"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," says senior author Eran Elinav, an immunologist at the Weizmann Institute of Science in Israel. "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."
Probiotic therapy may also help people with Crohn's disease and irritable bowel syndrome. Clinical trial results are mixed, but several small studies suggest that certain probiotics may help maintain remission of ulcerative colitis and prevent relapse of Crohn's disease and the recurrence of pouchitis (a complication of surgery to treat ulcerative colitis). Because these disorders are so frustrating to treat, many people are giving probiotics a try before all the evidence is in for the particular strains they're using. More research is needed to find out which strains work best for what conditions.
Bacillus is an interesting genus because these microbes have the ability to form endospores, tough outer coatings, when conditions are not suitable for them to flourish. There are five species of probiotic Bacillus: clausii, coagulans, indicus, licheniformis, and subtilis. Not every species of Bacillus is probiotic. Some Bacillus species are usually pathogens. Bacillus may normally be found in the GI tract, but they generally do not take up residence for long and will pass through and be eliminated if not replenished. Bacillus are common food spoilage organisms and are also found in probiotic supplements and in soil, air, and water.
"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."
​​​​​​AZO Complete Feminine BalanceTM is a daily probiotic supplement designed for the unique needs of women. Researchers that formulated the blend started by selecting species that are dominant in the healthy vaginal microbiota. Then they further refined the formula by selecting strains of probiotics that flourish in the vagina. The blend is clinically proven to help protect vaginal/feminine health.*
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.)
​​​​​​AZO Complete Feminine BalanceTM is a daily probiotic supplement designed for the unique needs of women. Many everyday things can throw off your balance (stress, sex, pregnancy, aging, even medications! This product supports your feminine health and maintain a healthy pH so that you can own your day! It contains INTELLIFLORATM: a probiotic blend of four lactobacilli that are associated with vaginal health* (Lactobacillus crispatus LBV 88, Lactobacillus rhamnosus LBV 96, Lactobacillus jensenii LBV 116, and Lactobacillus gasseri LBV 150.)  The INTELLIFLORATM blend has been shown in clinical studies to help restore and maintain the healthy balance of the vaginal microbiota.*
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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.
Yes, they may help. Lebwohl says there are reputable studies that show a link between the use of probiotics and the reduction in IBS symptoms, citing this meta-analysis. It's estimated that 11 percent of the world population complains of symptoms like abdominal cramps, diarrhea, constipation, excessive gas and/or mucus in their stools. While for some the condition can be attributed to certain dietary triggers, others appear to be stress-related, which brings us to the heart of where many claims about the effectiveness of probiotics lie—in the gut-brain axis.
Keep in mind that when supplements contain a specific number of organisms, this number may not be what is actually within each capsule at the time of purchase. Probiotics are living organisms and can die out easily. Especially if that supplement sits on your drugstore or warehouse shelf for months or longer, the number of organisms you get may be far less than what the bottle claims. Hardier strains have a longer shelf life. Capsule strength decays faster if the probiotic has been sitting around at elevated temperatures during transport to the store. Companies actually have to produce probiotics with a much higher CFU (colony-forming units; see below) count in each capsule in order to guarantee the label potency by the expiration date.
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.

To avoid those and other problems, I strongly recommend buying a professional brand from a reputable health care professional or other vendor who stands by their products and undergoes third-party testing. Some of these professional brands have created advanced technology that preserves a probiotic supplement’s survival on the shelf and in your gut.


The gut microbiota has been implicated in diseases ranging from obesity to Parkinson's disease and depression. Little wonder then that commercial probiotics have gained widespread popularity and are now estimated to command a US$37 billion market worldwide. But with research into the microbiome still in its infancy, increasing evidence suggests that both commercial and clinical use of probiotics is outpacing the science.
To factor strain-specific benefits into our efficacy score, we referenced the information in these guides. Products were rewarded for containing strains on these lists. Additionally, measured levels of each strain were compared to what is thought to be effective based on these guides, and scores were scaled accordingly. In cases where products did not list strain-specific amounts, or their listed strains were not included in these guides, total measured CFUs were compared to a general effectiveness threshold of 1 billion CFUs cited by research published in the American Journal of Clinical Nutrition11.

Cynthia is the assistant editor and frequent contributor. She’s originally from California, but has lived in many countries including South Korea, China and Germany. She currently lives with her husband in Minnesota. Cynthia is passionate about helping families find the best advice for family life and safety. Cynthia also has experience in early childhood education and holds a TEFL-C certificate from Teachers College, Columbia University. She has been writing about family-focused topics, advice and trends since 2014.
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.
Using probiotics benefits and balances immune function, influences hormone levels, aids in digestion and nutrient absorption, produces some vitamins, and balances blood sugar insulin responses. By preventing and reducing leaky gut and controlling levels of pathogens, probiotics reduce harmful bacterial by-products that can enter the brain and contribute to brain fog.
In the past five years, for example, several combined analyses of dozens of studies have concluded that probiotics may help prevent some common side effects of treatment with antibiotics. Whenever physicians prescribe these medications, they know they stand a good chance of annihilating entire communities of beneficial bacteria in the intestine, along with whatever problem-causing microbes they are trying to dispel. Normally the body just needs to grab a few bacteria from the environment to reestablish a healthy microbiome. But sometimes the emptied niches get filled up with harmful bacteria that secrete toxins, causing inflammation in the intestine and triggering diarrhea. Adding yogurt or other probiotics—especially the kinds that contain Lactobacillus—during and after a course of antibiotics seems to decrease the chances of subsequently developing these opportunistic infections.
Candida albicans is the most common species that causes yeast infections, but there are others. It is a normal inhabitant of the gastrointestinal tract and is often found in the female vaginal tract. Candida infections on the skin cause red, itchy rashes that often weep moisture, and in the vagina there is often a cottage-cheese-like discharge in addition to the skin symptoms.
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.
Kefir: This could be the most ideal probiotic dairy product because it contains both bacteria and yeast working together to provide the numerous health benefits. In a recent eight-week study, people with diabetes were given kefir milk containing Lactobacillus casei, Lactobacillus acidophilus, and bifidobacteria vs. conventional fermented milk. The hemoglobin A1C levels were significantly lower in the group consuming the kefir.
Dermatologist Dendy Engelman, MD, also points out the key role probiotics play in gut health and your body's immune system. "Probiotics are live microorganisms that may be able to help prevent and treat some illnesses," explains Engelman. "Probiotics can create 'holes' in bad bacteria and kill them. Similar to the way antibiotics work in the treatment of acne and rosacea, probiotics can help fight harmful bugs from triggering inflammation. In patients with acne and rosacea, living microorganisms on the skin are recognized as foreign by the body's immune system. The immune system springs into action to counter this potential threat resulting in the inflammation, redness, or bumps common in these skin conditions."

Probiotic therapy may also help people with Crohn's disease and irritable bowel syndrome. Clinical trial results are mixed, but several small studies suggest that certain probiotics may help maintain remission of ulcerative colitis and prevent relapse of Crohn's disease and the recurrence of pouchitis (a complication of surgery to treat ulcerative colitis). Because these disorders are so frustrating to treat, many people are giving probiotics a try before all the evidence is in for the particular strains they're using. More research is needed to find out which strains work best for what conditions.
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