The bottom line: Stick to trusted whole food sources of probiotics if you don’t know a probiotic supplement brand you trust. “Kimchi, pickled beets, Greek yogurt and sauerkraut are great sources of probiotics. If you don’t like them, throw them into a food you do like, like a smoothie, and add your favorite fruit to help mask the flavor,” Taub-Dix says.
Unless you have a perfect gut and are already eating lots of fermented foods—which is rare, although you can work up to this point—it’s difficult to get all the probiotics you need from diet alone. Most of us don’t have perfect guts—everything from antibiotics to high-carbohydrate diets to being born via a C-section can compromise the balance of bacteria in our microbiome. Supplementing with a probiotic can help to restore imbalances, and it’s also just a great preventative health measure, helping to keep your microbiome in balance and your immune system healthy to ward off illnesses.
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. 
The beneficial microbes, including probiotics, live with other microbes that are either benign, pathogenic (disease-causing), or opportunistic, meaning that they normally play nicely but can get out of control if given the opportunity. Actually, any microbe can cause you problems if it ends up in a place other than where it is supposed to be. Such a scenario can happen with intestinal permeability, commonly called leaky gut. Leaky gut happens when the layer of skin-like cells in your GI tract develops gaps in between the cells, allowing food particles, toxins, microbes, and other hazards to enter your bloodstream, if not stopped by the immune system. Since mucus, the thin layer of cells, and your immune system are your only defenses against the outside world within your digestive tract, it is very beneficial to you to have helpful microbes protecting you from potentially pathogenic microbes. These beneficial microbes can produce acids or antimicrobial products called bacteriocins, which hinder or kill pathogens. They can also stand in solidarity to prevent pathogens from taking up residence, or displace them if they do.
Quality matters for any supplement, and that goes triple for probiotics. Many commercial brands lack the technology to identify specific strains and how much of that strain each dose contains. That could mean you get an ineffective or potentially harmful dose. It's a great sign if the company is using strains that have been used specifically in clinical trials at a dose similar to or the same as that used in the study. This is one of the only ways to guarantee a probiotic's clinical effectiveness.
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.
Among their numerous health benefits, research shows these friendly microorganisms help prevent bowel diseases, improve your immune system, reduce traveler’s diarrhea, help you maintain a healthy weight, heal various skin conditions, improve bloating and other uncomfortable GI symptoms, and even boost your mood, helping to reduce the effects of anxiety and depression.
Two dangerous diseases in newborns, necrotizing enterocolitis (NEC) and neonatal sepsis, may meet their match with well-designed probiotic supplements. Both of these conditions are common in premature babies and are most dangerous in low birth weight and very low birth weight infants. Research has confirmed that when a pregnant mother takes high-quality probiotics during pregnancy, her baby is significantly less likely to develop either NEC or sepsis, particularly when the baby is breastfed after birth (and mom is still taking the supplements) and/or when probiotics are added to formula. A probiotic supplement with multiple strains seems to be the most effective in these cases.
Since the bulk of your natural flora exists in your gut, it makes sense that this is the part of your body that feels it most when bacteria become imbalanced. Women, in particular, can experience all kinds of digestive problems, particularly during hormone fluctuations. These are just some of the digestive symptoms a high-quality probiotic can help reduce and even treat:
Another study by Elinav and his colleagues suggests that not everyone’s gut reacts the same way to probiotic pills. They studied samples of microbiomes from antibiotic users before and after they took supplements for four weeks. The good bacteria were found in the digestive tracts of some people. But in others, the bacteria were present only in stool samples, not in their digestive tracts, where they’re thought to be needed to improve health.

Have you ever baked bread and had to proof the yeast? Proofing the yeast allows it to become active in the conditions it prefers the most: warm and moist with access to sugar. Baker’s and brewer’s yeast are both forms of Saccharomyces yeasts, as is Saccharomyces boulardii, but these yeasts are usually helpful to you and noninfectious, except in immunocompromised people or people with yeast allergies.
"The name itself is derived from the Latin 'pro-' meaning 'for' and the Greek '-biotic' meaning 'life,'" explains Jeannel Astarita, skincare expert and founder of Just Ageless NYC Wellness and Medspa. "Probiotics are the helpful bacteria that live primarily in your gut and play a crucial role in your overall health by fighting pathogens and yeast that lead to a weakened immune system."
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.”

That said, supplements with higher numbers of CFUs are sometimes used to treat conditions such as irritable bowel syndrome (IBS), allergies, and respiratory illness. While probiotics have generally been found to be safe for most people with normal immune systems, too much can cause gas and upset stomach. We narrowed our search to supplements with dosages between 1 billion and 100 billion CFUs.


