Brain, food, and cognition Nov. 2023

Summary: Nutrition stands as a fundamental cornerstone in overall brain health and well-being. However, it is imperative to acknowledge that different brain regions have varying nutritional prerequisites for their synthesis of pivotal components for neuromodulators (e.g., dopamine) and hormones (e.g., melatonin). The distinct roles and neuromodulators systems within various brain regions necessitate diverse nutritional components. Remarkably, the absence of even a single crucial food nutrient can yield deleterious effects. Thus, a comprehensive diet that incorporates a diverse array of nutrient-rich foods ensures that the brain receives the vital food nutrients it requires for optimal performance. Conversely, an imbalanced diet marked by suboptimal food choices, excessive consumption of unhealthy food items, or insufficient intake of essential nutrients can lead to adverse health outcomes; conditions like diabetes, cardiovascular issues, kidney and liver damage, and a weakened immune system. Moreover, an inadequate diet also contributes to cognitive deficits, including memory impairments, reduced concentration, compromised problem-solving abilities, and diminished learning aptitude. Over an extended period, an unbalance diet gives rise to chronic health conditions. For example, a diet lacking antioxidants like vitamins can precipitate oxidative stress, which is associated with cognitive decline and an augmented risk of neurodegenerative disorders, like Alzheimer's disease. As such, an incomplete diet, one lacking one or more essential nutrients, or too much of one food, impacts on the collaborative interplay among the brain area circuitries involved in the production of neuromodulators. This interconnectedness exerts a profound influence on the production of neurochemicals in different brains areas. In instances of inadequate nutrition, a disruption in this intricate neuronal interdependence can occur, leading to adverse effects on the production of neurochemicals necessary for optimal physical health, brain health, and cognition. Interestingly, the domain of artificial intelligence (AI) technology has given rise to innovative programs offering personalized nutritional guidance and tailored dietary plans designed to enhance an individual's comprehensive well-being. These conversational chatbots not only dispense nutritional recommendations but also curate food menus customized to align with an individual's distinctive medical and psychological profile.

Nutrition plays a pivotal role in shaping brain functions and cognitive abilities, such as memory, language processing, and problem-solving. Indeed, the brain, as the central regulatory hub of the body, coordinates a wide array of physiological and cognitive processes that define human potential. This intricate control over body areas and cognitive functions relies heavily on the presence of essential food nutrients to sustain and enhance brain performance.

There are certain foods enriched with nutrients that actively boost brain functionality. For example, omega-3 fatty acids, found in fatty fish, nuts, and seeds are essential for building and maintaining brain cell membranes. Other food nutrients for brain health include antioxidants found in fruits and vegetables, such as vitamins C and E, which protect brain cells from damage, and B vitamins, which are involved in energy production and neurotransmitter synthesis.

Consequently, maintaining a well-balanced and diverse diet is crucial for promoting optimal brain health, and cognitive capabilities. This ensures that the brain receives all the essential nutrients it needs to function at optimal level. However, it is important to acknowledge that specific nutrient deficiencies can occur, even in people who eat a healthy diet. In such cases, targeted dietary adjustments or supplementation may be necessary to correct the deficiency and restore proper cognitive function.

Cognition and nutrient-dependent brain centers

All cerebral centers rely on essential nutritional elements to operate at their optimal capacity. Moreover, it is crucial to recognize that brain regions constitute a highly interconnected network much involved in the execution of intricate tasks. For instance, the prefrontal cortex, depicted in Figure 1, is responsible for advanced cognitive functions. However, it cannot perform these functions independently; it requires input of other cerebral regions including the hypothalamus and hippocampus, as well as the thalamus and amygdale.

        Figure 1: Brain regions within the cerebral cortex, midbrain, and brain stem

The cerebral cortex is the outermost layer of the brain, primarily composed of gray matter, which consists dominantly of neurons cell bodies. The grey matter envelops the entire surface of the brain's hemispheres. The diencephalon is a region of the brain located between the cerebral hemispheres and the midbrain. It is composed of several structures, including the thalamus and hypothalamus. The brain stem is the lower part of the brain that connects the cerebrum, cerebral cortex, and spinal cord. It comprises three main structures: the medulla oblongata, the pons, and the midbrain.

The prefrontal cortex: A center for many higher cognitive functions. The prefrontal cortex (PFC) is a region at the front of the brain. It plays an essential role in cognitive functions, including memory, learning, decision-making, planning, and social cognition. Recent research highlight the significance of specific food nutrients like omega-3 fatty acids, choline, vitamins, and minerals in the development and maintenance of the PFC (Wilczynska & Modrzewski, 2019; Rajkumar, Patel, & Preedy, 2023; Watson & De Meester, 2016).

Good sources of omega-3 fatty acids include fatty fish, such as salmon, tuna, and mackerel, as well as walnuts and flaxseed. Choline is another critical nutrient for the PFC, as it contributes to the production of acetylcholine, a neurotransmitter important for memory, learning, and attention. Food rich in choline include eggs, beef liver, and soybeans. Vitamins and minerals, specifically B vitamins and zinc, also have a vital role in PFC function. B vitamins are involved in energy production and neurotransmitter synthesis, while zinc is essential for synaptic plasticity, which allows the brain to learn and adapt. Food sources of B vitamins include whole grains, legumes, and leafy green vegetables. Good sources of zinc include oysters, beef, and cashews.

A nutritionally inadequate diet can lead to a variety of cognitive impairments within the prefrontal cortex (PFC). These cognitive deficits encompass challenges in decision-making, planning, organization, task initiation, and problem-solving. Individuals may experience compromised working memory, inhibitory control, impulsivity, attention deficits, and difficulties in task-switching, known as set-shifting deficits. Moreover, the PFC has an intricate role in social cognition, which pertains to our capacity to comprehend, interpret, and respond to the thoughts, emotions, and intentions of others. Impairments in social cognition encompass an individual's limitations in demonstrating empathy, engaging in perspective-taking, and effectively conducting social interactions.

