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The Ultimate Guide To Probiotics

The Ultimate Guide To Probiotics

The human body is an ecosystem consisting of both of our own human cells but also of a vast array of microorganisms called the microbiome. It is estimated that the combined weight of the over 100 trillion bacteria, fungi, protozoa, and viruses living on and inside our body could be as much as 5 pounds! Acquired in the womb and shaped during the first few years of life, its composition is ever-changing and varies from person to person. Research into the microbiome has found links to childhood growth and development, digestion and absorption, immune system modulation, mood, and even inflammation.


The term probiotic is used to describe living microorganisms (bacteria or yeasts) that when ingested or applied topically in sufficient amounts, may provide beneficial effects. Research on probiotics has demonstrated effectiveness for conditions such as gastrointestinal issues[i] (antibiotic-associated diarrhea, constipation, irritable bowel syndrome (IBS), colic), respiratory tract infections, eczema[ii], lowering of cholesterol[iii], and more.

Probiotics may come from several sources and some occur naturally in cultured or fermented foods such as yogurt and sauerkraut. Eating these foods can be a great way to encourage diversity of gut flora but shouldn’t be considered therapeutic, since it is difficult to know the exact composition of microorganisms or their relative amounts. As a supplement, probiotics are available in capsule, powder, liquid, and topical (i.e., cream) form and are usually present in multi-strain combinations curated for various health conditions and applications.

This guide includes a list of some common types of probiotics and their uses, as well as useful information to aid you when choosing a probiotic.


Bowl of raw yogurt

What does each probiotic name mean? 

Found on the label of probiotic supplements, each bacteria is denoted by a genus and species name, e.g. Lactobacillus rhamnosus. The first name may also be abbreviated, e.g. L. rhamnosus. The two most common groups of probiotic bacteria found in the human body are Lactobacillus and Bifidobacterium.

Lactobacillus - a group of lactic acid-producing of bacteria found in our digestive, urinary, and genital systems

Bifidobacterium – a group of bacteria found in the gastrointestinal tract

Different species and strains of bacteria have different benefits. The strain of a bacteria is indicated by a series of letters and numbers in brackets after the species name, e.g., Lactobacillus acidophilus (CUL-60) or Bifidobacterium bifidum (HA-132). When a probiotic is used in a study, the strain is indicated, and the results may be specific to that particular strain. This is similar to how a certain breed of dog will have different traits than another breed of dog, even though they are both of the same species. For this reason, it is important for a supplement to include clinically studied strains in their formulas, to ensure the desired outcome can be repeated.


The dose of a probiotic strain will be indicated on the label by the unit “CFU” (colony-forming units), which is a measurement of the number of live microorganisms present in a serving and is generally in the millions or billions. An effective dose depends on the type of probiotic and the expected benefit.

Types of probiotic strains

Probiotic bacteria may originate from a variety of sources. Plant strains are naturally found living on plants, dairy strains naturally found in dairy, and human strains are naturally found on or inside the human body. To culture (grow) the bacteria for a probiotic supplement, a medium (food) is used, such as dairy or rice. Interestingly, dairy strains aren’t necessarily cultured in a dairy medium. In the production process, the bacteria is isolated from its growth medium, but there remains the possibility of a minute amount of residue from the medium. Those concerned about dairy or any other ingredient for allergy or ethical reasons should contact the manufacturer.

Delivery method

A key factor in the effectiveness of probiotic supplements is its ability to reach the site of action intact and alive since the human body can be a hostile environment. Supplement companies have devised ways to ensure these helpful microorganisms survive to do their work. Certain strains are pH resistant and can survive stomach acid. These strains are suited to delivery via powder or vegetable (hypermellose) capsule. Other strains need to be protected until they reach the small intestine and so are packaged in either a delayed-release or enteric-coated capsule.

How to store

Many of these precious bacteria are sensitive to heat and moisture, so to ensure they remain in hibernation, they must be protected. It was once understood that probiotic supplements found on the shelf were not as potent as those stored in the refrigerator. However, in recent years, packaging and encapsulation technology has evolved so microbes may survive room temperature storage. Boxes or bottles including a desiccant (to absorb moisture) or blister-packed capsules facilitate travel and may prevent supplements from being lost and forgotten in the home refrigerator.

