Gut flora makes up 70 to 80 percent of the human immune system. Too much bad bacteria can inflame and destroy intestinal walls, enter the bloodstream, and trigger a multitude of health issues — constipation, depression, skin problems, autoimmune disease, and even bad breath. Adding good bacteria protects the digestive tract from the harmful bacteria in sugars, pesticides, and saturated fats.
If you don’t have a specific health goal in mind and want to bolster the number of good bacteria floating around your system, Perlmutter recommends starting with a minimum of eight to 10 different bacterial species. He included a core five (L. Plantarum, L. Acidophilus, L. Brevis, B. Lactis, and B. Longum) and we added five more highly researched and universally beneficial strains for a general health pick. Vita Miracle, formerly Islands Miracle, has nine of those 10, plus 30 billion CFUs per serving.
There’s good and bad bacteria in there (fascinating fact: an estimated 100 trillion bacteria live inside your digestive tract): When the good outweighs the bad, your immune health soars; when the bad overpowers good, you get sick. You have diarrhea. Your immune system tanks. Your IBS, lactose intolerance, and other gut problems are exacerbated. It throws your entire system out of whack.
The best probiotic manufacturers will list their potency (in CFUs) at the time of expiration, ensuring you get the dosage you’re paying for. Dr. David Perlmutter, board-certified neurologist, American College of Nutrition Fellow, and author of The New York Times bestsellers "Brain Maker" and "Grain Brain" puts it this way: “Avoid products that indicate a specific number of bacteria ‘at the time of manufacture,’ and instead look for products that, like other supplements, have a shelf life.” Each of our top picks clearly shows a specific “best by” or “expires on” date on its bottle.
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.
Taking relatively high doses of these probiotic strains before, during, and after antibiotic treatment can help your microbiome get back on its feet: B. Lactis, B. Infantis, L. Acidophilus, L. Casei, L. Bulgaricus, L. Paracasei, L. Rhamnosus GG, and S. Boulardii. Our antibiotic combatant MegaFood MegaFlora has six of these strains, as well as eight others. One serving contains 20 billion CFUs to replenish the good bacteria.
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)
Many women are prone to yeast infections during or after antibiotic use. If you are one of these unlucky few, try taking a probiotic like the vH Probiotics with Prebiotics and Cranberry immediately before taking your antibiotics. (You may want to check with your doctor first though). These cultures may help with stomach upset and can also prevent a dreaded yeast infection!
The research also showed that while probiotics colonised the gastrointestinal tract of some people, the gut microbiome of others just expelled them. There was no way of telling from their stool sample which category people fell into. “Some people accept probiotics in their gut, while others just pass them from one end to the other,” says Elinav. They found that the probiotic colonisation patterns were highly dependent on the individual. That tells us that the concept that everyone can benefit from a universal probiotic bought from the supermarket is empirically wrong, he says.
But before you start reaching for the calcium supplements, there may be a more effective way to support your bone health. Like many other parts of the body, the health of your bones is closely tied to the health of your gut, especially your intestines. Temporary intestinal inflammation can trigger an immune response in which your body releases interleukins, proteins that have an immune function but also absorb bone tissue. If the temporary inflammation remains unaddressed, these molecules can take a toll on your bones, eventually weakening them.14