The thalamus: A nexus of food and connection: The thalamus, a paired walnut-sized structure located centrally within the brain, has a pivotal role in regulating various aspects of human behavior. It is closely intertwined with the reward and pleasure pathways, which carry profound implications for food-related behaviors. More specifically, distinct thalamic nuclei are intricately connected with the mesolimbic dopaminergic system, which encompasses the nucleus accumbens and the ventral tegmental area. This neural connectivity forms the basis for the experience of pleasure and the reception of rewards associated with eating, thereby contributing significantly to the reinforcement of positive dietary habits and the fostering of social bonds (Jones, 2007).

A variety of deficiencies associated with thalamic dysfunctions include iron, zinc, and iodine, as well as vitamin B1 (thiamine), B12, and folate. Iron deficiency can reduce neurotransmitter levels and disrupt neural signal transmission, thereby affecting attention, memory, and learning. Zinc, aside from its role in neurotransmitter production, also plays a vital part in immune system function. A deficiency in zinc can result in compromised cognitive function and as well as elevated susceptibility to infections. Vitamin B12, on the other hand, is intricately involved in the synthesis of myelin—a fatty substance crucial for insulating nerve cells. Finally, folate, also known as vitamin B9, is indispensable for DNA and RNA production, serving as the foundational building blocks of cellular structure and function (Misra & Kalita, 2021).

A diverse diet will provides a wealth of vital nutrients, including iron, zinc, vitamin B12, and folate. Iron, zinc, and vitamin B12 are abundant in animal-derived sources, such as beef liver, various fish species (e.g., clams, salmon, and sardines), and dairy products like milk, cheese, and eggs. On the other hand, folate, also known as vitamin B9, is prominently present in dark green leafy vegetables such as spinach, broccoli, asparagus, and Brussels sprouts, as well as citrus fruits like oranges, grapefruit, lemons, and limes. Furthermore, legumes like black and kidney beans, along with grains including brown rice, quinoa, and oats, represent excellent sources of folate.

It is worth noting that the iron and zinc content of foods can vary depending on the specific food item and, significantly, according to the method of food preparation. For instance, the cooking process has the potential to reduce the iron content in foods. Additionally, certain vitamins display differential susceptibility to the effects of freezing. As a general guideline, the percentage of vitamin loss in fruits ranges from 5% to 10% (Rickman, Barrett, & Bruhn, 2007).

More nutrient-dependent brain regions: Let’s reiterate that the optimal functioning of specialized neurons within various brain regions relies on the intake of essential nutrients to facilitate the production of specific neurochemicals. For example, the hippocampus necessitates choline for the synthesis of dopamine, a neurotransmitter with significant implications for learning and motivation. Interestingly, within the intricate interplay of brain area circuitry and neural pathways, neurochemicals generated in one brain region can influence the production of neurochemicals in other brain regions (Carhart-Harris & Nutt, 2017; Ressler & Nemeroff, 2000; Volkow, Koob & McLellan, 2022).

Further elaboration of various brain regions, including the hypothalamus, hippocampus, amygdala, and basal ganglia, along with the pineal and pituitary glands, is provided in subsequent sections. A detailed exploration of these brain regions enhances our comprehension of the intricate relationship between nutrition, brain health, and cognitive function.

Impact of individual food nutrient deficiency:

It is crucial to highlight that a deficiency or imbalance in specific, single, or individual food nutrients can significantly impact an individual’s neurological and overall well-being. The human body relies on a multifaceted interaction of nutrients to support a range of biochemical procedures, encompassing those that oversee cognitive and emotional capabilities. Notably, the human brain, which boasts an intricate network of neurons and signaling pathways, is especially responsive to the presence of essential nutrients.

Table 1 gives a brief overview of essential nutrients having a central role in the synthesis and regulation of critical neurobiochemicals. Insufficiencies or imbalances in any of these nutrients, such as proteins, fatty acids, vitamins, and minerals, can disrupt these processes, potentially resulting in a spectrum of neurological, metabolic, and psychological dysfunctions.

Excessive consumption of a single food nutrient:

It is noteworthy that, akin to the deficiency of a specific nutrient in one's diet, the excessive intake of a single food nutrient can also lead various adverse health consequences. Several prevalent issues arising from the overindulgence in a particular food nutrient include nutrient toxicity, nutritional imbalance, and an elevated risk of chronic diseases. Nutrient toxicity occurs when the body ingests an excess of a nutrient beyond its safe processing or utilization capacity. This condition may give rise to diverse health problems, including organ damage, neurological disorders, and, in extreme cases, fatality.

An increase susceptibility to chronic diseases arises when the intake of specific nutrients, such as saturated and trans fats, sugars, sodium (salt), and cholesterol (found in animal products), exceeds recommended levels. This heightened consumption elevates the risk of developing chronic conditions such as heart disease, stroke, and type 2 diabetes. Moreover, an excess of a particular vitamin can also precipitate health issues. Consuming an excessive amount of vitamin A, for instance, can result in liver damage, bone loss, and birth defects. Similarly, an overabundance of vitamin D can lead to elevated blood calcium levels, posing a threat to kidney function.

Let's underscore that the synthesis of neurotransmitters and hormones in the human body necessitates the consumption of an "appropriate" amounts of a variety of food nutrients. Any imbalance, be it an excess or deficiency in a specific food nutrient, can result in health problems. These essential components encompass a diverse range of food substances, including various fatty acids (such as saturated and monounsaturated varieties), amino acids like tryptophan, phenylalanine, and glutamine, as well as an assortment of vitamins (specifically A, C, B1, B3, and B6). Furthermore, minerals like copper, magnesium, and calcium, along with glucose as the primary energy source for cellular function, actively participate in this intricate biochemical orchestration.

The evaluation of concentrations of these single or specific nutrients in the circulatory system is conventionally carried out in response to signs of health problems, and presenting symptoms. The application of comprehensive blood tests for gauging the quantities of individual nutrients in the blood serves as an indispensable diagnostic instrument within the healthcare domain. This diagnostic approach not only facilitates the identification and control of clinical conditions but also empowers individuals to adopt proactive measures aimed at preserving their nutritional equilibrium and holistic well-being.

