Nutrition Psychiatry: Improving Your Mental Well-being through What You Eat

By: Jeremy Partl, Registered Dietitian

Does what you eat impact your mental health? Years of accumulating data suggest that what you eat is not only critical for your metabolic health, performance, and body composition but also significant for its effects on mood and mental well-being.

In this article, I will dive into current literature to explore the connections between diet and mental and emotional health. We will look at what associations have been uncovered and explore plausible physiological explanations for those associations. I will also provide some suggestions on what a diet to support mental health may look like.

What Does the Science Say?

While the determining factors of mental health are complex, increasing evidence indicates a strong association between a poor diet and the exacerbation of mood disorders, including anxiety, depression, and other neuropsychiatric conditions. And, as one might expect, a lot of evidence points to increases in well-being and happiness with improved diet quality.

Findings over the last decade have led to some of the following conclusions:

• A higher diet quality in later years of adult life is associated with a reduced risk of cognitive decline.^[1]
• A systematic review combining over 40 studies provided compelling evidence that a Mediterranean style diet can confer a protective effect against depression.^[2]
• Malnutrition and obesity are closely intertwined with mood regulation and stress sensitivity, suggesting a strong link between diet, metabolism, and mental well-being.^[3], ^[4]
• Eating a diet rich in fresh fruits and vegetables has been associated with increased reported happiness and higher levels of mental health and well-being. ^[5],^[6]
• In contrast to the potential protective effect of a diet high in fruits and vegetables, a recent meta-analysis suggested that a diet high in refined sugar and saturated fat may manifest an increased risk for ADHD or hyperactivity.^[7]
• Analysis of thirteen studies showed that increased intake of diets high in fruits, vegetables, fish, and whole grains reduced the likelihood of depression.^[8]
• Significant improvements in mood and reduced anxiety levels were observed in adults with major depression who followed a Mediterranean style diet. ^[9]

As with nearly every topic in nutrition research, there are studies contrasting consistently repeated findings. For instance, a recent meta-analysis of cohort studies revealed no significant association between adherence to the Mediterranean diet and risk of depression.^[10]

However, combing through Pubmed and Google Scholar would give you many more studies supporting a positive link between improved diet quality and improved mental and emotional health.

Physiological Mechanisms

The prime regulator of our mental health is the powerful machine that sits atop our bodies: our brain. The composition, structure, and function of the brain depend on the availability of appropriate nutrients, including lipids, amino acids, vitamins, and minerals, supporting the inference that food intake and food quality would have an impact on brain function and regulation. However, it seems that there are additional ways that our diet impacts our mental and emotional health.

Blood Sugar Fluctuations

When was the last time your hunger caused you to be angry? (“Hangry” much?) Blood sugar fluctuations are one of the main triggers of becoming hangry.

Date longitudinal research has shown an association between progressively higher dietary glycemic index and the incidence of depressive symptoms and has provided direct evidence of increases in depressive symptoms with experimental exposure to diets with a high glycemic load. This happens due to the repeated and rapid increases and decreases in blood glucose—aka the blood sugar rollercoaster—that can change your mood in an instant. ^[11],^[12]

Inflammation

Immune responses to chronic inflammation cause structural and functional changes in the brain. Psychological stress can cause an inflammatory response in the body, which has been linked to changes in physical and mental health. Diet can foster similar chronic inflammation responses in the body.

Excessive consumption of refined carbohydrates, low dietary fiber intake, and a high omega-6 to omega-3 ratio are strongly associated with the production of pro-inflammatory molecules.^[13]

The inflammatory effects of a diet high in calories and saturated fat are one possible mechanism through which the Western diet may have detrimental effects on brain health, including cognitive decline, hippocampal dysfunction, and damage to the blood-brain barrier.^[14]

The Gut-Brain Axis

The “gut-brain axis” is a two-way communication network that links the autonomic nervous system, hypothalamic-pituitary-adrenal (HPA) axis, and nerves within the gastrointestinal tract, allowing the brain to influence intestinal activities, and the gut to influence mood, cognition, and mental health.^[15]

Studies have emerged showing that changes in the microbiome may result in the development and proliferation of detrimental conditions, including anxiety, depressive disorders, schizophrenia, and autism.^[16]

Research also suggests that dietary patterns that are high in fiber, and those that include fermented foods, have the potential to modify the gut microbiome and promote a diverse gut microbiota, exerting positive benefits on mental health.^[17],^[18]

