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Probiotics are beneficial microorganisms that have been shown to offer a wide array of health benefits.

As such, probiotic supplements and probiotic-rich foods have become popular natural treatments for a number of health conditions, including digestive issues like diarrhea (1).

This article explains how probiotics may help combat diarrhea, reviews which strains are the most effective, and addresses the possible side effects associated with probiotic use.

In addition to being found in supplements and certain foods, probiotics naturally reside in your gut. There they play several important roles, such as maintaining immune health and protecting your body from infection and disease (2).

The bacteria in your gut — collectively known as the gut microbiota — can be both negatively and positively affected by various factors, including diet, stress, and medication use.

When gut bacteria composition becomes imbalanced and the normal population of probiotics is disrupted, it can lead to negative health effects, such as an increased risk of conditions like irritable bowel syndrome (IBS) and digestive symptoms like diarrhea (3, 4).

The World Health Organization defines diarrhea as having “three or more loose or watery stools in a 24‐hour period.” Acute diarrhea lasts fewer than 14 days while persistent diarrhea lasts 14 days or longer (5).

Supplementing with probiotics may help prevent certain types of diarrhea and help treat diarrhea by repopulating and maintaining beneficial gut bacteria and correcting an imbalance.

Probiotics fight pathogenic bacteria by competing for nutrients, boosting the immune system, and changing the gut environment to make it less conducive to pathogenic activity (5).

In fact, research has shown that probiotic supplements prevent and treat certain types of diarrhea in both children and adults.

Summary

Taking probiotics may help prevent and treat diarrhea by repopulating beneficial gut bacteria and correcting an imbalance in the gut microbiota.

Diarrhea has a number of different causes, including bacterial or viral infections, certain medications, and exposure to different microorganisms from traveling.

Research has shown that many types of diarrhea respond well to probiotic supplements.

Infectious diarrhea is diarrhea caused by an infectious agent, such as bacteria or parasites. Over 20 different bacteria, viruses, and parasites are known to cause infectious diarrhea, including Rotavirus, E. coli, and Salmonella (5).

Infectious diarrhea is more common in developing countries and can lead to death if not treated. Treatment includes preventing dehydration, reducing the time that a person is infectious, and shortening the duration of diarrhea.

One review of 63 studies in 8,014 people concluded that probiotics safely reduced the duration of diarrhea and stool frequency in adults and children with infectious diarrhea (5).

On average, the groups treated with probiotics experienced diarrhea for nearly 25 hours less than the control groups (5).

Antibiotics are medications used to treat an array of illnesses caused by bacteria. Diarrhea is a common side effect of antibiotic treatment due to the disruption of normal gut microbiota these medications cause.

Taking probiotics may help prevent diarrhea associated with antibiotic use by repopulating beneficial bacteria in the gut.

A review of 17 studies in 3,631 people demonstrated that antibiotic-associated diarrhea was significantly more prevalent in those who were not supplementing with probiotics.

In fact, nearly 18% of people in the control groups had antibiotic-associated diarrhea while only 8% of people in groups treated with probiotics were affected (6).

The review concluded that probiotics — particularly Lactobacillus rhamnosus GG and Saccharomyces boulardii species— may reduce the risk of antibiotic-associated diarrhea by up to 51% (6).

Traveling exposes you to many types of microorganisms that are not typically introduced to your system, which can cause diarrhea.

Traveler’s diarrhea is defined as “the passage of three or more unformed stools per day” with at least one related symptom, such as cramps or abdominal pain, occurring in a traveler after arrival to their destination. It impacts 20 million people annually (7, 8).

A review of 11 studies found that preventative treatment with probiotic supplements significantly reduced the occurrence of traveler’s diarrhea (9).

Another 2019 review of 12 studies showed that only treatment with the probiotic Saccharomyces boulardii resulted in significant reductions of up to 21% in traveler’s diarrhea (8).

Antibiotic-associated diarrhea and diseases that cause diarrhea are prevalent in infants and children.

Necrotizing enterocolitis (NEC) is a disease of the intestines that occurs almost exclusively in infants. This illness is characterized by intestinal inflammation that leads to an overgrowth of bacteria, which severely damages cells of the intestines and colon (10).