The impact of nutrient deficiencies on health

In general, a diet featuring moderate amounts of essential fatty acids, antioxidants, vitamins, minerals, and lean proteins plays a pivotal role in maintaining or enhancing optimal brain health (Palmer, 2014). A healthy dietary regimen not only aids in the prevention of neurological and cognitive disorders but also assumes a critical role in mitigating associated risks. However, malnutrition, stemming from inadequate intake of essential food nutrients or imbalances in nutrient proportions within one's diet, especially among individuals with specific predispositions, can lead to nutrient deficiencies and chronic ailments. In such circumstances, it becomes imperative to develop specialized dietary plans or to consider nutrient supplementation in order to meet the brain's nutritional requirements.

Morris (2015) investigated the detrimental effects of high-sugar diets on brain’s functions, with implication for cognitive performance. The research findings indicate that excessive intake of carbohydrates can trigger a systemic inflammatory response, resulting damage and dysfunction of internal organs, and specific brain centers such as the hippocampus crucial for memory and learning, and the hypothalamus involved in regulating appetite and energy balance.

Individuals following a Western diet, especially those grappling with chronic diseases such as heart attacks and type 2 diabetes, have exhibited this inflammatory response. Morris’ studies reveal the activation of inflammatory molecules, known as cytokines, in response to an overly-rich diet in carbohydrates. In such instances, the immune system responds by triggering an inflammatory reaction, especially in fatty body tissues. These fat deposits release substances that propagate inflammation throughout the body, including the brain. This occurs because the blood-brain barrier, which protects the brain, becomes compromised, allowing molecules to pass into the brain and ultimately leading to neuronal damage that adversely affects cognitive performance.

A diet abundant in fats, particularly in saturated and trans fats, has also been linked to an elevated risk of inflammation. For example, a study by Calder et al. (2011) highlights the pro-inflammatory effects of certain dietary fats, shedding light on their contribution to an imbalance in the immune system. Furthermore, a review by Asensi et al. (2021) emphasizes the association between a diet rich in unhealthy fats and other substances, which can adversely affect the body's inflammatory response and heighten the risk of chronic diseases.

Layé's research team conducted several studies aimed at unraveling the underlying mechanisms linked to cognitive changes resulting from nutritional imbalance in the context of neurological dysfunctions. Specifically, Layé investigated alterations in the brain resulting from the activity of a specific type of immune cell, namely microglial cells. These cells have a crucial role to play in the phagocytic process, wherein they engage in the consumption of neurons. Acting as macrophages, microglial cells mediate immune responses within the central nervous system, clearing cellular debris and dead neurons from nervous tissue through the process of phagocytosis, commonly referred to as "cell eating" (Bazinet & Layé, 2014; Leyrolle et al., 2019).

In instances of nutritional imbalance, insufficient essential food nutrients, or an excessive intake of particular food items (e.g., cereals or meat), microglial cells can lose their regulatory mechanisms, leading to the consumption of live neurons. Notably, microglial cells have been observed containing digested fragments of live neurons. Consequently, the excessive consumption of live neurons by microglial cells contributes to the destruction or disturbance of neural networks, including neurons that should ideally remain functionally intact. This disruption of neural networks has been linked to the emergence of neurodegenerative disorders such as Alzheimer and Vascular brain disease, autism spectrum disorders, and multiple sclerosis (Wolf, Boddeke & Ketenmann, 2017; Muzo, Viotti & Martino, 2012; Xu, Jin, Yang, & Jin, 2021).

Importantly, when the microglial cells react to inflammation, either via information travelling up the vagus nerve or with cytokines entering the bloodstream, they eat away the dendrites in an attempt preserve the neurons. The cell bodies of neurons have branches called axons, which in turn have numerous shorter branches called dendrites, extending in all directions to come into contact with dendrites projected from axons of other neurons. The microglial cells 'prune' away dendrites that are weak, so healthy dendrites can grow in response to new learning and experiences. However, during the inflammation process, exaggerated synaptic elimination in the prefrontal cortex during adolescence has been suggested as a contributing factor to the neuropathological changes of schizophrenia (Mallya et al., 2019). Case studies have shown that microglial pruning of other brain areas lead to loss of neurological functions. For instance, in one case, a patient's unhealthy diet that led to an inflamed brain causing an autoimmune attack against the neurons of her cerebellum (the movement center of the brain), leading to her loss of mobility (i.e., in the hands, arms and legs).

Genetic related brain diseases

A persistent and unhealthy dietary pattern represents a significant risk factor for a diverse range of ailments and chronic illnesses. Nevertheless, genetic or hereditary factors do exert a substantial influence on the emergence of neurological disorders. The clinical manifestations of these conditions can exhibit variations contingent upon the precise genetic anomaly and the degree of its impact. Typical symptoms encompass metabolic disorders often associated with cognitive deterioration, impaired learning abilities, and behavioral disturbances. Timely identification and the implementation of dietary interventions frequently yield more favorable results for individuals grappling with these disorders. Illustrative instances of genetic related brain diseases follow:

Huntington's disease: Huntington's disease is an inherited neurological disorder that gradually worsens movement, thinking, and emotional control. The disease is caused by an expansion of the CAG trinucleotide repeat within the huntingtin (HTT) gene, leading to the production of a mutant huntingtin protein. This mutant protein exerts toxic effects on neurons in specific brain regions, particularly those involved in movement, cognition, and emotional control (Paulsen, 2011).

The provision of nutritional support has a pivotal role in the management of individuals affected by Huntington's disease. Specifically, an optimal dietary regimen includes an assortment of nutrient-rich foods, encompassing fruits, vegetables, whole grains, lean protein sources, and healthy fats. It is worth noting that foods abundant in antioxidants, such as berries and leafy greens offer potential neuro-protective benefits. Moreover, the anti-inflammatory properties of omega-3 fatty acids, prevalent in fatty fish like salmon and mackerel, and flaxseeds, can support brain health (Huntington's Disease Society of America, 2020).

