Gut-Brain Connection: Stress and Mental Health

Published on January 2019.

Mental health continues to be a growing concern worldwide. Both Statistics Canada and The National Institute of Mental Health estimate that 1 in 5 Canadians and Americans live with a mental illness.1,2 The World Health Organization lists depression as the #1 cause of disability globally.3 Considering the rising rates and significant disease burden of mental illness, the increasing level of interest in novel clinical support options is no surprise.

One such option being explored is attempting to optimize the gastrointestinal (GI) environment to influence brain homeostasis and cognitive health.

Gut-Brain Connection

A connection between the GI environment and the central nervous system (CNS) has long been recognized,4 as have the positive impacts the microbiome has on various health markers. In fact, many psychological illnesses are frequently experienced alongside GI-related comorbidities, such as irritable bowel syndrome (IBS), leaky gut, and gastroesophageal reflux disease (GERD).5,6

The gut communicates with the brain through nerve connections, hormones, cytokines, neurotransmitters, and certain metabolites. Both directly and indirectly, the health of the GI tract plays an essential role in the health of the brain.

Research on causative factors of major depressive disorder (MDD) continue to evolve and suggest strong nutritional and lifestyle influences. Patients with MDD have been shown to have elevated levels of pro-inflammatory cytokines, increased oxidative stress, altered GI function, and lowered micronutrient and omega-3 fatty acid status.7

Significant differences have been identified between the gut microbiome of patients diagnosed with a depressive disorder compared to healthy controls,8 suggesting a balanced microbiome may play a role in the management of mental illness. Several of the factors associated with an increased susceptibility to mental illness are explored here.

Inflammation & Oxidative Stress

Research suggests that depression and inflammation fuel each other and hints to the fact that addressing depression thru an anti-inflammatory approach may enhance recovery and reduce the risk of recurrence.9

In the brain, pro-inflammatory cytokines can trigger neuroinflammation. Cytokines may also alter concentrations of various neurotransmitters in the brain related to mood regulation.10

Many studies show that a healthy microbiota helps reduce inflammatory burden in the body, not just benefiting gut-related disease, but the individual as a whole. In a recent study,11 researchers looked at inflammatory cytokines (CRP, TNF-a, IL-6) in patients with non-alcoholic fatty liver disease, measuring the markers before and after administration of a probiotic supplement. After taking the probiotics, inflammatory markers were substantially reduced.11

Oxidative stress, a contributing factor to mental illness, is often associated with high levels of tissue inflammation,12 and it has been suggested that people with depression are more likely to have increased oxidative stress.13 It is well documented that probiotics help improve antioxidant status and blunt oxidative damage.14,15

This research suggests that optimizing gut flora not only affects localized inflammation and oxidative stress in the digestive tract, but also outside the gut, and may be an effective strategy for addressing inflammation and oxidative stress associated with aggravation of depressive symptoms.

Hypothalamic Pituitary (HPA) Axis

Chronic stress leads to elevated hormones such as cortisol, the stress hormone, and may also cause lower levels of serotonin and other neurotransmitters in the brain, which have been linked to depression.16 In susceptible people, chronic stress may be a major contributing factor in the development of psychiatric diseases, such as anxiety and depression.

In a study using healthy volunteers, probiotic therapy was shown to reduce cortisol output and daily reported stress.17 It appears that a healthy microbiome may improve the stress response and reduce the likelihood of stress-induced depression and anxiety.

Metabolic Syndrome

Research shows a strong connection between metabolic syndrome and higher rates of depression.18 In fact, presence of diabetes doubles the risk of comorbid depression, making glycemic control a key potential target in the prevention and management of depression.19

Animal and human studies show an improvement in several metabolic markers with probiotic therapy. Supplementation with probiotics may ameliorate insulin resistance and reduce the expression of inflammatory adipocytokines.20

A 2010 human study determined that supplementation with L. acidophilus NCFM for 4 weeks preserved insulin sensitivity compared with placebo, suggesting an important role for probiotic therapy in the treatment of depression through glucose control.21

Several studies show positive influence on metabolic markers with probiotic therapy in women with PCOS, suggesting that the gut environment may offer a unique target as a therapeutic approach to metabolic dysfunction.22

Short-Chain Fatty Acids (SCFA)

A diet high in fiber has been shown to contribute to a healthy intestinal environment in several ways, one such way is by increasing SCFA production.

