplements, give these myth busters a read.
Myth #1 – Oral probiotics can colonize and alter the human gut microbiome.
The understanding of probiotics that most people have is that when you take a probiotic supplement, the beneficial bacteria make their way down to your gut and stay there, delivering positive effects to your microbiome and boosting your overall health. While probiotics do offer some great benefits when taken for certain conditions (which we will discuss more in depth a bit later), for the most part, the body has no interest in allowing new bacteria into the system. Our immune systems have carefully crafted and powerful mechanisms to defend themselves against foreign invaders, and although probiotics may have good intentions, the body does not always see it that way.
Of the billions of bacteria that you ingest in a probiotic supplement, most of those will be targeted and killed by your immune system or dissolved in the harsh conditions of your stomach acid, leaving few, if any, to colonize your gut. In fact, most probiotics do not colonize the human gut at all, and do not even have a measurable effect on the bacteria that already reside there.
Instead, as the probiotics pass through our digestive system, it is theorized that these bacteria interact with the cells surrounding them: immune cells, gut cells, and other bacteria, and produce compounds (such as antimicrobials that ward off pathogenic bacteria) that support the growth and development of a healthy microbiome. But even these benefits are still up for debate.
Like any other organism, some bacteria are hardier than others. A pretty significant research base now exists surrounding the most popular probiotic strains, including which ones have been shown to survive the exposure to stomach acid. If you do choose to take a probiotic, shoot for supplements that contain these hardy bacteria and have documented success in clinical trials – in clinical trials, products are tested on actual human beings versus just being experimented on in the lab, and therefore are a much more reliable way of determining the effect of supplements on the body.
Many fermented, probiotic-rich foods, such as yogurt and kombucha, may stand a better chance at surviving the harsh conditions of the body because they are grown in an acidic environment, and thus are more prepared to endure the acidic journey to the gut. For this reason, diet is often recognized as one of the main factors shaping your gut microbiome: a happy diet (not a happy meal) leads to a happy microbiome.
Myth #2 – All bacteria in oral probiotics are beneficial.
Many bacteria in our gut are commensal, meaning they actually do not directly benefit us at all. But that doesn’t mean that they serve no purpose! These commensal bacteria take up all of the available space in our gut, and by doing so, prevent the invasion of harmful, pathogenic bacteria that cause diarrhea and a slew of other gastrointestinal problems. By outcompeting harmful bacteria for limited space, these commensal bacteria allow our gut microbiome to stay healthy and infection-free.
Many of the bacterial strains used in probiotics are aimed at doing just that: by simply taking up space in our gut, these neither-friend-nor-foe microbes prevent our bodies from succumbing to pathogens when we are vulnerable.
Some probiotic strains of bacteria, however, do benefit us. In the remainder of this article, we will discuss some of the ways they do this, but for now what is important to note is that not all probiotics are created equal. Studies have shown that different species of probiotic bacteria help with different things, and different strains within these species may benefit different symptoms as well.
For example, the common probiotic bacteria L. rhamnosus Rosell-11 has been shown to stabilize the gut microbiome while the patient is taking antibiotics (which by definition, kill off many of your gut bacteria) and reduce the risk of antibiotic-associated diarrhea. A different strain of the same bacteria, L. rhamnosus GR-1, instead colonizes the vaginal tract and helps treat conditions such as bacterial vaginosis and thrush through the stabilization of the vaginal microbiome.
These two strains of bacteria, although not very different physiologically, serve completely different functions in the body, and, not unlike medications, should be used for different things.
Another myth that often comes up surrounding probiotics goes something like this: “because different probiotic strains do different things for your body, it’s better to take probiotic supplements with lots of different strains in them, so you can treat it all.” This isn’t necessarily true either. While different strains of probiotic bacteria do offer different benefits, supplementing your body with bacteria that it doesn’t need does nothing more than aggravate your body’s immune response, which flares up every time foreign organisms find their way in. L. rhamnosus GR-1, for example, which colonizes the vaginal microflora, would not be able to offer any significant benefits for men.
Bacteria in the genus Bifidobacteria, however, which colonize the large intestine and help ensure regular bowel movements, have been documented in rigorous clinical trials to help alleviate constipation. If you find yourself suffering from this, a multi-strain probiotic may not be necessary: the probiotic Bifidobacteria lactis BB-12 may be all you need to address the symptoms.