Phenylalanine (PKU): Phenylalanine is a genetic disorder characterized by the body's inability to metabolize the amino acid phenylalanine, which is commonly present in protein-rich foods. In the absence of appropriate treatment and dietary control, elevated phenylalanine levels can result in neurological issues and cognitive impairments, including intellectual disabilities and behavioral problems.

A diet recommended for individuals with PKU is rich in proteins, encompassing a wide range of foods, which are essential for tissue repair and growth, boosting immune function, and sustaining overall well-being. High-protein foods include lean meats, seafood, eggs, dairy products, nuts, seeds, and plant-based protein sources such as legumes (e.g., beans, lentils, and chickpeas). Furthermore, there exists a selection of commercial products designed to supplement the PKU diet with reduced phenylalanine content (MacDonald et al., 2020). Supplements include phenylalanine-free amino acid formulas, low-protein multivitamins, calcium and vitamin B12, and essential fatty acids.

Homocystinuria: Homocystinuria is a genetic disorder that disrupts the metabolism of the amino acid methionine, resulting in elevated levels of homocysteine in the bloodstream. Elevated homocysteine levels are linked to several neurological symptoms and cognitive impairments. The management of homocystinuria primarily revolves adhering to a low-methionine diet to mitigate the accumulation of homocysteine and its associated health complications. A low-methionine diet comprises foods with reduced methionine content, including fruits, vegetables, low-methionine grains such as rice and corn, and certain dairy substitutes such as low-protein pasta or rice milk (Papadakis & McPhee, 2023).

Other genetic metabolic disorders linked to neurological disorders include Wilson's disease, Gaucher's disease, Maple Syrup Urine Disease (MSUD), Alzheimer's disease, Niemann-Pick disease, Lesch-Nyhan syndrome, and Prader-Willi syndrome (Porter, 2005; Steadman, 2005). Wilson's disease specifically impacts copper metabolism, resulting in copper accumulation in various organs, including the brain. This accumulation leads to neurological symptoms such as movement disorders and psychological manifestations, including affective disorders, cognitive impairments and personality changes.

Prader-Willi syndrome is a rare genetic disorder that occurs in approximately 1 in 15,000 to 1 in 25,000 live births. It is characterized by hyperphagia (excessive eating) and obesity, accompanied with motor problems (hypotonia, or low muscle tone) as well as cognitive challenges, behavior impairments, and sleep disturbances.

An important takeaway concerning the influence of dietary nutrients in addressing neurological associated diseases are tailored diets and specific dietary supplements to alleviate the consequences stemming from genetic neurological disorders and disrupted endocrine functions. The identification of distinct nutritional deficiencies and imbalances associated with these conditions facilitates the formulation of purposeful diets that provide an optimal supply of essential nutrients, vitamins, and minerals necessary for the preservation of cognitive functions and the maintenance of hormonal equilibrium. It is imperative to acknowledge that while these interventions may not offer complete cures, they hold promise when used in conjunction with existing medical and psychological treatments, thereby augmenting symptom management and ultimately improving overall quality of life.

Spices on brain health and cognition

Spices, in addition to enhancing the flavor and versatility of culinary preparations, also hold the potential to enhance health, and confer cognitive benefits. Numerous spices contain nutrients commonly present in other food sources, including fatty acids, antioxidants, vitamins, and minerals, which serve a protective function for the brain, safeguarding it against harm and bolstering both health and cognitive abilities (Duke, 2002; Panickar, 2013; Peter, 2012; Wany, Singh & Kumar, 2022).

Saffron: The biological effects of saffron encompass a wide range of physiological and cognitive functions. Its anti-oxidative capabilities serve to safeguard cellular structures against oxidative stress, thereby contributing to overall well-being. Simultaneously, saffron's anti-inflammatory properties has a pivotal role in mitigating inflammatory responses within the body, potentially affording protection against chronic inflammatory conditions (Ghaffari, & Roshanravan, 2019; Hausenblas et al, 2015; Lopresti et al., 2020).

One facet of saffron's potential lies in its antidepressant properties, suggesting a possible natural remedy for individuals grappling with mood disorders. The potency of saffron's impact can be attributed to its rich composition of bioactive compounds. Among its primary constituents are crocins, crocetin, safranal, and picrocrocin, each contributing to the unique therapeutic profile of safrron. Saffron also contains kaempferol, naringenin, taxifolin, lycopene, and zeaxanthin, which further enhance its repertoire of beneficial elements. Moreover, saffron houses a spectrum of vitamins, with thiamine (vitamin B1) occupying a prominent role.

It is noteworthy that the bioactive compounds found in saffron parallel the influence of common food nutrients. For instance, thiamine is present in a variety of other foods, including pork, fish, seeds, nuts, beans, and green peas. This dispersion of thiamine underscores its significance in various dietary contexts and serves as a reminder of the interconnectedness of nutrients across different food sources, including those manufactured in laboratories, such as vitamin supplements, minerals like iron and zinc, selenium, collagen, creatine, and glucosamine and chondroitin.

Ginger: Ginger is renowned for its anti-inflammatory and antioxidant properties. In addition to these well-known attributes, ginger also exhibits vasodilatory effects, facilitating increased blood flow to the brain. This augmentation of blood flow ensures a sufficient supply of oxygen and essential nutrients critical for cognitive functions. Emerging research suggests that ginger can also have a positive impact on mood, thereby contributing to cognitive well-being and performance (Haniadka et al., 2013; Mashhadi et al., 2013; Saenghong et al., 2013).

Ginger shows promising cognitive benefits by positively influencing various aspects of brain health, memory retention, attention span, and the alleviation of symptoms associated with anxiety, stress, and depression. These potential health benefits are attributed to the presence of bioactive compounds in ginger. Noteworthy bioactive compounds found in ginger include gingerol, shogaols, zingerone, gingediol, paradols, and curcuminoids. Among these, gingerol stands out as one of the most extensively studied and recognized for its antioxidant and anti-inflammatory properties.

