The large intestine is home to hundreds of trillions of bacteria. Fortunately, most are neutral or even beneficial, performing many vital body functions. For example, they help keep “bad” bacteria at bay, play a role in immunity, help us digest food and absorb nutrients and may even have anticancer effects. But will consuming them as probiotics in foods or capsules make a notable difference to your health—especially if you are already healthy? Here’s a look at the evidence.
In these cases, IBS is essentially just TMI. “For the colon to be functioning properly, it needs to be contracting and relaxing in a way that is conducive to regular bowel movements that occur at predictable times and don’t occur too frequently or too rarely," Lebwohl says. "And the bowel needs to be giving infrequent feedback to the brain. People should not be getting updates from their bowel in terms of cramps or the feeling of having to have a bowel movement too often. Yet, people with IBS get very frequent unsolicited ‘progress reports’ from the bowel.”

Historically, people had plenty of probiotics in their diets from eating fresh foods from good soil and by fermenting foods to keep them from spoiling. Over a century ago, the Russian Nobel Prize winner Elie Metchnikoff theorized that “health could be enhanced and senility delayed by manipulating the intestinal microbiome with host-friendly bacteria found in yogurt.” Metchnikoff was ahead of his time with his view of probiotics benefits, but he also was aware that most citizens had regular access to probiotic foods.

"Probiotics applied topically sit on the skin's surface and prevent the skin cells from seeing the bad bacteria and parasites that can cause this immune system response," confirms Engelman. "This is known as 'bacterial interference,' as probiotics protect the skin and interfere with the ability of bad bugs like bacteria and parasites to provoke an immune reaction.
If you go with a supplement, know that the FDA regulates these products but treats them like foods and not medications. Unlike drug manufacturers, supplement makers don’t have to show their products are safe or effective to sell them. That means that these firms are in charge of checking the safety and labeling of their products before they sell them to make sure they meet FDA rules.
Other uses. Many other claims are made for probiotics—that they lower cholesterol, alleviate allergic skin conditions (like eczema), treat ulcers and urinary tract infections, improve vaginal health, reduce the risk of colon cancer, ease anxiety and depression, and ward off traveler’s diarrhea. Good evidence to support these claims is lacking. Research on probiotics for weight loss has yielded inconsistent results, and even studies with positive results have mostly found very small benefits, as was seen in an analysis of 15 clinical trials in Obesity Reviews in 2018.
A large analysis reviewed available research and determined that probiotics help lower blood pressure by improving lipid profiles, reducing insulin resistance, regulating renin levels (a protein and enzyme secreted by the kidneys to lower blood pressure) and activating antioxidants. Researchers consider them valuable prospects in the treatment of high blood pressure because their side effects are generally minimal or nonexistent. (82, 83)
In seven people, however, these bacterial levels persisted for more than five months after the treatment ended. “We never expected they would survive more than a few weeks,” Walter says. A follow-up analysis determined that these seven people had begun the experiment with lower levels of B. longum in the first place. In other words, their gut ecosystems had a vacancy that the probiotic filled. That is exactly the kind of insight that clinicians need to create and recommend more effective probiotics. If a doctor knows that an individual with severe diarrhea has an undersized population of a particular beneficial microbe, for example, then prescribing the missing strain should increase the chance of a successful treatment.
Some companies have been around for years, and you may know their names. Those that have made probiotics for a while likely have tested and studied them over and over. It's smarter to choose a product from them over one from a maker you don't know. Check a third-party certifier (like ConsumerLab or the USP) to see if they have tested the product and found that it’s safe and reliable. If you're in doubt, ask your doctor.