CFU: This is the number of "colony forming units" present in each dose, which are measured in the billions. And while more isn't always better, "you want at least 20 to 50 billion CFU," says Dr. Nazareth. Just for reference, a very high dose is 400 CFU, which most experts agree is not necessary unless your health care practitioner specifically recommends this for you. It's also important to check for the guaranteed CFU upon expiration, which should be listed clearly. "Some products only guarantee the CFU number at the time of manufacturing, therefore will be less potent by the time the product reaches your home," she says.
Antibiotics are also a major contributor to gut imbalances. Many of us have been overprescribed antibiotics by well-meaning, conventional doctors from childhood onward. Antibiotic use as a solution for every infection is ingrained in our culture. Every time you take an antibiotic throughout your life, you disrupt your gut flora for up to 12 months.
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.
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.
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.
Best Probiotic chose iFlora Multi-Probiotic by Sedona Labs as one of the best probiotic supplements. It is a blend that works well in both the large and small intestines and it can survive stomach acid to maintain effectiveness. According to Sedona Labs’ website, iFlora delivers 32 billion active cells through 16 probiotic strains, plus probiotic fiber.
Some people prefer probiotic supplements over foods, but Dr. Cresci notes that probiotic foods are a better choice. In particular, fermented foods — like yogurt, kefir (a yogurt-like beverage), kombucha (fermented black tea), sauerkraut (refrigerated, not shelf-stable), kimchi (made from fermented cabbage) and tempeh and miso (made from fermented soybeans) — provide a nourishing environment in which healthful bacteria thrive and release an important byproduct: short-chain fatty acids.

"The proprietary formula in this lotion supports a healthy microbiome of your skin promoting a more hydrated, stronger barrier function and protection from pathogens without harming the good stuff. Throw away your antibacterial soap and hand sanitizer and use this all over after your shower and after washing your hands," says Astarita, who is also a fan of the Nerium Prolistic Powder Pre & Probiotic Plus Vitamins ($45) and Be Well Probiotic Powder ($46) by Dr. Frank Lipman.
These statistics are staggering, yet poor gut health actually affects much greater numbers than these statistics illustrate because your digestive health affects every physiological system in your body. How is this such a complex system? Well, for one, the human microbiome contains 360 times more protein-coding genes than human genes themselves contain.

Proponents claim that probiotics (meaning “for life,” as opposed to antibiotics) confer health benefits primarily by rebalancing the normal microflora in the large intestine (colon). There are many general types of bacteria used as probiotics (two common ones are Lactobacillus and Bifidobacterium), and many different species as well as strains within species. They have different physiological effects—and thus possibly different health benefits (as well as possible risks). Some yeasts, such as Saccharmyces, can also act as probiotics.
Additionally, it's a good idea to take note of the number of colony-forming units (CFUs) that are in the supplement you're considering, Angelone says. CFU count tells you the number of viable, active bacteria present in a tablet, she explains, and one billion (yes, seriously) is a typical dose. However, if you're struggling with a specific health condition, you may need more than that, Warren says. Your doctor can help you decide whether that's the case and may be able to steer you toward a good supplement to get you started. Here are a few to consider if you decide that probiotics are right for you.
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.
If you are seeking non-dairy yogurt options, there are several that contain live probiotic cultures. Yogurts made from rice, soy and coconut milk are available on the market and also contain added probiotics that can provide the same benefits. Other alternative sources of probiotics include eating fermented foods like Brewer’s yeast, miso, sauerkraut, or micro algae. Whatever the source, always look for “live and active cultures” on the label.
This smooth, slightly tangy, and sippable yogurt contains a dozen different types of live active cultures. It's also 99% lactose-free, making it easier to digest for those with intolerant tummies. "If you have lactose intolerance, start slowly on kefir as a test. If you have no symptoms, go ahead and slowly increase your intake," advises Tallmadge. Plus, with 8 to 11 grams of protein per cup (depending on the brand), it can help fill you up for around 100 calories.
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.
According to a 2014 meta-analysis, probiotics benefit diabetics by improving insulin sensitivity and decreasing the autoimmune response found in diabetes. The authors suggest that the results were significant enough to conduct large, randomized, controlled trials (the “gold standard” of scientific studies) to find if probiotics may actually be used to prevent or manage diabetes symptoms. Combining probiotics with prebiotics may also help manage blood sugar, particularly when blood sugar levels are already elevated. (87)
Yogurt: It can contain Streptococcus thermophilus, Lactobacillus bulgaricus, L. acidophilus, and Bifidobacterium bifidum. Research has shown links with yogurt to have positive effects on the gut microbiota and is associated with a reduced risk for gastrointestinal disease and improvement of lactose intolerance (especially among children), type 2 diabetes, cardiovascular disease, allergies and respiratory diseases, as well as improved dental and bone health.
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:
They can break down substances in foods that keep you from absorbing the micronutrients inside. They not only protect against the consequences of rogue molecules passing through a leaky gut, but they assist your intestinal cells in staying healthy to optimize nutrient absorption. In addition, some of the metabolic by-products of probiotics, such as short-chain fatty acids and vitamin production, are very nourishing to your GI tract.
I’m 65 years of age. I have been taking acid reflux medication daily for at least 15 years and recently my doctor said my kidneys were declining. I’ve read that acid reflux medications taken over a long period of time, can cause kidney damage. By taking a probiotic, will it help reduce stomach acid, where I may be able to stop taking my acid reflux medication altogether?
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 boost the immune system, B. Lactis is a promising choice. One study had participants taking either a probiotic or a placebo for 6 weeks. At the end of the period, researchers measured antibody levels and found greater increases in antibodies of the B. Lactis group than in placebo participants, concluding that this probiotic may help improve immune function [1]. In addition, a 2009 study found that supplementation of the strain B. Lactis DN-173 led to self-reported improvements in digestive comfort [2].