The other way that probiotics help is the impact that they have on our immune system. Some believe that this role is the most important. Our immune system is our protection against germs. When it doesn't function properly, we can suffer from allergic reactions, autoimmune disorders (for example, ulcerative colitis, Crohn's disease, and rheumatoid arthritis), and infections (for example, infectious diarrhea, H. pylori, skin infections, and vaginal infections). By maintaining the correct balance from birth, the hope would be to prevent these ailments. Our immune system can benefit anytime that balanced is restored, so it's never too late.
Every day, we’re exposed to toxins and inflammation-causing molecules from food and the environment that negatively impact digestion through pathways, such as leaky gut, known in the medical field as intestinal hyperpermeability. In leaky gut, the tight junctions that are supposed to keep disease-contributing compounds from leaving the digestive system are disrupted, allowing a lot of things through into the bloodstream that don’t belong there.
Clinically shown to work in 7 days§, AZO Complete Feminine BalanceTM works differently because it contains the power of INTELLIFLORA,TM the only clinically proven blend with the 4 vaginal lactobacilli species most commonly found in healthy women.* Specially designed to restore the vagina’s microflora, it’s a safe and beneficial probiotic for women’s health—including pregnant women.*§ Add it to your daily regimen for help with protection and ongoing vaginal health support.*

The National Center for Complementary and Integrative Health (NCCIH) calls probiotics “live microorganisms (in most cases, bacteria) that are similar to beneficial microorganisms found in the human gut.” The NCCIH makes the point that we often think of bacteria as harmful “germs” — however, probiotic bacteria actually helps the body function properly.
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.
A 2017 survey of cancer patients showed that more than 80 percent were taking some sort of dietary supplement, vitamin, mineral, or herb to treat digestive issues they were experiencing due to chemotherapy. Researchers noted that while supplements can be beneficial in some cases, they can also change the metabolism of anti-cancer drugs, or lead to life-threatening conditions like sepsis because of the patient’s compromised immune system.
The science on what probiotics do is still emerging. There is some hard evidence that suggests eating probiotic foods and supplements can have a beneficial effect on health. Other evidence suggests probiotics benefits are limited to those individuals in good health and should be avoided by those who suffer from certain serious health conditions. There is no research that demonstrates the risks or the benefits of probiotic supplements on children.
Most people with diverticulosis have few if any symptoms at all. When people do experience signs and symptoms of diverticulosis (diverticular disease) they may include abdominal pain, abdominal cramps, diarrhea, constipation, and bloating. Diverticulitis is a condition in which diverticuli in the colon rupture. The rupture results in infection in the tissues that surround the colon. Treatment methods for diverticulitis includes prescription medications, and in some cases, diverticulitis surgery.

But sometimes you need a little help from outside sources in order to secure those benefits, which is why a lot of experts recommend getting an extra hit of probiotics through food. Fermented options — think keffir, sauerkraut, and kimchi — are a great place to start, says the International Scientific Association of Probiotics and Prebiotics, as are these other surprising foods with probiotics.


If you've tried a probiotic after following these steps and it doesn't seem to be working for you (or you just want some extra guidance in choosing one), head to your doctor (or a dietitian) to get a recommendation. "Have a thorough discussion with your doctor to make sure you are taking the appropriate bacterial strain for the appropriate reason," advises Dr. Ivanina. "Then, follow up after taking the probiotic to make sure it is having the intended effect."


Russian microbiologist Elie Metchnikoff (1845-1916) was the first to associate the large amounts of fermented dairy products with the good health and longevity of Bulgarians back in 1907. He proposed that the acid-producing organisms in fermented dairy products could prevent what he called "fouling" in the large intestine. He believed if eaten regularly, these foods could lead to a longer, healthier life. One version of the Old Testament even attributes Abraham's long life — 175 years — to the "consumption of sour milk." Fermented milk products may have also been used to treat illnesses of the digestive tract during Roman times.
All probiotic strains are manufactured through fermentation, and are then freeze-dried before blending with fructooligosaccharides (FOS). The result is a shelf-stable (two years at room temperature), nitrogen-filled probiotic of human origin: a probiotic that easily adapts to your body, and is both acid- and bile-resistant to survive the acidic environment of the human stomach. In other words, a probiotic that fulfills its promises.
A popular dish in Japan consisting of fermented soybeans, natto contains the extremely powerful probiotic bacillus subtilis, which has been proven to bolster your immune system, support cardiovascular health and enhance digestion of vitamin K2. Natto can also contain vitamin B12, which is usually lacking in vegan diets. It’s also one of the highest plant-based proteins.
Billions Of CFU – One of the first things you will notice on a bottle of probiotics is the phrase “X Billion CFU.” Probiotics vary in the number of billions of cultures they pack in each capsule, but the lingo always stays the same. CFU stands for Colony Forming Units, so if the bottle reads 5 Billion CFU, it means that there are 5 Billion Colony Forming Units per capsule. The higher the number, the more flora contained in each pill.
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.​”​
Jotham Suez, Niv Zmora, Gili Zilberman-Schapira, Uria Mor, Mally Dori-Bachash, Stavros Bashiardes, Maya Zur, Dana Regev-Lehavi, Rotem Ben-Zeev Brik, Sara Federici, Max Horn, Yotam Cohen, Andreas E. Moor, David Zeevi, Tal Korem, Eran Kotler, Alon Harmelin, Shalev Itzkovitz, Nitsan Maharshak, Oren Shibolet, Meirav Pevsner-Fischer, Hagit Shapiro, Itai Sharon, Zamir Halpern, Eran Segal, Eran Elinav. "Post-Antibiotic Gut Mucosal Microbiome Reconstitution Is Impaired by Probiotics and Improved by Autologous FMT." Cell (First published: September 6, 2018)  DOI: 10.1016/j.cell.2018.08.047
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