The Mind-Body Connection: Emerging Nutritional Neuroscience

The Mind-Body Connection: Emerging Nutritional Neuroscience

Michaela Long, WSU Dietetic Student

The mind-body connection is becoming more mainstream. How we feel mentally can have a big effect on how we feel physically, and vice versa. After being told bad news, you may get a stomachache. Inversely, being told that you just landed your dream job could make you completely forget about the headache you just had. What about the connection between diet and the mind? The effects of diet on mental health are not currently well understood, however emerging evidence is showing there’s an established relationship between the two. 

Mood disorders such as depression and anxiety are complex and may be caused by many factors, including genetic predisposition. While there is evidence that dietary factors may play a role in the development and severity of depressive symptoms, research is not yet strong enough to be used as a sole intervention for mental health disorders and this should not be used as medical advice. If you have questions about your mental health treatment plan, please reach out to your doctor, therapist, or psychiatrist.

Serotonin

Serotonin is a neurotransmitter that regulates sleep, appetite, mood, and inhibits pain. Contrary to common belief, there’s no clear evidence that low serotonin levels cause depression. However, low serotonin is often observed in depressed individuals, and selective serotonin reuptake inhibitors (SSRIs) remain a common drug class of antidepressants, effective for many in the management of their depression. About 95% of your body’s serotonin is produced in your digestive tract, stressing the importance of keeping your gut and yourself happy and healthy. 

A key player in gut health is the microbiome, or the collection of “good bacteria” that help your gut do its job. These bacteria help you absorb nutrients from your food, produce some vitamins such as Vitamin K and Biotin, and support your body’s immune system. Probiotics and prebiotics, either in supplements or the diet, help support and strengthen your microbiome. Fruits, vegetables, fiber, and fermented foods are some examples of your microbiome’s favorite foods. 

Other Neurotransmitters

Dopamine, noradrenaline, and γ-aminobutyric acid (GABA) are other neurotransmitters that are often associated with depression. Several studies have demonstrated that the amino acids tryptophan, tyrosine, phenylalanine, and methionine may be helpful in treating mood disorders including depression. Amino acids are the building blocks of proteins, which we can get in our diet from protein-rich foods.

Tryptophan is a precursor of serotonin, meaning that when consumed alone or on an empty stomach, it’s usually converted to serotonin. Have you ever felt sleepy after having a turkey dinner on Thanksgiving? That’s because turkey is a good source of tryptophan, inducing sleep and serenity. Like tryptophan and serotonin, the amino acids tyrosine and phenylalanine are precursors for dopamine and norepinephrine, other important mood-regulating neurotransmitters. Dietary supplements containing phenylalanine and/or tyrosine result in alertness and arousal, classic characteristics of dopamine and norepinephrine.

Methionine, another amino acid, undergoes a series of pathways in the body to help produce neurotransmitters in the brain. More studies are necessary to determine ideal supplemental doses of these amino acids to achieve antidepressant effects, so for now this is just a fascinating discovery to continue to investigate.

Omega-3s and Cognitive Health

Omega-3 polyunsaturated fatty acids (PUFAs) are found in high amounts in fish oil, especially from mackerel, salmon, herring, and sardines. Omega-3s beneficial effects on health have been well-studied, including reducing risk for cardiovascular disease, and improved cognition/brain health. It’s also been established that PUFAs have an anti-inflammatory effect, especially in contrast to their omega-6 counterparts. Some studies have shown that an omega-3 supplement (such as a fish oil capsule) showed a significant reduction in the development of depression for some populations, but not for others. Conversely, some studies have shown no improvement in patients with depression. PUFAs used alongside antidepressants, more severe depression, and presence of increased inflammation have been identified as factors influencing the efficacy of omega-3 supplementation.

Vitamin Deficiencies

Deficiencies in B-vitamins and magnesium have also been linked to depression in some cases. Studies have demonstrated that folate and/or vitamin B-12 supplementation has resulted in reduction of depressive symptoms, in addition to magnesium supplementation. While these vitamin deficiencies are some of the most common among individuals with mental disorders, note that it is impossible to know if you’re deficient in any given vitamin without speaking to a doctor or dietitian for assessment.

Carbohydrates

Eating a meal rich in carbs triggers the body’s release of insulin into the blood. Insulin acts like a key that opens the door to your body’s cells letting sugar in for energy. It also simultaneously triggers the entry of tryptophan to the brain, affecting neurotransmitter levels.

Sometimes consumption of diets low in carbohydrate can influence depression since the production of neurotransmitters serotonin and tryptophan are triggered by carb-rich foods. It’s been suggested that more fiber-rich carbs (ex: fruits, vegetables, whole grains) provide a moderate but long-lasting effect on brain chemistry, mood, and energy since they take longer to digest. In contrast, less fibrous carb sources (ex: sweets) provide an immediate but temporary relief of symptoms. Who knew there was some science behind those Snickers commercials!

Closing Remarks

“Additional research is necessary” is a frustrating term that is all too common in nutrition research. Research on the mind-body connection between diet and mental health is fascinating but still being developed. My personal philosophy as a soon-to-be Registered Dietitian in just a few short months: do what feels good to you. Check in with your body and mind before, during, and after each meal and see how you feel. Sometimes keeping a journal can be helpful or reach out to a dietitian in your area for more individualized advice and guidance. As previously stated, if you’re reading this article in hopes for an alternative treatment for depression or other mood disorders, please seek guidance from a licensed mental health professional. 

Resources:

1. https://www.health.harvard.edu/blog/nutritional-psychiatry-your-brain-on-food-201511168626
2. Bremner JD, Moazzami K, Wittbrodt MT, et al. Diet, Stress and Mental Health. Nutrients. 2020;12(8):2428. Published 2020 Aug 13. doi:10.3390/nu12082428
3. Rao TSS, Asha MR, Ramesh BN, Rao KSJ. Understanding nutrition, depression and mental illnesses. Indian J Psychiatry. 2008;50(2):77-82. doi:10.4103/0019-5545.42391

1. Taylor AM, Holscher HD. A review of dietary and microbial connections to depression, anxiety, and stress. Nutr Neurosci. 2020;23(3):237-250. doi:10.1080/1028415X.2018.1493808