Most research that has been conducted and published on the microbiome has been within the past five years! That is not much time at all, meaning we actually understand very little about it and there is much more to be found out. Some of the research that has been conducted follows.



  • The strength and diversity of the microbiome depends on many factors but mainly environment, diet, and antibiotic use. Research is unveiling that a typical Western diet, high in processed carbohydrate foods like sugar and flour while low in fiber and fresh produce, is associated with decreased diversity of gut microbes, higher prevalence of noncommunicable diseases (NCDs), and increased rate of obesity [3]

  • An interesting connection to note is the role the microbiome plays in weight regulation. When compared to normal weight, obesity is correlated with lowered bacterial richness. Alternately, energy restriction and weight loss in overweight individuals is associated with an increase in bacterial richness [6]. A Danish study involving 123 non-obese and 169 obese participants found that the non-obese had a significantly higher bacterial gene count than the obese.The study notes that participants with a functionally robust microbiome had a lower prevalence of obesity and metabolic disorders.  Those with lower bacterial gene counts harbored a high percentage of pro-inflammatory bacteria, which can be attributed to many different disease-states. It is suspected that decreased bacterial colonization in the gut contributes to obesity by increasing dietary energy harvest, triggering systemic inflammation, and promoting fat deposition [4]

  • There are implications connecting gut microbiota to neurodevelopment and mental health. Studies done on humans and germ-free animals reveal that animals brought up in a sterile, germ-free environments showed reduced expression of neuronal growth factor and neurotrophic factor in the cortex of brain and hippocampus, patterns that can also be observed in brains of those suffering from anxiety and depression [3]. Preclinical studies on rodents suggest certain strains of probiotics (Bifidobacterium infantis, Lactobacillus rhamnosus, Lactobacillus helveticus R0052, and Bifidobacterium longum) possess antidepressant effects likely due to their anti-inflammatory actions [7].

  • To further support the idea that the gut plays a role in mental health, specific probiotics found in yogurt can produce GABA, a neurotransmitter that can help to calm the brain and treat anxiety.  “As the major inhibitory neurotransmitter in the mammalian central nervous system, GABA improves the function of growth hormones, increases the plasma concentration, and promotes protein synthesis in the brain. Additionally, GABA exhibits antihypertensive, tranquilizing, anti-diabetic and anti-stress effects in humans.” [8]


Probiotic Potential & Sources
The potential benefits of probiotics are vast, as there are hundreds of species, all with separate functions and unique benefits. Many probiotic supplements contain multiple species and strains that work in combination to provide the host with an array of benefits. These probiotic supplements can be purchased here at the clinic, through our online dispensary (at a discount), at health food stores, and many grocery stores (they are often in the refrigerated section).

Dietary sources of probiotics include: yogurt, kefir, kombucha, fermented vegetables (such as sauerkraut and kimchi), miso, fermented cheese, tempeh, pickles, and apple cider vinegar. These sources must contain LIVE cultures, generally meaning they need to be refrigerated (some sauerkraut and other fermented vegetables can be found in the dry sections of stores but these versions do not contain live probiotics).  All in all, consuming probiotics, whether from food or supplement, can have extensive benefits to human health.

Common Probiotics, Their Benefits, & Food Sources

ProbioticPossible BenefitsFood Sources
Lactobacillus rhamnosus GGAtopic dermatitis in children, treatment of infectious diarrhea. Promotes vaginal health. Yogurts (both dairy & nondairy), kefir, kombucha
Lactobacillus reuteriReduce inflammation and allergies. Some studies suggest may also reduce infection and inflammatory markers in rheumatoid arthritis and cystic fibrosis. Additional links have been made to reduction of dental carries and eczema in children.Fermented vegetables, dairy products
Lactobacillus plantarumMost beneficial bacteria in body for immunity, psychological health, and metabolic functions. Controls inflammation in gut, digests protein helping to prevent allergic reactions, fights bad bacteria, helps fortify gut lining reducing permeability. May also help reduce BMI, blood pressure, and cholesterol. Fermented foods of plant origin: Nondairy yogurt, kimchi, kombucha, sauerkraut, pickled vegetables
Lactobacillus caseiPlays role in gut-brain axis, improving both mental and neurological health. Also may improve symptoms of Irritable Bowel Syndrome (IBS).Yogurts (both dairy & nondairy), lassi, kefir
Lactobacillus acidophilusBacterial vaginosis, reduction of diarrhea, immunity boosting.Yogurts (both dairy & nondairy), kefir, miso, tempeh
Bifidobacterium infantisBeneficial to mental health. Studies show probiotic blends containing this strain improved symptoms of depression, anxiety, and autism. Yogurt (dairy & nondairy), kefir, miso, pickles, tempeh, some wines/vinegars, sauerkraut, sourdough bread
Bifidobacterium bifidumBoosts immunity. May serve as treatment for GI conditions such as constipation, IBS, traveler’s diarrhea, and ulcerative colitis. Yogurt (dairy & nondairy, kefir

