All you need to know about probiotics! Are they actually beneficial or is it a marketing scam?

Updated: Dec 10, 2019

Probiotics are a hot topic right now! They have a good reputation for improving gut health and reducing symptoms of gastrointestinal disorders. Many companies are now adding probiotics in different foods and coming out with more probiotic supplements. But is it a marketing technique? Or is it an added value we should be looking for? Let's dive deep and learn more about probiotics.


Probiotics were first studied in the 1900's when the association between yogourt and human longevity was discovered. More studies were done throughout the century but it was only in 2001 that the World Health Organization defined probiotics as "live microorganisms which when administered in adequate amounts confer a health benefit on the host". From that point forward, more and more studies were done on probiotics to identify different families (genus) and how they affect our gut. Probiotics are classified by genus, species and strain (See picture below for a visual!). As of now there are over 400 species of probiotics identified. You might of heard of Bifidobacterium and/or Lactobacillus, which are the two of most known and studied probiotic families (genus). It is important to know that every probiotic plays a different role in our health, therefore when taking a probiotic, it is crucial to know which one you are taking and what health benefits is associated to it.


Let's review the different health benefits that have been demonstrated over the recent years!

Gastrointestinal Disorders

Many studies show the wide range of benefits probiotics have on our gastrointestinal track. Probiotics have shown to treat and manage diarrhea (more specifically antibiotic-associated diarrhea), constipation, irritable bowel syndrome and lactose intolerance. Furthermore, studies show that probiotics supplementation could also help with improving stool consistency, regulating bowel movement and reducing irritation caused by abdominal bloating in otherwise healthy individuals.

Immune System

Did you know that the gut plays a predominant role in regulating our immune system? Actually, many antibodies are produced in our gut lining. Interestingly, more and more studies are linking autoimmune disease with gut bacteria imbalance. So the question is, can probiotics affect our immune system? Studies report that probiotic supplementation can in fact improve immune functions and regulate immune response. These studies showed that probiotics had a beneficial effects on preventing the common cold and flu but had no effects on influenza infections.

Diabetes and Blood Glucose

Type 2 diabetes is a chronic illness on the rise in North America. An individual who has type 2 diabetes has become resistant to insulin which makes it very difficult to get glucose into the cells. Some animals studies demonstrated that probiotics can improved glucose tolerance and reduce hyperglycemias. There are some evidence in human studies however many of these studies had very few participants (which makes it difficult to generalize results) and also many studies had other conflicting factors (which makes it difficult to know if the probiotics were actually the real cause of the results). Furthermore, some studies demonstrated a significantly lower fasting glucose with consumption of probiotics in participants with diabetes but no effects on the fasting insulin levels. That being said, more studies are needed to explore the link between diabetes and probiotics.

Blood Lipids/Cholesterol

There has been many studies on the potential effect of probiotics on reducing blood lipids. Some studies have shown positive results where individuals demonstrated a significant decrease in their lipid profile when consuming probiotics vs placebo. However, many other studies failed to correlate probiotics and blood lipids levels. A recent systematic review (2018), did not find enough strong evidence to conclude that probiotics had a significant effect on participants blood lipids.


Interesting studies have compared the gut microbiome of obese and healthy participants.

In one study with 123 non-obese and 169 obese Danish individuals, researchers found that people with low amounts of healthy bacteria had more marked overall adiposity, insulin resistance, dyslipidemia and inflammation compared with healthy-gut folks. They also noted the obese people with lower healthy bacteria gained more weight over time. However no studies have shown evidence of weight loss with probiotic consumption to this date.


Did you know that our gut produces 95% of serotonin? Serotonin is a neurotransmitter that is known as a mood stabilizer or the "Happy" neurotransmitter. In fact, when individuals have normal amounts of serotonin, they feel happier, calmer, more focused and less anxious. Many anti-depressant actually aim to increase serotonin in order to brighten mood. The link between mood disorders and gastrointestinal disorders has been known for quite some time now. Psychological distress has shown to reduce the quantity and diversity of microorganisms in the gut. Conversely, gut health can modulate mood by secreting different signalling molecule that will in-turn change neuronal signalling. However only recently has the link between probiotics and psychological state been proven. A 2018 literature review suggests that probiotic is linked to reduce symptoms of depression as well as reducing stress and anxiety.



All fermented foods are a great source of probiotics. These include food like yogourt, kefir, sauerkraut, kimchi, kombucha, tempeh, miso, natto and pickles. These foods can be marketed as having probiotics however since the probiotics are found naturally in them they are not regulated and therefore do not need to state which strain of probiotics is present and in which quantity.


Supplements can be another great alternative if you aren't getting those probiotics through food. Supplements are regulated by Health Canada and therefore you will know exactly which probiotic you are consuming and in what quantity. The appropriate dosing amount required to experience benefits varies according to the probiotic however in average studies showed that you require at least 100 millions daily.


To conclude, probiotics seem to be an added value to our overall nutrition. It's important to mention that different strains will have different effect therefore it is important to use the right strains for the symptoms you are trying to treat. Furthermore, when ingesting probiotics they do not stay in your intestinal tract forever. you will lose them in transit which is why you need to consume them daily to see results. I believe in eating your probiotics and finding food sources over supplements. However, for some individuals supplement might be more efficient. If you have any of the mentioned about conditions, feel free to reach out for a nutritional assessment so I can help you determine what would be most beneficial for you :) (Click here to book consult)

Marie-Pier Pitre-D'Iorio, RD


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2-FAO/OMS. 2002. Guidelines for the evaluation of probiotics in food. Report of a Joint FAO/WHO Working Group on Drafting Guidelines for the Evaluation of Probiotics in Food. London (Ontario)

3-Food and Agriculture Organization and World Health Organization Expert Consultation. Evaluation of health and nutritional properties of powder milk and live lactic acid bacteria. Córdoba, Argentina: Food and Agriculture Organization of the United Nations and World Health Organization; 2001. Available from:

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5-Huang, R., Wang, K. & Hu, J. Effect of probiotics on depression: a systematic review and meta-analysis of randomized controlled trials. Nutrients. 2016;8:8.

6-Khalesi, S., Bellissimo, N., Vandelanotte, C., Williams, S., Stanley, D. & Irwin, C.A review of probiotic supplementation in healthy adults: helpful or hype? European Journal of Clinical Nutrition. 2018;

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