Dr. Michelle Schoffro Cook says there’s no single best strain of bacteria, though some strains, like L. Acidophilus or B. Bacterium, have wide-reaching effects. They often act as a starting point from which to add other strains with more specific impacts. Already have probiotics on hand or want to arm yourself with raw knowledge before you shop? The table below shows the research- and expert-backed strains we looked for in each use case:

Unlike MegaFood, the Renew Life label’s cold-storage recommendation is printed so small we nearly missed it (and it didn’t ship with a cold pack). If a probiotic requires refrigeration, be vigilant when buying it — the retailer that stores it or the company that ships it should keep it refrigerated until it gets to you. Otherwise, some of its potency might diminish in storage or transit.
If you get sick often, probiotics might be the immune booster you've been looking for. The Cleveland Clinic says they've been shown to strengthen immunity by enriching and replenishing the good bacteria in the body. And when you eat foods with probiotics regularly, it's easier for your body to produce vitamins and enzymes that help keep your intestines happy. 

Experts agree that this is the most important factor to consider in choosing a probiotic. "You should absolutely choose a probiotic based on what you are looking to address," says Chang. "Because strain specificity will impact outcomes, it is important to consider that one strain that works for one condition will not necessarily be effective for other conditions."
Unfortunately, many commercial brands don’t measure up. They are unstable in stomach acid. Quality control measures aren’t intact, including ensuring supplements have been handled correctly and maintain their freshness. Moisture slipping into probiotic supplements can reduce their efficacy. Companies that use bioshield capsules produce higher quality probiotic supplements that are able to endure the stomach acid, releasing their contents within the small intestine, where a more alkaline environment ensures the survival of the bacteria.
Several large-scale studies and two meta-analyses have confirmed that probiotics should be a major consideration in determining natural remedies for diabetes. In a massive study involving almost 200,000 subjects and a total of 15,156 cases of type 2 diabetes, researchers confirmed that a higher intake of probiotic-rich yogurt reduced the risk of developing diabetes.
Directions Take 2 Vegetarian Capsules with or without food. As a dietary supplement, take two (2) capsules once daily. For best results, take one (1) capsule during the day and one (1) capsules in the evening. Repeat the process daily. Do not exceed two capsules per day. As a dietary supplement, take one (1) veggie probiotic capsule once daily. Because our probiotic uses delayed release capsules, do not chew or crush. Our capsules help ensure the active probiotic strains reach your intestinal tract. Adults take 1 capsule daily. May be taken with or without food. Capsules can be opened. Contents can be taken directly with water or juice. Not intended for children.
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.

There is one Voluntary Certification Program by which a supplement manufacturer can choose to be evaluated. ConsumerLab.com (CL) is the leading provider of independent test results and information to help consumers and health-care professionals identify the best quality health and nutrition products. Products that have passed their testing for identity, strength, purity, and disintegration can print the CL Seal of Approval on their product. This is one step toward being confident that one is getting the amount and type of probiotic promised by the manufacturer.


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.
The bad news about constipation is that there can be many causes, from simple causes like dehydration and lack of fiber to complicated structural causes or disease. While constipation may seem to be only a nuisance that causes uncomfortable symptoms such as abdominal bloating or pain, the truth is that constipation increases the risks of several diseases.
Despite the uncertainty, foods enriched with probiotics and probiotic supplements are increasingly popular in the U.S. Finding probiotic supplements in grocery and health food stores is easy. For example, you may already know that yogurt contains probiotic bacteria such as lactobacillus and bifidobacteria. Many clinical studies suggest these bacteria relieve symptoms related to lactose intolerance.
Dr. Vincent M. Pedre, medical director of Pedre Integrative Health and president of Dr. Pedre Wellness, is a board-certified internist in private practice in New York City since 2004. His philosophy and practices are a blend of both Western and Eastern medical traditions. He is a clinical instructor in medicine at the Mount Sinai School of Medicine and is certified in yoga and medical acupuncture. His unique methodology is best described as integrative or defined by a functional, systems-based approach to health. With his holistic understanding of both sides of the equation, he can help each patient choose the best course of action for their ailments to provide both immediate and long-term relief. His holistic approach incorporates positive, preventive health and wellness lifestyle choices. Dr. Pedre Wellness is a growing wellness platform offering health-enhancing programs along with informative social media and lifestyle products, such as dietary supplements, books, and weight-loss programs.
★100% NATURAL, NON-GMO, GLUTEN FREE★NewRhythm 50 Billion Probiotics is Formulated with 100% Natural Ingredients and Independently Tested in 3rd Party Labs in USA. Our Turmeric Supplement is Verified NON-GMO, Gluten Free and Verified Free of Sugar, Soy, Yeast, Egg, Wheat, Corn, Peanuts, Fish, Shellfish, Magnesium Stearate, Artificial Ingredients, Fillers, Binders, Preservatives.

