What You Need to Know About Probiotics
The composition of the microbiome is very important to a host of body processes. In fact, researchers now know that the bacteria that live in the gut are not only crucial for proper immune function, but also that specific strains of good bacteria may alleviate certain medical conditions. Gut bacteria are involved in controlling hunger, defending against harmful infections, and even regulating some aspects of the nervous system. Multiple studies have identified correlations between deficiencies in gut bacteria and many different illnesses, ranging from irritable bowel syndrome to Crohn’s disease to certain forms of cancer. New studies are showing evidence that taking a quality probiotic may help reduce anxiety and promote cognitive function in times of stress.
Live-culture foods and probiotic supplements help support a healthy and robust population of gastrointestinal flora, which can protect you against digestive problems, certain autoimmune diseases, opportunistic infections and even the common cold and flu. Probiotics are living microorganisms that can provide wide-ranging health benefits when taken in sufficient quantities.
The diet is very influential for the makeup of the microbiome. Good bacteria thrives on soluble and insoluble fiber, and if your diet is lacking in these, your microbiome might be deficient in the good bacteria you need for optimal digestive and immune function. Bad bacteria thrive on sugar and other simple carbohydrates. If you’re interested in increasing the good bacteria in your gut, a high-fiber diet and live-culture foods can help, as can taking a high-quality probiotic. See the list below for specific strains that might be helpful for your ailment. There are very few contraindications for probiotic supplements, with the exception of patients with compromised immune systems or who are seriously ill.
Here’s what you should look for when choosing a probiotic supplement:
– The label should say “Viable through end of shelf life,” and not just “viable at the time of manufacture.” This ensures that the product you’re choosing will actually be effective in contributing live “good bacteria” to your gut.
– Capsules that have a coating may be better than powders and pressed pills as the probiotics should pass through your stomach to your colon and not get broken down by the stomach acid.
– Genus and species of the microorganisms contained in the product. Bonus points if the product label also lists the specific strains contained. Species and strains in the genera Lactobacillus and Bifidobacterium are the most commonly used bacteria in dietary supplements and are generally regarded as “good bacteria” powerhouses.
– Unless you’re taking a specific probiotic strain to treat a specific problem, generally look for at least 7 strains and at least 5 billion colony forming units (CFUs).
– The probiotic product should be made by a high-quality manufacturer and if possible, independently tested for accurate labeling and dosage. All of the products recommended on this page went through our stringent methodology for selection.
Probiotics are specifically effective to counteract the digestive side-effects of antibiotics, as long as they are started concurrently. Take probiotics at least 2 hours after any antibiotic medication for it to have maximum effect. Continue taking them for several weeks after being done with the antibiotic prescription to repopulate your gut with beneficial bacteria.
Generally, take probiotics 20 minutes prior to a meal. If you’re simultaneously changing your diet or taking a strong probiotic, you may experience some digestive effects like bloating and gas. This is temporary – it’s an effect of the adaptation a die-off of the “bad bacteria” and colonization by the new “good bacteria.”
A Closer Look at the Microbiome
The microorganisms that live in your gastrointestinal tract are astonishingly numerous and diverse: they outnumber the cells in your body by a multiple of ten. There are dozens of distinct species of gut bacteria that help perform a variety of important bodily functions in the digestive system and beyond.
Good bacteria are vitally important to the function of the gastrointestinal tract, as well as overall health. The World Health Organization defines probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit on the host.” If the ecosystem of gut bacteria — also known as the microbiota or the microbiome — becomes unbalanced, opportunistic infections and gastrointestinal disorders may develop, particularly following an illness or a course of antibiotics. Physicians may recommend probiotic therapy to treat irritable bowel syndrome, antibiotic-induced changes in gut bacteria diversity, or certain gastrointestinal infections. There is increasing evidence that high-quality probiotic supplementation may also act as a preventative measure for common illnesses and to strengthen the immune system.
Here’s a short overview of what you need to know about probiotics:
- Maintaining a healthy gastrointestinal (GI) microbiome improves overall health.
- Microflora deficiency can lead to serious health problems, infections, and digestive issues.
- Sources of probiotics include yogurts and other food products that are fortified with live cultures, as well as dietary supplements.
- If you already have a healthy GI microbiome, you may not experience any additional benefits from taking probiotic supplements.
There is also new research that indicates that maintaining a healthy gut microbiome may be an important part of healthy aging.