Of interest is that gingerol, along with related ginger compounds, exert neuroprotective effects, thus contributing to cognitive enhancement. These effects are postulated to result from the antioxidant and anti-inflammatory properties of these compounds, which work to safeguard brain cells against damage and inflammation.

Nutmeg: Nutmeg has gain recognition for its potential health benefits, particularly its impact on cognitive function. Specific compounds within nutmeg have been found to enhance memory and positively influence the learning process. These benefits are attributed to the antioxidant and anti-inflammatory properties of certain nutmeg compounds, which are thought to safeguard brain cells from damage and possibly slow down cognitive decline. These properties may aid in preserving cognitive function as individuals age (Al-Qahtani et al., 2022; Ashokkumar et al., 2022; Tripatih, Vimal, & Sanjeev, 2016).

A key compound in nutmeg is myristicin, a natural organic compound responsible for the spice's distinctive flavor and aroma. Nutmeg also contains other bioactive compounds such as elemicin, eugenol, and safrole. Myristicin has been subject to research due to its potential neuroprotective properties. Studies suggest that myristicin's cognitive-enhancing effects may be linked to its anti-inflammatory and antioxidant qualities. Inflammation and oxidative stress are factors that can contribute to cognitive decline, and compounds capable of countering these processes have had a significant role in maintaining cognitive health.

Herbs: There are many other spices, as well as many herbs such as thyme, rosemary, tarragon, basil, and oregano. Herbs, like spices, are used to flavor a wide range of dishes. Moreover, some herbs share certain properties with spices. For instance, garlic is used globally for its strong flavor. It contains allicin, a compound with potential health benefits, including immune system support. As such, incorporating a variety of spices and/or herbs into our diet can contribute to a more diverse and flavorful culinary experience while potentially offering various health-promoting effects.

Caution is warranted when considering the potential cognitive benefits of spice or herbs consumption. For instance, nutmeg contains compounds that can be toxic in high doses, leading to adverse effects such as hallucinations and neurological symptoms. This caution should extend to other spices as well, as overindulging in a single spice or combination of spices may have adverse effects on health (Kuete, 2017). The potential side effects encompass toxicity, digestive distress, allergic reactions, impaired nutrient absorption, as well as fluctuations in blood sugar levels and blood pressure. Therefore, it is advisable to approach the use of spices with moderation and awareness of individual sensitivities and health conditions.

Synthetic spices: their potential and pitfalls

Synthetic cannabinoids, commonly referred to as “spice, have gained significant prominence, presenting the potential to reshape the culinary landscape. These replicated compounds are adept at mimicking the flavors of traditional spices, offering chefs and food manufacturer’s innovative tools to craft unique and consistent taste profiles. For instance, envision a pumpkin spice latte, entirely created from replicated spices, highlighting the potential for novel seasonal offerings.

However, while the use of synthetic spices presents enticing possibilities, it is important to acknowledge the controversies surrounding their consumption. Emerging research suggests that certain replicated spice compounds may exert adverse effects on brain functions and internal organs. There is growing concern that specific artificial spice formulations potentially disrupt the production of neurobiochemicals, thereby impacting neurological health, and bodily functions.

These concerns about synthetic spices extend beyond just the neurological realm and can have broader implications for general health. The synthetic compounds have been noted to disrupt the delicate balance of neurotransmitters and hormones within the body, leading to detrimental effects on various physiological systems. This disruption in hormonal balance can potentially result in adverse health outcomes, affecting not only the brain but also the endocrine system and other internal organs.

Importantly, though synthetic spices are engineered to closely mimic the flavor and aroma of natural spices, they do not have the same diversity and proportion of bioactive compounds associated with the nutritional benefits inherent to natural spices. Natural spices typically harbor a multitude of phytochemicals, antioxidants, vitamins, and minerals that contribute to their potential health-promoting properties. While synthetic spices can replicate certain sensory qualities, they fall short in encompassing the complete spectrum of bioactive compounds found in natural spices. Therefore, when contemplating the utilization of artificially replicated spices and substitute sweeteners, it is essential to acknowledge that their primary purpose often revolves around providing flavor or sweetness without incurring the same caloric or nutritional impact.

Food preservatives: the pros and cons

Throughout history, humans have employed natural food preservatives to extend the shelf life of food. These natural agents hinder or delay spoilage caused by microbial growth, oxidation, or other chemical reactions. Common examples of natural food preservatives include sugar, salt, vinegar, rosemary extract, and oregano oil. Sugar, one of the oldest and most widely used natural preservatives, creates a high-osmotic environment that renders bacteria and other microorganisms unable to thrive effectively.

Currently, a wide array of lab-manufactured food additives used in the food industry is to achieve various preservation goals. The synthetic preservatives are designed to target specific aspects of food deterioration. For instance, benzoates compounds like sodium benzoate and benzoic acids have antimicrobial properties that inhibit the growth of bacteria, yeasts, and molds. Nitrates and phosphates are used in processed meats and canned foods are pH regulators that improve texture, and enhance water retention. Silicon dioxide and calcium silicate serves as anti-caking agents designed to prevent the clumping and caking of powdered or granular foods like spices, salt, and baking mixes.

Certain food preservatives have become controversial due to ongoing debates surrounding their safety and potential health impacts. The controversies primarily center around the perceived risks associated with prolonged exposure to these additives. Notably, sugar substitutes such as aspartame, saccharin, sucralose, and acesulfame potassium are subjects of concern regarding their long-term effects on health. Some studies have indicated potential links to adverse health outcomes (Anand & Sati, 2013).

In addition to sugar substitutes, Butylated hydroxyanisol (BHA) and Butylated hydroxytoluene (BHT) are synthetic antioxidants commonly employed to prevent oxidation and extend the shelf life of fats, oils, and processed foods. Research has suggested that these compounds may have potential carcinogenic effects and could disrupt endocrine systems (Chassaing et al., 2023).

