Probiotics are undoubtedly in demand, but many of us don’t even realize the immense healing potential they hold. The power of these living microorganisms goes well beyond boosting the immune system and enhancing your gut health.

Probiotics have the potential to improve a whole host of health conditions, from arthritis and allergies to celiac disease and even cancer. However, knowing the best probiotics to supplement with and the best probiotic strains to incorporate in your diet that is specific to your health and active lifestyle needs is a critical piece of the puzzle.

In this article, we answer the following questions about probiotics:

  • What are probiotics?
  • What’s all the fuss about gut health?
  • How do probiotics work?
  • What are the best probiotic strains for specific health conditions common in athletes?

What are Probiotics?

To really understand the benefits of probiotics, we should first dive into the basics. What the heck are they?  What exactly classifies something as probiotic?

Getting down to the core of it, according to a joint position statement put out by the Food and Agriculture Organization of the United Nations and World Health Organization (FAO/WHO) in 2001, a probiotic is, “life microorganisms which, when administered in adequate amounts, confer a health benefit to the host.”

In other words, these bacteria improve your health. For this reason, they are often referred to as  “friendly” or “good” bacteria.

Probiotics are found naturally in some fermented foods, such as yogurt, miso, kimchi, kombucha, tempeh, kefir, and sauerkraut. You may have also seen probiotics in the form of dietary supplements and purpose-made probiotic products.

The most common strains of bacteria used in probiotics are Bifidobacterium and Lactobacillus. However, there is also non-bacterial microorganisms used in probiotics at times (probiotics do not have to be bacterial, they just need to beneficial microorganisms). These often include Saccharomyces cerevisiae and Saccharomyces boulardii which are microorganisms found to be beneficial in the intestines as well as throughout various bodily systems.[1]    

Are the Benefits of Probiotics for Everyone?

Without a doubt, YES.  

From preterm infants to athletes to cancer patients, probiotics are beneficial for everyone.

Adding to the excitement of probiotics benefiting everyone is high-quality research proving they help with just about any condition, syndrome, diagnosis, or lifestyle.  From weight loss, depression, colic in infants, diarrhea in elderly adults, to GI upset in marathon runners. The research has gone on to prove the benefits of probiotics.

Here are just a few major areas probiotics have been found to help:


If you’re pre-diabetic or overweight, taking a daily probiotic may help ward off the development of Type II Diabetes by lowering inflammation within your gut.

Type II Diabetes is a progressive condition during which the body becomes resistant to insulin, and/or the pancreas gradually loses the ability to produce sufficient insulin.

Without insulin, the body cannot effectively convert glucose into energy leading to high blood glucose levels in your blood.

Recent research suggests low-grade inflammation and high amounts if pathogenic bacteria can trigger inflammatory responses that contribute to the development of insulin resistance and Type II Diabetes. In fact, overweight and diabetic individuals have less “good” bacteria in their gut, particularly Bifidobacterium and Faecalibacterium prausnitzii, both of which have anti-inflammatory properties.[2]

Probiotics may improve the prognosis of diabetes by increasing the “good” microbiota in the gut. A recent study demonstrated that probiotics reduce inflammatory responses and increase the expression of adhesion proteins within the intestinal epithelium, which reduces intestinal permeability and can increase insulin sensitivity.[3]

Furthermore, a 2009 study fed mice with obesity and diabetes either prebiotic food or non-prebiotic food and assessed changes in gut permeability. Mice treated with probiotics had lower blood lipids and blood glucose levels, in addition to lower inflammatory and oxidative stress markers. A reduction in these inflammatory markers indicates that the probiotics lowered intestinal permeability and improved tight-junctions, which are all signs of a better gut barrier function during obesity and diabetes.[4]


Hypertension, also known as high blood pressure, is the leading risk factor for heart disease and stroke and is estimated to cause 9.4 million deaths each year. A complex interplay between family history and lifestyle factors are responsible for the development of the condition. A growing body of literature has illustrated that an imbalance of gut microbiota can trigger inflammation that contributes to hypertension.