NEC is a serious condition with a death rate as high as 50% (10).

One of the symptoms of NEC is severe diarrhea. Antibiotics are often used to treat this disease, which can lead to antibiotic-associated diarrhea that can worsen the patient’s condition.

Additionally, some experts suggest that antibiotic treatment may be one factor that causes NEC (11).

Studies have shown that probiotics may help reduce the risk of NEC and mortality in preterm infants (12).

A review of 42 studies that included over 5,000 infants under 37 weeks old found that the use of probiotics reduced the incidence of NEC and demonstrated that probiotic treatment led to a decrease in overall infant mortality (13).

Additionally, another review concluded that probiotic treatment was associated with lower rates of antibiotic-associated diarrhea in children aged 1 month to 18 years (14).

Other studies have found that certain strains of probiotics, including Lactobacillus rhamnosus GG, may treat infectious diarrhea in children as well (15).

summary

Taking probiotics may help prevent and treat diarrhea associated with infection, traveling, and antibiotic use.

There are hundreds of types of probiotics, but research shows that supplementing with a select few is most beneficial when combating diarrhea.

According to the latest scientific findings, the following types are the most effective probiotic strains for treating diarrhea:

  • Lactobacillus rhamnosus GG(LGG): This probiotic is among the most commonly supplemented strains. Research shows that LGG is one of the most effective probiotics for treating diarrhea in both adults and children (6, 16).
  • Saccharomyces boulardii: S. boulardii is a beneficial strain of yeast that’s commonly used in probiotic supplements. It has been shown to treat antibiotic-associated and infectious diarrhea (6, 17).
  • Bifidobacterium lactis: This probiotic has immune-boosting and gut-protective qualities and may significantly reduce the severity and frequency of diarrhea in children (18).
  • Lactobacillus casei: L. casei is another probiotic strain that has been studied for its anti-diarrheal benefits. Some studies suggest that it treats antibiotic-associated and infectious diarrhea in children and adults (19, 20).

Although other types of probiotics may help treat diarrhea, the strains listed above have the most research supporting their use for this particular condition.

Probiotics are measured in Colony Forming Units (CFU), which indicate the number of beneficial bacteria concentrated in each dose. Most probiotic supplements contain between 1 and 10 billion CFU per dose.

However, some probiotic supplements are packed with over 100 billion CFU per dose.

While choosing a probiotic supplement with a high CFU is essential, the strains included in the supplement and product quality are equally important (21).

Given that the quality and CFU of probiotic supplements can vary widely, it’s a good idea to work with a qualified healthcare professional to choose the most effective probiotic and dosage.

SUMMARY

Lactobacillus rhamnosus GG, Saccharomyces boulardii, Bifidobacterium lactis, and Lactobacillus casei are some of the most effective strains of probiotics for treating diarrhea.

While probiotics are generally considered safe for both children and adults and serious side effects are rare in healthy people, some potential adverse effects may occur in certain populations.

People who are vulnerable to infections, including individuals recovering from surgery, critically ill infants, and those who have indwelling catheters or are chronically ill are more at risk of experiencing adverse reactions after taking probiotics (22).

For example, probiotics may cause serious systemic infections, diarrhea, excessive immune system stimulation, abdominal cramping, and nausea in immunocompromised individuals (23).

Less serious side effects related to taking probiotics can occasionally occur in healthy people as well, including bloating, gas, hiccups, skin rashes, and constipation (24).

While probiotics are generally considered safe for most people, it’s always a good idea to consult your healthcare provider before adding any supplement to you or your child’s diet.

summary

Probiotics are widely considered safe but can cause serious side effects in immunocompromised individuals.

According to the latest research, certain types of probiotics may help treat and prevent different types of diarrhea, including antibiotic-associated, infectious, and traveler’s diarrhea.

Although there are hundreds of strains of probiotics available in supplement form, only a few have been proven to treat diarrhea, including Lactobacillus rhamnosus GG, Saccharomyces boulardii, Bifidobacterium lactis, and Lactobacillus casei.

If you’re interested in using probiotics to treat or prevent diarrhea, consult your healthcare provider for advice.

You can purchase probiotic supplements locally or online. Be sure to search for the strains your medical provider recommended.