follow us:

Why Use Probiotics?

Why Use Probiotics?

Though it may surprise some of you, our bacteria actually outnumber our human cells by a factor of 10 to 1.  These bacteria play an important role in the function of the human body–particularly involved with metabolism and nutrition.

Most probiotics contain various strains and species of bacteria–though there are some exceptions including certain types of yeast.

probiotic yogurt

Do Probiotics Work?

Among other roles, bacteria play an important role in the following:

  • synthesize compounds such as vitamin K and B vitamins
  • break down cholesterol
  • digest polysaccharides that would otherwise be unavailable for energy use
  • contribute to host defense / play a role in the immune system
  • inhibit colonization of pathogenic bacteria
  • produce ‘bacteriocins‘ which are small molecular weight peptides that kill other pathogenic bacteria

In short, our commensal microbes coexist with us in a symbiotic relationship. It almost makes you want to give them a big hug–if you only could.

What Are Probiotics?

The most common and cited definition of probiotics is sourced from the United Nations and World Health Organization:

“live microorganisms which, when administrated in adequate amounts, confer a health benefit on the host”

Sounds simple enough, so what’s with all of the confusion?  To start off with, different sources of probiotics whether they be from yogurt or dairy products, dietary supplements, or other related products contain different species, strains, dose, delivery vehicle, etc of probiotics.

Should You Take Probiotics?

The first problem is that health benefits conferred by probiotic bacteria depend on the specific species and strain of bacteria.

Secondly, probiotics are not INERT ingredients.

For example, you go to the store and buy a probiotic dietary supplement in a pill form.  To start off with, there’s a good chance that the label information has inaccuracies in terms of the strain and species of bacteria along with the actual dose.

After that, the number of bacteria in your product will degrade over time as well.  Maybe you brought the product because you’re going on a trip to Mexico and you want to prevent traveler’s diarrhea, but you purchased the wrong type of probiotic for that purpose to make matters worse.

Bottom line:   Not all probiotics are indicated for the same health conditions.

Though not a complete overview, a recent study published by researchers from Queen’s University provides an overview of common types of probiotics that are currently available.  Those included on this list have been relatively well-studied and researched for certain medical conditions such as antibiotic-associated diarrhea or ulcerative colitis.

Overview of Common Probiotics:

VSL#3: A Mixture of Different Gram-positive Bacteria


The probiotic VSL#3 is a mixture of 8 different species of bacteria:

  • Streptococcus salivarius subsp. thermophilus
  • Lactobacillus casei
  • Lactobacillus plantarum
  • Lactobacillus acidophilus
  • Lactobacillus delbrueckii subsp. bulgaricus
  • Bifidobacteria longum
  • Bifidobacteria infantis
  • Bifidobacteria breve.

Health Conditions used for:

  • chronic intestinal inflammation
  • ulcerative colitis

E. Coli Nissle 1917: A Gram-negative Probiotic

  • diarrhea
  • ulcerative colitis

Lactobacillus Rhamnosus GG: Gram-positive Probiotics

  • acute diarrhea in the pediatric population (most effective for rotavirus diarrhea)
  • antibiotic-associated diarrhea – strong level of evidence for preventing this.

Lactobacillus Reuteri: Gram-positive Probiotics

  • acute diarrhea in children

Saccharomyces Boulardii: A Probiotic Yeast

  • prevent antibiotic-associated diarrhea
  • treating recurrent Clostridium difficile-associated disease (a common type of antibiotic-associated diarrhea)
  • ***important safety concerns including fungal infections in immunocompromised and elderly.

Source:  Antiinflamm Antiallergy Agents Med Chem. 2009 Sep 1;8(3):260-269.


  • doc

    Much of data indicates that probiotics are more benficial in preventing sickness and promoting positive health.

  • Patricia

    Great information here Jarret. You have obviously researched it well. I have seen a lot of foods advertising that they contain probiotics and wondered what this was all about. Now I know. thanks Patricia Perth Australia

  • bryan

    hmm very interesting post you have here. i didn't know there's a yeast to treat Clostridium Difficile Infections and a Gram Negative Probiotics, something i've never heard of. Thanks for the insightful post

  • Dawn

    Great article - makes a confusing subject understandable. So many people think that all probiotics are the same. Yes, the probiotic yeast Saccharomyces boulardii has a well documented track record with both AAD and C difficle. It was originally discovered nearly fifty years ago. You'll find the original yeast in Florastor and cheaper alternatives in brands such as Jarrows. Still some debate as to whether the cheaper alternatives are as good.

    • Jarret Morrow, M.D.

      I met the founder of Jarrows at a conference back in 2007. Clearly, there's more need for research in the area of probiotics. Thanks for sharing your thoughts Dawn.

      • Dawn

        That would have been interesting. I LOVE Jarrow's Fem Dophilus - it is simply the best probiotic out for normalizing bacteria in female areas. Jarrow have fully supported the work done by Dr Gregor Reid who discovered the two probiotics, Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14, that are in Fem Dophilus. A very well researched probiotic.

Comments are closed.

JM logo

Dr. Jarret Morrow MD on Instagram.