An introduction to the role of food on mood

Our friendly gut micro-organisms activate complex pathways between our gut and our brain. You may have heard this referred to as the ‘gut-brain axis’ or the ‘gut-brain-microbiome axis’, or simply the gut-brain link.  We have much to learn about the ‘how’ and ‘why’, but the body of evidence is growing larger that what we eat affects our mood. Studies have shown and it is now widely accepted that ‘Traditional’ or ‘Blue Zone’ anti-inflammatory dietary patterns, such as the Mediterranean or Japanese diet, significantly lower the risk and levels of depression and anxiety in humans.  [1]

These types of dietary patterns have much in common. They are low in red meat, but high in fruit and veg, fish and seafood, unprocessed grains, nuts and seeds, and fermented foods. Specifically which nutrients contained in these traditional diets do we think are responsible for their beneficial effects on the brain?  A number of recent studies have shown that B vitamins including folate, vitamin D, zinc, omega 3s, SAMe (S-adenosyl methionine) and NAC (N-acetyl cysteine) appear to play vital roles.

B vitamins are necessary for proper neuronal function. Neurons are the cells of the brain and nervous system. A deficiency in folate (aka vitamin B9 or you may know it as folinic or folic acid supplements) has been reported in people living with depression, and particularly in those that do not respond well to anti-depressant medication. [2]

Vitamin D has an effect not only on the function of individual brain cells but also on the brain as a whole, influencing our behaviour. [3]

Zinc deficiency is linked to increased symptoms of depression. Studies have shown that it improves mood when used in conjunction with anti-depressant medication. [4]

Omega 3s have been shown to play a role in the prevention of psychosis in studies on bipolar, PTSD and depressive populations. Omega 3s or ‘Omega 3 fatty acids’ modulate neurotransmitters (chemical messengers) such as dopamine and serotonin which are our ‘feel good’ hormones, and have anti-inflammatory effects in the brain. [5],[6]

SAMe is an important component for the creation of serotonin and, like zinc, has been shown to improve mood when used in conjunction with anti-depressants [7]

NAC modulates glutamate (stimulating/excitatory neurotransmitter) which acts with GABA (calming neurotransmitter) to maintain a healthy nervous system. An imbalance between these two chemical messengers can affect levels of anxiety and depression. Studies have shown its effect in bipolar, schizophrenia and compulsive disorders. [8]

A quick word about the vagus nerve, also known as the ‘superhighway’ connecting our gut and brain. Contrary to some claims found online, we do not yet have evidence that the serotonin created in the gut is exported to the brain. It is created for use locally and studies have shown that it cannot cross the blood-brain barrier [8]. Selective serotonin reuptake inhibitors or SSRIs are a class of anti-depressants. The authors of a recent study found that “vagus nerve dependent gut-brain signalling contributes to the effects of oral SSRI.” In other words, it helps SSRI anti-depressants work better. [9]

Nutritional psychiatry is a fascinating and relatively new discipline, focusing on the use of food and supplements to provide treatment for mental health disorders. Although this approach is not yet widely accepted by mainstream medicine, “the field of nutritional psychiatry has provided a significant body of evidence to suggest that dietary patterns are relevant to common mental illnesses. However, continued research is required to translate the evidence base into clinical and public health recommendations”. [10]

To discuss if changes to your diet may help your mental health, contact us via the form at the bottom of this page for an obligation-free quick chat, or go to our Facebook page to book a consultation.

References

1 Harvard Health, Nutritional psychiatry: Your brain on food, accessed 12 January 2022 from <www.health.harvard.edu/blog/nutritional-psychiatry-your-brain-on-food-201511168626>

2 Fava M, Mischoulon D. Folate in depression: efficacy, safety, differences in formulations, and clinical issues. J Clin Psychiatry 2009; 70 (suppl 5): 12–17.

3 Eyles DW, Burne TH, McGrath JJ. Vitamin D, effects on brain development, adult brain function and the links between low levels of vitamin D and neuropsychiatric disease. Front Neuroendocrinol 2013; 34: 47–64

4 Lai J, Moxey A, Nowak G, Vashum K, Bailey K, McEvoy M. The efficacy of zinc supplementation in depression: systematic review of randomised controlled trials. J Affect Disord 2012; 136: e31–39.

5 Mischoulon D, Freeman MP. Omega-3 fatty acids in psychiatry. Psychiatr Clin North Am 2013; 36: 15–23.

6 Sarris J, Mischoulon D, Schweitzer I. Omega-3 for bipolar disorder: meta-analyses of use in mania and bipolar depression. J Clin Psychiatry 2012; 73: 81–86.

7 Papakostas GI, Mischoulon D, Shyu I, Alpert JE, Fava M. S-adenosyl methionine (SAMe) augmentation of serotonin reuptake inhibitors for antidepressant non-responders with major depressive disorder: a double-blind, randomized clinical trial. Am J Psychiatry 2010; 167: 942–48.

8 Berk M, Malhi GS, Gray LJ, Dean OM. The promise of N-acetylcysteine in neuropsychiatry. Trends Pharmacol Sci 2013; 34: 167–77.

9 Kanova M, Kohout P. Serotonin-Its Synthesis and Roles in the Healthy and the Critically Ill. Int J Mol Sci. 2021 May 3;22(9):4837.

10 McVey Neufeld, KA., Bienenstock, J., Bharwani, A. et al. Oral selective serotonin reuptake inhibitors activate vagus nerve dependent gut-brain signalling. Sci Rep 9, 14290 (2019) 10 Marx, W., Moseley, G., Berk, M., & Jacka, F. (2017). Nutritional psychiatry: the present state of the evidence. The Proceedings of the Nutrition Society, 76(4), 427–436.