The National Yogurt Association, who created this seal of approval, requires all yogurt manufacturers to include it on products that meet the standard of having a sufficient number of probiotics. The probiotics in store-bought yogurt need to meet this standard in order to be shelf-stable and reach your body alive. But even then, this standard isn’t all that useful in practice. The number just refers to the total number of live cultures and not the levels for each of those microbes. It’s possible, Taub-Dix says, that a product won’t have high enough levels of a certain probiotic to have any effect.
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.
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.
While the logic behind probiotics might seem sound, it is clear that we have a long way to go before understanding the complexity of the microbiota and the effects—both good and bad—that probiotics might have. All individuals have a unique gut microbiome, and the effects of different bacteria on different people are likely to be highly variable; as such, probiotic use might even need to be personalised for optimal benefits. Commercially available products might not contain the correct strains or quantities of bacteria to provide benefits, and most probiotic supplements contain only single strains, vastly oversimplifying the complexity of the microbiota. While taking a supplement for improved health is certainly an attractive prospect, those looking to aid their gut microbiota might be better served by consuming a healthy, varied diet. In the meantime, rigorous clinical trials are needed to substantiate potential health benefits and to confirm whether probiotics are elixirs or just empty promises.
The price is great on these, but definitely BEWARE! I do not recommend taking 2 pills in the beginning if you have not taken probiotics in the past! I had been eating very clean for a couple months, but got a sinus infection and was recommended by a nutritionist to take a probiotic to boost gut health since I was on antibiotics. Anyway-taking 2 pulls a day gave me horrible diarrhea, until I figured out they were causing the issue and cut back the pills to one a day! Everything fine since then, will try to build back up to 2 a day...I also take at bedtime just in case there would be any stomach issues!
The scientists discovered that the probiotics successfully colonized the GI tracts of some people, called the "persisters," while the gut microbiomes of "resisters" expelled them. Moreover, the persister and resister patterns would determine whether probiotics, in a given person, would impact their indigenous microbiome and human gene expression. The researchers could predict whether a person would be a persister or resister just by examining their baseline microbiome and gut gene expression profile.
Dr. Vincent M. Pedre, medical director of Pedre Integrative Health and president of Dr. Pedre Wellness, is a board-certified internist in private practice in New York City since 2004. His philosophy and practices are a blend of both Western and Eastern medical traditions. He is a clinical instructor in medicine at the Mount Sinai School of Medicine and is certified in yoga and medical acupuncture. His unique methodology is best described as integrative or defined by a functional, systems-based approach to health. With his holistic understanding of both sides of the equation, he can help each patient choose the best course of action for their ailments to provide both immediate and long-term relief. His holistic approach incorporates positive, preventive health and wellness lifestyle choices. Dr. Pedre Wellness is a growing wellness platform offering health-enhancing programs along with informative social media and lifestyle products, such as dietary supplements, books, and weight-loss programs.
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.

EDITOR’S CHOICE: As the only probiotic formula we reviewed backed by a New York Times Bestselling author and expert in the human biome, the Garden of Life Dr. Formulated Once Daily Women’s Probiotic is our top choice for overall digestive and women’s health. With 50 billion cultures and 16 probiotic strains, this probiotic helps to promote women’s digestive, immune and vaginal health.
The recent buzz has helped bring probiotics into the main stream.  Due to being covered on major news sites and television personalities, probiotic supplements are now more accessible than ever.  The main benefits of probiotics begin within the gut and digestive system.  The gut plays such an important role, that the level of healthy bacteria in our bodies can actually alter our mood.  It’s true!  What we eat actually affects how we feel.  This is why the gut has been called our “second brain”.
"There is an increasing interest in probiotic interventions," wrote the authors of one of the most recent studies, a meta-analysis of previous research in a recent issue of the Journal of the American Medical Association. Those researchers found that probiotics were particularly useful against a common gastrointestinal problem: antibiotic-associated diarrhea (AAD).
Renew Life offers a powerful, high potency blend of 10 specially selected Lactobacillus and Bifidobacterium strains designed to help restore your body’s good, natural ora. Their probiotics come in a special capsule designed to survive stomach acid and make it intact into the intestines to deliver the probiotics more effectively where they are most needed.

