Nutrition and the Brain
Along with antioxidant research, brain nutrition is one of the fastest-growing and most exciting categories of nutrition science. It is also one of the most important. The brain shares with the liver the dual distinction of being on the one hand enormously important to survival and well-being, and on the other hand enormously vulnerable. Fortunately, as is the case with the liver, the brain is extremely responsive to nutritional protection and optimization.
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At no time in human history has the importance of the brain to survival and quality of life been more evident. We live in a world of high technology, in which "computer literacy" is often as important to getting a job as the ability to read. The proliferation of information and "labor-saving devices," which were supposed to make our lives easier, has produced the opposite result: our lives have become bewilderingly complex. To add irony to irony, the industrial revolution that has made all of this high technology possible has altered our lives in ways which may be extremely detrimental to brain health.
In order to function optimally, the brain needs the proper nutrients, which may be compromised in the modern world. The pressures of daily life make it difficult for modern Americans to devote the necessary time to prepare food properly. As a consequence of this and a constant barrage of advertising, a high proportion of many people's diets consists of fast foods and packaged foods, low in many essential nutrients and high in sodium and sugar. Excess sodium can create a relative imbalance in the sodium/potassium ratio, and potassium is an important nutrient for nerve conduction (see "Potassium," page #). Excess simple sugar intake can, paradoxically, cause low blood sugar, thus depriving the brain of the fuel it needs.
Even people who eat a 'balanced' diet may be affected by the fact that the soil on which our grains and vegetables are grown is often depleted of nutrients and minerals that may be essential for the health of the brain. Commercial farming uses chemical fertilizers to artificially enhance the growth rate of plants. The most common such fertilizer is a simple mixture of nitrogen, phosphorus and potassium. Over time, complex organic substances and trace minerals are leached out of the soil, resulting in vegetables that may look big and healthy, but are devoid of much of the nutrient and mineral complexity needed to optimally nourish the brain.
Complex Nutritional Needs for a Complex Organ The human brain is not only the most complex organ in the body, it is arguably the most complex object in the known universe. Its nigh-unimaginable complexity has evolved in layers, which can be seen when one examines its various parts, all of which have specialized functions. The brain stem or 'reptilian brain,' the most ancient and primitive part of our brains, determines our general level of awareness, "notifies" the rest of the brain in a general way about incoming data, and controls basic bodily functions such as breathing and heart rate. The cerebellum or 'little brain' is responsible for maintaining and adjusting posture, coordinating muscle movement and storing 'memories' for correcting motor functions. The cerebellum in the human brain has more than tripled in size in the last million years. The limbic system, called the "mammalian brain" because it is most highly developed in mammals, developed some two hundred to three hundred million years ago. In addition to playing a key role in primal emotional reactions such as hunger, sexual arousal and the ''fight or flight' reflex, it helps to maintain body temperature, blood pressure, heart rate and blood sugar levels. One portion of the limbic system, called the hippocampus, also plays a key role in storing memories.
And finally, much larger and more complex than in any other animal, the cerebral cortex is the part of the brain that makes us human. The cerebral cortex is divided into four sections or lobes: the frontal lobe, which is involved in planning, decision making and purposeful behavior; the parietal lobe, where sensory information from the body is processed; the occipital lobe or "visual cortex," which processes visual information; and the temporal lobe, which is involved with hearing, perception and memory. It is the cerebral cortex that gives rise to all the various levels of thought, from simple decisions like what to order in a restaurant, to creative endeavors like the creation of a new recipe or the writing of a sonnet, to complex, multifaceted challenges that require all of the wisdom and perspective acquired in a lifetime to solve.
Source Naturals carries perhaps the most comprehensive and sophisticated line of brain nutrients available today. These "Neuroceuticals"® optimize the functioning of the brain in three important ways: 1. They boost the energy available to the brain by bolstering metabolic energy-production cycles; 2. They enhance communication between brain cells by supporting the production and action of neurotransmitters; 3. They provide protection for the brain's delicate tissues by enhancing its antioxidant potential; and 4. They provide raw materials to support the structure of healthy cell membranes.
Energy and Neurons
One means of enhancing the brain's activity through nutrition is to boost the energy available to it. The brain weighs only about three pounds - about 2% of our total weight - yet uses 15% of the energy generated by the entire body. The reason the brain uses such a huge amount of energy has to do with the way nerve cells, or neurons, carry impulses.
