Evidence from clinical trials is mixed and often of low quality, but findings from meta-analyses suggest that probiotics can provide benefits in the treatment of some conditions, such as infectious and antibiotic-associated diarrhoea. As such, taking probiotics after antibiotic treatment is an increasingly common practice. However, two studies recently reported in Cell question whether taking highly concentrated supplements of so-called good bacteria aids the recovery of normal gut flora.
Probiotics are generally considered safe8 for most healthy people, but may cause gastrointestinal discomfort (abdominal tenderness, pain, gas, and/or diarrhea) if intake exceeds individual needs. People with certain health conditions like suppressed immunity or sensitivity to probiotics may experience more severe side effects9. Probiotics can also interact with some medications. Please consult your doctor before starting any new supplement.

There are two main types of probiotics; the first is the live cultures I describe above, like the strains of Lactobacillus and Bifidobacterium. You might have heard some naysaying about this kind of probiotic—the typical argument against them is that the classic form of live cultures is destroyed by the acidic environment in the stomach. To get around this, quality probiotics are made with an acid-resistant capsule so that they don’t get immediately broken down. (Which means you don’t have to take the probiotics with food, although I normally do. I’ll sometimes break the capsule and mix it into a smoothie, or use the powder form. You might lose a bit of potency but it’s not significant.)


Probiotics are a big and rapidly growing business and are now among the most popular dietary supplements. The term probiotic refers to dietary supplements (tablets, capsules, powders, lozenges and gums) and foods (such as yogurt and other fermented products) that contain “beneficial” or “friendly” bacteria. The organisms themselves are also called probiotics.
The U.S. Clinical Guide to Probiotic Products1, Canadian Guide to Probiotic Supplements2 and the WGO Global Guidelines for Probiotics and Prebiotics3 provide suggested effective amounts of specific strains for treating certain health conditions, such as constipation or IBS. All 37 products listed the species of bacteria they contained, but only 14 listed amounts of individual strains. We found that 9 of those 14 products provided beneficial bacteria at effective levels. The Center for Responsible Nutrition recommends4 the industry move toward specifying strains as a best-practice because whether a product works and for what purpose depends on its strains.
Back to the question of what are probiotics: There are five main types, each in its own classification called a genus. Within each genus there are multiple species, and within those species there are multiple strains. For example, Lactobacillus is a very common genus of probiotics. Within that genus are numerous species, such as rhamnosus. The genus and species of a microbe are always italicized, making it easy to know that a microbe is involved. In a species such as Lactobacillus rhamnosus (often abbreviated L. rhamnosus), there are many strains. An example of the name of a strain is L. rhamnosus GR-1.

Most probiotics are like what is already in a person's digestive system. Some probiotics have been used for a very long time throughout history, such as in fermented foods and cultured milk products. These don't appear to cause illness. But more study is needed on the safety of probiotics in young children, the elderly, and people who have weak immune systems.
Niv Zmora, Gili Zilberman-Schapira, Jotham Suez, Uria Mor, Mally Dori-Bachash, Stavros Bashiardes, Eran Kotler, Maya Zur, Dana Regev-Lehavi, Rotem Ben-Zeev Brik, Sara Federici, Yotam Cohen, Raquel Linevsky, Daphna Rothschild, Andreas E. Moor, Shani Ben-Moshe, Alon Harmelin, Shalev Itzkovitz, Nitsan Maharshak, Oren Shibolet, Hagit Shapiro, Meirav Pevsner-Fischer, Itai Sharon, Zamir Halpern, Eran Segal, Eran Elinav. Personalized Gut Mucosal Colonization Resistance to Empiric Probiotics Is Associated with Unique Host and Microbiome Features. Cell, 2018; 174 (6): 1388 DOI: 10.1016/j.cell.2018.08.041
The probiotic industry is booming, but the benefits of probiotic products and the quantity of viable bacteria they contain can vary. So, instead of adding bacteria from an outside source, you might be better off consuming prebiotics, like fermentable fiber, which support your own beneficial bacteria, Dr. Cresci says. Good dietary sources of prebiotics include dried beans and other legumes, garlic, asparagus, onions, leeks, certain artichokes, green bananas and wheat. Prebiotic supplements are available, as well.

Minerals And Extracts – Many probiotics, especially those marketed for women, also contain blends of vitamins, minerals, and plant extracts for optimal results. In some cases, these blends can be so inclusive that they actually replace your traditional multi-vitamin, and can be an excellent source of nutrition for women that don’t receive enough vitamins or nutrients in their basic diets.
Probiotics produce enzymes that help break down chemicals the average human gut has a hard time with, like the oligosaccharides in legumes. That results in less gastrointestinal distress and better absorption of nutrients. Probiotics also elicit an immune response that helps your body deal with harmful pathogens and other GI problems. The hard research, especially on recommended CFU dosages, is minimal, but it’s expanding as interest in the product does.