Why “Good Bacteria” in the Gut is Crucial for Health
There are more than one hundred trillion microorganisms living in the human body, some of which are helpful and some of which are harmful. In order to stay healthy, the body needs to have higher levels of good bacteria than bad bacteria. Ingesting a probiotic, either in food or supplement form, is one method that can provide the body with an influx of good bacteria.
The most common probiotics are various strains of the beneficial microbe genera Lactobacillus and Bifidobacterium.[6, 7, 8] These are the good bacteria that reside in the colon and intestines, collectively known as the “gut.” They exist in a symbiotic relationship with their hosts, our bodies. Gut flora play a crucial role in digestion, helping the body to break down carbohydrates, polysaccharides, and fiber that would otherwise be impossible to process.[9, 10] Gut flora also assist in the production of important hormones such as ghrelin and leptin, which regulate hunger; modulate components of neurotransmitters in the bloodstream; and have a functional role in controlling the hypothalamic-pituitary-adrenal axis, a major neuroendocrine system. Additionally, gut microbiota help to maintain the GI-tract epithelial barrier, which prevents harmful pathogens and toxins from entering the bloodstream. A healthy gastrointestinal microbiome protects the intestines from infection by producing antimicrobial molecules and by outcompeting harmful bacteria for nutrients.
Ultimately, gut flora have an impact on human health via four primary mechanisms:
- Interference with potential pathogens. A healthy and diverse gastrointestinal microbiome protects the body from harmful bacteria, both by fighting them off and by outcompeting them for resources.
- Improving gut barrier function. The ability of the intestinal mucosal barrier to prevent the harmful contents of the intestines from passing through to the rest of the body is enhanced by a robust GI microbiome.
- Modulation of the immune system. Several studies have found that a healthy gut microbiome may decrease, or modulate, immune responses that can cause allergic reactions and autoimmune conditions.
- Production of neurotransmitters. Gut flora influence the production of GABA and serotonin, which are important neurotransmitters that synapses use to signal one another in the nervous system.[14, 15, 16]
We can effectively “use up” the good bacteria in our bodies through excess stress, unhealthy diet, genetic disorders, environmental factors, and illness. More dramatically, taking antibiotics to combat bacterial infections has the unfortunate side effect of targeting all of the bacteria in the body, regardless of whether it is beneficial or harmful.[5, 17] During and after taking course of antibiotics, taking probiotics can be helpful in order to replenish the levels of good bacteria in the body. Furthermore, certain illnesses related to imbalanced gut flora, including necrotizing enterocolitis, atopic dermatitis, and irritable bowel syndrome (IBS), have been treated with probiotic interventions with promising outcomes. More clinical studies are needed to confirm these results and determine precisely which probiotic strains are the most beneficial.[19, 20]
Benefits of Probiotics
- When the body contains an excess of harmful bacteria, the pH level in the intestines becomes more basic because of all the ammonia that the bacteria release. Probiotics can neutralize the pH level and maintain it at the optimal level for the digestive system.
- Probiotics can optimize food processing by ensuring that the stomach’s pH is at the correct acidity level. This allows the stomach to break down food more effectively, thus enhancing the bioavailability of nutrients. Good microbes in the bowels can help to relieve constipation and they can prevent nutrients from passing out of the body in unhealthy stools. One of the main purposes of probiotics is to help move food through your digestive system, and they are especially effective in preventing various forms of diarrhea caused not only by “bad bacteria” but also by viruses, parasites, and antibiotics.
- Research has shown that probiotics can lessen the severity of lactose intolerance by helping to complete certain biological pathways. Specifically, Lactobacillus provides the lactase enzyme that the body needs in order to break down lactose, the sugar found in milk. This can help ease symptoms of lactose intolerance such as stomach cramps, flatulence, and diarrhea.
- For long-term health preservation, maintaining high levels of good bacteria in the body contributes to the prevention of gastrointestinal diseases and inflammatory bowel diseases such as ulcerative colitis, Crohn’s disease, and pouchitis.[7, 17] Bifidobacteria have been found to be particularly effective at easing the symptoms of irritable bowel syndrome (IBS), particularly bloating and flatulence.
- Certain probiotics (Lactobacillus rhamnosus and Saccharomyces boulardii) are recommended for preventing antibiotic-associated diarrhea in children.
- There is some promising evidence to suggest that probiotics can help prevent premature babies from developing a dangerous condition known as necrotising enterocolitis, which causes gut tissues to become inflamed and die.
