10 Things I Hate About Probiotics

People, we are on probiotic overload. You can find them added in unlikely food sources (probiotic bread is now a…thing), bottled beverages in every cooler, and even beauty products. I literally will not be surprised if I come home with probiotic dental floss next week. I know we all want to have top notch digestive health, and I’m right there with you, but we may have gone a little overboard. This is especially true considering we as consumers are wildly unaware of the limits that our current research on probiotic supplements has in terms of their effectiveness. That, and the supplement marketing game is strong and isn’t telling consumers everything because it really doesn’t have to. So let’s dive into a little research on exactly how effective probiotic supplements are and whether or not you need to be spending $60 a month on a product with 500 billion-trillion CFUs (aka colony forming units) that “needs” to be refrigerated… or else.

There may not be anything to hate about probiotics (and I may have just wanted an excuse to use that movie title), but there is certainly more to consider. And to be fair, I’m referring to probiotic supplements and not naturally probiotic-containing foods, which I’ll touch on as well.

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Supplement regulation is less than you’d think.

I’ll start with the bottom line: Like all supplements in the United States, probiotics do not need to show effectiveness or safety to be marketed. The Food and Drug Administration (FDA) allows dietary supplements to create claims that describe the effect it may have on the structure or function of the body. They are allowed to make these “structure and function” claims as long as they are not making any health claims in regards to a certain health condition, as this would classify them more as a medication and therefore subject to more regulation. Moreover, dietary supplements do not require FDA approval prior to marketing as long as they don’t make any of these specific health claims. Yikes!

While the FDA monitors the manufacturing of dietary supplements for things like sanitation practices and contamination, it doesn’t mean all facilities or companies are totally compliant. Studies have actually shown certain probiotic supplements to contain different life-threatening contaminants and microorganisms that were not listed on their labels despite FDA requirements and requirements. Of course, these cases are rare, but I think it’s still good to keep in mind.

Interestingly, Canada requires probiotic supplement manufacturers to disclose exactly what strains are in a product and the number of live cultures per serving (because the word “live” is key here). It also has more stringent safety testing standards than does the United States, which is also great. Just great.


Probiotics are not well-researched in “healthy” people.

While much of the research surrounding the benefits of probiotics relates to their use in treating specific medical conditions, probiotic use is arguably higher among healthy adults. This is a bit concerning because large, long-term clinical trials to show the benefits of probiotics for healthy individuals do not exist. In other words, the scientific community can’t definitively say right now if probiotic supplements are beneficial or even safe for healthy adults, and more research is needed (although probiotic use among healthy people is said to have a good safety record). People of all ages take probiotics to assist in normal digestive function, boost their immune systems, help with reproductive and heart health, and even promote weight loss, but we’re not quite sure if this use is beneficial or warranted (aka, you may be wasting your money, but we’re not sure. Isn’t science great?). Although some research does show that probiotic use in healthy individuals with normal immune systems did stimulate the immune system.

In terms of medical conditions with stronger research, the use of probiotics is well supported by evidence for Clostridium difficile-related diarrhea, and it is promising for use with rotaviral diarrhea, IBS, allergic rhinitis, atopic dermatitis, functional constipation, ulcerative colitis, and preventing respiratory tract infections. Evidence to support its use for vaginal cadidiasis, Crohn’s disease, and obesity is negative.


Probiotic supplements are not without risks.

Because these supplement labels don’t follow a ton of restrictions aside from the structure and function claims they can make, they also don’t need to be as clear as they should about the potential adverse effects they may have. This is especially worrisome for individuals who have serious medical issues. Reports have surfaced that show critically ill patients (adults and infants), post-surgical patients, and immunocompromised individuals are most at risk for dangerous side effects. Probiotic use in these populations has resulted in the development of opportunistic infections due to bacteremia and fungemia (the presence of bacteria and fungi in the blood, respectively). Again, these cases are rare, and certainly relate to very specific circumstances, but something to be aware of as an educated consumer. Experts say probiotics should also be used cautiously or avoided all together in patients who require long-term hospitalization, those on multiple broad-spectrum antibiotics, and those who have impaired gut integrity and are at risk for bacteremia.

The risk of opportunistic infections resulting from probiotic use, especially in immunocompromised individuals, is a scary effect of these supplements that warrants more investigation. As Dr. Cohen notes in JAMA, there is no structured system to report adverse events in most probiotic clinical trials, which, coupled with a lack of systems to detect harm that’s resulted from supplements currently on the market, means the actual rate of opportunistic infections stemming from probiotic use is unknown. What this means for you is that probiotic supplements may not be as safe as we think because we don’t know what “unsafe” truly looks like.