Bowl of vegetables and grains


Any living thing requires a food source. The term prebiotic refers to a non-digestible complex carbohydrate that nourishes the microorganisms in the body. Whereas probiotics can be thought of as seeds for the microbiome, prebiotics would be the compost or fertilizer. Prebiotics are abundant in many whole plant foods such as onions and garlic, Jerusalem artichokes, oats, and chicory root. They are often included in probiotic supplements to help support the growth of the microbes once the capsule opens and they become active.

The two main prebiotic types commonly found in probiotic supplements are fructo-oligosaccarides (FOS) and galacto-oligosaccharides (GOS)[iv]. Prebiotic fibre supplements in the form of powder or capsules may also be consumed to help promote a healthy gut microbiome. These may include fibres such as inulin, acacia gum, or hydrolyzed guar gum.

Common Probiotic Strains

The variety of microbes comprising probiotic supplements is extensive. Product labels may give some indication of the purpose of a particular formula. Note that in Canada, health claims can only appear on a supplement label where there is supporting research. At the same time, labels provide limited real estate and not every documented possible benefit will be listed. Knowledgeable health care practitioners or retail staff, product websites and supplemental educational material are good resources when making your choice.

There are many species of microbes that have demonstrated benefits for various health concerns. Here are some that are commonly found in supplement formulas.

Lactobacillus acidophilus – the most prevalent strain in the human body, found primarily in the gastrointestinal tract and vagina;

Lactobacillus rhamnosus – found in the body and especially in some dairy products, useful for the prevention or treatment of diarrhea in children and adults and of antibiotic-associated diarrhea[v]; relief of colic in infants[vi], prevention of recurrent bacterial vaginosis[vii]; prevention of respiratory tract infectionsv

Lactobacillus casei – this transient dairy strain is known to inhibit growth of E.coli[viii] and to be effective against Candida overgrowth[ix]

Lactobacillus plantarum – a resilient plant strain that produces its own antibiotic targeting bad bacteria; studies show improvement in atopic dermatitis (eczema)[x] and lowering cholesteroliii

Lactobacillus gasseri – found throughout the human body, including in breast milk; primarily studied for its positive effects in weight loss[xi] and IBS[xii]

Lactobacillus reuteri – best know for helping to relieve symptoms of colic in infants[xiii], it has also been shown to reduce both gingivitis and plaque in the mouth[xiv], and to lower cholesteroliii

Lactobacillus salivarius – found living in every part of the human body, L. salivarius can reduces symptoms and drug usage in children with allergic rhinitis[xv]

Bifidobacterium bifidum – by far the most common probiotic in the human body, it helps in the prevention of upper respiratory tract infections[xvi] and in protection and management of inflammatory bowel disease[xvii]

Bifidobacterium infantis – one of the first probiotics a mother passes on to her baby through breastmilk, B. infantis supports a mature immune response, reduces inflammation[xviii] and reduces intestinal permeability in infants, and relieves many of the symptoms of IBS[xix] in adults

Bifidobacterium lactis – found in the colon in great numbers, B. lactis has been shown to enhance immunity[xx], relieve constipation[xxi], IBS[xxii], and lower cholesteroliii

Saccharomyces boulardii – first discovered on lychee and mangosteen fruit in 1923, S. boulardii is a probiotic yeast rather than bacteria; S. boulardii has proven clinical efficacy in the prevention and treatment of antibiotic associated diarrheav and infectious diarrhea[xxiii] such as due to Clostridium difficilev; it is often included in travel formulas


Considering the high CFU counts of probiotic supplements (generally in the billions), it is natural to wonder about safety. (It is important to note however that what may seem like a large number is actually a drop in the 100 trillion-count bucket!)

Probiotics have been used safely for years and are generally considered safe for all ages, but caution is advised for those with weakened or compromised immune systems, or serious health conditions. These individuals should discuss the use of any probiotic with their doctor. In addition, those with allergies or intolerances should take special care, read the label carefully, and contact the manufacturer with any questions.

Side Effects

When first taking any probiotic, some individuals may notice a change as their body adjusts. Symptoms experienced are usually mild, often digestive in nature, and affect a small portion of the population. They may include gas, bloating, constipation, diarrhea, or increased thirst and should only last a few days to a few weeks.

