If you’re most interested in taking a probiotic supplement for overall gut health, I suggest starting with 30 to 50 billion CFUs. Take probiotics on an empty stomach once or twice a day for at least three months. After that time, reassess and decide if the benefits warrant continuing a maintenance dose of the probiotic supplement. However, if you have SIBO, beware of starting a probiotic too soon after your treatment. In this case, it’s best to work with a health practitioner on which probiotic is right for each stage of the treatment.
Probiotics may seem new to the food and supplement industry, but they have been with us from our first breath. During a delivery through the birth canal, a newborn picks up the bacteria Bacteroides, Bifidobacterium, Lactobacillus, and Escherichia coli from his/her mother. These good bacteria are not transmitted when a Cesarean section is performed and have been shown to be the reason why some infants born by C-section have allergies, less than optimal immune systems, and lower levels of gut microflora.
After suffering from liquid nighttime but painless diarrhea for over a year (which I semi-controlled with one Imodium/day), I had a colonoscopy that gave a diagnosis of microcolitis. After the colonoscopy, I developed for the first time excrutiatingly painful gas pain in the LLQ. Usually this pain started during aerobic activity such as walking, but not always. Sometimes I woke up with it. CT scan revealed nothing. Will a probiotic help and if so, which would be best? There are so many it is hard to choose.

"Although all of our probiotic-consuming volunteers showed probiotics in their stool, only some of them showed them in their gut, which is where they need to be," says Segal. "If some people resist and only some people permit them, the benefits of the standard probiotics we all take can't be as universal as we once thought. These results highlight the role of the gut microbiome in driving very specific clinical differences between people."

Overall, I really like TruBiotics as a daily probiotic. First of all, the capsules are easy to take and you only need one a day. I also like the choice of strains they used in this probiotic. Overall, TruBiotics is a great daily probiotic that’s quick and convenient and may be very effective with regards to many different digestive issues.   Read the full review here… or click here to go buy it now!
It’s great to get some healthy sour foods. I often add one tablespoon of apple cider vinegar to a drink, twice a day. Before breakfast and lunch or breakfast and dinner, add one tablespoon of apple cider vinegar in your meal, and then start consuming more fermented vegetables like sauerkraut and kimchi, or drinking kvass. Is apple cider vinegar a probiotic itself? No, but apple cider vinegar probiotic content makes it an excellent source of probiotics benefits.
Specially formulated by none other than Dr. Perlmutter himself, Garden of Life’s line of Dr. Formulated probiotics are packed with more than just healthy micro-organisms. With years of experience paving the way in nutrition and supplements, this probiotic is ideal for any woman that wants to incorporate the benefits of a probiotic into their daily life in a reliable way!
Large bodies of evidence suggest that probiotics are effective against several forms of diarrhea, including antibiotic-associated diarrhea, acute diarrhea, traveler’s diarrhea, infectious diarrhea and other associated diarrhea symptoms. They also help with constipation relief. Probiotics have also been found in meta-analyses to reduce the pain and severity of irritable bowel syndrome (IBS) symptoms, aid in the eradication of H. pylori and treat pouchitis, a condition that occurs after the surgical removal of the large intestine and rectum.
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.
An imbalance between good bacteria and pathogenic bacteria, yeasts or fungi, or a change in the bacteria species that colonize the digestive tract is called dysbiosis. It can have short and long-term effects on our body functions. These disruptions can reduce the immune system’s effectiveness, create unpleasant digestive symptoms (diarrhea, constipation, gas, etc.), be a contributor to certain chronic illnesses like obesity, and participate in producing pro-inflammatory metabolites.
Anal itching is the irritation of the skin at the exit of the rectum, known as the anus, accompanied by the desire to scratch. Causes include everything from irritating foods we eat, to certain diseases, and infections. Treatment options include medicine including, local anesthetics, for example, lidocaine (Xylocaine), pramoxine (Fleet Pain-Relief), and benzocaine (Lanacane Maximum Strength), vasoconstrictors, for example, phenylephrine 0.25% (Medicone Suppository, Preparation H, Rectocaine), protectants, for example, glycerin, kaolin, lanolin, mineral oil (Balneol), astringents, for example, witch hazel and calamine, antiseptics, for example, boric acid and phenol, aeratolytics, for example, resorcinol, analgesics, for example, camphor and juniper tar, and
About 60 to 80 percent of our immune system lives in our gut. Imbalances in the gut’s microbiome (which is primarily made up of bacteria) lead to digestive issues, while many many other potential effects can be felt throughout the body—from feelings of fatigue to depression, thyroid dysfunction, autoimmunity, and a host of skin issues. Conditions like rosacea, psoriasis, eczema, and acne are really inflammatory conditions, and often a manifestation of something that is happening deeper within the body. When you fix the gut (which, depending on your health, might include getting rid of an infection like Candida, eating a clean diet, and taking a probiotic), skin issues often resolve as well.
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.
In a separate study involving 21 healthy volunteers, also published today in Cell, the same group of researchers found that taking probiotics after treatment with broad spectrum antibiotics may actually delay the return of people's normal gut microbiome. This goes against the idea that probiotics can help "repopulate" people's gut bacteria after antibiotics wipe them out.
Although people often think of bacteria and other microorganisms as harmful “germs,” many microorganisms help our bodies function properly. For example, bacteria that are normally present in our intestines help digest food, destroy disease-causing microorganisms, and produce vitamins. Large numbers of microorganisms live on and in our bodies. Many of the microorganisms in probiotic products are the same as or similar to microorganisms that naturally live in our bodies.
In the second study, the researchers questioned whether patients should be taking probiotics to counter the effects of antibiotics, as they are often told to do in order to repopulate the gut microbiota after it's cleared by antibiotic treatment. To look at this, 21 volunteers were given a course of antibiotics and then randomly assigned to one of three groups. The first was a "watch-and-wait" group that let their microbiome recover on its own. The second group was administered the same generic probiotics used in the first study. The third group was treated with an autologous fecal microbiome transplant (aFMT) made up of their own bacteria that had been collected before giving them the antibiotic.
Most of the prebiotics identified are oligosaccharides. They are resistant to the human digestive enzymes that work on all other carbohydrates. This means that they pass through the upper GI system without being digested. They then get fermented in the lower colon and produce short-chain fatty acids that will then nourish the beneficial microbiota that live there. Oligosaccharides can be synthesized or obtained from natural sources. These sources include asparagus, artichoke, bamboo shoots, banana, barley, chicory, leeks, garlic, honey, lentils, milk, mustards, onion, rye, soybean, sugar beet, sugarcane juice, tomato, wheat, and yacón. The health benefits from these oligosaccharides is a topic of ongoing research.

