Diet plays a role in symptoms of anxiety and depression, but where does the gut microbiome come into play? Here’s what science has to say about the correlation between the microbiome, nutrition and mental health.

If you are experiencing anxiety, depression, or other mental health conditions, you may want to take a closer look at what you put on your plate. Science shows that nutrition has an impact on mental health, and that dietary intervention can be important in alleviating some of these issues [1]. But what is the connection between the gut and mental health? Let’s take a closer look at this relationship to understand how diet impacts the brain.

The mind-gut connection

The gut microbiome refers to all the microbes in your intestines, and consists of 40 trillion bacterial cells and 1,000 different species of bacteria. These microbes help synthesize neurotransmitters which can send chemical messages to the brain informing it to regulate sleep, appetite, mood, and emotions [1].

The majority of these microbes are symbiotic (where both your body and microbiota benefit), but some are disease-promoting. While your body needs both to coexist and keep you healthy, a disturbance in this balance–otherwise known as dysbiosis–can make you more susceptible to chronic disease, inflammation, and weight gain. It can also affect mental health conditions. The neurotransmitters serotonin and GABA are produced in the gut, which can contribute to feelings of happiness, fear, and anxiety, so if dysbiosis occurs, these neurotransmitters get thrown out of balance [2,3]. 

How does food negatively affect mental health?

The foods you eat can greatly impact the quality of both gut and mental health. Here are some aspects of a poor diet that can exacerbate mental health issues and further disrupt the microbiome.

• Added sugars: Added sugars can induce inflammation throughout the body, and trigger imbalances in brain chemicals [4]. This can lead to anxiety symptoms and depression. Studies have even shown that those who consume a higher amount of sugar (67 grams or more per day) are far more likely to have clinical depression [5].
• Alcohol: Consuming alcohol can increase symptoms of anxiety disorder. Studies have found that those who cope with their symptoms of anxiety disorder using alcohol are more likely to have persistent alcohol dependence and increased anxiety [6]. Therefore, avoiding alcohol or consuming in moderation may be necessary for someone with mental health concerns.
• Caffeine: Many people consume caffeine for additional alertness, but it may have some negative outcomes for mental health–anxiety is shown to increase as caffeine consumption increases [7].
  
• Saturated fats: Research has shown that a diet high in saturated fats can disrupt dopamine signaling which contributes to many mood disorders [8].

How to improve mental health with nutrition

Instead of focusing on what you need to eliminate, let’s emphasize what nutrients can be beneficial to improve your overall gut and mental health, and how you can add more of them to your diet. 

Vitamin C

This vitamin is important for mental health because it acts as an antioxidant that protects neurons against oxidative stress. Studies have shown that it can aid in mental illnesses like depression, anxiety, and even schizophrenia and Alzheimer’s disease [9].

Some foods that are particularly rich in vitamin C include red and green peppers, oranges, grapefruits, strawberries, and broccoli. To get more vitamin C in your diet, try sprinkling some peppers in your eggs for breakfast, adding berries to a smoothie, or including roasted broccoli with dinner.

Magnesium

Studies have shown that magnesium can relieve depression by blocking a specific receptor responsible for a major causative factor in depression [10].

Good sources of magnesium include spinach, legumes, nuts, seeds, and whole grains. To add more of this macro mineral to your diet, try including spinach in your salads, throwing seeds like chia into your smoothies and yogurt, and eating more whole grains.

B Vitamins

Vitamins B6, B12, thiamin, and folate have all been shown to help prevent and treat depressive disorders, as well as other mental illnesses [11]. Interestingly, studies have found that vegetarians are more likely to have B vitamin deficiencies, which might contribute to higher levels of depressive symptoms [12].

Some great sources of B vitamin rich foods include meats, seafood, poultry, eggs, and dairy. To increase your B vitamin intake, try eating an animal based protein at meals. If you’re a vegan or vegetarian, you may want to consider supplementation to meet your needs.

Omega-3 Fatty Acids

Omega 3’s are directly correlated to improving overall mental health. Multiple studies have found that increasing omega 3 intake reduces the risk and the severity of depression, schizophrenia, ADHD, and even reduced the cognitive decline in Alzheimer’s disease patients [13].

Some great sources of omega 3’s include salmon, herring, walnuts, chia and flax seeds, and sardines. To eat more of these brain-healthy fats, try eating fatty fish a few times a week, sprinkling chia and flax seeds on toast, or munching on walnuts for snack.

Summary

The correlation between the microbiome, nutrition and mental health is a topic of interest among researchers, with new information emerging every year. However, it’s been found that a diet rich in added sugars, caffeine, alcohol and saturated fats can negatively affect the gut and mental health. As such, it’s recommended to add more nutrient rich foods that contain B vitamins, magnesium, vitamin C, and omega 3’s to boost the microbiome and decrease symptoms of anxiety and depression.

For other health and wellness content, check out these other blogs:

Oxidative Stress and the Role of Antioxidants
Why is Vitamin D Important?
Why Should You Work with a Functional Dietitian?
Glyphosate and its effects on health

References: 

1. Adan, R., van der Beek, E. M., Buitelaar, J. K., Cryan, J. F., Hebebrand, J., Higgs, S., Schellekens, H., & Dickson, S. L. (2019). Nutritional psychiatry: Towards improving mental health by what you eat. European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology, 29(12), 1321–1332. https://doi.org/10.1016/j.euroneuro.2019.10.011 
2. Mazzoli, R., & Pessione, E. (2016). The Neuro-endocrinological Role of Microbial Glutamate and GABA Signaling. Frontiers in microbiology, 7, 1934. https://doi.org/10.3389/fmicb.2016.01934 
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5. Knüppel, A., Shipley, M.J., Llewellyn, C.H. et al. (2017) Sugar intake from sweet food and beverages, common mental disorder and depression: prospective findings from the Whitehall II study. Sci Rep 7, 6287. https://doi.org/10.1038/s41598-017-05649-7 
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8. Melo, H. M., Santos, L. E., & Ferreira, S. T. (2019). Diet-Derived Fatty Acids, Brain Inflammation, and Mental Health. Frontiers in neuroscience, 13, 265. https://doi.org/10.3389/fnins.2019.00265
9. Han, Q. Q., Shen, T. T., Wang, F., Wu, P. F., & Chen, J. G. (2018). Preventive and Therapeutic Potential of Vitamin C in Mental Disorders. Current medical science, 38(1), 1–10. https://doi.org/10.1007/s11596-018-1840-2 
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