Flora offers a high potency blend of eight super strain probiotics for general gut health and immune system support including multiple varieties of Lactobacillus and Bifidobacterium, among others. Containing up to 42 billion CFUs per capsule, this powerful health-boosting blend uses only strains found naturally in the human body, which increases its effectiveness.
Immunity and colds/flu.There’s a close connection between the bacteria in your colon and the immune system. Several studies, including one in 2012 in the British Journal of Nutrition, have found that certain probiotic strains boost measures of immune response—but whether this translates into any clinical benefits is uncertain. Studies have been inconsistent, for example, as to whether probiotics will actually curb colds and other upper respiratory infections. In 2014 a review in the British Journal of Nutrition, which looked at 20 clinical trials, linked probiotics to shorter duration of colds, but not necessarily reduced incidence or severity. Similarly, a 2015 Cochrane review of 12 clinical trials concluded that certain probiotics may help prevent or shorten such infections, though the quality of the studies was poor.
Many studies have shown that probiotics reduce diarrhea associated with taking antibiotics in both adults and children. In fact, it is common for physicians and pharmacists to recommend eating a probiotic-fortified yogurt every day during a course of antibiotics to prevent diarrhea. More research is needed to determine which probiotics are associated with the greatest effect for specific antibiotics.
Historically, people had plenty of probiotics in their diets from eating fresh foods from good soil and by fermenting foods to keep them from spoiling. Over a century ago, the Russian Nobel Prize winner Elie Metchnikoff theorized that “health could be enhanced and senility delayed by manipulating the intestinal microbiome with host-friendly bacteria found in yogurt.” Metchnikoff was ahead of his time with his view of probiotics benefits, but he also was aware that most citizens had regular access to probiotic foods.

There are four significant takeaways from this study: (1) murine gut mucosal probiotic colonization is only mildly enhanced by antibiotics, (2) Human gut mucosal probiotic colonization is significantly enhanced by antibiotics, (3) After taking antibiotics, probiotics delay gut microbiome and transcriptome reconstitution in mice and humans, (4) Autologous fecal microbiome transplant (aFMT) restores mucosal microbiome and gut transcriptome reconstitution. 
Probiotics are very promising and used quite often in practice. Many physicians, including myself, use them regularly for many gastrointestinal issues and other issues like infant colic, preventing diarrhea in patients taking antibiotics and for overall immune and respiratory health. There is still a lot more research that needs to be conducted but it is clear that they are here to stay, and the research base is likely only going to lead to increased use in many other conditions in both preventing and treating diseases.
Myriad factors – antibiotics, diet, stress, and age, among them – affect the balance of diverse microbes present in your gut. While you can replenish your gut bacteria by eating well and incorporating natural probiotics (ex. yogurt and kefir) into a healthy diet, these processes can take weeks or months; taking a regular probiotic is an easy and effective way to ensure your gut (and immune system) stays healthy, always.
Quick note about some formulations with multiple strains (including this one): Take a look at the label below and you’ll see that the supplement contains a mix of strains, but the label just says there is a total of 20 billion CFUs (how they measure the amount of bacteria). This does not tell us how much of each particular strain there is, and we want to know that there are at least 1 billion CFUs per strain to get a beneficial effect.
The term "prebiotics" is often thrown around when probiotics are mentioned, and they're related to probiotics in a sense. According to Angelone, prebiotics are complex sugars that we don't digest but that are used as fuel by bacteria — including probiotics — that's already in your gut. Registered dietitian-nutritionist Beth Warren, founder of Beth Warren Nutrition and author of Living a Real Life with Real Food, explains that you can think of prebiotics as food for probiotics. You can get prebiotics from foods including asparagus, bananas, garlic, and onions, she says.
More than 80 years later, probiotics have become wildly popular and incredibly profitable. A 2012 survey by the National Institutes of Health showed that 3.9 million Americans stated they had used some form of probiotics or prebiotics (a type of dietary fiber thought to feed the friendly bacteria in your gut) in the last 30 days—3 million more people than in the previous study in 2007. Probiotics are now available for consumption in almost every imaginable form—pills, tablets, yogurts, juices, cereals, and energy bars. They have been touted as having benefits not only for digestive health, but also mood disorders, cancer, cold and flu prevention, and reproductive health issues.
They probably are. Lebwohl says probiotics may decrease the risk of getting diarrhea during the course of taking antibiotics, and may also play a role in specifically preventing the development of the dreaded antibiotic-related super diarrhea called C. difficile or C. diff. Antibiotics can wipe out the good bacteria that keep you from getting sick if you’re exposed to C. diff, or if you already have it in your system. C. diff symptoms can range from a moderate watery diarrhea several times a day to severe infections, which can be accompanied by fever, bloody stools, rapid heart rate, and can even lead to kidney failure. 500,000 Americans were infected with C. diff in 2015 and 15,000 died from it.
Even for healthy people, there are uncertainties about the safety of probiotics. Because many research studies on probiotics haven’t looked closely at safety, there isn’t enough information right now to answer some safety questions. Most of our knowledge about safety comes from studies of Lactobacillus and Bifidobacterium; less is known about other probiotics. Information on the long-term safety of probiotics is limited, and safety may differ from one type of probiotic to another. For example, even though a National Center for Complementary and Integrative Health (NCCIH)-funded study showed that a particular kind of Lactobacillus appears safe in healthy adults age 65 and older, this does not mean that all probiotics would necessarily be safe for people in this age group.
"Probiotics applied topically sit on the skin's surface and prevent the skin cells from seeing the bad bacteria and parasites that can cause this immune system response," confirms Engelman. "This is known as 'bacterial interference,' as probiotics protect the skin and interfere with the ability of bad bugs like bacteria and parasites to provoke an immune reaction.