Sick of fighting off cold after cold? The Align Daily Immune Support Probiotic Supplement is a great way to give your immune system a boost while protecting your gut bacteria. Align is one of the most popular probiotic brands out there and is trusted by both doctors and nutritionists. The Daily Immune Support has Bifidobacterium lactis BB-12, a probiotic strain thought to be most beneficial to your immune health. It’s a lactic acid bacteria that can also help to fight lactose intolerance. This probiotic contains five billion CFUs (generally, most adults should take at least one billion CFUs in a probiotic) and is meant to be taken once a day.


If you decide to use a probiotic supplement and get clearance from your doctor for doing so, be sure to read the label carefully. You want to be sure that the supplement contains live strains of the bacteria or yeast, and that the life of these strains is guaranteed at the time of use, and not at the time of manufacture. Other points of comparison are the number of bacteria strains and the number of colony-forming units, although this does not necessarily guarantee results.
A slightly more surprising result, however, seems to be the way that probiotics may impact some of the symptoms of autism. Autism and gut health have been discussed for some time, as patients with the disorder typically suffer from a large number of digestive issues. However, based on animal studies, it seems possible that altering the quality of gut bacteria might benefit not only the digestive system, but the abnormal behaviors in autism, too. In 2016, a case study of a boy with severe autism was reported. While being treated with probiotics for digestive problems, the patient spontaneously improved on the ADOS scale, a diagnostic rating system for people with autism. The score dropped from 20 down three points to a stable 17, and according to the report, ADOS scores do not “fluctuate spontaneously along time” and are “absolutely stable.”
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.