Prebiotics are fuel for the good bacteria (probiotics) in your gut; without prebiotics, probiotics can’t do their job. There are tons of prebiotics in whole fruits and vegetables, including onions, garlic, bananas, asparagus, and artichokes. If you’re worried you’re not getting five to 20 grams per day (more on prebiotic-rich foods here), consider taking a prebiotic supplement, usually a powder or drink mix.


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.)
Once the GI microbiome is disrupted, and especially if an infection is treated with antibiotics, it can take time for the resident microbiota to recover, if it ever does. A disrupted gut microbiome sets the stage for altered motility, intestinal hypersensitivity, gut immune activation, leaky gut, altered bile, mental disorders, and a host of other factors that can play a role in IBS. Good probiotics, along with a proper diet, can help the GI tract get the microbes it needs to function normally.
Those who took probiotics did replenish gut microbiome more successfully than the “watch-and-wait” group. That said, there was also an unexpected backlash to probiotic use. The researchers were alarmingly surprised to discover that successful microbiome colonization via probiotics actually prevented the host's pre-antibiotic microbiome and gut gene expression profile from returning to its natural state for months after the treatment. But there is good news: Using aFMT resulted in the third group's native gut microbiome and gene expression profiles returning to normal within days after they stopped taking antibiotics.
Because there's a huge variety of probiotic products available on the market, many people struggle to find the right one for them. "There are many different strains of bacteria in different combinations within different probiotic supplements," explains Brooke Scheller, a clinical and functional nutritionist. "For example, a probiotic may contain a single strain of bacteria or many. It may also contain other vitamins, minerals, or other ingredients that may tout health benefits," she says. There are many different dosages, delivery systems (powder, tablets, capsules), and formulations (refrigerated vs. shelf-stable), and some probiotics also contain prebiotics, which basically act as fertilizer for the probiotics. (Related: Why Your Probiotic Needs a Prebiotic Partner)

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.
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.
When shopping for a probiotic, the first things to look at are CFUs count and probiotic strains. CFUs is the acronym for colony forming units, and is the measure of how many probiotic bacteria are capable of dividing to form colonies. In other words, the higher the CFUs, the higher the number of active, live good bacteria. Generally speaking, the higher the CFUs, the better, although there are exceptions.
If that's not enough, your doctor may also suggest a probiotic supplement. But don't go and grab just anything off the pharmacy shelf. Probiotic supplements are not all the same, and they often contain different strains to serve different needs, says naturopathic physician Amy Fasig. Example: What one person gets to battle strep throat is different from what would be prescribed for someone suffering from Irritable Bowel Syndrome, she says.

★100% NATURAL, NON-GMO, GLUTEN FREE★NewRhythm 50 Billion Probiotics is Formulated with 100% Natural Ingredients and Independently Tested in 3rd Party Labs in USA. Our Turmeric Supplement is Verified NON-GMO, Gluten Free and Verified Free of Sugar, Soy, Yeast, Egg, Wheat, Corn, Peanuts, Fish, Shellfish, Magnesium Stearate, Artificial Ingredients, Fillers, Binders, Preservatives.
Probiotic supplements and foods can play a major positive role in brain fog. Lactobacillus, in particular, can produce neurotransmitters used for brain neuron-to-neuron transmission to facilitate thinking. Probiotics can interact with the vagus nerve to the brain, with the enteric nervous system that can communicate with the brain, and with the brain via chemical messengers.
That’s why adding probiotics and prebiotics to your diet provide the best possible outcome from a bacterial perspective. It isn’t always easy to eat naturally prebiotic-enriched foods, however, because they are often distasteful to eat in quantity. Would you enjoy eating several cups of raw onion or garlic every day? Probably not. Other foods that contain prebiotic fiber, such as bread and bananas, are high in calories. Consuming hundreds of calories of these foods every day is counterproductive if you’re trying to lose weight.
In a food allergy, there is an immediate immune reaction to the offensive food. Classic allergic symptoms such as tingling lips, burning/tightness in the mouth/throat, gastrointestinal upset, difficulty breathing, rashes, hives, and even anaphylaxis may be present. Although any food can cause an allergic reaction, the most common offenders are peanuts, tree nuts, dairy, fish, shellfish, eggs, soy, and wheat.
Today, most of the Japanese population begins the day with a warm bowl of miso soup, believed to stimulate the digestive system and energize the body. Made from fermented soybeans, rice or barley, adding a tablespoon of miso to some hot water makes an excellent, quick, probiotic-rich soup. The fermentation process can take anywhere from a few days to a couple of years to complete, and the end result is a red, white or dark brown paste with a buttery texture.
"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."
I did the “milk test” on these New Rythm probiotics, along with Culturelle I had purchased in 2 different states (TX & MA, as I was traveling); my mother’s CVS brand acidophilus; and one “control” cup with milk only (so, 5 cups total in my experiment). The New Rythm became a solid yogurt consistency, while the other 4 remained liquids. I did the experiment twice, just to be sure of the results. I could not believe it!!! New Rhythm is my brand, hands down!!! I also would like to mention that my product usually arrives the day after it ships. So it will take a few days to ship when I select standard shipping, which is to be expected, but it doesn’t stay in transit long which is ideal for preserving the living cultures.