Similarly, bacteria in the genus Lactobacilli live in the small intestine and help secrete digestive enzymes to break down food; supplementing these bacteria alone has been shown to help those suffering from indigestion. Ultimately, while it is tempting to treat all probiotic supplements as similar, it should be recognized that each strain provides different benefits and should be used accordingly.
Myth #3 – More bacteria is better.
A billion of anything is a hard number to conceptualize; 10 billion is even harder. We tend to gloss over numbers this large, lumping them with other large sums, like a stadium full of people, or a sky full of stars. Manufacturing companies that sell probiotics take advantage of this, assuming that we will play into the Western dogma of “more is better,” and that upon first glance, a label that reads “10 billion bacteria” will be more appealing than a label reading 1 billion. Is this true, though? Are more bacteria in a probiotic supplement really better?
Research seems to suggest not. A study was recently conducted in which a probiotic supplement containing the bacteria B. lactis BB-12 was given to 1,200 volunteers suffering from constipation over the course of 4 weeks. A third of the patients received a pill containing 1 billion bacteria, a third received a pill containing 10 billion bacteria, and the final third received a placebo, containing no bacteria.
Interestingly, both treatments in which the patients received the probiotic saw improvements in their constipation, with more frequent bowel movements, but there was no difference between the two. 1 billion bacteria seemed to do the same job as 10 billion bacteria, suggesting that the quality of the probiotic is more important than the quantity.
If the quality of a probiotic is poor, and it cannot survive the harsh conditions of your body, it doesn’t matter how many billions of it there are, it will not offer you any benefits. When choosing a probiotic supplement, focus more on the bacterial strains within it rather than the number on the label. The ideal probiotic dose is always the one that has been shown to have beneficial effects on humans in clinical trials, not the one with the most bacteria.
Myth #4 – Probiotics can help with weight loss, sleep, sugar cravings, healthy skin, a strong immune system, energy levels, stomach problems and more.
People take probiotics because of their proclaimed abilities to alleviate gastrointestinal discomfort, to fortify the immune system, to protect against harmful bacteria, to prevent cardio-metabolic disease, to increase mental and behavioral capacity, and to promote wellbeing, among even more far-fetched claims. However, many of these benefits are hotly debated, and while research has demonstrated that certain probiotics can be effective in alleviating conditions like constipation, diarrhea and bacterial vaginosis, no studies have actually shown that probiotics have a significant positive effect on healthy people with regard to any of these factors.
The reality is that many of the beneficial effects listed above have not actually been proven through scientific study or clinical trials, and the research we do have tends to suggest that probiotics may not be capable of conferring most of these benefits at all.
A study performed by an Israeli group of scientists led by Niv Zmora earlier this year attempted to determine the effect of long-term consumption of a multi-strain probiotic on the human gut microbiome in order to provide insight on its proclaimed “benefits” on patient health. Zmora and her fellow researchers were able to follow the probiotics as they traveled through the body, and discovered that many of the bacteria were able to survive the journey through the gastrointestinal tract and stay viable even as they were excreted as poop. This was good news for the probiotic.
However, the authors also discovered that the gut microbiome of the patients exhibited resistance to the probiotics, meaning that although the probiotics had survived the body’s immune response and harsh, acidic environment, the original gut microflora actually rejected them, and very little colonization by the new bacteria was seen.
This discovery was key, because in our current medical system, the functionality of probiotics is usually determined by checking for live probiotics in stool samples of the patients; that is to say, if these probiotics survived a trip through the body, it was assumed that they also successfully colonized the gastrointestinal tract. Zmora and her group proved this to be incorrect; bacteria may make it through the gut alive, but most strains pass through the GI tract without being able to incorporate into the gut microbiome, and their effect on us is therefore short-lived and ultimately, not very significant.
Studies like this one poke huge holes in the arguments of the supplement manufacturing companies endorsing these products and mark a really important difference between research-backed science and pseudoscience. Probiotics are currently in use as a dietary supplement by almost 4 million Americans and constitute a global market of almost $50 billion because of false advertising.
Supplement companies draw in consumers by constructing a narrative that is not supported by real research, and in doing so, have become incredibly successful selling these probiotics that may not really offer any of the benefits they claim to! We simply need more research in order to continue to debunk these unsubstantiated claims, as well as to build a more accurate picture of the role of probiotics in our overall and gut health.
For now, though, it is important to note that there are no studies that have supported the long-term use of probiotics by healthy people to improve overall health, and our current understanding is that any incorporation of these bacteria into our system is transitory, and probiotic strains are removed within days or weeks after the patient stops taking the supplement.