B. Bifidum has also been shown to prevent intestinal pathogens or digestive disrupters from flourishing in the gut, essential in restoring the bacterial balance and optimizing digestion. Clinical research found it supports a significant reduction in IBS symptoms, an improvement in quality of life and even helps relieve occurrences of ulcerative colitis – a chronic inflammatory bowel disease. [1].
Cleaning up your diet to remove things that bother you and to add nutrients you and your microbiota need, physical activity to reduce stress and increase feel-good neurotransmitters, mindfulness to discover how your thoughts affect your feelings, and daily consumption of probiotic pills and foods are easy ways to improve your mental health outlook.
As you progress with increasing dosages of probiotics internally, you may experience increased abdominal gas, upset digestion with diarrhea, headache, fever, muscle pain, brain fog, and/or anxiety. If the symptoms become too uncomfortable, decrease the dosage for a few days and try again. These symptoms are your body’s way of telling you that things—such as a die-off of pathogens or an awakened intestinal reflex—are changing.
If you suffer from a food allergy or intolerance, make sure to check those labels! Probiotics with these dietary features often say so right on the front of the bottle, but you will also want to take a quick peek at the ingredients list as well. A word to the wise: anyone with a food allergy should also check the manufacturer’s information to ensure that cross-contamination is not likely to have occurred on-site in the packaging facility.
Digestive problems. The best evidence for probiotics is for reducing diarrhea, especially following antibiotic use. A 2010 review from the Cochrane Collaboration concluded that probiotics shorten episodes of acute infectious diarrhea. And in 2011, a Health Canada monograph stated that products containing certain probiotics (such as Lactobacillus rhamnosus GG) help manage acute infectious diarrhea and antibiotic-associated diarrhea. A 2012 research review in the Journal of the American Medical Association (JAMA) found that probiotics reduced the risk of antibiotic-associated diarrhea by 42 percent—but many of the studies had flaws, so these findings should be interpreted with caution. A 2013 Cochrane review of 23 trials also concluded that probiotics may be effective for preventing antibiotic-related diarrhea. However, two large, well-designed studies, in the Lancet in 2013 and the Annals of Internal Medicine in 2014, found that probiotics were no better than a placebo in preventing diarrhea in older people taking antibiotics. A review of 19 studies, published in Gastroenterology in 2017, found that probiotics reduce the risk of Clostridium difficile-related diarrhea in hospital patients, especially when the supplements were started during the first two days of antibiotic treatment.
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
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:
Our gut is home to over 500 bacterial species. These “visitors” form a bioreactor, which facilitates digestion, provides nutrients, and helps form the immune system. Some important nutrients made by this bioreactor include several B vitamins, vitamin K, folate, and some short-chain fatty acids. Up to 10% of an individual’s daily energy needs can be derived from the byproducts of the good bacteria in your gut.
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!
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.

However, a 2003 pilot study and 2011 randomized, controlled trial both reported that RA activities remained unchanged, but the subjects treated with probiotics reported statistically significantly higher levels of “subjective well-being.” One suggested reason for this was that the trials were too short to establish changes in the observable changes in the internal earmarks of RA.
Probiotics' side effects, if they occur, tend to be mild and digestive (such as gas or bloating). More serious effects have been seen in some people. Probiotics might theoretically cause infections that need to be treated with antibiotics, especially in people with underlying health conditions. They could also cause unhealthy metabolic activities, too much stimulation of the immune system, or gene transfer (insertion of genetic material into a cell).
Inside your body bacterial and other microbial cells live in close contact with your own cells, and in healthy conditions the thing that separates them from you is a layer of mucus. Between that layer of mucus and the inside of you is a layer of skin-like cells one-cell thick. One thing you have to understand about your gastrointestinal (GI) tract is that although it resides within you, it is really connected to the outside world, from your lips to your anus, and the things that protect you from the outside world are the mucus; the skin-like layer of cells with immune, nervous, and endocrine cells below it; and the beneficial microbes. At least 70 percent of your immune system is in your GI tract! This is why taking probiotics benefits the immune system greatly.
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Since feminine health is all about balance, it only makes sense that vH’s formula would also contain a healthy dose of probiotic cultures. These live bacteria work with the prebiotic formula and pre-existing bacteria in your system to create a thriving environment for your feminine health. These probiotics are particularly helpful at promoting vaginal and urinary tract health.