And speaking of opportunistic infections, because probiotic supplements contain bacteria, those bacteria may be resistant to antibiotics (naturally or acquired). This would present an obvious problem if someone developed such an infection to a certain antibiotic resistant strain and needed treatment. Where this really gets scary is if those bacteria can transfer their antibiotic-resistant genes to bacteria that already resides within your gut. But it’s Friday and I won’t ruin your weekend with that because more research is still needed to see how possible this really is.


But what are we really getting?

Short answer: we’re not really sure. The supplement label could say one thing, and the product inside may have something else. Or it could have the strains it claims to have but in quantities that are much less than you’d think. This is especially troubling given the fact that much of the research on probiotics identifies specific beneficial strains, and if you’re not even getting what you pay for, then what’s the point?

To me, this next part is the most concerning and something I consistently discuss with patients who are considering probiotic use. How much, and which types, of the bacteria in a probiotic supplement actually survive the trip through the digestive tract to their end point? Are they alive when they get there? Does the pill capsule even open properly? The question is: If the bacteria aren’t getting to your colon, then what’s the point? And the answer is: Not sure. This area of probiotic research needs increased attention, especially in the guts of healthy individuals where research is already lacking. There have been a number of studies that examine the colonization of participants’ guts after taking a specific probiotic, and the results leave much to be desired. In short, these studies show that while participants may have shown the bacteria in their stool, the majority of participants did not have intestines with notable colonization.

When you look at a package of probiotics, you’re probably judging effectiveness based on a few things, perhaps most often the number of billions of CFUs present. CFUs, or colony forming units (or bacterial colony counts), represents an estimate of the number of bacterial cells that are present. The number of CFUs on a label represents the amount that was present when the product was manufactured, not necessarily the amount that will be present at consumption after packaging, transporting, and storage. Experts argue that this number may not in fact reflect the actual number of viable CFUs, and therefore lack effectiveness, and that the labeled number of colonies often can’t be verified and strains have not been found to be viable at all. However, this study showed that most brands examined did have viable counts close to their claimed amount. Either way, there are clear inconsistencies.

Bacterial colonies grown from the probiotic-containing beverage, kombucha, from probiotic researcher and lecturer Sandra Buerger. Courtesy of www.bu.edu.

Bacterial colonies grown from the probiotic-containing beverage, kombucha, from probiotic researcher and lecturer Sandra Buerger. Courtesy of www.bu.edu.


So should we just eat our probiotics in food instead of through supplements?

Maybe. Interestingly, a study by Sandra Buerger at Boston University looked at the growth patterns of bacterial strains found in both probiotic supplements and probiotic-containing foods (miso soup, apple cider vinegar, and kombucha). They found that the bacteria from the food sources colonized in less organized and less uniform patterns than did the pill sources, which led them to conclude that the foods had greater bacterial diversity than did the supplements. Diversity of strains you consume is key when you’re thinking about what an ideal gut flora with great variety would look like, but this is true only of beneficial strains rather than potentially pathogenic ones. I will mention that variety in probiotic strains in a supplement is not always more effective than single-strain products when it comes to certain medical conditions. And there’s a host of other benefits that you’d gain by eating a probiotic-containing food versus taking a supplement. First of all, having something like kefir or sauerkraut or miso soup offers you more nutrients (think energy, protein, fiber, micronutrients) than consuming probiotics via pills. It can also be a most cost-effective way to get the proposed benefits of live cultures instead of paying some of the outrageous prices for supplements that exist.

The real.

I think much of this research is a convincing argument to avoid spending a ton of money on pricey probiotic supplements. I hate the feeling of not getting what I pay for (who doesn’t?), especially if what I’m “paying for” isn’t even well studied for my intended use. With that said, I don’t think there’s a lot of harm to eat probiotic-containing foods. I wouldn’t discourage someone from doing this as long as the foods are from a safe source (say no to food borne illness, am I right?) because a) these foods usually offer some sort of other benefit, and b) these foods may be beneficial, we just don’t know for sure yet. Another thing to consider is how you feel when you either take probiotics, don’t take probiotics, or eat probiotic-containing foods. I’m sipping on my kefir right now and I can say for sure that I feel better when I drink it, so I’ll continue to do that. One thing I do recommend, however, is if someone is interested in purchasing a supplement, I suggest avoiding the most expensive product on the shelf because, as I’ve stressed here, we just don’t know if it’s actually going to work for you. There are also resources related to the proposed effectiveness of common commercial probiotic products that could be helpful in determining if a certain product is right for you. And as always, it’s a good thing to check with your doc before adding any new supplements, especially if you have an underlying medical condition (and as always, this blog isn’t intending to diagnose or treat any health condition, it’s purely informational).

So, to recap: There aren’t really 10 things to hate about probiotics, but there are a few things to consider before taking them, and 10 Things I Hate About You is a really great movie. Period. I hope this gives you a little more clarity so you’re able to make a more informed decision about whether or not to use probiotics.

Emmy Bawden