The connection between nutrition, mental health, and cognition has deepened substantially over the years. The saying "you are what you eat" holds true not just in a physical sense but also in relation to our mental health and cognitive abilities.
It's clear that nutrition does more than just fuel the growth of our body's structural components, like fat, protein, and connective tissues; it profoundly influences our mental well-being and cognitive functions. In this exploration, we aim to shed some light on the intricate relationship between our diet and our mental and cognitive health, with a particular focus on how the ketogenic diet fits into this dynamic. Given the vast scope of this topic, we're merely touching the surface, as the complexities of how diet impacts mental health are both profound and continuously evolving.
How Are Diet And Mental Health Related?
A crucial link between mental health and nutrition originates in the gut, where an impressive 95% of our serotonin is produced. Serotonin, a monoamine neurotransmitter, plays a vital role in regulating mood and sleep, modulating appetite and digestion, influencing pain perception, promoting blood clotting through platelets, contributing to sexual function and desire, and supporting cognitive functions such as memory and learning.
Serotonin is produced in the gut from the essential amino acid l-tryptophan through a sequence of enzymatic transformations. Initially, tryptophan undergoes hydroxylation—the addition of a hydroxyl group—courtesy of the enzyme tryptophan hydroxylase, resulting in the creation of 5-hydroxytryptophan (widely known as 5-HTP). Following this, 5-HTP is decarboxylated, which involves the removal of a dicarboxylic acid group, by the enzyme aromatic l-amino acid decarboxylase (AADC) to synthesize serotonin. Tryptophan is plentiful in animal products such as beef, lamb, pork, poultry, and dairy, but is also present in nuts, seeds, whole grains, and legumes.
Our microbiome plays an important role in influencing our body's capacity to produce serotonin. Specific beneficial bacteria generate metabolites that impact the availability of tryptophan in the gut, thereby affecting serotonin production. It's crucial to note that serotonin synthesized in the gut cannot cross the blood-brain barrier, meaning it doesn't directly influence the brain. However, it can exert systemic effects, like signaling to the nervous system via the vagus nerve, which indirectly affects our mood and overall sense of well-being.
When considering methods to improve the gut microbiome, our minds often turn to probiotics. However, the effectiveness of probiotic products can be highly variable. While some may be active and beneficial, many are dead on arrival and yet carry a hefty price tag. Personally, I'm not opposed to using probiotics, particularly after a course of antibiotics, but it's essential to verify that the product you choose is proven to effectively repopulate the gut before investing your money.
One aspect not discussed enough in conversations about gut health is the role of prebiotics, or the dietary fibers that nourish our gut microbiome. While prebiotic supplements are available and can offer benefits, I believe that the most effective method to support our gut microbiome is through our diet. It might not be as sexy as the latest prebiotic supplement trend, but natural food sources usually taste better and are more affordable. Interestingly, a recent randomized control trial (RCT) comparing mental health outcomes in diets rich in prebiotic fiber, supplemental probiotics, and their combination revealed that individuals consuming high amounts of prebiotic foods reported better mental health outcomes than those solely relying on probiotic supplements.
In recent years, individuals have been leveraging the ketogenic diet for improving their metabolic health, which in turn may be beneficial to improving mental and cognitive health. Here we will go into a brief explanation of what this diet is and some of its history.
The Ketogenic Diet
Humans have instinctively utilized ketosis since the dawn of our existence, and it has been consciously applied for its therapeutic benefits since the 1920s, particularly for managing epileptic seizures in children. However, as time passed, medication emerged as the frontline treatment. The scenario once again shifted in the 1990s, largely due to the establishment of the Charlie Foundation for Ketogenic Therapies, named after Charlie Abrahams, a young boy who successfully managed his epilepsy through this diet. This resurgence sparked renewed interest in the ketogenic diet for treating other neurological disorders and conditions, including Alzheimer's, Parkinson’s, type 2 diabetes mellitus, as well as for weight loss and improving metabolic health, and more recently, even bipolar disorder.
The ketogenic diet is generally a diet that is quite low in carbohydrates (20-50g), has moderate protein intake, and high fat intake. Some of the popular types of the ketogenic diet are:
- Standard Ketogenic Diet (SKD): The most common version, characterized by very low carb, moderate protein, and high fat.
- Cyclical Ketogenic Diet (CKD): Involves periods of higher-carb refeeds, such as 5 ketogenic days followed by 2 high-carb days.
- Targeted Ketogenic Diet (TKD): Allows adding carbs around workouts.
- High-Protein Ketogenic Diet: Similar to SKD but includes more protein.
Maintaining the ketogenic diet can be straightforward and consists of limiting your carbohydrate intake to 20-50 grams per day, while aiming for a ratio of about 3-4 grams of fat for every gram of protein. That being said, some individuals can achieve ketosis on higher amounts of carbohydrate, and lower ratios of fat to protein (2:1 instead of 3:1 or 4:1). To sustain ketosis, it's crucial to moderate your protein consumption. Consuming excessive protein, in the absence of sufficient fats, can prompt your body to generate glucose from protein via gluconeogenesis. By ensuring adequate fat intake and keeping protein levels moderate, your body is encouraged to enter ketogenesis, the process responsible for producing ketone bodies. During this process, fatty acids are transported to the liver and undergo beta-oxidation, leading to the production of acetyl-CoA. When the production of acetyl-CoA surpasses the Krebs cycle's capacity to utilize it, the liver converts the surplus acetyl-CoA into primarily beta-hydroxybutyrate (BHB) and acetoacetate, facilitating the ketosis state. Another ketone that is produced is acetone!