All of the brain's activity, from conscious experience and thought to unconscious instructions to autonomic systems, consists of patterns of activation of neurons. A neuron is a specialized type of cell with a number of branching extensions or processes called dendrites and one long process called an axon. Neurons, like all cells, maintain the proper balance of ion concentration necessary for cell integrity by pumping sodium ions out of the cell and potassium ions into the cell, using ATP-driven protein pumps called Na+K+ ATPase pumps, or sodium-potassium pumps. Potassium ions are allowed to leak out through special ion channels, a process which continues until a negative charge builds up (generated by negatively-charged protein molecules inside the cell). This negative charge prevents any more of the positively-charged potassium ions from escaping, and creates a slight difference in electrical charge between the inside and outside of the cell membrane. The difference in ionic concentration combined with the difference in electrical charge across the cell membrane is called an electrochemical gradient.
Neurons utilize this electrochemical gradient to carry signals. When a neuron receives a message to 'fire,' either from the environment or from another neuron, ion channels open in the cell membrane which allow positively charged sodium ions to flood into the cell, abruptly changing the electrical polarity of a small region of the membrane. This change in polarity causes nearby voltage-gated ion channels to open, allowing more sodium ions to flood into the cell, further depolarizing the membrane and causing more ion channels to open and so on. The opening of sodium channels, depolarizing the cell membrane and forming an electrical wave that travels down the length of the cell, is followed closely by the opening of voltage-gated potassium channels, causing an efflux of potassium that helps bring the membrane back to its resting potential. The sodium-potassium pumps then pump furiously to bring the cell back to proper sodium/potassium balance, readying it to fire again. All of this, at any given moment on the body, is happening in thousands of cells at once. It occurs in a fraction of a second - so quickly that we jerk our hands away from a flame before the thought 'That's hot!' has even registered.
The maintenance of the proper sodium/potassium balance in the nerve cells of the brain requires an astonishing amount of energy. And all of this energy must be produced locally in the brain &endash; no part of the body can 'lend' ATP energy to any other part. Consequently, in addition to the proper fuel - high in complex carbohydrates, low in simple sugars - it is vital for the energy needs of the brain to supply it with an abundance of the nutritional cofactors which act as biochemical 'sparkplugs' in the cellular engine that converts carbohydrates to energy. These nutrients are called coenzymes.
Coenzymes are organic compounds that are utilized by protein catalysts called enzymes as carriers of chemical energy in biological reactions. The 'superstar' of coenzymes is ATP or adenosine triphosphate, often called the "energy coin" of life because it supplies energy in virtually all of life's energy-requiring processes, from the building of new organic molecules to the contraction of muscles to the workings of the brain. Before ATP can supply energy, however, it must be created. This takes place locally inside each cell in three interlocking metabolic cycles called glycolysis, the Krebs cycle and the electron transport chain. In these processes, carbohydrates, organic molecules rich in high-energy bonds between carbon and hydrogen, are broken down into low-energy molecules of carbon dioxide and water, and the resultant energy transferred into ATP. A variety of nutrients function as crucial coenzymes and cofactors in this process, among them all of the B vitamins, minerals like magnesium and manganese, and specialty nutrients such as coenzyme Q10 and lipoic acid. All of these nutrients play key roles in support of optimal brain function.
At one time it was thought that all of the brain's activity was electrical - that nerve impulses 'sparked' across the synaptic gap to trigger other neurons. It is now known that the picture is far more complicated than that.
Neurotransmitters and Nutrition
It has been suspected since 1921 that neurons communicated with each other chemically, but only in the past thirty years has the variety of these biochemicals, called neurotransmitters, and the complexity of their action, been established. More than 50 substances which can be defined as 'neurotransmitters' have been isolated; the most important of these are the small-molecule transmitters, which can be divided into three categories: the amino acid transmitters, which includes gamma-aminobutyric acid or GABA, glycine and glutamate; the biogenic amines, which includes dopamine, epinephrine, norepinephrine and serotonin; and acetylcholine, which is in a class by itself.
When a nerve impulse travels down the length of a neuron and reaches an axon terminal, it causes neurotransmitters to be released from small sacs called vesicles. The neurotransmitters rapidly diffuse across the synaptic gap and plug into ion channels called receptors, causing them to open. Generally, receptors (and the neurotransmitters that correspond to them) fall into two categories: excitatory receptors, which allow sodium ions to pour into the cell, thus initiating a nerve impulse, and inhibitory receptors, which allow negatively-charged chloride ions into the cell and/or potassium ions to flood out, thus preventing membrane depolarization and inhibiting nerve impulses. Excitatory neurotransmitters thus tend to stimulate mental activity whereas inhibitory neurotransmitters tend to quiet it, playing an important role in inactive mental states such as rest and sleep. While the action of neurotransmitters is complex, some general statements can be made about the nerve activity and mental states they are associated with.