There are a few physiological explanations for how alterations in the gut microbiome can impact our health:

• Increased Permeability (Negative): Since the gut microbiota support tight junction integrity between the cells of the GI system, a lack of certain populations of gut bacteria cause open doors of inflammatory molecules that are now recognized features of autoimmune conditions, Alzheimer’s disease, asthma, and other mental health conditions.^[19]
• Production of Short-Chain Fatty Acids (Positive): While genetics and lifestyle choices play a partial role in gut microbiota composition, the key determinants of gut microbiota composition and function are most likely diet and nutrition. When we eat foods that are rich in fiber, the fibers are not digested and absorbed by our bodies. Instead, the bacteria get to ferment them and produce short-chain fatty acids that have been identified as key players in improving the gut environment and have been found to be beneficial in reducing the frequency and severity of mental conditions.^[20]
• Neurotransmitter Production (Positive): The production of neurotransmitters like serotonin is highly influenced by the billions of bacteria that make up your intestinal microbiome. If you have not heard of serotonin, many people refer to it as the “mood” neurotransmitter. An estimated +90% of our serotonin is produced in the gut. In addition to regulating mood, serotonin helps regulate sleep, appetite, and other body functions, which all have downstream effects on mental health. If we are not providing the nutrients our body needs to produce this (and other neurotransmitters), we are not going to give the body the right tools to stay healthy.

The study of these and other mechanisms regarding the connection between what we eat and our mental health suffers from the criticisms applicable to all types of research. And Further work is still needed to improve our understanding of the complex pathways through which diet and nutrition can influence the brain. But what continues to drive the research forward is the regular and consistent observations that what we eat affects us on more than a physical level. From being merely hangry to possibly contributing to depressive episodes, it is worth considering the mental health aspects of nutrition as a part of whole-body total wellness.

Moving Toward a Mental-Friendly Nutrition Approach

Although all nutrients are necessary for brain functioning, some key nutrients support neurodevelopment and optimal operation of our brains. These include protein, iron, choline, folate, iodine, vitamins A, D, B6, and B12, and long-chain polyunsaturated fatty acids. ^[21]

Where can you find these nutrients in foods?

If you have picked up a general theme in my previous articles, you know that I am not the type to really get specific, especially when it comes to working with the general population. There are certain cases where I will recommend that a person adds specific nutrients to fill the gaps in a diet. However, those are rare cases, and most people will do much better by building a nutrition plan with the big rocks.

So, what are the big rocks when it comes to dietary patterns that support mental health?

• Consume a balanced diet that includes plenty of vegetables, fruits, whole grains, legumes, nuts, seeds, seafood, other lean proteins, and healthy unsaturated fats.
• Do your best to eliminate and avoid added sugar, highly processed foods, and sugary beverages.
• Eat adequate fiber daily to support a healthy gut microbiome.
• Eat adequate amounts of protein to provide building blocks for neurotransmitters.

Remember, small changes are easier to maintain than trying to overhaul your whole diet pattern.

Wrapping Up

As a dietitian, I feel that nutrition is often overlooked when treating mental health conditions. I am one of the biggest supporters of working with licensed professionals and working in stress-reduction techniques into your lifestyle to improve your mental and emotional health.

However, as cliché as it is, remember the wise words of Hippocrates: ”let food be thy medicine.” As you may have noticed, eating for mental health, physical health, recovery, and performance all involve pretty consistent recommendations. High-quality whole foods and exercise are the best kinds of medicine; they improve long-term mental and physical health, prevent illness and come with only positive side effects.

References

^[1] Smyth, A., Dehghan, M., O’Donnell, M., Anderson, C., Teo, K., Gao, P., … & Yusuf, S. (2015). Healthy eating and reduced risk of cognitive decline: A cohort from 40 countries. Neurology, 84(22), 2258-2265.

^[2] Lassale, C., Batty, G. D., Baghdadli, A., Jacka, F., Sánchez-Villegas, A., Kivimäki, M., & Akbaraly, T. (2019). Healthy dietary indices and risk of depressive outcomes: a systematic review and meta-analysis of observational studies. Molecular psychiatry, 24(7), 965-986.

^[3] Dallman, M. F. (2010). Stress-induced obesity and the emotional nervous system. Trends in Endocrinology & Metabolism, 21(3), 159-165.