Myth #5 – Don’t take probiotic supplements while taking antibiotics.
While antibiotics offer a fantastic solution to bacterial infections, it is well understood that they can cause damage to your gut microbiome by killing off a lot of your beneficial bacteria as well. This often leads to antibiotic-associated diarrhea, which is caused by the invasion of harmful bacteria to the “free space” left by friendly bacteria killed by the antibiotic. Probiotics offer a great solution to this problem, providing friendly bacteria that the body can use as “placeholders” until the gut microbiome can recover.
However, because probiotics are just live bacterial cultures, they are also able to be killed by antibiotics. For this reason, it was assumed that probiotic supplements should be taken following antibiotic treatments, with no overlap, to help rebuild the network of friendly bacteria in the gut that was depleted by the antibiotic. Fortunately, research has identified several probiotic strains to be extremely robust, which can actually survive both antibiotic exposure and the harsh conditions of the human gut.
These strains, such as L. rhamnosus Rosell-11 and L. acidophilus Rosell-52, are able to help maintain levels of friendly bacteria and to reduce the risk of antibiotic-associated diarrhea even during antibiotic treatments, and are worth considering.
After antibiotics destroy many of the bacterial communities in the gut, the recovery of the gut microflora is slow and often incomplete. It does eventually recover, though, and human gut microbiomes analyzed before and after an antibiotic trial tell us that the types of bacteria inhabiting the gut are pretty much the same before a person takes the antibiotic and after they make a full recovery. Probiotics have been proposed as a method of holding that space until the normal gut bacteria can recover, and to test this, another recent study was conducted by the same authors as mentioned before, led by Nim Zmora.
In this experiment, human volunteers were given various antibiotics and their gut microflora were analyzed before and after the treatment, with some taking probiotic supplements and some recovering on their own. What they noticed was that the probiotic bacteria did fill the gaps left by dying gut bacteria and helped avoid the invasion of pathogens. Interestingly, though, probiotic supplementation after the antibiotic treatment actually delayed the recovery of the microbiome.
The supplementation of these friendly (but foreign) bacteria seemed to impair the body’s ability to heal its internal environment back to the original state. This was a surprise to the researchers.
These findings demonstrate an important tradeoff: although probiotic supplementation during antibiotic conditions resulted in these bacteria being able to colonize the gut and prevent infection, their presence significantly delayed the full recovery of the microbiome for at least 5 months after the patient stopped taking the probiotic. These bacteria are therefore able to serve that protective “placeholder” function during the antibiotic treatment, but make it harder for the system as a whole to get back to healthy levels.
Probiotics, like any other medical treatment, may confer benefits, but they are not risk-free.
Regardless of these risks, however, probiotic supplementation during antibiotic treatments is often used as a method for managing the occasional side effects from the antibiotics themselves. Patients who take probiotics with their antibiotics are less likely to experience antibiotic-associated diarrhea, making their recovery easier. More importantly, the mitigation of these symptoms makes the patient more likely to complete the entire course of antibiotics, which is usually the reason that people stop taking their antibiotics early. This, in turn, helps combat the development of antibiotic-resistant bacteria, which are becoming much more prevalent due to the premature discontinuation of antibiotic treatments.
What can we take away from all this? First of all, we can be confident about one thing: all benefits of probiotics aside, they are not enough on their own to maintain a happy gut, and they are not a substitute or replacement for traditional medications. Research is currently underway to confirm or deny the claims that they can contribute significantly to aspects of our health, such as the ability to improve our immune system, ward off pathogens, and enhance our mental acuity. For now, the only evidence we have about their benefits are for managing the symptoms of gastrointestinal disorders, and even then, only some strains have been shown to be effective.
If you’re not experiencing any gastrointestinal distress or you are otherwise healthy, probiotics simply may not be for you.
While there is much to be learned about the effects of probiotics on our health, evidence seems to be accumulating to suggest they have a net beneficial effect. They have been shown to be predominantly safe, and there is no harm in experimenting with nutritional supplements to see what works and doesn’t work with your body. Still, there is not enough research to determine the most effective dose, the most effective species or strain, and the best timing to take them.
At the end of the day, all bodies are different, all gut microbiomes are different, and all responses are different. To date, the largest factors we are aware of that can boost the health of our gut are regular exercise, a well-balanced diet, and getting plenty of sleep. Sometimes, a healthy lifestyle is the best medicine.