There are also many proposed benefits of probiotics that remain unproven but promising. The following benefits have been suggested by certain studies but lack the evidence needed to definitively recommend probiotics as a useful treatment for these conditions.
- Just as it helps to ease the symptoms of lactose intolerance, Lactobacillus may also be able to complete the missing portions of the biological pathways that prevent allergies. Certain studies have shown that Lactobacillus strains can treat atopic eczema in children, although other scientific reviews have questioned these findings.
- Some studies have suggested a link between the microbiome composition and the risk of cardiovascular diseases, metabolic syndrome, and type 2 diabetes. Others have proposed that probiotics can improve dental and bone health.
- Some small studies have suggested that probiotics can treat colic in infants who had been exclusively breastfed, but this claim still needs more supporting evidence.
Internal Processing of Probiotic Cultures
When enough probiotics are ingested, the pH in the gut is neutralized. The neutral pH prevents bad microbes from functioning and the environment effectively kills them off. This allows the good microbes residing throughout the digestive system to perform positive functions such as helping to complete biological pathways and transferring genetic materials.[8, 26] Ideally, the microbiota of the human gut should consist of 90% “good bacteria,” spread across some 30 to 40 different strains.
After being ingested, probiotics pass into the digestive system. It is not yet fully understood whether ingested probiotics remain in the gastrointestinal tract or whether they simply pass through and out of the body. Some experiments have shown that Lactobacillus and other probiotic strains associated with yogurt fermentation survive passage through the GI tract, although results have been varied as to the proportion of ingested probiotics that ultimately colonize the digestive system. The survival rates of some strains in the digestive system have been estimated at 20% to 50% of ingested cultures.
Beneficial Bacteria Deficiency
Due to lifestyle choices, unhealthy diets, and even genetic factors, people can become deficient in the gut flora that we need in order to stay healthy. High stress levels, excessive alcohol use, diets that are high in fat and sugar, excessive consumption of meat, high levels of chlorine and fluoride from drinking water, intake of antibiotics, and exposure to environmental toxins can all contribute to the depletion of gut flora. A deficiency in microbiota, formally known as “dysbiosis,” can also arise because of an illness or infection, as a result of metabolic changes, or because of immunodeficiencies.
The most common signs of probiotic deficiency are digestive problems such as stomach pain, indigestion, constipation, and diarrhea. Lactose intolerance may also be related to an imbalance of gut flora. Gastrointestinal diseases and inflammatory bowel diseases such as ulcerative colitis and Crohn’s disease can also indicate a lack of good gut microbiota. Dysbiosis can manifest itself in a variety of different ways, including yeast infections, fungal infections, and urinary tract infection, as well as psoriasis, chronic fatigue, eczema, and even some cancers.[30, 31, 32, 33, 34] There is also some evidence to suggest that food poisoning, allergies, and even mood disorders can indicate dysbiosis. And although you may not display outward symptoms, it is safe to assume that levels of gut flora have been diminished after a course of antibiotics. In many cases, probiotic supplementation can be an effective way to reverse the effects of depleting these helpful types of bacteria.
Research shows that only 12% of the microbiome variance from person to person can be explained with genetics. Diet plays the major role in the ultimate gut composition and ratio of good to bad bacteria that resides within. Taking a course of probiotics while eating live-cultures and a high-fiber diet is the best way to correct any deficiencies in the gut. If the previous diet included simple carbs, there is bound to be a “die-off” of bad bacteria as they are deprived of their favorite sustenance (sugar) and newly introduced good bacteria can form successful colonies and confer the benefits on the host.
It’s worth noting that aging may have an impact on the microbiome as well, decreasing good bacteria, and decreasing overall colonization of the gut. This makes the elderly especially susceptible to the negative side-effects of antibiotics and especially good candidates for probiotic supplementation.
Getting to the Optimal Microbiome Composition
The natural method for introducing good bacteria into the body is by consuming fermented food, mainly dairy products, which contain strains of helpful Lactobacillus bacteria. Kimchi, sauerkraut, miso, tempeh, and kombucha all contain varying amounts of probiotics. In particular, yogurt and kefir can provide good bacteria alongside other healthful nutrients such as protein and calcium. However, only about 6% of the U.S. population consumes yogurt on a daily basis. Yogurt is especially healthy because manufacturers can add additional nutrients to the product while using heat and chemicals to kill off any bad bacteria it might contain. Additionally, several studies have shown that consuming probiotics in yogurt is more effective than consuming them in plain milk or water. Other food products that may contain probiotics include cheese, ice cream, nutritional bars, breakfast cereal, and infant formula.