In the 2016 paper, Dr. Ghannoum and is research partners looked at parameters of microbiome makeup in Crohn’s Disease patients and healthy members of the same families in an area in Belgium.  The researchers said they “​identified positive interkingdom correlations between C.​ ​tropicalis​ (a fungus), E.​ ​coli, and S.​ ​marcescens​ (both microbial species) ​in CD patients and validated these correlations using in vitro biofilms​. These results provide insight into the roles of bacteria and fungi in CD.​”​


This story has played out before, most notably with vitamin supplements, which decades of research have revealed to be completely unnecessary for most adults and, in some cases, dangerous, correlating with higher rates of lung, breast and prostate cancers. But that has not stopped marketers from pushing another nutritional craze. According to a National Institutes of Health survey, the number of adults in the U.S. taking probiotics or their cousins, prebiotics (typically nondigestible fibers that favor the development of gut bacteria), more than quadrupled between 2007 and 2012, from 865,000 people to nearly four million. San Francisco–based business consulting firm Grand View Research estimates that the global probiotics market exceeded $35 billion in 2015 and predicts that it will reach $66 billion by 2024.
Got your gut on your mind? Then you’re probably up on the health benefits of probiotics. From boosting immunity to improving digestion, probiotics have been touted as the “superhero” of the gut bacteria underworld. And yet, there’s a lot we still don’t know about probiotics because the research is just heating up. To date, most studies that have been done on probiotics are on the Lactobaccilus, Bifidobacterium and Streptococcus thermophilus strains. Meanwhile, there are, oh, upwards of 100 trillion gut-friendly bacteria out there — some of which are popping up in trendy new waters, chocolates, nut butters and more. Here’s what you need to know before giving your gut the royal treatment.
If this happens, it's time to consider switching to a new probiotic. Other reasons a probiotic may not be the right fit: SIBO or Candida. If you have either of these conditions, the strain of the probiotic could potentially make your symptoms worse. Remember, if you think a probiotic is not helping, seek the advice of a functional medicine provider to help you navigate the choices out there.
In a food sensitivity, the immune reaction is delayed, usually several hours to days after the exposure. Food sensitivities are the most difficult to determine since there is not an immediate reaction. These kinds of issues with foods can cause a wide range of physical and mental problems. An elimination diet followed by reintroduction is one of the best ways to determine a food sensitivity.