How do we form neurotransmitters in the body? Neurotransmitter synthesis is highly dependent upon having the proper materials present, such as amino acids, small, nitrogen-containing organic molecules, and a variety of other nutritional factors. For example, the neurotransmitter acetylcholine is constructed from the B vitamin-like substance choline and a coenzyme form of vitamin B5 called acetyl CoA. Hence neurotransmitters are dependent upon dietary factors for their production. Thus, one highly effective means to increase neurotransmitter production in the brain is to increase consumption of dietary precursors for those neurotransmitters; increased dietary levels of the amino acid glutamine, for instance, may increase brain levels of the neurotransmitters GABA and glutamate, while increased dietary levels of tyrosine or phenylalanine may increase levels of the neurotransmitters dopamine, epinephrine and norepinephrine, collectively known as catecholamines. Much nutrition research has focused on the neurotransmitter acetylcholine, largely because a lack of acetylcholine or impairment of acetylcholine receptors is associated with many forms of age-related cognitive decline. Acetylcholine is one of the most important and abundant neurotransmitters in the human body. It is the neurotransmitter that sends instructions to our muscles to contract (see "Calcium," page #), it is intimately associated with our ability to think and reason, and it is essential for both the storage and recall of memory.
The abundance and activity of neurotransmitters can be enhanced in three ways: 1. In the case of certain neurotransmitters, such as GABA, by consuming the neurotransmitter preformed as a supplement; 2. By consuming the raw materials from which the neurotransmitter is formed in the body; for instance, consuming tyrosine or phenylalanine to support the body's production of catecholamine neurotransmitters; and 3. By supporting the metabolic pathways through which neurotransmitters are generated. The chemical reactions that create neurotransmitters from their constituent products don't happen by themselves; like most biochemical processes, they require a bioenergetic 'push' which is supplied by an organic macromolecule called an enzyme. Most enzymes are inert until they are "activated" by a chemical 'key' in the form of a B vitamin coenzyme or a mineral cofactor (see "Coenzymes," page #). Multiple enzymatic pathways, and hence multiple coenzymes and cofactors, may be required for the synthesis of one neurotransmitter. For instance, acetyl CoA, one of the components of acetylcholine, is a Krebs Cycle compound that contains coenzyme A, a coenzyme form of vitamin B5. The enzyme that creates acetyl CoA from coenzyme A and pyruvate, another Krebs Cycle compound, is activated by thiamin pyrophosphate, a coenzyme form of thiamin (vitamin B1). The other component of acetylcholine is choline, which the body synthesizes from the phospholipids phosphatidyl choline and its precursor, phosphatidyl ethanolamine, a chemical reaction which is activated by vitamin B12 and folic acid. And so on. One of the "design features" of the brain that gives it its remarkable resilience is the high degree of 'redundancy' inherent in its structure. This means that, even though neurons do not reproduce and some of our brain cells die every day, the 'circuits' associated with various kinds of mental activity are duplicated many times over; if one neural pathway is damaged, another can often take over its function. Consequently, we may not notice the decline in cognitive ability that takes place with age until it becomes acute, but this doesn't mean it's not happening. Nutritional protection for the brain is essential throughout life.
Protecting the Brain With Nutrition As centrally important to human life, and as complex and powerful as the brain is, it is also extremely delicate and vulnerable. For this reason, the body takes extreme measures to protect it. Unlike any other bodily part, the brain is completely encased in a hard, thick container of bone. Beneath the surface of the skull, the brain is cushioned against impact by cerebrospinal fluid and three layers of membranes. And more than any other organ, the brain is extremely particular about what kinds of substances may be allowed to make contact with it. It is protected against the body's internal environment by specialized capillaries referred to collectively as the blood-brain barrier.
But despite these protective measures, the brain can still be harmed by insidious molecules known as free radicals. Free radicals are deposited in the body in two ways: either they are introduced to the body from the outside world, or they are actually produced within the body as a by-product of metabolism. Certain lifestyle habits, such as smoking and drinking alcohol, promote free radical formation in the body. Free radical damage is a particular danger in the brain for two reasons: one, because the brain uses such an enormous amount of energy and two, because apart from water, the brain is mostly made of fat. One of the primary ways in which free radicals cause damage to bodily tissues is by the peroxidation, or rancidification, of fats or lipids.