It is important to recognize that while food preservatives can offer benefits in terms of food safety and quality, there is a pressing need to address the potential health risks associated with certain synthetic food preservatives. In response to these concerns, to safeguard consumer health, global regulatory authorities maintain rigorous oversight of food preservative usage, ensuring their safe application in the food supply.

Refined sugars and natural sweeteners

The controversy surrounding artificially lab-manufactured products extend to the utilization of synthetic sweeteners, including aspartame, saccharin, and advantame. Concerns regarding potential health risks associated with the consumptions of synthetic sweeteners have been raised in certain studies and anecdotal reports. Certain individuals have experienced side effects following the consumption of artificial sweeteners, such as headaches, gastrointestinal discomfort, and an unpleasant aftertaste.

In light of the potential adverse effects of artificial sweeteners, individuals and the food industry have increasingly embraced natural sweeteners like stevia and maltitol, commonly found in sugar-free candies, chocolates, chewing gum, and various confectionery products. Research suggests that these sugar substitutes are not fully absorbed by the body during digestion, leading to a lower impact on blood sugar levels compared to sucrose, or table sugar. Another noteworthy natural sweetener is coconut sugar, recognized for its low glycemic index (GI). Its minimal impact on blood sugar levels often makes it a preferred alternative to refined sugar: its glycemic index is reported to be three times lower than that of refined sugars.

Paradoxically, some studies have suggested that consuming of artificial sweeteners may not result in the anticipated weight loss and could even be associated with weight gain in some cases. It is hypothesized that artificial sweeteners trick the body into thinking that it is consuming sugar, which then trigger the release of insulin. Insulin is a hormone that has control sugar levels in the bloodstream and helps the body store calories as fat. The concerns with these artificial sweeteners is that it could lead to insulin increase, and potentially contribute to insulin resistance, Another issue is that when the body does receive the expected calories from artificial sweeteners, it might lead to imbalances in hunger and satiety signals.

Addictive foods and food related addictions

Sugar, primarily in the form of sucrose and high-fructose corn syrup, has been recognized as having addictive properties. Other potentially addictive foods include processed foods high in refined carbohydrates, meats like sausage high in fat, salt and flavor enhancers, sweets, like pastries, donuts, and other sweet baked goods made with a combination of sugar, salt and fat. These dietary components have been associated with addictive behaviors, contributing to over consumption, associated with potential health issues, and higher order cognitive deficits.

Imagine you're in a coffee shop and you see a delicious pastry prominently displayed. Your frontal cortex, the part of your brain responsible for decision-making, quickly engages in response to this visual stimulus. If the frontal cortex determines that the pastry has a low value, perhaps because you've recently eaten or you're not hungry, it will communicate with the prefrontal cortex, that part of the brain involved in decision-making. The prefrontal cortex will then interface with the ventral tegmental area (VTA), a crucial component of the brain's reward system. This communication acts as a regulatory mechanism, similar to a red traffic signal, effectively halting any lingering desire for the pastry.

However, if the frontal cortex assigns a high value to the pastry, perhaps because it looks particularly delicious or you have a sweet tooth, a different sequence of events unfolds. The reward and pleasure pathways in your brain ignite, as if a symphony of pleasure centers is lighting up in response to this tempting treat. Your brain is essentially saying, "This pastry is worth it!" As a consequence of this heightened valuation, dopamine, a neurotransmitter that has a key role in motivation and reward, is liberally released into the neural circuitry. Dopamine compels you to satisfy your craving, and ultimately, you succumb to the irresistible allure of the pastry. You purchase it and savor it in a gratifying manner. This particular experience is etched into your cognitive framework as a positive one, further fortifying your affinity for similar pastries in future encounters.

On the other hand, if a previous encounter with a similar pastry left an unpleasant impression, perhaps due to its stale or excessively sugary nature, your brain would likely categorize this particular pastry as undesirable. The frontal cortex would swiftly transmit signals to the prefrontal cortex, and together, they would engage in communication with the VTA (ventral tegmental area) to suppress any potential cravings. In essence, our brain would declare, "This pastry is not worth indulging in!" In this scenario, dopamine would not be released, effectively quashing the temptation to indulge. You would likely continue on your way, unfazed by the presence of the pastry, your taste buds still basking in the pleasant memory of your last satisfying meal.

Whether one surrenders to the pastry's allure or successfully resist its emptation, our brain is continuously evaluating the situation, carefully weighing the potential rewards and consequences. The intricate interplay between the frontal cortex, prefrontal cortex, and VTA acts as a delicate balance between impulsive urges and controlled or even obsessive thinking and behaviors, shaping your decisions and influencing your dietary choices.

More nutrient-dependent brain regions

As we have previously discussed, the brain regions rely on a steady supply of food nutrients to orchestrate a complex symphony of functions. These brain regions produce neurobiochemical compounds, each serving specific functions in the regulation of cognition, mood, sleep, and various other critical physiological processes.

The hippocampus: Role of fatty acids and antioxidants on memory. The hippocampus is a seahorse-shaped neural structure situated within the medial temporal lobe. The hippocampus is intricately associated with different forms of memory. Notably, autobiographical memory, a subset of episodic memory, encompasses recollections about oneself, including emotions, relationships, and life events (Davis, 1999). In contrast, contextual memory involves the capacity to retain the environmental circumstances in which information was acquired. Furthermore, the hippocampus assumes a central role in declarative memory, facilitating the conscious retrieval of factual knowledge and information (Yavas, Gonzalez & Fonselow, 2019).

Omega-3 fatty acids and antioxidants (e.g., vitamins, curcumin found in turmeric, and selenium) represent two dietary constituents that have demonstrated the ability to enhance memory and cognitive functioning through their support of hippocampal neuron health and maintenance. The inclusion of food sources rich in omega-3 fatty acids, such as fatty fish, flaxseeds, and walnuts, coupled with the consumption of a diet abundant in fruits and vegetables, contributes to optimal hippocampal performance and augmentation of memory capabilities (Welty, 2023). Over the long term, adopting a diet replete with these essential nutrients holds the potential to bolster overall health and foster cognitive longevity.