Prebiotics and Probiotics
Prebiotics are nutrients that help maintain probiotic bacteria growth in the body. They are often paired with probiotics because they help Lactobacilli and Bifidobacteria to survive and thrive within the body, so that you don’t have to continually ingest such large quantities of probiotics to replenish good bacteria. Prebiotics are carbohydrate-based and high in fiber, mostly from inulin-based and oligofructose foods. Whole wheat, onions, honey, artichokes, bananas, garlic, and leeks are common food sources that provide prebiotics for the body. Ingesting approximately 38 grams of daily fiber from fruits and vegetables can help ensure that gut bacteria have the nutrients they need to thrive.
Individuals with gastrointestinal problems should especially consider taking probiotic supplements to improve gut health. A wide range of probiotic supplements are currently available over the counter to promote a balanced GI microbiome. Even people with apparently healthy digestive systems can take probiotic supplements to maintain a population of good bacteria in the body and prevent gastrointestinal issues from arising. Supplementation is typically recommended for patients who have dietary issues, exhibit digestive or GI symptoms, or who are taking antibiotic medications. Supplements typically provide a more concentrated dose of viable bacteria than probiotic foods, and thus are more likely to produce a therapeutic effect.
The most commonly used species in probiotic supplements belong to the genera Lactobacillus and Bifidobacterium. Probiotic supplements may contain one or more of the following strains of bacteria, all of which are known colonizers of the GI tract:
· Lactobacillus acidophilus
· Lactobacillus casei
· Lactobacillus plantarum
· Lactobacillus rhamnosus
· Lactobacillus fermentum
· Bifidobacterium bifidum
· Bifidobacterium lactis
· Bifidobacterium infantis
· Streptococcus thermophilus 
Besides taking probiotics orally to improve gastrointestinal health, women can take probiotics vaginally in order to treat yeast infections, which are caused by bad bacteria building up in the vaginal region. Some research suggests that in addition to treating yeast infections, Lactobacilli can help prevent pregnancy complications and pelvic inflammatory diseases.[5, 7]
Recent comprehensive literature reviews, in which multiple research studies were compared to determine the overall scientific consensus regarding the efficacy of probiotics, indicated that there is positive clinical evidence for many of the purported health benefits of probiotics.[40, 41] Most research indicates that supplements that contain species of Lactobacillus and/or Bifidobacterium will usually produce the best results.
Proper Dosage and Contraindications
Most probiotic supplements contain anywhere from one billion to 10 billion colony-forming units, although certain high-dosage preparations can contain as many as 450 billion live bacteria. Probiotic products may consist of one particular strain of Lactobacillus or Bifidobacterium, or they may be made up of a combination of many different strains. Probiotics can be ingested in the form of fermented milk or yogurt products, as well as capsules, tablets, and powders. To treat yeast infections, probiotics can be introduced into the body through vaginal suppositories.
If you are considering taking probiotics with a particular health goal in mind, rather than to simply improve your overall digestive health, then it is worth noting that there are certain doses and strains that are recommended for preventing or treating specific health conditions.
Taking with antibiotics: Lactobacillus rhamnosus GG and/or Saccharomyces boulardii. Look for at least 10 billion CFUs.
To treat a viral infection like the cold or flu: Bifidobacterium animalis lactis Bi-07 and Lactobacillus acidophilus NCFM. These strains may be especially beneficial in producing antibodies that help your body fight off the virus faster.
Digestive distress or IBS: Bifidobacterium bifidum MIMBb75, Bifidobacterium infantis 35624, and Lactobacillus plantarum 299V have been shown to relieve symptoms of digestive distress such as bloating, pain and gas.[43, 44, 45] Other species and strains may also work and it’s worth it to experiment with a few to find the right one for you. This is an active area of current research.
Avoiding diarrhea from international travel: take Saccharomyces boulardii for at least a few weeks before your trip. Research shows that depending on your destination, this probiotic species can help prevent traveler’s diarrhea.
For lactose intolerance: Lactobacillus bulgaricus, Lactobacillus acidophilus and Streptococcus thermophilus.
For fat loss: 100 billion CFUs of Lactobacillus gasseri SBT2055 (LG2055), or Lactobacillus rhamnosus CGMCC1.3724, known as LPR. The strains Bifidobacterium breve B-3 and Pediococcus pentosaceus LP28 have also shown promise in human research studies.