After further analyzing the data, the researchers found that they could predict whether the probiotics would take hold in people's guts by examining their microbiome and gene expression in the gut taken at the start of the study. However, this prediction method needs to be confirmed in future studies. The researchers called for further research to better understand why some people resist colonization by probiotics, as that future research may enable researchers to counteract the resistance.

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 Lactobacillus and Bifidobacterium species are naturals at protecting and improving gut health. Additionally, research in animals and humans has shown that probiotics decrease scores on depression assessments, thereby alleviating depression. As a matter of fact, there is a new term, psychobiotics, for these microbes that influence mental health conditions like depression.
Improving the health of your GI tract involves removing foods, drinks, and toxins that are irritating to it and your nervous, immune, and endocrine systems. Experiencing the benefits of foods and probiotics for depression also involves finding out what nutrients and substances you are low in or missing, and re-inoculating with beneficial microbes such as good probiotics.

For most of my life, I thought of probiotics as something I’d only drink if I lost a bet. Then stress-induced irritable bowel syndrome (IBS) turned my intestinal tract into a nonstop river of shit—we’re talking weeks of everything I ate shooting straight out my butt in liquid form. The internet said probiotics were my best non-pharmaceutical bet to help my digestive system calm down, so I swallowed my pride (and my first kombucha ever) and kinda sorta saw the light. My IBS wasn’t cured, but probiotics did help me spend less time on the toilet wide-eyed with terror, and more time doing what’s really important in life—watching TV with my family.

Undaunted, researchers looked into whether probiotics might be beneficial in a host of disorders, even when the connection to gut health and the microbiome was tenuous. Reviews show that there is insufficient evidence to recommend their use to treat or prevent eczema, preterm labor, gestational diabetes, bacterial vaginosis, allergic diseases or urinary tract infections.


What about prebiotics vs probiotics? Prebiotics are the food fibers that go through the gut unchanged and are then used by good colon bacteria as a food source for their own growth. Everyone already has most of these good bacteria present, but often in small quantities. Prebiotics are used to stimulate their growth. Simply stated, you already grow your own probiotics within your colon. You do not rely on them to make the passage through the stomach acid — acid that can destroy many probiotic bacteria. That’s why taking a probiotic supplement or adding probiotic foods to your diet does not always help your digestive system. You can eat as many probiotic bacteria as you want, but if they don’t survive the trip to the colon, your effort will be fruitless.
We are clearly getting to the strain level by going beyond “Saccharomyces boulardii” and to “Saccharomyces boulardii CNCM I-745”. They did a great job by actually putting it on the label so you don’t even have to contact the company to see exactly what strain you’re getting. (P.S. this is a well-researched strain that I highly recommend, especially for preventing antibiotic-associated diarrhea.)
After the antibiotics had cleared the way, the standard probiotics could easily colonize the gut of everyone in the second group, but to the team's surprise, this probiotic colonization prevented the host's normal microbiome and gut gene expression profile from returning to their normal state for months afterward. In contrast, the aFMT resulted in the third group's native gut microbiome and gene program returning to normal within days.
Bacteria die out over time. Some supplements list the potency when they were manufactured (before they rode in a truck, sat on the shelf at the grocery store, or hung out in the kitchen cupboard for a few months). In this case, there could be dramatically fewer viable bacteria by the time you consume them than when they were first encapsulated, and good bacteria are no good to you dead.
A number of probiotic products are on the market, including yogurts containing probiotics, as well as supplements and skin creams, and an estimated 3.9 million Americans use such products. Some studies suggest that probiotics may help with diarrhea or symptoms of irritable bowel syndrome (IBS), but strong evidence to support their use for most health conditions is lacking, according to the National Center for Complementary and Integrative Health.
Following a healthy and active lifestyle and eating a balanced diet are the best ways to foster a bountiful gut flora. Taking care of your gut flora can help with things like irritable bowel syndrome and chronic constipation, among other things. Even if you’re not sold on pursuing probiotics for your allergies, they’re good to consider if you’re experiencing any gastrointestinal issues.
Cleaning up your diet to remove things that bother you and to add nutrients you and your microbiota need, physical activity to reduce stress and increase feel-good neurotransmitters, mindfulness to discover how your thoughts affect your feelings, and daily consumption of probiotic pills and foods are easy ways to improve your mental health outlook.
Notably, after someone was tagged a “persister” or “resister” clear patterns emerged on how probiotics would impact his or her indigenous microbiome and gut bacteria profile. "Although all of our probiotic-consuming volunteers showed probiotics in their stool, only some of them showed them in their gut, which is where they need to be," Eran Segal said in a statement. "If some people resist and only some people permit them, the benefits of the standard probiotics we all take can't be as universal as we once thought. These results highlight the role of the gut microbiome in driving very specific clinical differences between people."

The good news keeps stacking up for probiotics, the good-for-you bacteria that keep your GI system functioning in tip-top shape. "Research is finding that a healthy microbiome may play a role in reducing inflammation, a risk factor involved in illnesses ranging from colds to cancer, heart disease, arthritis, and cognitive decline," says Katherine Tallmadge, RD, author of Diet Simple. In addition, the bacteria may help burn body fat and reduce insulin resistance, she says. So to stay slim and healthy, consider adding more probiotic foods to your diet. Start with these truly yummy 13.