Aside neurotransmitters, hormones such as cortisol and testosterone also significantly impact hippocampal function. Testosterone offer protection to the hippocampus. Conversely, cortisol, released in response to stress, or in response to a high sugar diet, has the potential to damage the hippocampus. Excessive cortisol levels in the bloodstream, a condition known as hypercortisolism, can lead to hippocampal shrinkage and result in various cognitive issues, including problems with concentration, memory, decision-making, and spatial orientation. In addition to cognitive challenges, hypercortisolism has broader health implications, contributing to high blood pressure, cardiovascular diseases, diabetes, osteoporosis, and weight gain (Uwaifo & Hura, 2023; Miller & Auchus, 2020).

The hypothalamus: Orchestrating nutrient harmony for optimal brain function. The hypothalamus, located at the core of the brain, is primarily recognized for its vital role in regulating various physiological functions. However, it also plays a significant role in cognitive processes, encompassing emotion regulation, stress response, memory and learning, motivation and rewards, and social behavior. The physiological functions coordinated by the hypothalamus encompass appetite and feeding behavior, hormone regulation, circadian rhythms, and autonomic functions (Morton et al., 2006). The hypothalamus, through its intricate connections with other brain regions, ensures the precise secretion of a host of hormones and neurotransmitters (Goel et al., 2023)

One of the primary roles of the hypothalamus is the regulation of glucose levels, ensuring that the body maintains a stable supply of this essential energy source. In addition, it plays a crucial role in protein utilization, which is essential for maintaining neurohormone (e.g., oxytocin) balance and optimal brain function. Amino acids, derived from dietary protein sources such as meat, dairy, and legumes, are utilized in the synthesis of hormones like insulin, thyroid hormones, and sex hormones (Cota et al., 2006). Furthermore, neurotransmitters like dopamine, serotonin, and norepinephrine, which are integral for mood regulation and cognitive performance, rely on amino acids for their synthesis (Fernstrom, 2005). In the absence of sufficient dietary protein, the synthesis of hormones could be impeded, potentially affecting mood, cognition, and overall brain function.

The amygdala: The neuro-nutritional nexus. The amygdale is an almond-shaped cluster of nuclei deep within the brain temporal lobe. It is involved in processing emotions, such as fear, anger and pleasure. The amygdala also contributes to the domains of learning and memory, especially for highly emotionally charged events, such as traumas. The amygdala has intricate connections with the hippocampus. These connections allow the amygdala to influence the encoding and storage of memories in the hippocampus. In particular, the amygdala can signal to the hippocampus which memories are important to remember and which can be discarded (Phelps, 2006).

Among the essential nutrients that emerge as key players in supporting the amygdala, magnesium and tryptophan take center stage. Tryptophan, an essential amino acid, serves as a precursor to serotonin, a neurotransmitter that has a crucial role in regulating mood, emotion, and overall well-being (Young, 2011). Meanwhile, magnesium is abundant in nuts, seeds, and dark chocolate, while tryptophan, is found in turkey, chicken, and nut. Magnesium is essential for the transmission of nerve impulses and the contraction of muscles. It helps regulate blood pressure, by relaxing blood vessels, reducing the risks of heart diseases, such as heart arrhythmias

The basal ganglia: Integrating nutrition, cognition, and reward. The basal ganglia, a cluster of deep-seated nuclei residing within the central nervous system, have historically been associated primarily with motor functions, particularly in the regulation of voluntary movements (Bostan & Strick, 2018). However, recent advancements in neuroscience have unveiled the basal ganglia's broader significance as a critical cerebral region that seamlessly integrates nutritional cues, cognitive processes, and reward-driven mechanisms.

The basal ganglia rely on essential fatty acids, like omega-3, to support the structural integrity of neuronal membranes and promote synaptic plasticity. Also closely associated with the basal ganglia's functions are micronutrients such as vitamins and minerals. These micronutrients (e.g., vitamins C and B6 along with cooper, magnesium and zinc) are essential for the synthesis of dopamine, a neurotransmitter. A deficiency in these nutrients could disrupt dopamine signaling, potentially impacting reward-based decision-making and motor control.

It is worth noting that dopamine is produced in several regions of the brain such as the hippocampus and the amygdala. However, other neurobiochemical compounds, including dopamine, are also produced in peripheral tissues like the adrenal glands, where they serve distinct functions from their role in the brain. Moreover, the gut also produces an array of neurobiochemicals (e.g., dopamine as well as serotonin, endocannabionoids, peptides, and hormones) that help communicate with the brain and other body areas. This connection between the gut and the brain is often referred to as the "gut-brain axis," and it involves bidirectional communication between the central nervous system (CNS) and the enteric nervous system (ENS), which is a complex network of neurons in the gastrointestinal tract (Anderson, Cryan & Dinan, 2017; Mayer, 2016).

The pineal gland: Regulating bodily functions and promoting brain health. The pineal gland is a small, pinecone-shaped structure located at the base of the brain, just beneath the hypothalamus. As a vital component of the endocrine system, the pineal gland assumes a central role in regulating a multitude of bodily functions, transcending the realms of sleep and reproduction to influence growth, metabolism, and immune function.

The pituitary gland produce a variety of hormones and neurotransmitters, including melatonin, serotonin, and the thyroid-stimulating hormone (TSH). The production of these essential substances depends on the availability of specific amino acids derived from the diet. A diet abundant in lean meats, poultry, fish, dairy products, and plant-based protein sources can supply the requisite amino acids to facilitate hormone production by the pineal gland (Wang et al., 2021). Conversely, an insufficient intake of proteins or the amino acid tryptophan may limit serotonin production, subsequently diminishing melatonin synthesis, and potentially affecting the circadian rhythm and the sleep-wake cycle (Reid, Gee-Koch & Zee, 2011)).