Fiber is fermented by bacteria to produce SCFA. High levels of SCFA have been shown to play an important role in reducing inflammatory markers22 and also exhibit antidepressant and anxiolytic effects,23 thereby contributing to a healthy brain.

The Blood-Brain Barrier (BBB)

The brain is sensitive to inflammation, cortisol, glucose, toxins, and other chemicals. Strict control of access to the brain tissue is required to maintain health.

The BBB is an important layer of cells surrounding the brain that acts to control what gets in to maintain homeostasis of the CNS. A healthy, balanced gut flora has been shown to decrease permeability of the BBB and increase tight junctions (i.e., making the BBB less leaky),23 yet another unique way that a healthy gut microbiome contributes to overall health and vitality.


Probiotic therapy is one method to promote a healthy, balanced gut environment. A diet rich in fiber is another. Stress, a significant factor in MDD, is known to negatively alter GI microflora, lowering levels of Lactobacilli and Bifidobacteria.7 Thus, stress management is also an important part of a healthy gut protocol.

Much of the research and mainstream marketing of probiotic products are attempting to use probiotic therapy in a “this-strain-for-that” approach, but the evidence suggests otherwise. Although individual strains may show promising benefits in certain areas, generally the research points to a more holistic approach – a healthy gut environment contributing to overall health and wellness. Ongoing research continues to elucidate what microbial mix in the gut is “healthy” and what factors contribute to that mix.

A balanced gut microbiome may help reduce the inflammatory response and oxidative stress, as well as increase the expression of adhesion proteins within the intestinal epithelium, reducing intestinal permeability.20 Such effects increase insulin sensitivity and reduce autoimmune response. Research suggests that a healthy microbiome can communicate with the CNS and may have the potential to lower systemic inflammatory cytokines, decrease oxidative stress, improve nutritional status, and correct conditions associated with dysbiosis.15 These effects are not only supportive in the prevention and management of mental illness, but in any number of chronic diseases.

At the end of his life, Louis Pasteur, the scientist who developed the germ theory, is quoted to have said: “the microbe is nothing; the milieu is everything.” The research seems to indicate he was on to something.


