Introduction
With phrases such as ‘good food, good mood’ and ‘you are what you eat’ floating around, it is hard not to wonder if there is a truth behind these sayings. Recent studies are examining the role of diet in mental illnesses and the impact of shifting to a traditional diet in individuals affected by mental disorders like anxiety and depression. The direct correlation between physical health and diet is common knowledge. However, while treating mental issues, the perspective of a diet is often neglected, with importance only given to conventional treatment modalities such as pharmacological therapy, psychotherapy, behavior management strategies, etc.
What Is Nutritional Psychiatry?
It can be described as the application of food and nutritional science to brain health. It can be used to augment results obtained from conventional treatment modalities. Though the determinants of mental health are complicated, a poor diet is strongly linked to the escalation of mood disorders, such as anxiety and depression, as well as other neuropsychiatric illnesses. Studies have yielded evidence that shows people consuming whole grains and unprocessed food, which makes up much of Mediterranean, Japanese or Scandinavian diets, are less susceptible to developing mental health disorders. Randomized control trials in individuals suffering from mental diseases showed that shifting to a healthy diet was associated with a decrease in symptoms and benefited their overall quality of life. However, current scientific evidence does not pinpoint specific nutrients or the underlying mechanism for benefits to mental health.
Neuropsychiatric disorders are among the most urgent social concerns of our day with an upward trend. All evidence indicates that the burden of mood disorders, stress-induced cognitive impairments, and psychiatric diseases will increase in the coming decades. This combined with the severe side effects of some antidepressant and antipsychotic medication is expected to boost the growth and importance of nutritional psychiatry in battling mental disorders.
What Is the Gut-Brain Connection?
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About 95 % of the neurotransmitter serotonin is produced in the gastrointestinal tract. Serotonin regulates sleep, mood, and appetite, and curbs pain perception. A network of millions of neurons is present in the gut lining; in addition, the vagus nerve (the tenth cranial nerve) connects the gut to the brain. Thus, a direct operating relationship exists between the brain and the gut with the exchange of signals and chemicals affecting moods and sleep.
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The gut microbiome refers to different groups of bacteria that reside in the gut. It is unique to each individual and is established within a thousand days after birth. These bacteria have several beneficial roles, which include protecting the intestinal lining, keeping bad bacteria, toxins, and inflammation under check, breakdown of carbohydrates into simple sugars, production of vitamins, better nutrient absorption, and activation of neural pathways between the brain and the gut. An alteration in the dynamics of the microbiome with the balance tipped towards bad bacteria can lead to a variety of health issues, such as malabsorption, irritable bowel disease, and an interrupted interaction between the microbiome and the immune system. Obesity, metabolic syndrome, diabetes, mood, and cognitive function are also associated with altered microbiomes. Studies have shown that the microbiome in individuals with psychiatric afflictions was markedly different from healthy individuals. A western diet consisting predominantly of processed food with a number of food additives contributes to increased inflammation in the gut and, consequently, in the brain. These foods are associated with the generation of free radicals and oxidative damage in the brain. A disturbed circadian rhythm and irregular feeding time have now been implicated in gut microbiome disturbance. Eating time in addition to diet quality is an important factor in the maintenance of gut health.
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The presence of the nutrients in the diet, such as lipids, amino acids, vitamins, and minerals, affects the composition, structure, and function of the brain. Lack of essential nutrients in diet or malabsorption affects brain function.
What Are Some Known Diet-Disease Relationships?
Examples of dietary interventions that help mental conditions are:
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Epileptic children, when put on a ketogenic diet, experienced reduced symptoms. Though the mechanism remains unknown, an altered energy supply to the brain through ketone bodies resulted in decreased seizure episodes.
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Cognitive abilities in those with phenylketonuria were preserved with an elimination diet.
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Vitamin B12 deficiency leads to fatigue, poor memory, depression, and lethargy; it has been shown to be associated with mania and psychosis.
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Niacin (Vitamin B3) deficiency is related to pellagra with dementia.
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Folic acid deficiency can cause neurodevelopmental problems in the womb as well as during infancy and increases susceptibility to depression during adulthood.
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Refined sugars and processed foods were shown to increase the risk for attention deficit hyperactivity disorder (ADHD). Supplementation with free fatty acids and micronutrients lead to better attention and emotional stability in affected individuals.
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A gluten-free and casein-free diet with vitamin D and micronutrient supplementation was shown to be beneficial in autism. However, conclusive evidence is required to establish a more solid link and explain the mechanisms of the efficacy of such diets.
What Foods Exert a Negative Impact on Mental Health?
A few food items and ingredients associated with a greater risk of disorders like anxiety and depression include foods with excessive refined sugars, hydrogenated fats, color and artificial flavoring additives, processed grains, etc. Unbalanced foods increase the risk for cognitive decline and other cardio-metabolic disorders. Limiting these components in your diet can preserve the gut microbiome and prevent a host of illnesses.
What Are Brain Superfoods?
A diet composed of fresh vegetables and fruits packed with vitamins and antioxidants, whole grains rich in fiber and healthy carbohydrates, and seafood that contains omega-3 fatty acids are considered brain-friendly. It is healthier to consume fruits and vegetables as it is rather than as juices. Diets rich in polyunsaturated fatty acids (PUFA), polyphenols, and vitamins (A, D, B12, and B6 notably), iron, folate, protein, iodine, etc are favorable to mental health, stress reactivity, and cognitive performance. Probiotics are live bacteria that are ingested to improve gut health and digestion. Some medications, like antibiotics, cause a disruption of the gut microbiome by killing gut-friendly bacteria.
To summarize, microbiomes in the prenatal as well as postnatal environments influence brain development, function, and the future risk of psychiatric diseases; this in turn is governed by diet and nutrition.
Conclusion
Nutritional psychiatry is a discipline that incorporates nutrient-rich food to positively impact mood and symptoms of mental health disorders. There exists an anatomical connection between the gut and brain in terms of the gut microbiome, neural pathways, and neurotransmitter regulation. A diet-microbiome-host interaction is at work. More research is required to understand the mechanism by which specific nutrients affect mental health positively or adversely. However, existing studies have demonstrated improved quality of life in psychiatric patients with changes in diet incorporated along with traditional treatment methods. Nutritional psychiatry is an emerging field with great scope, given the rising burden of psychiatric diseases the world over. Integrating nutritional psychiatry with conventional treatment is a holistic way of treating psychiatric disorders.
