Most people have heard of probiotics. These bacteria-based supplements are currently a buzz-world in the world of healthcare and new research on them is on-going. But what exactly are probiotics and what are they good for? Are prebiotics and probiotics the same? Does it matter which probiotic I choose? I hope to answer all these questions and more to help clear up the confusion surrounding these powerful medicinal supplements.

Bacteria in the Body

There are an estimated 100 trillion microorganisms representing more than 500 different species in a normal, healthy bowel. These bacteria keep harmful microorganisms at bay, regulate the immune system, aid in digestion and nutrient absorption and help us maintain a healthy weight.

Beneficial bacteria are not only present in our digestive tract. They are also abundant on our skin as well as in the reproductive tract. In fact, there are more bacterial cells in our body than human cells! Makes you think twice about what it means to be human, eh?

In women, the microorganisms in the vagina, specifically lactobacilli, help keep the vaginal pH low; this creates an acidic environment that prevents harmful microbes from surviving. When the lactobacillus levels are depleted by thing such as antibiotics, spermicides or the birth control pill, harmful bacteria and yeasts start to thrive resulting in yeast, bacterial and urinary tract infections.

Clearly, these microorganisms are needed to keep us healthy in more ways than one and we need to keep their populations thriving to keep us thriving.

What are probiotics?

Probiotics are live microorganisms which, when administered in adequate amounts, confer a health benefit to the host (FAO, 2001). The most well-studied probiotics are the Lactobacillus and Bifidobacterium species; however, as noted above there are hundreds of different strains of bacteria that are helping us remain healthy.

What are prebiotics?

Prebiotics are not the same as probiotics. A prebiotic is an non-digestible fiber that is used as a food source to stimulate the growth and/or activity of of one or more beneficial bacterial species in the colon in order to beneficially affect the host (i.e. you!).

Prebiotics (e.g. fructooligosaccharides (FOS), arabinooligosaccharides (AOS), inulin, etc.) promote the growth of Bifidobacteria and Lactobacillus species, lower intestinal pH, produce short-chain fatty acids and improve the absorption of minerals.

If you find that your probiotics are causing your symptoms to worsen, it may be due to the prebiotics in your supplement causing a growth of the harmful bacteria in your bowel. In these cases, talk to your naturopath about getting tested for small-intestine bacterial overgrowth (SIBO).

Do all probiotics function the same way?

In general, different strains have been found to exert different effects on human health. Therefore, when a health effect has been proven for one strain, it is not true to assume that there will be the same health effect for other probiotic strains.

For general health, it is best to supplement with a high-dose multistrain probiotic to confer the health benefits of all the strains to the host.

How much should I be taking?

Most probiotic supplements pass through the intestinal tract in 3 to 30 days and do not permanently adhere to the intestinal wall. Therefore, long-term use is not thought to be harmful.

Most studies recommend a daily dose of 10 to 100 billion CFU (colony-forming units). The dose depends on the particular strains of bacteria present in the supplement you choose and hence, more bacteria per dose does not equate to a better supplement. It is more important to choose a probiotic supplement that is specific to your own particular health concern and then follow the recommended dosing on the label.

For example, Bifidobacterium infantis has been shown to be effective in alleviating the symptoms of irritable bowel syndrome (IBS) at a dose of 100 million CFU/day whereas studies with VSL#3 have used sachets with 300-450 billion CFUs 3x/day with success.

Antibiotic Use

Antibiotics are great at killing harmful bacteria that make us ill. However, antibiotics are also really great at killing the beneficial bacteria that keep us healthy. For example, antibiotic-associated diarrhea (AAD) occurs in about 25% of people taking probiotics. High-dose probiotics are great at preventing AAD while taking your course of antibiotics as well as to re-establish healthy bacteria levels after your antibiotic course is finished. Talk to your healthcare provider about an appropriate high-dose probiotic for use during and/or after antibiotics to keep you feeling your best!

The Research

Now that you understand what probiotics are and what they are good for, let’s look at the research showing which strains of probiotics have been proven to be useful and for what conditions.