  1. Statistics Canada. Accessed January 16, 2019.
  2. Accessed January 14, 2019.
  3. Accessed January 14, 2019.
  4. Dinan TG et al. Psychobiotics: a novel class of psychotropic. Biol Psychiatry. 2013;74(10):720-726.
  5. Saulnier DM et al. The intestinal microbiome, probiotics and prebiotics in neurogastroenterology. Gut Microbes. 2013;4(1):17-27.
  6. Quirk SE et al. Physical health comorbidities in women with personality disorder: Data from the Geelong Osteoporosis Study. Eur Psychiatry. 2016;34:29-35.
  7. Logan AC et al. Major depressive disorder: probiotics may be an adjuvant therapy. Med Hypotheses. 2005;64(3):533-538.
  8. Sriven M et al. Neuropsychiatric disorders: influence of gut microbe to brain signaling. Diseases. 2018;6(3):E78.
  9. Kiecolt-Glaser JK et al. Inflammation: depression fans the flames and feasts on the heat. Am J Psychiatry. 2015;172(11):1075-1091.
  10. Kim N et al. Mind-altering with the gut: modulation of the gut-brain axis with probiotics. J Microbiol. 2018;56(3):172-182.
    Javadi L et al. Pro- and prebiotic effects on oxidative stress and inflammatory markers in non-alcoholic fatty liver disease. Asia Pac J Clin Nutr. 2018;27(5):1031-1039.
  11. Lindqvist D. Oxidative stress, inflammation and treatment response in major depression. Psychoneuroendocrinology. 2017;76:197-205.
  12. Black CN et al. Is depression associated with increased oxidative stress? A systematic review and meta-analysis. Psychoneuroendocrinology. 2015;51:164-175.
  13. Seo JS et al. Cellular and molecular basis for stress-induced depression. Mol Psychiatry. 2017;22(10):1440-1447.
  14. Gong ZY et al. Glutamine with probiotics attenuates intestinal inflammation and oxidative stress in a rat burn injury model through altered iNOS gene aberrant methylation. Am J Transl Res. 2017;9(5):2535-2547.
  15. Babadi M. The effects of probiotic supplementation on genetic and metabolic profiles in patients with gestational diabete mellitus: a randomized, double-bing, placebo-controlled trial. Probiotics Antimicrob Proteins. 2018;Dec 8 [Epub ahead of print].
  16. Allen AP et al. Bifidobacterium longum 1714 as a translation psychobiotic: modulation of stress, electrophysiology, and neurocognition in healthy volunteers. Transl Psychiatry. 2016;6(11):e939.
  17. Dunbar JA et al. Depression: an important comorbidity with metabolic syndrome in a general population. Diabetes Care. 2008;31(12):2368–2373.
  18. Lustman PJ et al. Depression in diabetic patients: the relationship between mood and glycemic control. J Diabetes Complications. 2005;19(2):113-122.
  19. Le TK et al. Oral administration of Bifidobacterium spp. improves insulin resistance, induces adiponectin, and prevents inflammatory adipokine expressions. Biomed Res. 2014;35(5):303-310.
  20. Andreasen AS et al. Effects of Lactobacillus acidophilus NCFM on insulin sensitivity and the systemic inflammatory response in human subjects. Br J Nutr. 2010;104(12):1831-1838.
  21. van der Beek CM et al. Role of short-chain fatty acid in colonic inflammation, carcinogenesis, and mucosal protection and healing. Nutr Rev. 2017;75(4):286-305.
  22. van de Wouw M et al. Short-chain fatty acids: microbial metabolites that alleviate stress-induced brain-gut axis alterations. J Physiol. 2018;596(20):4923-4944.
  23. Ahmadi S et al. Probiotic supplementation and the effects on weight loss, glycaemia and lipid profiles in women with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial. Hum Fertil (Camb). 2017;20(4):254-261.
  24. Braniste V. The gut microbiota influences blood-brain-barrier permeability in mice. Sci Transl Med. 2014;6(263):263ra158.
    Gomes AC et al. Gut microbiota, probiotics and diabetes: a review. Nutr J. 2014;13:60.


Melissa Blake, BSc, ND

Dr. Melissa Blake is a clinical specialist on the Medical Information team at Metagenics. She completed her bachelor degree at Dalhousie University in Halifax, Nova Scotia and obtained her naturopathic medical training from the Canadian College of Naturopathic Medicine. Dr. Blake, ND has over 10 years of clinical experience, specializing in the integrative and functional management of chronic diseases.

Healthier Alternatives to Sugar

Ahhh, the white stuff.

Sugar is arguably one of the most addictive substances on the planet. It’s accessible, acceptable, and sneaky! Even when you think you are avoiding it, you’re probably not.

Sure it tastes good but the negative effects on health make it worth looking at alternatives.