For some, the prebiotic included in the supplement may be a source of the gas and bloating. These individuals may fare better with a prebiotic-free or FOS-free product. If symptoms persist beyond a few weeks, discontinue use and consult a health care practitioner. To reduce the likelihood of side effects, especially for those with sensitive digestive systems, it may be wise to begin with a small amount of the probiotic and increase the dose over a few weeks.


Faced with a refrigerator or shelf full of probiotic supplements, the selection is overwhelming. A simple box or bottle of probiotics is anything but simple. Everyone’s body and microbiome is unique and dynamic. At some point in the future, it may be possible to analyze an individual’s microbiome and determine the probiotics most likely to address their health concerns. Until that point, rather than attempting to mix and max individual microbes, the best option is to look to reputable companies who have created targeted probiotic formulas using clinically proven strains.

Our Recommendation

Genestra Human MicroFlora (HMF) has been a leader in the field of probiotics for over 20 years. The incorporate clinically researched, pH resistant human strains. Their products have a high standard of quality, purity and potency on label claims. Available in condition-specific formulas, HMF Probiotics are designed for all ages and life stages.

The complex interplay of microbes inside and outside of our body is responsible for keeping our health in delicate balance. We can protect these tiny helpers by avoiding toxins in our food, water, body care and cleaning products, drugs and alcohol, and our environment. A diet rich in whole plant foods will provide ample fibre to serve as nourishment for our countless microorganisms. The garden that is our human microbiome can flourish and sustain us with the right care.


[i] Probiotics for Gastrointestinal Conditions: A Summary of the Evidence.

[ii] Treatment efficacy of probiotics on atopic dermatitis, zooming in on infants: a systematic review and meta-analysis.

[iii] Hypocholesterolemic Effects of Probiotic Mixture on Diet-Induced Hypercholesterolemic Rats.

[iv] Prebiotics: Definition, Types, Sources, Mechanisms, and Clinical Applications.

[v] Meta-analysis of probiotics for the prevention of antibiotic associated diarrhea and the treatment of Clostridium difficile disease.

[vi] Role of Lactobacillus rhamnosus (FloraActive™) 19070-2 and Lactobacillus reuteri (FloraActive™) 12246 in Infant Colic: A Randomized Dietary Study.

[vii] Effects of probiotics on the recurrence of bacterial vaginosis: a review.

[viii] Lactobacillus casei LC2W can inhibit the colonization of Escherichia coli O157:H7 in vivo and reduce the severity of colitis.

[ix] Enhanced antifungal activity of bovine lactoferrin-producing probiotic Lactobacillus casei in the murine model of vulvovaginal candidiasis.

[x] Lactobacillus plantarum IS-10506 supplementation reduced SCORAD in children with atopic dermatitis.

[xi] Effect of Lactobacillus gasseri BNR17 on Overweight and Obese Adults: A Randomized, Double-Blind Clinical Trial.

[xii] A double blind, placebo-controlled, randomized clinical trial that breast milk derived-Lactobacillus gasseri BNR17 mitigated diarrhea-dominant irritable bowel syndrome.

[xiii] Role of Lactobacillus rhamnosus (FloraActive™) 19070-2 and Lactobacillus reuteri (FloraActive™) 12246 in Infant Colic: A Randomized Dietary Study.

[xiv] Decreased gum bleeding and reduced gingivitis by the probiotic Lactobacillus reuteri.

[xv] Effect of probiotics on allergic rhinitis in Df, Dp or dust-sensitive children: a randomized double blind controlled trial.

[xvi] Bifidobacterium bifidum R0071 results in a greater proportion of healthy days and a lower percentage of academically stressed students reporting a day of cold/flu: a randomised, double-blind, placebo-controlled study.

[xvii] New probiotic strains for inflammatory bowel disease management identified by combining in vitro and in vivo approaches.

[xviii] Bifidobacterium longum subspecies infantis: champion colonizer of the infant gut.

[xix] Efficacy of an encapsulated probiotic Bifidobacterium infantis 35624 in women with irritable bowel syndrome.

[xx] Enhancement of natural immune function by dietary consumption of Bifidobacterium lactis (HN019). 

[xxi] The effect of probiotics on functional constipation in adults: a systematic review and meta-analysis of randomized controlled trials.

[xxii] Efficacy of synbiotic, probiotic, and prebiotic treatments for irritable bowel syndrome in children: A randomized controlled trial.

[xxiii] Saccharomyces boulardii CNCM I-745 influences the gut-associated immune system.

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