One way to help control inflammation and blood pressure is to improve the regulation of G protein-coupled receptors (GCPRs).  These receptors are responsible for a host of bodily functions and are the ability to influence them are the target of a countless number of drugs.  In fact, it was estimated that in 2018, 180 billion dollars was spent on drugs targeting GPCRs.[5]   

Probiotics help the gut release short-chain fatty acids (SCFAs), such as acetate and propionate, by the fermentation of fiber.  SCFAs are metabolites that help improve communication between the gut and other bodily physiological processes by positively influencing GPCRs.[34]

So, instead of always opting for drugs, by improving our gut health its possible we may not even need many medications.   

Athletic Performance

Considering that probiotics have been shown to reduce inflammation and improve regulation of bodily processes, it’s no surprise there are several studies showing the positive effect probiotics have with athletes.  A summary of many of the results from several studies are highlighted here:

  • Division 1 Baseball Players: In a double-blind, placebo-controlled, randomized control trial, athletes given Bacillus subtilis DE111 for a 12 week training period demonstrated reduced TNFa (Tumor Necrosis Factor Alpha), an inflammatory cytokine protein that impairs recovery when training occurs.[6]
  • Female Division 1 Soccer and Volleyball Players: 23 female athletes of multiple sports were given a probiotic with the Bacillus subtilis strain during offseason resistance training did not demonstrate performance improvements but did significantly improve body composition compared to those given a placebo.[7]  
  • Female Division 1 Swimmers: Probiotic supplementation did not improve performance during offseason training but did enhance cognition.[8]
  • Marathon Runners: Marathon runners given a probiotic containing strains of Lactobacillus rhamnosus GG during 3 months of training experienced a shorter duration of GI-symptoms when symptoms occurred compared to those given a placebo.[9]
  • Elite Distance Runners: In a double-blind, placebo-controlled trial of 20 elite distance runners prophylactically given a probiotic with the Lactobacillus strain,  a 50% reduction in days and severity of respiratory illness was found.[10]
  • Novice Long Distance Triathletes: Novice triathletes given a multi-strain probiotic (Lactobacillus acidophilus, Lactobacillus acidophillus, Bifidobacterium bifidum, and Bifidobacterium animalis subspecies lactis)  with a prebiotic (fructooligosaccharides/ and α-lipoic acid) demonstrated reduced endotoxins before and after races as well as reduced intestinal permeability.[11]   

Are Probiotics Safe?

Yes.  Probiotics are overwhelmingly safe for most everyone.  From preterm infants to athletes to HIV patients to the elderly, there is overwhelming research that probiotics are beneficial and do little to no harm.[13]  In fact, one review paper that analyzed 27 different studies on probiotic use in preterm infants found a reduced risk of enterocolitis without affecting mortality rate, growth, or feeding.[12]  

The research in support of probiotics is substantial.  Considering that probiotics improve the health of the gut and everything from our immune system, hormone secretion, to brain function depend on the gut in order to function properly, it’s easy to understand why probiotics help just about everything and everyone.  

While the research is strong, we highly encourage you to always consult your doctor and functional dietitian when considering if you should start and what type of probiotic to use.  Additionally, take special precautions when considering probiotics if you or someone you know is immune-compromised or on immunosuppressive medications.[13]

What’s all the Fuss About Gut Health?

The gastrointestinal tract (aka your gut) houses some 100 trillion microorganisms, including bacteria and fungi. This community of microorganisms is known as your gut microbiota. It performs numerous functions that are essential for health, including modulating our immune system, metabolizing nutrients and synthesizing important vitamins.[14]

When there is a disruption to your gut microbiota, it can lead to a serious health condition known as dysbiosis. Gastrointestinal dysbiosis is an imbalance of “good” and “bad” bacteria within our gastrointestinal tract—including your stomach and intestines. The imbalance can occur due to the loss or addition of community members, or due to changes in the relative abundance of bacteria.

