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Probiotics 101

Category: Educational Articles

The Microbiome

It may be hard to imagine, but our bodies are home to more than 100 trillion microorganisms…this means that the bacteria in your body outnumber your body’s cells 10 to 1! You are more bacteria than you are…well, “you”. The majority of these bacteria reside in the gut, and are roughly 70% “good” or healthy bacteria, and 30% “bad” bacteria. Most of the gut flora is found in the colon, or large intestine, the last part of the digestive tract.

The gut flora performs a variety of functions that are important for health. In fact, 70% of our immune cells are located in the digestive tract, making the health of the digestive tract critical to overall health. A healthy and well-balanced gut flora facilitates digestion, protects us from pathogens, provides vitamins and nutrients and helps form the immune system.

What Are Probiotics?

Probiotics are those bacteria that are often referred to as “good”, “friendly” or “beneficial” bacteria.

The World Health Organization (WHO) defines probiotics as “a living microorganism which, when administered in adequate amounts, confers health benefits to the host.” Probiotic bacteria may be consumed in foods or supplements. Probiotic-rich foods include yogurt, kefir, sauerkraut, tempeh and kimchi. When consumed, probiotics are able to thrive in the intestinal environment and provide benefits that aid in digestion and support normal bowel function.

Categories of Probiotics
Many types of bacteria are classified as probiotics, and they all have different benefits. The name of a bacterium will tell you its genus, species and particular strain. For example:

Lactic Acid-Production Bacteria (LAB)

The most well-known probiotic bacteria are the lactic acid-producing bacteria (LAB) Lactobacilli and Bifidobacteria. Lactobacillus is a lactic acid producing bacteria that resides and functions in the small intestines, while Bifidobacteria reside and function in the large intestines. In addition to producing lactic acid, bifidobacteriaproduce acetic acid which reduces growth of yeasts and molds. In addition to bifidobacteria and lactobacilli, there are other beneficial LAB strains such as Streptococcus thermophiles.

Spore forming bacteria such as Bacillus subtilis and Bacillus coagulans are a diverse group of very hardy bacteria, characterized by their ability to form endospores to protect themselves in varying conditions, such as high temperatures and the acidic environment of the gut. The Bacillus subtilis species of microorganism has been known for almost 100 years, having first been isolated and described in 1915. It is considered to be a normal inhabitant of the gut in animals and humans

Probiotics are typically bacteria, but there are also types of yeasts that function as probiotics, such as Saccharomyces boulardii.

Benefits of Probiotics
Dozens of different probiotic bacteria have been shown to have health benefits. And within each group, there are many different species, and each species has many strains. Different probiotic strains affect different health conditions.
For example, studies have found particular benefits associated with many of the LABs:

  • Lactobacillus acidophilus – Maintains integrity of intestinal walls
  • Lactobacillus fermentum – Helps neutralize toxic products made during digestion, promotes a healthy balance of bacteria in the gut
  • Lactobacillus rhamnosus – The “travel probiotic“- found to be effective in reducing occurrences of traveler’s diarrhea
  • Bifidobacteria bifidum – Promotes healthy digestion in both small and large intestines; especially helpful for proper digestion of dairy
  • Bifidobacteria longum – Helps crowd out bad bacteria, helps neutralize everyday toxins in the gut, breaks down carbohydrates without producing excess gas

Similarly, spore-forming probiotic bacteria have demonstrated the ability to crowd out bad bacteria for a more balanced gut flora, and increase immune reaction of intestinal cells. For example, the Bacillus subtilis strain exhibits a wide range of probiotic benefits, including:

  • Produces many enzymes, several of which help break down food including plant materials the human body can’t digest
  • Has been shown to inhibit the growth of H. pylori, an organism associated with the occurrence of ulcers Has beneficial effects on the immune system
  • Produces some fungicidal compounds, which control fungal pathogens such as Candida

Measuring Potency
The potency of probiotics is measured in colony forming units (CFU). CFUs are derived by allowing the organisms to grow on appropriate media under controlled conditions and then counting the number of colonies. Typical counts may be in the range of 5-10 billion cells per serving. Because not all the bacteria will remain viable when they arrive at their intended destination, manufactures tend to begin with higher doses of probiotic bacteria than is required to promote wellness. If an expiration date is applied to the label, the CFU count must reflect the number remaining at the end of the expiration date.

Refrigeration requirements vary amongst probiotic organisms, but generally cooler temperatures and dryer conditions will yield a longer shelf life. Spore-forming strains, such as the Bacillus genus, have a more stable shelf life, and are better suited to withstand environmental factors, allowing for greater potency when consumed.

Creating a Probiotic Supplement Formula
Each type and strain of probiotic, spore and non-spore forming, performs a different role with particular benefits in terms of digestion and immunity, as well as where in the GI tract they act. Multi-strain probiotic supplements provide a broad spectrum of benefits.

The guidelines established by the Food and Agriculture Organization of the United Nations (FAO) along with the World Health Organization (WHO) provide a superb “checklist” for evaluating a probiotic supplement product:

  • Genome Sequencing – Proper identification to the level of strain of all probiotics in the product, with deposit of all strains in an international culture collection
  • Physiological Testing – Characterization of each strain for traits important to its safety and function
  • Clinical Studies – Validation of health benefits in human studies, including identification of the quantity of the microorganism required to provide the benefit
  • Stability – Truthful and not misleading labeling of efficacy claims and content through the end of shelf life


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Digestible is your go-to resource for learning about enzymes, probiotics and their impact on digestive health. Keep up with the latest trends in dietary supplements, learn why gut health is critical to overall wellness and immunity, and the science behind it all.

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