The membranes of neurons, like all cells, are composed of lipids, as is the myelin sheath. Both the integrity of the myelin sheath and the integrity of neurons themselves can be compromised by free radical damage. Free radicals attack cell membranes by setting off electrochemical chain reactions which can spread like a brush fire, altering the chemical composition of fats and making them rancid. This process of lipid peroxidation can produce a host of toxic compounds, including hydroperoxides, epoxides, and aldehydes. Lipid peroxidation also produces cellular debris called lipofuscin or 'age pigment.' This yellow-brown pigment accumulates in the brain and other vital organs as we age. Some researches believe lipofuscin is injurious to brain cells, especially those researchers who support the "membrane theory of aging," which postulates that aging is the result of a lifetime of accumulated free radical damage to cell membranes. Fortunately, nature has created substances which neutralize free radicals called antioxidants. The importance of antioxidants to the brain can be seen by looking at the degree to which the body hoards antioxidants in brain tissue. The level of vitamin C in the cerebrospinal fluid (the fluid that surrounds and cushions the brain) is ten times higher than the level of vitamin C found in plasma.
In recent years, certain plant pigments, or bioflavonoids, have been found to have potent antioxidant activity. Source Naturals has dubbed these amazing substances Plantioxidants™. Certain of these nutrients, including ginkgo and grape seed extract (Source Naturals' product Proanthodyn™) have a special affinity for the brain. Aside from their powerful antioxidant action, these plantioxidants work synergistically with vitamin C to promote the construction of collagen. Collagen is the most plentiful protein in the body; it is the structural material out of which the intercellular connective mesh is formed which gives form and shape to our brains and all of our other tissues. It is vital to the integrity of the tiny capillaries that deliver blood to the brain, vessels with a diameter so small that red blood cells can only pass through one at a time, in single file. Ginkgo and Proanthodyn support the health of these brain capillaries, first by helping to maintain their integrity and flexibility, and second by dilating them, thus actually increasing the flow of blood to the brain.
Neuron Structure & Phospholipids Neurons are the only cells in the body that do not reproduce; the number of neurons we have when we are born is the maximum we will ever have. This doesn't mean, however, that the brain does not develop. Neurons can develop new connections to other neurons by growing new dendrites. A single neuron may have more than 100,000 dendrites; this web of dendritic connections is the "hardware" that largely determines the limits of our intelligence, memory and ability to perceive. Neurons continually die as we age, but the number of functional dendritic connections in a healthy brain may make up the difference, preventing the gradual loss of mental faculties we tend to associate with aging in this culture. Unfortunately, for most people in America this is not the case.
The integrity of this dense web of dendritic connections is dependent upon the proper balance of lipids in our nerve cell membranes. The membranes of nerves, like all cell membranes, are composed of phospholipids &endash; organic molecules composed of two fatty acid chains attached to a backbone of glycerol (a 3-carbon organic alcohol). The third carbon of the glycerol molecule is attached to a phosphate (a molecular group that contains phosphorus and oxygen), which is in turn attached to two long hydrocarbon chains known as fatty acids. The phospholipid phosphatidyl choline also has a molecule of the B. A variety of different phospholipids, with different properties, make up the cell membrane. Studies have shown that the lipid composition of cell membranes changes with age, affecting such factors as membrane viscosity, which can interfere with the cell's ability to exchange nutrients and waste products with the surrounding environment. One of the effects of this may be a gradual reduction in the number of dendritic connections in the aging brain.
This, of course, is another key area in which nutrition can make a positive difference in brain health. Lecithin, a rich mixture of phospholipids found in many plant and animal tissues, has been available as a dietary supplement for years; lecithin contains virtually all of the raw materials from which the phospholipid portion of nerve cell membranes is constructed recent years, high-quality plant sources of two extremely important cell membrane phospholipids, phosphatidyl choline and phosphatidyl serine, have become available.
Putting it All Together: Comprehensive Nutritional Support for the Central Nervous System Ultimately, all of the health and nutrition issues - indeed, all the issues of any kind - that we face begin and end with the brain. The body attests to the brain's importance by devoting a huge share of its vital nutritional resources to the care and feeding of this single, and singular, organ. At Source Naturals we have mirrored this fact by devoting the lion's share of our resources to developing the most comprehensive and advanced brain nutrition supplements in existence.
Source Naturals Neuroceuticals, like all of Source Naturals' specialty formulas are based on the concept of dynamic homeostasis. The dynamic homeostasis model of human health recognizes that the body is intelligent: it constantly monitors and 'fixes' itself, with tools thousands of times more sophisticated than anything designed by science. The body, however requires the proper raw materials to conduct its work: raw materials that can only be supplied through nutrition.
Knowing what the nutritional issues associated with optimal brain nutrition are: supporting the brain's production of energy, providing the raw materials for the production and utilization of neurotransmitters, protecting the brain's delicate structures, and supporting the structure of the brain's cell membranes - can help you make informed choices about your nutritional needs. Source Naturals is committed to being a partner in your quest for optimal performance, health and happiness.
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