Dysbiosis of the gut microbiota is associated with increased inflammation and has been linked to several diseases, including:

  • Irritable bowel syndrome (IBS)
  • Inflammatory bowel disease (IBD)
  • Colon and rectum cancer
  • Yeast infections
  • Type II Diabetes
  • Depression
  • Leaky gut syndrome
  • Obesity
  • Hypertension and heart disease

How do Probiotics Work?

Probiotics can help boost the number of “good” bacteria throughout the gastrointestinal tract, thereby contributing to the maintenance of a balanced intestinal microbiota that fulfills all its physiological functions.

Probiotics have five key mechanisms within the body:

  1. Enhance the epithelial barrier of your intestinal wall
  2. Alter mucus secretion along your intestinal wall
  3. Compete against pathogenic bacteria
  4. Increase the production of antimicrobial substances
  5. Improve the immune system by modulating antibodies and inflammatory cytokines

Posts related to our Best Probiotic Strains post:

What are the Best Probiotic Strains? (Divided by Types of People or Health Condition)

The health benefits of probiotics are strain-specific. Therefore, in order to determine the exact impact of any given probiotic, you will need to take a close look at all three elements, including the genus, species, and strain.

Take “Lactobacillus acidophilus la-14” for example. Lactobacillus is the genus, acidophilus is the species, and la-14 is the strain.

Now that you understand the basics, here are the best probiotic strains for common conditions experienced by athletes and active individuals:


Intense physical activity can temporarily suppress the immune system, placing athletes at an increased risk of contracting upper respiratory tract infections or gastrointestinal bugs.

Clinical trials have shown that probiotic supplements can reduce exercise-induced immune suppression.  One study investigated the use of Lactobacillus fermentum VRI-003 in 20 elite male runners during a 4-month-long heavy training season. Athletes taking the probiotic supplement reported 40 fewer days of respiratory symptoms, compared to the placebo (32 vs. 72). The severity of Illness was also lower for the supplementation group. [15]

A more recent study published in the Nutrition Journal assessed the effectiveness of a daily probiotic containing Lactobacillus fermentum PCC for 11 weeks on the immune system of 109 cyclists. Lactobacillus counts increased 7-fold in males and 2-fold in females, along with a substantial decrease in the severity of gastrointestinal illness in males. [16]

Best probiotic strains to support immune function in athletes:

  • L. acidophilus (LA14)
  • L. fermentum (PCC)
  • L. fermentum (VRI-003)
  • B. longum (BL05)

To learn more about the best probiotic supplements for conditions commonly seen in active individuals, check out our Probiotic Supplement Guide.

Irritable Bowel Syndrome

Regular, moderately intense exercise can provide beneficial effects for the intestinal microbiome. However, female athletes who regularly engage in intense exercise or prolonged endurance training report a higher prevalence of irritable bowel syndrome (IBS). Fortunately, specific probiotic strains can help relieve gastrointestinal symptoms related to IBS, including diarrhea, constipation, abdominal pain, and bloating.[17]

A 2018 clinical trial involving 113 patients demonstrated that a combination of Lactobacillus acidophilus CL1285, Lactobacillus casei LBC80R, and Lactobacillus rhamnosus CLR2 is effective at relieving symptoms of IBS. In the study, patients received either 2 x daily probiotic capsule or a 2 x placebo capsules and were assessed for symptoms over the course of 12 weeks. This combination of probiotics strains did not significantly improve abdominal pain, but it did significantly improve stool frequency and consistency.[18]

A 2011 double-blind randomized clinical trial assessed the efficacy of Bifidobacterium bifidum MIMBb75 on the severity of symptoms of 122 patients with IBS. One half received a daily probiotic for four weeks, while the other half received a placebo. Patients rated the severity of their symptoms a 7-point scale each day. The results showed that Bifidobacterium bifidum MIMBb75 significantly reduced the severity of global symptoms, including pain, bloating, urgency and difficulty of bowel movements.[19]

Best probiotic strains for the management of IBS:

  • L. acidophilus (CL1285)
  • L. casei (LBC80R)
  • L. rhamnosus (CLR2)
  • B. bifidum (MIMBb75)
  • B. longum (35624)
  • B. infantis (35624)

To learn more about the best probiotic supplements for conditions such as IBS and IBD, check out our Probiotic Supplement Guide.