How it harms the body:

  1. Sugar suppresses immune function – A study published in the American Journal of Clinical Nutrition watched how white blood cells behaved in response to a dose of sugar. Researchers found that not only did sugar dramatically reduce the ability of the white blood cells to target and engulf bacteria, but the effect lasted for up to 5 hours!!  Sugar did not impact the number of white blood cells but rather their function. Apply this to real life. A child consumes a bowl of sugary cereal and a glass of juice before heading to school. By the time she gets on the bus, her ability to defend against bacteria is dramatically reduced. By mid-morning, her immune function has hit rock bottom. If she doesn’t consume any more sugar that day (unlikely), she will have returned to normal function by the time she gets on the bus to come home. Yikes!
  2. Sugar creates inflammation – Various inflammatory chemicals (including cytokines and NF kappa B) are released after relatively low doses of sugar intake. Sugar also contributes to oxidative stress. Chronic inflammation has been identified as an underlying factor in pretty much every chronic disease, including the big “killers”, heart disease and cancer.
  3. Sugar contributes to insulin resistance and diabetes – even small doses of refined sugar cause rapid increase in blood glucose levels. The body quickly responds by releasing insulin. In fact, it responds so well that often TOO much insulin is released and blood sugar levels drop! This causes sugar cravings in an effort
  4. Sugar causes weight gain – high sugar foods provide little to no nutritional value. They are empty calories and are easy to overeat. They also taste good and leave us wanting more! The “drug-like” effect sugar has on the body make it hard to consume in moderation. Overconsumption as well as the impact on blood sugar control make sugar a major contributor to obesity.

Luckily, avoiding refined sugar doesn’t mean you can’t enjoy a sweet treat. Although I would still recommend using alternatives in moderation, there are a few good options you can switch to when working towards a refined sugar-free life!

  1. Raw, local honey – yes, honey is still a sugar but it also contains minerals and vitamins that contribute to wellness. Honey has been shown to benefit seasonal allergies, promote healthy sleep, and support immune health due to it’s powerful antioxidant content. One of my favourite nighttime routines is to enjoy a hot cup of Yogi Tulsi Spiced Berry Tea with a teaspoon of Bee Powered from BeeKeeper’s Naturals.
  2. Coconut sugar – basically, coconut sugar is a less refined version of sugar. It maintains some nutritional value and causes a slower and lower rise in glucose levels.
  3. Stevia – this sweetener comes from a plant that just happens to taste sweet while having no impact on blood sugar levels. Use stevia in it’s natural form.


Just because there are alternatives doesn’t mean eating honey (or stevia or coconut sugar) by the spoonful is healthy. Moderation is key. The great thing about the alternatives is that you have more control over how much sugar you are consuming. Rather than getting doses of refined sugar throughout the day, you can become more mindful of your intake and keep it to a minimum and as a treat. There is a big difference between 1 tsp of honey everyday compared to the average intake of 19 teaspoons!! Eating whole, natural foods helps you maintain control of your intake.

Sugar free can still be sweet 😉


Daily Detox Tip #6 – Good BMs

As an ND, I spend lots of time chatting about poo. It’s been my experience that if the digestive system isn’t working right, nothing is. This is especially true when it comes to detoxification.

As we’ve already discussed, the liver is responsible for making toxins water or fat soluble and putting them into circulation to be eliminated through the kidneys or through the bowel.

When the bowels are moving well, toxins spend very little time hanging out and get eliminated efficiently. Constipation results in recirculation of these toxins and puts extra stress on the detoxification pathways.

Keeping the gut healthy is about more than just regular bowel movements. A well-functioning gastrointestinal tract also requires well-balanced gut microbiome. Having enough friendly bacteria is key in keeping harmful microorganisms in check. These helpful bacteria also aid in digestion and nutrient absorption and play an important role in immune health.

Good bacteria themselves play a role in detoxification. Some have the ability to bind to toxins in food and water before they have a chance of getting into circulation!