Evidence-based Pediatric Indications for Probiotics and Prebiotics

DisorderProbiotic StrainRecommended Dose
Treatment of acute infectious diarrheaLactobacillus rhamnosus GG10-100 billion CFU 2x/day
Saccharomyces boulardii200mg 3x/day
Prevention of antibiotic associated diarrheaSaccharomyces boulardii250mg 3x/day
Lactobacillus rhamnosus GG10 billion CFU 1-2x/day
Bifidobacterium lactis + Streptococcus thermophilus10 million + 1 million CFU/g of formula
Lactobacillus rhamnosus20 billion CFU 2x/day
Prevention of nosocomial diarrheaLactobacillus rhamnosus GG10-100 billion CFU 2x/day
Bifidobacterium lactis + Streptococcus thermophilus100 million + 10 million CFU/g of formula
Prevention of common gastrointestinal infections acquired in the communityLactobacillus casei10 billion CFU/day
Bifidobacterium lactis or Lactobacillus reuteri10 million CFU/g of formula powder
Adjuvant therapy for H. pylori eradicationLactobacillus casei10 billion-1 trillion CFU/day for 14 days
Alleviates some symptoms of functional bowel disordersLactobacillus rhamnosus GG10-100 billion CFU 2x/day
Lactobacillus reuteri100 million CFU/day
Infantile colicLactobacillus reuteri100 million CFU/day
Prevention of necrotizing enterocolitis in preterm infantsBifidobacterium bifidum + Lactobacillus acidophilus1 billion CFU of each strain 2x/day
Lactobacillus acidophilus + Bifidobacterium infantis100 million CFU of each strain 2x/day
Bifidobacterium infantis, Bifidobacterium bifidum, Streptococcus thermophilus1 billion CFU of each strain per day
Treatment of mildly active ulcerative colitisVSL#3 mixture400-900 billion CFU 2x/day

Evidence-based Adult Indications for Probiotics and Prebiotics

DisorderProbiotic StrainRecommended Dose
Treatment of acute diarrheaEnterococcus faecium100 million CFU 3x/day
Lactobacillus paracasei or Lactobacillus rhamnosus GG1 billion CFU 2x/day
Saccharomyces boulardii2-6 billion CFU/day
Prevention of antibiotic associated diarrhea in adultsEnterococcus faecium100 million CFU 2x/day
Saccharomyces boulardii4 billion CFU/day
Lactobacillus rhamnosus GG10-100 billion CFU 2x/day
Lactobacillus casei10 billion 2x/day
Bacillus clausii2 billion spores 3x/day
Lactobacillus acidophilus + Lactobacillus casei50 billion CFU 1-2x/day
Prevention of C. difficile diarrhea in adultsLactobacillus casei10 billion CFU 2x/day
Lactobacillus acidophilus + Bifidobacterium bifidum20 billion CFU of each strain per day
Oligofructose4 g 3x/day
Lactobacillus rhamnosus + Lactobacillus acidophilus1 billion CFU of each per day
Lactobacillus acidophilus + Lactobacillus casei5 billion CFU 1-2x/day
Saccharomyces boulardii2-3 billion for 28 days
Coadjuvant therapy for H. pylori eradication in adultsLactobacillus rhamnosus GG6 billion CFU 2x/day
Bacillus clausii2 billion spores 3x/day
Saccharomyces boulardii2-4 billion CFU/day
Lactobacillus reuteri100 million CFU/day
Alleviation of some symptoms of IBSBifidobacterium infantis100 million CFU/day
Bifidobacterium animalis10 billion CFU 2x/day
Lactobacillus acidophilus10 billion CFU/day
Lactobacillus rhamnosus GG, Lactobacillus rhamnosus, Bifidobacterium breve + Propionibacterium freudenreichii10 billion CFU/day
Bifidobacterium longum, Lactobacillus acidophilus, Lactococcus lactis + Streptococcus thermophilus10 billion CFU/day
Short-chain fructooligosaccharides5 g/day
Galactooligosaccharides3.5 g/day
Bacillus coagulans2 billion CFU/day
Maintenance of remission in ulcerative colitisEscherichia coli50 billion viable bacteria 2x/day
Treatment of mildly active ulcerative colitis or pouchitisVSL#3 mixture1.8 trillion CFU 2x/day
Prevention and maintenance of remission in pouchitisVSL#3 mixture900 billion CFU 2x/day
Treatment of constipationLactulose20-40 g/day
Oligofructose>20 g/day
Treatment of hepatic encephalophyLactulose45-90 g/day

Yours in health,

Dr. Nicole Hartman

About Dr. Nicole Hartman

Dr. Nicole Hartman is a naturopathic physician, a world traveler, a hiker, and a blogger. She focuses her practice in fertility and women's health and takes an integrative, evidence-based approach to healthcare.