Considerations When Choosing an Effective Probiotic Supplement
With the rising popularity of probiotics there are many products and brand names emerging into the consumer market. With so many different options it is important to know what to look for in an effective probiotic supplement. Consider the following when choosing a probiotic:

  • Culture count: Refers to the total number of bacteria present in a single dose. For minor digestive issues and general health 50 billion microorganisms per capsule is sufficient. If taking antibiotics or treating a health condition 80-100 billion microorganisms per capsule would be best.
  • Variety and type of strains: since different strains of probiotics serve different purposes a probiotic supplement containing various strains offers a wider range of benefits. When treating a specific health condition with probiotics it is best to use a targeted formula containing the bacteria that correlates with the condition (Ex: Lactobacillus casei is correlated with reducing symptoms of Irritable Bowel Syndrome).
  • Delivery system: Many probiotics can not survive the acidic environment of the stomach so the capsule they come in should have an enteric coating to protect bacteria until delivered to the intestines where they will be utilized by the body.
  • Living bacteria and expiration date: Check to make sure the bacteria are LIVE. Due to probiotics sensitivity to heat most supplements are found in the refrigerated section of stores (though some supplements with freeze-dried organisms and moisture resistant packaging are shelf stable). The label should specify an expiration date and ensure that with proper storage the potency is guaranteed until expiry [9].


Final Thoughts
As research continues we will be able to further understand these miraculous microscopic organisms. Though most research on the microbiome and the role of probiotics has only just begun, it is clear that probiotics play a key role in many physiological functions of the body and can truly aid us in optimizing our health.

Talk to one of our nutritionists to find out which strains may be the most beneficial for you!


Written by Makala T., BS in Nutrition & Dietetics


  1. Ellis, E. (2018, March/April). The Potential of Probiotics. Food & Nutrition, 7(2), 19-21.
  2. Bested, A. C. et al. (2013). Intestinal microbiota, probiotics and mental health: from Metchnikoff to modern advances: Part II – contemporary contextual research. Gut Pathogens, 5(3). Retrieved from:
  3. West, C. E. et al. (2015). The gut microbiota and inflammatory noncommunicable diseases: Associations and potentials for gut microbiota therapies. The Jorunal of Allergy and Clinical Immunology, 135(1), 3-13. Retrived from:
  4. Jandhyala, S. M. (2015). Role of the normal gut microbiota. World Journal of Gastroenterology, 21(29). Retrieved from:
  5. Macpherson A.J. et al. (2004) Interactions between commensal intestinal bacteria and the immune system. Nat Rev Immunol 2004(4), 478-485.
  6. Borgeraas, H. et al. (2017). Effects of probiotics on body weight, body mass index, fat mass and fat percentage in subjects with overweight or obesity: a systematic review and meta‐analysis of randomized controlled trials. Obesity Reviews (19), 219-232. Retrieved from:
  7. Huang, R. et al. (2016). Effect of Probiotics on Depression: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients, 8(8), 483. Retrieved from:
  8. Park, Sun-Young et al. The Probiotic Characteristics and GABA Production of Lactobacillus plantarum K154 Isolated from Kimchi. Food Sci. Biotechnol. 2014; 23(6).
  9. Farquhar, Caroline. Probiotics: Why Yogurt is Not Enough. Accessed 2018 May 5. Retrieved from: