What To Look For In A Probiotic

Risa Groux, CN
 | Published: 
November 15, 2021

With the increase in chronic stress, poor diets, dysbiosis from birth, environmental toxins, pharmaceutical drug use, and functional gastrointestinal disorders, it is more imperative than ever before that routine probiotics become as necessary as a multivitamin for nearly every life stage. A healthy microbiome is foundational for general health and wellness, and nearly all health disparities can be linked, in part, to an imbalanced microbiome (dysbiosis).

A healthy balance of resident microbes is vital for various metabolic processes, adequate digestion, fermentation of carbohydrates into short-chain fatty acids, lipid metabolism, vitamin synthesis, maturation of the immune system and ongoing immunity, protection against pathogens and toxins, control of inflammation, and brain function and behavior, among other tasks. So it makes sense that the microbiome should be evaluated and corrected as part of nearly every treatment protocol.

The response to the need for probiotic supplementation in microbiome management has led to the discovery of some common problems with formulating an effective product. Let’s take a look at some of these issues.

Strain Identification and Diversity

Not all probiotic strains are created equal. Many probiotic formulas will label genus and species, but will neglect to mention the specific strain. The species’ therapeutic ability is dependent upon its strain, but common microbiological tests cannot identify strains, making this necessary detail difficult to obtain without employing the use of unique (and albeit, time-consuming and expensive) identification procedures. Equally concerning is the fact that many commercial probiotic formulas have incorrectly labeled the strains. In fact, in one study, 26 out of 58 tested strains were incorrectly labeled.

The intestinal microbiome has been estimated to consist of at least 1000 species, but only 10 species contribute 95 to 99 percent of all bacteria by number. A higher concentration of these species, including Lactobacillus and Bifidobacterium, is associated with a healthier intestinal tract and will possess greater therapeutic potential. Information on strain specificity and diversity is critical for practitioners to evaluate which formula will best assist with their patient’s health issues.


Colony-forming units (CFU) are the units used to describe the quantity of viable probiotic strains in a formula. Probiotics are only as effective as their quantity, which will determine their ability to colonize within the gut and, therefore, infer their intended health benefits. Depending on the strain’s ability to resist gastric acid and bile salts, more or less viable strains may be needed for clinical effectiveness; therefore, CFU counts must be species-specific. For example, L. plantarum NCIB 8826, L. salivarius 433118 and some Bifidobacterium spp. have a high survival capacity and can reach the ileum at a minimum dose of 105 cfu/ml; however, Bifidobacteriun animalis ssp. lactis (BB-12) is only viable at a minimum dose of 1010 cfu/day. Additionally, higher doses of specific strains may be necessary for acute infections or when recovering from antibiotic therapy. It is important to ensure each probiotic strain in a formula meets the minimum requirements for viability and the clinician’s therapeutic goal. Unfortunately, many probiotic formulas do not disclose strain specific CFUs, making it difficult to determine a product’s effectiveness.

Acid/Bile Resistance and Survivability

Probiotic viability is dependent on the strain’s ability to survive during its passage through the gut, so it can ultimately colonize in the gut mucosa of the host. The acidic, protease-rich gastric juices and bile salts present the largest challenges to viability. Probiotics are normally exposed to gastric juices for 60 minutes and a vast majority will not survive. Therefore, an effective probiotic formula must contain carefully chosen strains, proven to have a high tolerance for these harsh conditions. In the past, formulations have relied on unique delivery systems to increase viability, but strain specificity is a more guaranteed mode of ensuring viability.

Intestinal Adhesion

After surviving the harsh environment of the upper gastrointestinal tract, probiotic strains must have the ability to adhere to the gut mucosa and/or epithelial cells in order to colonize and provide therapeutic value. In fact, bacterial adhesion may be considered one of the most preferable characteristics of probiotic strains. The interaction with the gut mucosa brings the probiotic strain in close contact with the intestinal immune system, giving it a better opportunity to modulate the immune response. It may also protect against enteric pathogens by competing with pathogens for adhesion sites and nutritional resources. Host-microbe interaction is also necessary for rebuilding the intestinal mucosal barrier, reducing intestinal permeability, and producing health-promoting compounds such as short-chain fatty acids and protective antimicrobial agents. The ability of probiotics to adhere to the gut mucosa and/or epithelium is predominantly strain-specific but can be aided by specialized encapsulation delivery modes.

Antibiotic Resistance

Antibiotic resistance is quickly becoming a global health problem due to indiscriminate antibiotic use. It has shown us the power of microorganisms to adapt and survive. As probiotic use increases in response to the dysbiosis caused by antibiotic therapy, researchers have raised concern regarding the potential problem of antibiotic resistance genes being passed vertically or horizontally to probiotic species competing for the same environment. When 162 individuals from China, Denmark, and Spain were screened for antibiotic resistance genes, 1,093 antibiotic resistance genes were found and nearly 75 percent of the genes were resistant against three antibiotic classes – tetracycline, macrolides, and beta-lactams. In response, probiotic strains are now being screened for antibiotic resistance and it is imperative that strains are chosen which have not been shown to confer antibiotic resistance.

Probiotics are undoubtedly becoming a foundational element in health management, making it vital to choose an effective formula, as not all formulas are designed to maximize their therapeutic potential.

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