A few tips to ensure your digestive tract, and the bacteria that live in it, stay happy and healthy:

  1. Stay hydrated! Aim for 1.5-2L per day.  Read more on the importance of hydration for detoxification in the article Daily Detox Tip #1.
  2. Eat a diet rich in fibre. This includes veggies, fruit, whole grains, beans, nuts, and seeds. There is no upper limit for fibre intake and the average recommendation for adults is 30g per day, although most people benefit from consuming closer to 45g per day. Here is a list of high fibre foods. Track your intake for 3-4 days and add more fibre rich foods as needed.
  3. Get cultured! Support a balanced gut flora by consuming fermented foods daily. Common examples of fermented or cultured foods include sauerkraut, miso (soybean paste), Kombucha tea, natural yogurt, aged cheeses, and kefir. For more information, check out the article on  Fitting In Fermented Foods.
  4. Tummy Rubs. A gentle but effective way to show your digestive system some love is with a tummy rub. Combine a few drops of your favourite essential oil (peppermint or lavender are good examples) in a small amount of carrier oil (castor oil is messy but effective). With medium pressure, massage around the belly button in a clockwise direction. This technique helps increase circulation and promote healthy bowel movements. Repeat daily for best results. This is great to do for maintenance and also when constipation or bloating are concerns.
  5. Identify Food Sensitivities. A major contributor to digestive distress, food sensitivities can be difficult to identify. Elimination diets and specialized testing can help put a finger on the culprits. Avoid these foods leads to a reduction in inflammation and overall improvement in bowel health.


These suggestions are great on a regular basis to support your detoxification processes and promote optimal health. Occasionally your system may need more assistance. I frequently recommend colonics, enemas, rectal ozone therapy, and supplements as ways to get the digestive system back on track. For more information about the many naturopathic options, get in touch!



The Worst Toxins of All

The most harmful and damaging toxins we can expose ourselves to are negative emotions and thought patterns.

A toxic mind has the potential to cause the most harm because we are exposed to it on a continual basis.

Example of toxic emotions that contribute to dis-ease include: fear, guilt, shame, regret, judgement, resentment, and envy. These kinds of thoughts and emotions impact every cell in the body, making them potent poisons to our emotional, spiritual, and physical health.

I’m not suggesting that we should all be giddy and happy all the time and never experience a single moment of any of the toxic emotions I listed above. That isn’t realistic, nor is it healthy. What I am suggesting is that we become acutely aware of how we talk to ourselves and begin to understand the power held in that dialogue. That we work through uncomfortable emotions rather than identifying with them and feeling like we have to stay there.

When we are stuck on what we cannot control, we avoid taking responsibility, putting the blame on external circumstances. When we place blame, we avoid action.

However, you are the creative force of your own life. We each need to generate a sense of responsibility for our actions and happiness.



The way you respond to the things you cannot control will determine the trajectory of your life. How can we cultivate a positive perspective and shift from a mindset focused of lack to one of abundance?

  1. Catch yourself. Awareness is always step 1. When we know better, we can do better. Listen carefully to your self-talk and shut it down when it becomes judgemental or mean.
  2. Practice gratitude! Spending just a few minutes a day on gratitude will change your life. A simple daily practice helps remind us of how much we have to be thankful for and how truly blessed we are.
  3. Start a meditation practice. Busy minds are hard to tame. Meditation helps settle the mind so you can become more aware of the repetitive thoughts and will be more likely to pause instead of react when presented with triggers.
  4. Voice your thoughts. It’s important to work thru uncomfortable thoughts and emotions rather than suppress them. Find a mentor or coach you can unpack your junk with.
  5. Surround yourself with positive people. Toxic people are contagious. Avoid them. Instead, spend your time with people who are embracing the powerful role they play in their own happiness and are working on their stuff. Above all, be your own best friend.


“True wealth is having a healthy mind, body, and spirit. True wealth is having the knowledge to maneuver and navigate the mental obstacles that inhibit your ability to soar.”
― RuPaul




Daily Detox Tip #5 – Lemon Water

Lemons have many benefits. They are a source of vitamin C, promote digestion, help alkalinize the body, and encourage more water intake! When it comes to detoxification strategies, drinking lemon water offers gentle but effective support.