Overall, there is a lack of comprehensive industry standards for the manufacture of probiotics, which needs to be addressed to ensure complete consumer safety. At the moment, probiotics are considered to be food, rather than medicine, so they are not tested nearly as rigorously as medicines.
Because the U.S. Food and Drug Administration (FDA) has little influence over how supplements are manufactured, probiotics could have the potential to cause harm if not enough attention is given to which bacterial strains they contain. Bacteria are susceptible to receiving genetic materials from other cells in the body due to genetic recombination. For example, it is possible for antibiotic resistance genes to transfer into certain bacterial strains and interfere with helpful antibiotic activities within the body.
Fortunately, research is currently underway to ascertain which strains of Lactobacillus and Bifidobacteria are viable in the body and which are not. Furthermore, probiotic foods and supplements are generally considered safe for healthy individuals with strong immune systems, even if some manufacturers’ claims about their health benefits have been exaggerated. Consumers should also be aware of the wide variety of probiotics on the market; pharmaceutical-grade probiotics, such as the ones used in clinical trials, are likely to have more of an impact than store-bought supplements and food products such as yogurt or kefir.
Because the digestive system is already home to 100 trillion bacteria, it is extremely difficult to “overdose” on probiotics. Some people may experience mild symptoms such as stomach upset, bloating, gas, or diarrhea at the onset of a new probiotics regimen; if this happens, you may want to cut back on your probiotic intake or switch to a different supplement. On the other hand, if your microbiome is changing due to a new probiotic regimen, a new medication (like Metformin) or a new diet, then temporary digestive distress is a normal part of adaptation. Individuals who experience an allergic reaction or have long-term ongoing, unusual bowel movements after taking probiotics should stop taking them immediately and consult a doctor.
Individuals with weakened immune systems are strongly advised not to take probiotics without first consulting a doctor, as in some cases they may cause infection. Likewise, probiotics should not be taken alongside medications that affect the immune system, such as azathioprine (Imuran), basiliximab (Simulect), cyclosporine (Neoral, Sandimmune), daclizumab (Zenapax), muromonab-CD3 (OKT3, Orthoclone OKT3), mycophenolate (CellCept), tacrolimus (FK506, Prograf), sirolimus (Rapamune), prednisone (Deltasone, Orasone), and corticosteroids (glucocorticoids).
Since antibiotics kill off bacteria in the body regardless of whether those bacteria are “good” or “bad,” antibiotics and probiotics should not be taken at exactly the same time. Probiotics should be taken at least two hours before or after antibiotics to allow for proper processing and to alleviate potential digestive side effects of antibiotics.
Product Selection and Methodology
There are several significant ways in which probiotic supplements may differ from one another — how many different strains of good bacteria they include, what those specific strains are, and the number of individual live bacteria in each dose. Probiotics with higher bacterial counts or multiple strains may be more effective at targeting and treating specific health issues, but for healthy individuals, a probiotic supplement with just one strain may be just as effective as a high-dose supplement with multiple strains. More serious, medical-grade probiotics also exist for people with chronic digestive medical conditions such a Crohn’s and IBS.
Probiotic supplements usually contain anywhere from one billion to hundreds of billions of live bacteria. For example, the supplement VSL#3 has a bacterial content of 450 billion microorganisms and shipes with an ice pack.
It is always important to make sure that you are buying a supplement that has been independently tested and reviewed, not only to ensure its safety but to make sure that it contains all of the ingredients it advertises. The products recommended on this page have been thoroughly vetted through independent testing, formulation analysis, manufacturing research, and other relevant factors.
Certain probiotic products also contain prebiotics, which help good bacteria to stay alive inside your body. Some supplements may require refrigeration, and some have potentially allergy-causing ingredients such as dairy, yeast, gluten, and soy.
Many probiotic supplements may contain fillers such as hydrogenated oils or high amylose starch that act as carriers to transmit the probiotics to the GI tract. Probiotic supplements vary in whether they should be taken with or without food and they can vary significantly in shelf life. Better-quality supplements will come with an enteric coating to prevent stomach acid from destroying the probiotics before they reach your intestines. You always want to make sure that you are buying a product that will be viable up to its expiration date, to ensure that you are actually ingesting live bacteria. Food products should feature the label “live and active cultures” and should always be consumed before their expiration date. After purchase, you should store your probiotic product in the fridge to prevent premature expiration.
Recommended here are the probiotic products that went through our thorough vetting process.