Having a healthy gut flora means an abundance for your health, digestion, wellbeing and even beauty! As we saw last week, there is ongoing communication between your GI and your brain known as the gut brain axis. This means a healthy gut can benefit the regularity of your digestion as well as cognitive function like mood and depression, and even the health and appearance of your skin.
★50 BILLION 20 STRAINS TARGETED RELEASE FORMULA★NewRhythm 50Billion Probiotics Capsules is Scientifically Backed and Clinically Proven, Formulated by Doctor with 50 Billion Living Organisms Per Serving, Featuring Targeted Release Technology to Help Probiotics Survive Stomach Acids and Reach Your Intestinal Track. Organic Prebiotics Fiber is also Included In the Formula.
Jigsaw Essential Blend Probiotics uses five of the most researched (and effective) live strains to promote a healthy digestive system, restore flora after antibiotics use, and help with optimal vitamin absorption. Jigsaw products are also third-party certified, so you can rest assured that each batch is safe and pure. The bottom line? If you’re looking for a vegan-friendly formula — the capsules are made from HPMC (Hypromellose - Hydroxypropyl Methylcellulose), gelling agent (Gellan gum), and water — with a high CFU count, this product is for you. There are 90 capsules per bottle.
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.
When seeking out the best probiotic for you, consider your overall health, dietary needs, antibiotic use, GI challenges, and similar concerns. Then, review our list of the ten best probiotic supplements, which offer everything from raw probiotics, which must be refrigerated, to shelf-stable, slow-release probiotics that concentrate fewer CFUs in tiny, once-daily capsules.
Look for the probiotic yeast Saccharomyces boulardii (S. Boulardii)—you can take it as a separate supplement or find it in multi-strain probotics. Studies show that it is effective at preventing antibiotic-induced diarrhea and Clostridium diffcicile (C. difficile) infection, which a course of antibiotics can cause. Saccharomyces boulardii increases your secretory IgA—in other words, it strengthens the immune system in the gut. (Some people say that Saccharomyces boulardii is also the panacea for Candida—it’s a yeast that fights yeast—but while it’s helpful for some, other people do not tolerate it well, so I recommend trying it as an individual supplement first to see how you respond.)
If this happens, it's time to consider switching to a new probiotic. Other reasons a probiotic may not be the right fit: SIBO or Candida. If you have either of these conditions, the strain of the probiotic could potentially make your symptoms worse. Remember, if you think a probiotic is not helping, seek the advice of a functional medicine provider to help you navigate the choices out there.
Since feminine health is all about balance, it only makes sense that vH’s formula would also contain a healthy dose of probiotic cultures. These live bacteria work with the prebiotic formula and pre-existing bacteria in your system to create a thriving environment for your feminine health. These probiotics are particularly helpful at promoting vaginal and urinary tract health.
Do you strain with infrequent bowel movements? Do the feces look like separate hard lumps or like bunches of hard lumps stuck together, or are they pencil-thin? You may have constipation. The Bristol stool chart (BSC) was developed by two doctors as a way to differentiate between states of constipation, normal elimination, a state of lacking fiber, and states of inflammation. Stools are supposed to be long and sausage-like, with few or no cracks in the surface.
Probiotics: Health benefits, facts, and research Every human on the planet has microbes living in their body. While bacteria get a bad reputation, many can promote good health. Probiotics are a type of 'good bacteria' that provide health benefits for the host. The health benefits of probiotics include treatment of diarrhea and irritable bowel syndrome. Read now
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!

We’ll start with the headliner: the BIO-tract peral, which packs the equivalent of 75 billion CFUs into one tiny, filler-free, 5-billion CFUs pearl. The trick is in protecting those 5 billion CFUs over an 8 to 10-hour period, so they bypass your acidic stomach and reach your intestinal tract, alive and well, allowing you to experience the full and multitudinous benefits of plentiful and beneficial gut bacteria.
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.
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.
If you have a tendency to forget to take your probiotics (which, let’s be honest, we all have), try storing them in a place that you look at directly each and every day. We recommend somewhere like your bathroom sink near your toothbrush or even on your kitchen counter, so you never miss a dosage! This one can be taken with or without food, and it doesn’t have to be stored in the fridge – perfect!
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."

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.
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.

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!
Although probiotics have been around since the early 1900s, they have recently gained popularity due to their ability to treat a wide range of ailments. Research also suggests that probiotics can help you lose weight and maintain a healthy body-mass index, according to a meta-analysis that reviewed 20 studies that was published in May 2016 in the International Journal of Food Sciences and Nutrition.
Some of their benefits are universal, no matter your age or gender: supporting gut health, healthy skin, weight management, and strong teeth. But gender-specific probiotic benefits also exist. For instance, women who take probiotic supplements may be more likely to maintain vaginal and breast health, and expecting mothers who take probiotics can get support with some of the less pleasant side effects of pregnancy.
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

​​​​​​Every woman’s microbiota is different and so results will vary. However clinical studies using the blend of probiotic strains in AZO Complete Feminine BalanceTM demonstrated benefits in as little as 7 days. We suggest continuing with use of the product for a minimum of 30 days. Also, keep in mind that for regular maintenance, you may not SEE results but the product is still helping to protect and maintain a healthy vaginal flora.*
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?
Here’s a startling fact: For every one human cell we have, there are ten bacteria cells in our body to match it. That means that the majority of DNA in our body isn’t even human; it’s from the 500 bacteria species that call us home.1 Thinking about that much bacteria might have your skin crawling, but the relationship between human and bacteria is really a perfect synergy: we give bacteria room and board, and in return, they work hard to protect our intestinal health, which ultimately protects the health of our immune system and overall well-being. But if we have that much bacteria already living in our gut, you might be thinking to yourself, what are probiotics’ benefits?
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.”
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