One of the liver’s main roles is to produce bile. Bile helps metabolize dietary fat and trap fat soluble toxins for elimination thru stool. Lemon juice helps create the optimal pH in the stomach, which is a signal for the release of bile. Lemon juice is also a mild diuretic, which promotes kidney function.

In these ways, lemon juice stimulates digestion and helps promote detoxification!

A great way to start the day is to drink a large glass of room temperature lemon water. This helps flush out stagnant bile and prime your system for the day. Lemon water is also a great pre-meal support and can be added to smoothies and hot or cold herbal teas for added health benefits.

A way to get the most out of your lemons:

Check the discount shelves for bags of lemons. Take them home and juice them. Pour the juice into ice cube trays and freeze. Pop out a cube or two as needed.

Another option is to use a few drops of good quality lemon oil (I recommend DoTerra brand) in your water bottle throughout the day. Lemon oil is made from the rind of lemons, so the properties are different from the juice but the benefits are similar.

Lemon water is an ideal way to support detoxification and can also be a gentle solution for bloating, indigestion, and skin problems.


The Antiperspirant Debate

Most people do not particularly enjoy sweat, especially if there is an odour to it.

Did you know that human sweat is odourless? Any foul smell is produced by bacteria on the skin.

It isn’t the first time I’ve said this and it won’t be the last: we are mostly bugs! In fact, we have BILLIONS of bacteria living in EACH armpit. (I’m suddenly itchy, are you?)

When we sweat, bacteria on the surface of our skin breakdown proteins in the sweat and release an odour as a bi-product.

All this is completely normal, however most of us spend at least a portion of every day trying to prevent body odour—showering with pleasant smelling soaps and body washes, applying deodorants or antiperspirants regularly, and using scented lotions and perfumes to avoid any trace of stink.

The downside to smelling good is that many conventional body products contain chemicals that aren’t that great for you.

Antiperspirants that contain aluminum salts create plugs that prevent or decrease sweating. Less sweat on the skin means less for bacteria to work on and therefore, less odour. Deodorants and other fragrant body products work by providing a nice smell to mask other not so nice smells.

The point is, sweating is a healthy, natural response to exercise, stress, and other triggers. Using products that block this process might not be the best choice.  But, unless you live alone at the top of a tower with very little human interaction, I bet you’d prefer not to smell like a hockey team’s locker room.

So what are our options?

  1. Manage your stress. Stress can often trigger sweating and also increases apocrine secretions, which tend to be smellier. If you suffer from anxiety or have performance stress, consider speaking with a naturopathic doctor to help calm your response.
  2. Consider reducing your use of conventional antiperspirants . Use them only for times you cannot go without – like maybe for a work presentation, giving a speech at a wedding, or working out with friends (at least if you want to keep them).
  3. Try using natural deodorants. There are lots of great options available. These products work by reducing the amount of bacteria, absorbing odour, and providing natural fragrance to mask it. I really like Sola’s Coconut Deodorant and Weleda has some great spray options as well.
  4. Use essential oils! Many oils not only smell great but have anti-bacterial properties as well. Keep it simple by making a spray or using a roll on (which you can throw in your pocket for touch ups during the day). There is some evidence that using peppermint oil orally can influence not only breath odour but body odour as well.
  5. Support your detoxification pathways. (You knew this was coming, right?) If you notice a change in body odour, it can be a sign that your detox systems need some help. If it is coupled with other signs of toxicity (fatigue, brain fog, skin reactions, headaches, etc) you may want to consider discussing a detox plan with your naturopathic doctor.

Some people sweat and stink more than others, so not all of these suggestions are for everyone. There are also a few medical conditions that can alter a person’s body odour, including diabetes, cancer, and infections. These conditions are outside the scope of this article, except to say, if you notice a change and cannot explain it, talk to your doctor! (As a side note: researchers are currently training dogs to pick up on these odours as part of early detection programs! Science rocks.)