^[4] Gibson, E. L. (2006). Emotional influences on food choice: sensory, physiological and psychological pathways. Physiology & behavior, 89(1), 53-61.

^[5] Mujcic, R., & J. Oswald, A. (2016). Evolution of well-being and happiness after increases in consumption of fruit and vegetables. American Journal of Public Health, 106(8), 1504-1510.

^[6] Conner, T. S., Brookie, K. L., Carr, A. C., Mainvil, L. A., & Vissers, M. C. (2017). Let them eat fruit! The effect of fruit and vegetable consumption on psychological well-being in young adults: A randomized controlled trial. PloS one, 12(2), e0171206.

^[7] Del-Ponte, B., Quinte, G. C., Cruz, S., Grellert, M., & Santos, I. S. (2019). Dietary patterns and attention deficit/hyperactivity disorder (ADHD): a systematic review and meta-analysis. Journal of affective disorders, 252, 160-173.

^[8] Lai, J. S., Hiles, S., Bisquera, A., Hure, A. J., McEvoy, M., & Attia, J. (2014). A systematic review and meta-analysis of dietary patterns and depression in community-dwelling adults. The American journal of clinical nutrition, 99(1), 181-197.

^[9] Jacka, F. N., O’Neil, A., Itsiopoulos, C., Opie, R., Cotton, S., Mohebbi, M., … & Brazionis, L. (2018). The SMILES trial: an important first step. BMC medicine, 16(1), 237.

^[10] Shafiei, F., Salari-Moghaddam, A., Larijani, B., & Esmaillzadeh, A. (2019). Adherence to the Mediterranean diet and risk of depression: a systematic review and updated meta-analysis of observational studies. Nutrition reviews, 77(4), 230-239.

^[11] Gangwisch, J. E., Hale, L., Garcia, L., Malaspina, D., Opler, M. G., Payne, M. E., … & Lane, D. (2015). High glycemic index diet as a risk factor for depression: analyses from the Women’s Health Initiative. The American journal of clinical nutrition, 102(2), 454-463.

^[12] Salari-Moghaddam, A., Saneei, P., Larijani, B., & Esmaillzadeh, A. (2019). Glycemic index, glycemic load, and depression: a systematic review and meta-analysis. European Journal of Clinical Nutrition, 73(3), 356-365.

^[13] Neustadt, J. (2011). Western diet and inflammation. Integrative Medicine, 10(2), 50-54.

^[14] Noble, E. E., Hsu, T. M., & Kanoski, S. E. (2017). Gut to brain dysbiosis: mechanisms linking western diet consumption, the microbiome, and cognitive impairment. Frontiers in behavioral neuroscience, 11, 9.

^[15] Appleton, J. (2018). The gut-brain axis: Influence of microbiota on mood and mental health. Integrative Medicine: A Clinician’s Journal, 17(4), 28.

^[16] Clapp, M., Aurora, N., Herrera, L., Bhatia, M., Wilen, E., & Wakefield, S. (2017). Gut microbiota’s effect on mental health: the gut-brain axis. Clinics and practice, 7(4).

^[17] Gopinath, B., Flood, V. M., Kifley, A., Louie, J. C., & Mitchell, P. (2016). Association between carbohydrate nutrition and successful aging over 10 years. Journals of Gerontology Series A: Biomedical Sciences and Medical Sciences, 71(10), 1335-1340.

^[18] Aslam, H., Green, J., Jacka, F. N., Collier, F., Berk, M., Pasco, J., & Dawson, S. L. (2020). Fermented foods, the gut and mental health: a mechanistic overview with implications for depression and anxiety. Nutritional neuroscience, 23(9), 659-671.

^[19] Clapp, M., Aurora, N., Herrera, L., Bhatia, M., Wilen, E., & Wakefield, S. (2017). Gut microbiota’s effect on mental health: the gut-brain axis. Clinics and practice, 7(4).

^[20] Silva, Y. P., Bernardi, A., & Frozza, R. L. (2020). The role of short-chain fatty acids from gut microbiota in gut-brain communication. Frontiers in Endocrinology, 11, 25.

^[21] Georgieff, M. K., Ramel, S. E., & Cusick, S. E. (2018). Nutritional influences on brain development. Acta Paediatrica, 107(8), 1310-1321.