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.​”​
The other thing to remember is that these microorganisms are not all created equally. In fact, the genus, strain, and species all need to be the same for the results that found in the study to be the results that one hopes to achieve when taking it. For example, with the strain Lactobacillus rhamnosus GG, the genus is Lactobacillus, the species is rhamnosus, and the strain is GG. If any one of those is different in your supplement, you may not attain the same results.
Because there's a huge variety of probiotic products available on the market, many people struggle to find the right one for them. "There are many different strains of bacteria in different combinations within different probiotic supplements," explains Brooke Scheller, a clinical and functional nutritionist. "For example, a probiotic may contain a single strain of bacteria or many. It may also contain other vitamins, minerals, or other ingredients that may tout health benefits," she says. There are many different dosages, delivery systems (powder, tablets, capsules), and formulations (refrigerated vs. shelf-stable), and some probiotics also contain prebiotics, which basically act as fertilizer for the probiotics. (Related: Why Your Probiotic Needs a Prebiotic Partner)
Culturelle Probiotics, although very basic, is still a great probiotic supplement.  The results I got from trying it were positive– I felt pretty good throughout the entire trial period. Although this product only contains one strain of probiotic, the one they chose is a solid one.  The cell count is 10 billion, which is a good number for a daily probiotic.  Lastly, Culturelle doesn’t contain any frequently-irritating ingredients like milk, dairy or gluten.  Read the full review here… or click here to go buy it now!

I did the “milk test” on these New Rythm probiotics, along with Culturelle I had purchased in 2 different states (TX & MA, as I was traveling); my mother’s CVS brand acidophilus; and one “control” cup with milk only (so, 5 cups total in my experiment). The New Rythm became a solid yogurt consistency, while the other 4 remained liquids. I did the experiment twice, just to be sure of the results. I could not believe it!!! New Rhythm is my brand, hands down!!! I also would like to mention that my product usually arrives the day after it ships. So it will take a few days to ship when I select standard shipping, which is to be expected, but it doesn’t stay in transit long which is ideal for preserving the living cultures.
A woman’s anatomy is different than a man’s, and so are our nutritional needs! That’s why Garden of Life designed a specially formulated mixture of digestive, immune, and feminine health probiotics exclusively for women. If you’re curious about the specific probiotic strains that are included in the Garden of Life Dr. Formulated Once Daily Women’s Probiotic, check out our complete list below:
If you've ever been to an Indian restaurant, then you've probably seen a lassi—a smoothie made of milk, yogurt, fruit, honey, and cardamom. The drink goes well with spicy Indian food because it helps extinguish the fiery feeling in your mouth. If you want to try it at home, you can pick up bottles from brands like Dahlicious, which contain 15 billion live probiotics per serving and are available in flavors like mango and turmeric. Or, try this mango lassi recipe.
Scientists are investigating probiotics, and their combined effects, by trying to classify the probiotic benefits of ingesting specific probiotic strains and understanding their role in the digestive tract. At present, the methodological and ethical limitations of human studies still make it difficult to fully understand the mechanisms of action of probiotics, but some explanations are available. Nevertheless, benefits linked to the consumption of probiotic strains have already been suggested (e.g. helping to support the immune system, help support digestive health), and others are still being investigated.
From Lactobacillus acidophilus to Bacillus Coagulans, the BlueBiotics blend is a veritable list of the most researched and proven probiotic bacteria known to science. And recent advances on the blend have made it the only full-spectrum probiotic supplement on the market, as it contains strains which are typically not available to the general public (Bacillus Coagulans and S. boulardii). The CFU count alone is remarkable enough, leaving most comparable spectrums in the dust… HOWEVER even more surprisingly our tests showed that a whopping 98% of the probiotic colonies in BlueBiotics were still alive, making this BY FAR the most effective probiotic supplement that we have ever reviewed. Also, because of the diverse pool of strains in BlueBiotics, users have reported a wide variety of benefits from weight loss, to increased energy, improved digestive health and cognitive function. Many of our staff switched to these probiotics, as well as myself and my family.
Taking probiotics can also help keep your urinary system working properly. While you might think that yeast imbalances or urinary tract issues are primarily women's problems, both are common in men as well, especially in those whose bacterial balance is off-kilter. Taking probiotics can help address these issues by encouraging the growth of good bacteria to crowd out unwanted yeast.10