Unlike many of the probiotics on the market today for women, Vitamin Bounty’s formula is fermented naturally and encased in a delayed-release capsule for more efficient digestion. Specifically, this capsule helps to protect the micro-organism strains from stomach acid, which can dissolve them before your gut has a chance to absorb all of their healthy goodness. With this Women’s Pro-Daily Probiotic design, you can expect more cultures and, as a result, fewer stomach upsets and feminine health problems!
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:
Jo A. Panyko is a Master Nutrition Therapist and author of two books about probiotics. She is a professional member of the National Association of Nutrition Professionals (NANP) and works as a functional medicine nutrition therapist (nutritionist) at her company, Chrysalis Nutrition and Health. She writes about how to be healthy with probiotics on her website, powerofprobiotics.com.
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.

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.
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.
Importantly, patients with gastrointestinal conditions are not the only ones taking probiotics. 3·9 million people in the USA alone regularly take probiotic supplements, with promised benefits ranging from improved digestion and immune function to improved mental health and prevention of heart disease. However, evidence for these benefits is lacking, and because probiotics are often sold as supplements, manufacturers in many countries are not required to provide evidence of their safety and efficacy to regulatory bodies. The ubiquity of probiotic products would suggest that, at worst, they are harmless. Nevertheless, some safety concerns have been raised, including the risk of contamination, possibility of fungaemia or bacteraemia (particularly in immune-compromised, elderly, or critically ill individuals), small intestinal bacterial overgrowth, and antibiotic resistance. Adding to concerns, clinical trials of probiotics have not consistently reported safety outcomes.
Lebwohl says IBS isn’t just about intestinal distress. For many IBS sufferers, it’s about the way our brain receives messages about pain. He describes the human colon as “almost reptilian” in the way that it contracts and relaxes throughout the day, but says these contractions are usually happening way below our threshold of consciousness, so we don’t even notice. In people with IBS, the neurotransmitters in our gut (yes, we have them in there too) may be sending severe distress signals to the brain about benign contractions happening in digestive tract.
However, this particular probiotic does not contain any additional vitamins, minerals, or plant extracts like some of the other brands we have reviewed. The Probiotic Pearls are a great option for women looking for an introductory probiotic or one with less fuss, but likely won’t pack the same punch as probiotics that include mineral blends and added vitamins in their formulas. This probiotic was also not designed to treat or prevent urinary tract problems, and may not be as suitable as other brands for women with recurrent urinary tract infections.
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. 
Every person's microbiome is different, which means what worked for others might not work for you. "What you eat, whether you were born by C-section or vaginally, what antibiotics you have been exposed to, and whether or not you have ever developed food-borne illness are just some of the many factors that impact your gut microbiome," explains Scarlata. And while research can help you determine which strains to take at which dosages, there may still be several different formulations to choose from.
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

Jo A. Panyko is a Master Nutrition Therapist and author of two books about probiotics. She is a professional member of the National Association of Nutrition Professionals (NANP) and works as a functional medicine nutrition therapist (nutritionist) at her company, Chrysalis Nutrition and Health. She writes about how to be healthy with probiotics on her website, powerofprobiotics.com.
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.