Let’s note that the regulation of the circadian rhythm is highly dependent on exposure to natural light during the day and darkness at night (Foster & Kreitzman, 2013). An improper diet that leads to disturbances in sleep patterns or reduces the body's ability to respond to light cues can disrupt the pineal gland's melatonin production (James & Carter, 2020).

The dysfunctions of the pineal gland can manifest in various neurological and cognitive issues. For instance, irregular secretion of growth hormone (GH) has been linked to growth disorders in children, such as dwarfism or gigantism (Kriström, & Lundberg, 2018). Notably, GH, aside from its role in growth and development, also exhibits influence on aging and lifespan. Some potential advantages of growth hormone replacement therapy in adults encompass improvements in muscle mass, bone density, mood enhancement, and increased cognitive functions, including memory and attention.

The pituitary gland: The master gland of the endocrine system. The pituitary gland, a pea-sized organ situated at the base of the brain, serves as a pivotal component of the endocrine system. This gland is anatomically divided into two lobes, namely the anterior and posterior pituitary, each endowed with distinct functions (Amar & Weiss, 2003; Melmed, 2011; Smith & Vale, 2006). Recognized as the "master gland," the pituitary gland assumes a critical role in the orchestration of the endocrine system and the maintenance of overall health.

The proper functioning of the pituitary gland relies on a diverse range of nutrients. For example, Iodine, a trace element found abundantly in iodized salt, seafood, and dairy products, is indispensable for synthesizing thyroid hormones (T3 and T4). These hormones, in turn, significantly influence pituitary function. In tandem, zinc (Zn) plays a pivotal role in hormone synthesis, encompassing those originating from the pituitary gland.

Selenium contributes to the conversion of thyroid hormones, potentially impacting overall endocrine health. Copper, through its involvement in hormone production, also exerts influence on pituitary function. Additionally, vitamins D and E, omega-3 fatty acids, vitamin C, B-vitamins, and protein collectively play a role in maintaining hormonal balance. This intricate interplay of nutrients underscores their collective importance in sustaining the pituitary gland crucial functions within the broader context of the endocrine system.

Melatonin, aging, and longevity

Melatonin levels decline with age due to changes in the pineal gland and other endocrine glands, such as the pituitary and adrenal glands (Hardeland et al., 2015). Studies have shown that melatonin supplementation can extend the lifespan in animals, and promote longevity in humans. For example, one study found that mice that were given melatonin supplements lived an average of 20% longer than mice that did not receive melatonin supplements. Another study reported that people with higher levels of melatonin had a lower risk of death from all causes, and a third study found that people who took melatonin supplements had a lower risk of developing Alzheimer’s disease (Barthi et al., 2023).

Melatonin is reported to promote longevity in a number of ways. First, melatonin is a powerful antioxidant. It protects cells from damage caused by free radicals. Second, melatonin has anti-inflammatory properties. It helps to reduce inflammation, which is a major contributor to aging and age-related diseases. Third, melatonin helps to regulate the sleep-wake cycle. Disruptions to the sleep-wake cycle have been linked to a number of age-related health problems, including cardiovascular disease, diabetes, and obesity (Poeggeler, 2005; Suzen, 2018).

Conclusion:

The findings presented in this review highlight the profound connection between nutrition and brain health, emphasizing the indispensable role of food nutrients in facilitating the functioning of brain regions indispensable for producing neuromodulators like neurotransmitters and hormones. These critical substances have a central role in fostering overall health and optimizing cognitive function. Any imbalances in essential nutrients, whether in excess or deficiency, can disrupt the delicate coordination among brain regions involved in the production of neurobiochemicals, resulting in impairments in cognitive function and overall health.

It is noteworthy that while the body can store some nutrients for short-term use, such as fat-soluble vitamins and glycogen, it requires a continuous supply of essential food nutrients on a regular basis. The conversion of these nutrients into neurotransmitters or hormones and other biochemicals the body and brain require is a complex and dynamic process that occurs over different time frames. For example, the complete conversion of the amino-acid tyrosine, precursor to catecholamines like dopamine, norepinephrine, and epinephrine, can take anywhere from minutes to a few hours. This conversion, involving multiple enzymatic steps, can be influenced by various factors, including the availability of cofactors (such as vitamins and minerals), the type of nutrients that are available during the conversion process, the regulatory feedback mechanisms, and the specific metabolic state of the cell.

In essence, as the brain serves as the central regulator for all bodily functions, to operate optimally, the body including various brain regions needs to work in a coordinated manner. In order to achieve this, a balanced and varied diet incorporating a mix of different food groups is generally recommended to ensure an adequate supply of essential nutrients. The specific nutrient needs can also vary based on more factors such as age, sex, dietary preferences and habits, health status, body-weight and composition, genetics, medical conditions, pregnancy and lactation, and physical activity level.

AI generated meals/diets: In instances of inadequate or insufficient nutritional intake, fluctuations in essential nutrients levels can impact bodily function and cognitive processes. Thankfully, the integration of artificial intelligence (AI) technology and nutrition heralds a transformative development in the health and wellness domain. This technological advancement enables individuals to access personalized nutritional guidance tailored to their specific dietary requirements, whether for managing existing health conditions or enhancing overall well-being.

Moreover, the incorporation of educational support, customized meal plans, nutritional analysis, real-time monitoring through health tracking devices, and the continuous learning and improvement inherent in the process significantly enhance the comprehensive nature of this innovative application. This holistic approach ensures that individuals not only receive tailored dietary recommendations but also ongoing support and refinement based on their evolving needs and feedback.

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Further readings

Coleman, Daniel. (1995). Social Intelligence. Bantam Books.

Logan, A. C. (2006). The brain diet: The connection between nutrition, mental health, and intelligence. Cumberland House. Nashville, Tennessee.

Reader’s digest. (1997). Foods that harm, foods that heal: An A-Z guide to safe and healthy eating. The Readers’ Digest Association Limited.