There’s hard science saying probiotics can help with certain kinds of diarrhea, but for other conditions, it’s a bit of a crapshoot (har har). Lebwohl says that one of the first things that needs to change for probiotics to go widespread legit in the medical community is their regulation. Since they’re currently marketed as dietary supplements, they’re not subjected to the same FDA standards that medications are. That means that not only have they not been proven to work, it also means there’s also no assurance that what’s on the labels of these products actually matches what’s inside the bottle.
Yes! Beneficial yeast is a probiotic, defined as a microorganism that supports human wellness. (Probiotic means “for life.”) Saccharomyces boulardii is a remarkable yeast that can significantly support your whole internal ecosystem. It helps reduce problematic yeasts, such as Candida, and replenishes healthy gut flora.* While many probiotic supplements only deliver friendly bacteria without yeast, Probiotic All-Flora contains 5 billion CFU of beneficial yeast for complete support.
Our gut is home to over 500 bacterial species. These “visitors” form a bioreactor, which facilitates digestion, provides nutrients, and helps form the immune system. Some important nutrients made by this bioreactor include several B vitamins, vitamin K, folate, and some short-chain fatty acids. Up to 10% of an individual’s daily energy needs can be derived from the byproducts of the good bacteria in your gut.
When the digestive tract is healthy, it filters out and eliminates things that can damage it, such as harmful bacteria, toxins, chemicals, and other waste products. The healthy balance of bacteria assists with the regulation of gastrointestinal motility and maintenance of gut barrier function. Research has shown some benefits for the use of probiotics for infectious diarrhea, antibiotic-associated diarrhea, gut transit, IBS, abdominal pain and bloating, ulcerative colitis, Helicobacter pylori infection, nonalcoholic fatty liver disease (NAFLD), and necrotizing enterocolitis.
The statements on this website have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease. The contents of this website are not medical advice and are intended for general knowledge and informational purposes only. Probiotics support many facets of overall health when taken regularly as part of a balanced diet and healthy lifestyle.
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.
While past studies have investigated similar questions, they have all used patients' excrement as a proxy for microbe activity in the GI tract. Instead, Elinav, his colleague Eran Segal, (a computational biologist at the Weizmann Institute), and their teams spearheaded by Niv Zmora, Jotham Suez, Gili Zilberman Schapira, and Uria Mor of the Elinav lab collaborated with Zamir Halpern, Chief of Gastroenterology at the Tel Aviv Medical Center to measure gut colonization directly.
Supplements: dietary probiotic supplements -- which are available in capsules, tablets, powders and liquid extracts -- each contain a specific type of probiotic. These products are available at health food and natural food stores, vitamin shops, and other stores. As an example, one commonly used supplement is acidophilus, which is available from several supplement manufacturers.
In the United States, most probiotics are sold as dietary supplements, which do not undergo the testing and approval process that drugs do. Manufacturers are responsible for making sure they're safe before they're marketed and that any claims made on the label are true. But there's no guarantee that the types of bacteria listed on a label are effective for the condition you're taking them for. Health benefits are strain-specific, and not all strains are necessarily useful, so you may want to consult a practitioner familiar with probiotics to discuss your options. As always, let your primary care provider know what you're doing.
We have to give a nod to the most famous probiotic food: yogurt. Whether you love Greek or regular, low-fat or full-fat, look for the phrase "live active cultures" on the label. And although choosing a plain yogurt has less added sugar than the flavored kinds, Tallmadge gives you the okay to choose a fruit-infused flavor if that's the only way you'll eat it. Just be sure to aim for fewer than 15 grams of the sweet stuff per serving; sugar can feed the bad bugs in your gut.

The high quality supplement comes in veggie capsule form, and no refrigeration is necessary. This probiotic is made in an FDA registered facility (in the US), and it meets GMP standards. It’s an all natural supplement, that’s free of lactose, soy and gluten. It also contains no artificial coloring. DNA Shift probiotic also offers prebiotic fiber for an extra healthy brain and gut.


"People have thrown a lot of support to probiotics, even though the literature underlying our understanding of them is very controversial; we wanted to determine whether probiotics such as the ones you buy in the supermarket do colonize the gastrointestinal tract like they're supposed to, and then whether these probiotics are having any impact on the human host," Eran Elinav said in a statement. "Surprisingly, we saw that many healthy volunteers were actually resistant in that the probiotics couldn't colonize their GI tracts. This suggests that probiotics should not be universally given as a 'one-size-fits-all' supplement. Instead, they could be tailored to the needs of each individual."
Cleaning up your diet to remove things that bother you and to add nutrients you and your microbiota need, physical activity to reduce stress and increase feel-good neurotransmitters, mindfulness to discover how your thoughts affect your feelings, and daily consumption of probiotic pills and foods are easy ways to improve your mental health outlook.
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