Taking relatively high doses of these probiotic strains before, during, and after antibiotic treatment can help your microbiome get back on its feet: B. Lactis, B. Infantis, L. Acidophilus, L. Casei, L. Bulgaricus, L. Paracasei, L. Rhamnosus GG, and S. Boulardii. Our antibiotic combatant MegaFood MegaFlora has six of these strains, as well as eight others. One serving contains 20 billion CFUs to replenish the good bacteria.
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
If you’re new to Bio-K+, know that each bottle contains 50 billion live and active probiotic bacteria. Probiotics are good for a wide variety of digestive issues, so it’s best to customize your dosage based on what your specific needs are. If you are looking to take a preventative dosage to support the health of your microbiome, start with a ¼ bottle per day. If you suffer from digestive health issues or regularly take antacids, start with a ½ bottle of Bio-K+ per day. If you have more serious gastrointestinal issues or have had to take antibiotics, Bio-K+ probiotics are great for getting your system back on track. Start with a full bottle per day and see how you feel (we’ve had amazing results from our fans!)
You may have heard some questions over whether SBOs are safe: The NIH has a presumed case report, which hasn’t been 100 percent verified, of someone with Lymphoma getting septicemia from taking a SBO (the organism B. subtilis). Some say that if you have leaky gut, you should heal it before supplementing with SBOs. If you are immunocompromised or have cancer, you can consult with a physician first to be safe.
Topping the probiotic market numbers at 100 Billion CFU divided between 34 probiotic strains, Garden of Life’s Ultimate Care probiotic was definitely a contender for our Best Probiotic of 2018. Free from preservatives and additives, RAW scored impressive marks across the board. Although this shortens the lifespan of the probiotics strains somewhat, buying in small quantities can easily solve this problem and – honestly – at CHR we always prefer purity to additives.
Some studies suggest that certain probiotic strains may also help in mild to moderate ulcerative colitis and possibly for bloating and gas in irritable bowel syndrome (IBS). Probiotic supplements, on the whole, “improve global symptoms, bloating, and flatulence in IBS,” by modifying the gut microbiome, according to a 2014 monograph from the American College of Gastroenterology. As IBS researchers said in a paper in Gastroenterology & Hepatology in 2015, “The concept of manipulating the microbiome is one of the most promising new ways in which to treat patients with IBS, but there is still much to learn.”
A closer look at the science underlying microbe-based treatments, however, shows that most of the health claims for probiotics are pure hype. The majority of studies to date have failed to reveal any benefits in individuals who are already healthy. The bacteria seem to help only those people suffering from a few specific intestinal disorders. “There is no evidence to suggest that people with normal gastrointestinal tracts can benefit from taking probiotics,” says Matthew Ciorba, a gastroenterologist at Washington University in St. Louis. “If you're not in any distress, I would not recommend them.” Emma Allen-Vercoe, a microbiologist at the University of Guelph in Ontario, agrees. For the most part, she says, “the claims that are made are enormously inflated.”
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 (First published: September 6, 2018) DOI: 10.1016/j.cell.2018.08.041
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.
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.

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.
Previous studies have been contradictory, with some yielding more positive results about the benefits of probiotics, but most of them looked at probiotics in stool samples, not directly in the gut itself. In the new research, the scientists used more invasive methods to take samples of gut bacteria directly from different areas of the digestive system.
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