Inflammatory Bowel Disease

Inflammatory Bowel Disease involves both Crohn’s disease and ulcerative colitis. Commonly shortened to IBD, it is often confused with Irritable Bowel Syndrome (IBS), which is a completely different condition.

A randomized double-blind study found that the administration of a non-pathogenic strain of Escherichia coli (Nissle 1917) is just as effective at preventing ulcerative colitis as mesalazine, a mainstream drug currently used to treat the condition. The study involved 116 patients with active ulcerative colitis. 59 received mesalazine and 57 received the probiotic. At 12 months follow-up, 73% of patients from the mesalazine group relapsed, while just 67% of the E. coli group relapsed.[20]

Currently, there is insufficient evidence to draw any conclusions on probiotics for Crohn’s Disease.

Best probiotic strains for the treatment of ulcerative colitis:

  • Escherichia coli (Nissle 1917)

Infectious Diarrhea

Athletes travel regularly for both interstate and international competitions and are therefore at greater risk of contracting infectious diarrhea. However, there is strong evidence to suggest that probiotics are beneficial in the prevention and treatment of acute diarrhea. In 1994, a clinical trial demonstrated a 4-fold reduction in the number of loose stools among infants with diarrhea who were fed a formula supplemented with Bifidobacterium bifidum.[21]

Another clinical trial in 2001, demonstrated that Lactobacillus rhamnosus GG significantly reduced diarrhea in infants compared to controls.[22]

In addition, a 2007 meta-analysis found that several probiotic strains are effective as a preventative measure for traveler’s diarrhea, including Saccharomyces boulardii and a mixture of Lactobacillus acidophilus and Bifidobacterium bifidum.[23]

The following strains may help prevent infectious or traveler’s diarrhea:

  • L. rhamnosus (GG)
  • L. acidophilus
  • L. reuteri (DSM 17938)
  • B. bifidum
  • B. lactis (BB-12)
  • Saccharomyces boulardii

To learn more about the best probiotic supplements for diarrhea, check out our Probiotic Supplement Guide.

Antibiotic-Associated Diarrhea

Diarrhea develops in 5-39% of adults taking antibiotics. Probiotics have proven beneficial as an adjuvant therapy to prevent the duration of antibiotic-induced diarrhea in six clinical studies and experts suggest that Lactobacillus probiotics may decrease antibiotic-associated diarrhea in both children and adults by up to 57%.[24]

In a 2013 study on patients hospitalized for a spinal cord injury, Lactobacillus casei Shirota reduced the incidence of antibiotic-associated diarrhea.[24] Another study at Gothenburg University in Sweden found Lactobacillus plantarum, when taken with antibiotics, can reduce antibiotic-associated diarrhea as well.

Best probiotic strains to prevent antibiotic-associated diarrhea:

  • L. casei Shirota
  • L. reuteri (DSM 17938)
  • L. plantarum

Small Intestinal Bacterial Overgrowth

Small Intestinal Bacterial Overgrowth (SIBO) involves an increase in the number of bacteria or an alteration in the type of bacteria within the upper gastrointestinal tract. Symptoms include bloating, diarrhea, malabsorption, weight loss, and malnutrition.

Animal studies suggest that probiotics can enhance the intestinal barrier, modulate the immune system and have anti-inflammatory effects in patients with SIBO.[14] One study to date has suggested that Lactobacillus plantarum and Lactobacillus rhamnosus GG may help to ameliorate symptoms of small bowel bacterial overgrowth.[27]

Best probiotic strains to improve Small Intestinal Bacterial Overgrowth:

  • L. plantarum
  • L. rhamnosus (GG)

To learn more about the best probiotic supplements for SIBO, check out our Probiotic Supplement Guide.

the BEST PROBIOTIC strains for your health.