Unfortunately, the U.S. has no federal standards for probiotic supplements. Therefore, you run the risk of purchasing a product without any guarantee that it contains its advertised probiotic strains, that the strains are alive, or that the product is free from unhealthy ingredients. Therefore, it may be best to choose a brand-name probiotic that has research backing their effectiveness. Here are some examples:

Amy Shapiro, MS, RD, CDN, founder and director of Real Nutrition based in NYC, discusses the effect probiotics have on immune system issues. "Probiotics compete with pathogenic microorganisms and produce chemicals that inactivate or kill pathogens," says Shapiro. "They help prevent immune-mediated diseases by improving the gut mucosal immune system. Overall, probiotics protect the body from infections and allow the body to maintain homeostasis."
Because of the way bacteria spread from the rectum to the vagina and urinary tract in women, probiotics have been a proposed remedy for urinary tract infection (UTI) in women. A 2012 review confirmed that probiotics seem to be effective in preventing recurrent UTIs, but more research is required before a determination can be made. The healthy strains of bacteria that help achieve this are also somewhat less common, which means proper treatment could be logistically complicated.
Probiotic supplements and foods can play a major positive role in brain fog. Lactobacillus, in particular, can produce neurotransmitters used for brain neuron-to-neuron transmission to facilitate thinking. Probiotics can interact with the vagus nerve to the brain, with the enteric nervous system that can communicate with the brain, and with the brain via chemical messengers.
While raw probiotics tend to be the freshest (and most effective!) cultures on the market, it is important to ensure that you will store these properly in between each use. Cultures can die unrefrigerated in as little as a few hours, rendering them completely ineffective and, if you’re especially unlucky, even harmful to your body’s natural flora. Think about it, when has stale or moldy bread made your tummy feel better? The same thing goes for stale probiotic cultures!
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.
Probiotics and raw fermented foods and drinks, such as sauerkraut and kefir that contain probiotic-like microbes, are very helpful for digestion. They help to keep your gastrointestinal tract at the proper pH for optimal digestion and help to break down foods. They also regulate the motion of your intestines so that food moves through at the proper pace.

Probiotics seem to be all the rage these days. With many purported benefits and a relatively low risk of side effects, manufacturers are taking advantage of booming business opportunities. Rather than leave your health in the hands of big business, it is important that you be as educated as possible about the best types of probiotics so you can choose what is right for you and your family.
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.
Cardiovascular health is a major concern for men in Western societies. While some of the main challenges to maintaining a healthy heart (like excessive drinking and smoking) aren’t nearly as widespread as they once were, unwanted changes in heart function are still one of the most common reasons for men to need emergency medical care.1 But taking probiotics can help you keep your heart firing on all cylinders, even as you age.
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.
Even if some of the bacteria in a probiotic managed to survive and propagate in the intestine, there would likely be far too few of them to dramatically alter the overall composition of one's internal ecosystem. Whereas the human gut contains tens of trillions of bacteria, there are only between 100 million and a few hundred billion bacteria in a typical serving of yogurt or a microbe-filled pill. Last year a team of scientists at the University of Copenhagen published a review of seven randomized, placebo-controlled trials (the most scientifically rigorous types of studies researchers know how to conduct) investigating whether probiotic supplements—including biscuits, milk-based drinks and capsules—change the diversity of bacteria in fecal samples. Only one study—of 34 healthy volunteers—found a statistically significant change, and there was no indication that it provided a clinical benefit. “A probiotic is still just a drop in a bucket,” says Shira Doron, an infectious disease expert at Tufts Medical Center. “The gut always has orders of magnitude more microbes.” 

While one 2009 study did show some evidence for reducing cold and flu symptoms in children ages three to five and a 2015 analysis showed probiotics to be better than placebo in preventing acute upper respiratory infections, neither were enough to convince the National Institutes of Health of the efficacy of probiotics for colds and flu. The NIH confirms, “the evidence is weak and the results have limitations.”
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