If you have an immune system problem or another serious health condition, you may have a greater chance of issues. Some reports have linked probiotics to serious infections and other side effects. The people most likely to have trouble are those with immune system problems, people who've had surgery, and others who are critically ill. Don't take probiotics if you have any of those issues.
In the past, probiotics have been proposed as part of a weight loss diet. However, a 2015 meta-analysis looked at available randomized, controlled trials investigating this effect and determined that the studies did not seem to support this hypothesis, as body weight and BMI were not consistently reduced. The researchers did point out the need for better designed trials, because they were not convinced the results were based on well-designed science.
We also found strains linked to five other health benefits like weight loss and lowering cholesterol. We feature options for those cases below, but they aren’t top picks because those use cases aren’t as heavily researched as immune health or IBS relief. Still, chances are any probiotic supplement is going to make some improvement to your digestive health, so don’t be afraid to experiment.
Even for those without an urgent problem, probiotics can help with overall digestive management. Challa argues in his book, Probiotics For Dummies, that good bacteria help "crowd out" bad bacteria. That's because the intestine is lined with adherence sites where bacteria latches on. If the sites are populated with good-for-you microbes, there's no place for a harmful bacterium to latch on.
Ultimate Flora tested significantly higher than the majority of general probiotic blends. Critical Care is composed of very well-documented probiotic strains and is an effective addition to any lifestyle, capable of conferring a wide variety of health benefits. The probiotic strains are not only diverse, they were also resilient to outside influences and, in many cases, were successful in establishing colonies within the digestive tracts of study participants.
What’s more, RAW Probiotics are exactly what they purport to be – raw! They’re uncooked, untreated and unadulterated, and have no fillers or binders. You also won’t find any displeasing carriers, such as maltodextrin or dextrose. And since RAW Probiotics are kept in temperature-controlled cold storage through delivery and until they make it into your fridge, you can be sure your probiotics “arrive alive.”
Overall, Enzymatic Therapy Acidophilus Pearls are a great daily probiotic supplement. They give you a ton of flexibility and is convenient since it doesn’t need to be refrigerated and can be taken with or without food! This probiotic makes on-the-go belly support a breeze. All in all, Enzymatic Therapy Acidophilus Pearls finally make it easy to travel with probiotics, are simple to take, and can give you the piece of mind that the money you’re spending on probiotics isn’t being wasted at the first sign of stomach acid.  Read the full review here… or click here to go buy it now!
Deep Immune Support Probiotics started with a simple premise: Most probiotic strains present on the market today cannot survive the acidic environment of the human digestive system. Additionally, most of the most powerful probiotics require refrigeration, meaning they won’t survive standard delivery services or even room temperatures during your commute or travel.
The popular frenzy surrounding probiotics is fueled in large part by surging scientific and public interest in the human microbiome: the overlapping ecosystems of bacteria and other microorganisms found throughout the body. The human gastrointestinal system contains about 39 trillion bacteria, according to the latest estimate, most of which reside in the large intestine. In the past 15 years researchers have established that many of these commensal microbes are essential for health. Collectively, they crowd out harmful microbial invaders, break down fibrous foods into more digestible components and produce vitamins such as K and B12.

Oral health. An increasing number of probiotic lozenges and gums are promoted for oral health—to reduce periodontal disease, throat infections, and bad breath, for example. There’s preliminary evidence that certain strains may have some benefits, but commercial products may not have the same strains and formulations as those tested in published studies.


The idea that consuming probiotics can boost the ability of already well-functioning native bacteria to promote general health is dubious for a couple of reasons. Manufacturers of probiotics often select specific bacterial strains for their products because they know how to grow them in large numbers, not because they are adapted to the human gut or known to improve health. The particular strains of Bifidobacterium or Lactobacillus that are typically found in many yogurts and pills may not be the same kind that can survive the highly acidic environment of the human stomach and from there colonize the gut.
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