Women’s Health

Probiotics are especially effective at warding off chronic yeast and bacterial infections.

Bacterial vaginosis (BV), aka non-specific bacterial vaginosis, involves an imbalance of bacteria within the vagina. The vaginal microbiota is normally dominated by Lactobacillus, however, when a person has BV other bacteria levels rise, including Atopobium vaginae, Gardnerella vaginalis, Prevotella spp and Mobiluncus spp.

Vulvovaginal candidiasis, aka thrush, is a common condition caused by an overgrowth of the fungus, Candida albicans, which normally lives in the mouth, throat, intestine, and vagina. The overgrowth can be triggered by a variety of factors such as a suppressed immune system, overuse of antibiotics, and pregnancy.

If you have persistent or recurrent BV or thrush, you may benefit from taking the following Lactobacillus probiotic strains to improve the balance of “good” bacteria.

Best probiotic strains to improve bacterial vaginosis or thrush:

  • L. rhamnosus (GR-1)
  • L. reuteri (RC-14)
  • L. crispatus (LbV 88)
  • L. jensenii (LbV 116)
  • L. gasseri (LbV 150N)

If you’re undertaking a course of antibiotics for BV, such as Metronidazole or Clindamycin, consult your physician before taking probiotics.

Urinary Tract Infections

Urinary tract infections (UTI) affect millions of women each year in the United States, with approximately 85% of cases resulting from the pathogenic bacteria strain Escherichia coli, which originates in the bowel.

Lactobacilli strains can prevent the adherence, growth, and colonization of Escherichia coli within the vagina.[16] Clinical trials have shown that a weekly capsule of freeze-dried Lactobacillus strains L. rhamnosus GR-1 and L. fermentum B-54, in addition to a daily capsule of Lactobacillus strains L. rhamnosus GR-1 and L. reuteri RC-14 can repair the vagina’s normal lactobacilli-dominated flora. [17] These probiotics can help prevent the movement of Escherichia coli bacteria from the intestines into the bladder.

Best probiotics strains to reduce the incidence and severity of Urinary Tract Infections:

  • L. rhamnosus (GR-1)
  • L. reuteri (RC-14)
  • L. fermentum (B-54)

To learn more about the best probiotic supplements for candida overgrowth and UTIs, check out our Probiotic Supplement Guide.

Gastroesophageal Reflux

Gastroesophageal Reflux (GER), aka acid reflux, occurs when your stomach content comes back up the esophagus. This can cause a burning sensation in your throat and chest. If you experience GER more than twice a week, you may have a more serious condition known as Gastroesophageal Reflux Disease (GERD).

The best way to treat acid reflux is to avoid the trigger. However, we know that patients with esophagitis have a greater proportion of pathogenic bacteria within their esophageal microbiome.[30] Therefore, taking a daily probiotic could help to balance out the microbiome.

A 2010 study published in the European Journal of Clinical Investigation proved this theory when supplementing formula milk with Lactobacillus reuteri accelerated gastric emptying and improved reflux in infants [19]. Another study in China, involving 80 premature infants also found that probiotics reduced the number and length of reflux episodes.[33]

Best probiotic strain to reduce gastroesophageal reflux:

  • L. reuteri

Experience Microbial Balance with Probiotics

Probiotics are a beneficial addition to everyone’s daily routine (when dosed appropriately), whether you’re a professional athlete looking for a competitive edge or a busy mom who needs some help keeping up with the kids. By arming yourself with knowledge about the benefits of specific probiotic strains, you’re well on the road to microbial recovery!

If you’re ready to learn more, check out our post on the top probiotic supplements then learn about the best time to take probiotics to make sure you aren’t simply killing the bugs and flushing your money down the drain.  Taking them the right way could make the complete difference between experiencing amazing results vs nothing at all!