Adhering to a dietary plan with 3 to 4 grams of fat per gram of protein and maintaining carbohydrate intake between 20-50g daily can effectively induce ketosis. However, to truly optimize this state for the individual (and yes we are ALL different), it's advisable to monitor your progress with both a blood glucose and ketone monitor. For example, I initially restricted my carbohydrate intake to 20-30 grams daily, maintaining ketosis but at the expense of my workout performance. Experimenting with my diet, I increased my carbohydrate consumption to about 150-200 grams in my evening meal. This adjustment meant I wasn't in ketosis upon waking, but it significantly enhanced my workout performance, and I would return to a state of ketosis post-exercise until my next large carbohydrate meal. This experience highlights how ketosis can be tailored to individual needs and goals, demonstrating its flexibility and adaptability.
The Ketogenic Diet, Mental Health, and Cognitive Disorders
In recent years, the ketogenic diet has been applied to a range of mental health and cognitive disorders. Although the body of research is not extensive, with many findings stemming from case studies, the outcomes appear to be quite promising. It's important to note that results can vary significantly from person to person, yet the overall trend is overwhelmingly positive. In the following sections, we'll delve into examples from the literature showcasing individuals' experiences on the ketogenic diet for bipolar and major depressive disorder.
Bipolar Disorder
Recent research suggests that bipolar disorder may be linked to metabolic dysfunction, including issues like reduced glucose metabolism in the brain, oxidative stress, and anomalies in mitochondrial function and neurotransmitter activity. The ketogenic diet offers an alternative energy source through ketones, which are thought to protect the brain by stabilizing neural networks and reducing inflammation. Additionally, this diet may indirectly benefit individuals with bipolar disorder by enhancing insulin sensitivity and positively affecting weight and lipid profiles.
Campbell and Campbell conducted an analytical observational study by gathering data from patients through online bipolar forums. Remarkably, 85% of the 141 participants reported positive mood effects while on the ketogenic diet. These individuals experienced greater mood stabilization and symptom relief compared to those on other diets, such as omega-3 enriched or vegetarian diets. Furthermore, participants noted a reduction in depressive symptoms, enhanced clarity of thought and speech, and a boost in energy levels.
Additionally, two studies assessed the impact of the ketogenic diet on individuals with bipolar disorder who continued to experience a diminished quality of life despite using lamotrigine for mood stabilization. These individuals maintained a state of ketosis for 2-3 years and were able to discontinue their mood-stabilizing medication, showing considerable subjective improvements. Importantly, they reported no negative side effects from adhering to the ketogenic diet.
Major Depressive Disorder
As it relates to major depressive disorder (MDD), Cox et al. discovered that the ketogenic diet significantly aided a patient in managing her type 2 diabetes mellitus and improved her symptoms of major depressive disorder. The patient's progress was evaluated using the Patient Health Questionnaire-9 (PHQ-9), with her scores dropping dramatically from 17 (indicating moderately severe depression) to 0 (no symptoms). Additionally, in the context of her type 2 DM, her HbA1C levels fell from 8% to 5.4%, and her average daily glucose readings decreased from 216 to 96 mg/dL. Remarkably, she was able to reduce her medication usage by 75% by the study's conclusion.
The ketogenic diet has demonstrated potential benefits for individuals with major depressive disorder (MDD) by increasing levels of gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter known for its calming effects. Often, patients with MDD are prescribed positive allosteric GABA modulators, such as benzodiazepines, which, despite their effectiveness, may lead to adverse side effects and addiction. Although adhering to the ketogenic diet might present its own challenges compared to taking medication, it does not carry the same negative side effects, such as drowsiness, sedation, dizziness, light-headedness, cognitive impairment, dependency, gastrointestinal distress, blurred vision, respiratory depression, emotional blunting, or an increased risk of dementia.
The application of the ketogenic diet in addressing mental health conditions extends beyond bipolar disorder and major depressive disorder (MDD). For the purpose of conciseness, we'll explore additional conditions in a separate discussion. Conditions such as Alzheimer's disease, anorexia nervosa, autism spectrum disorder, narcolepsy, and schizophrenia have also shown potential for improvement through the ketogenic diet. This highlights the diet's broad therapeutic potential across a diverse range of neurological and mental health disorders.
As we explore the intricate relationship between diet and mental health, it becomes clear that the adage "you are what you eat" extends far beyond physical health, deeply influencing our mental well-being and cognitive functions. The burgeoning field of research linking nutrition to mental health underscores the profound impact our dietary choices have on our brain's functionality and emotional state. From the pivotal role of gut-produced serotonin in regulating mood and cognition to the promising effects of ketogenic diets on neurological disorders, the evidence points to nutrition as a key player in mental health.
Moreover, the exploration of prebiotics and probiotics offers exciting avenues for enhancing gut health, potentially mitigating mental health disorders rooted in dysbiosis and inflammation. While the journey through the complex landscape of nutrition and mental health is just beginning, it's evident that fostering a healthy diet could be a cornerstone in preventing and managing mental health issues. Embracing a holistic approach to wellness, where dietary strategies complement traditional treatments, might not only illuminate new paths to mental resilience but also empower individuals with tools for lasting well-being. As we continue to unravel the connections between what we eat and how we feel, the potential for nutrition to support mental health and cognition offers a beacon of hope for millions worldwide, affirming that nourishing the body is indeed a powerful way to nurture the mind.
Stay tuned for two!