Some day in the future, when you're watching a 21st-century remake of The Graduate, don't expect "plastic" to be the word whispered into Benjamin's ear. Instead, it's likely to be "neurotransmitters."
That night as you're getting ready for bed, you'll probably be eating a snack that's been specially "nutritioneered" for you to sleep soundly and perchance to dream. It will be one of many custom foods and menus formulated for you — based on your personal genetic disposition and metabolic profile — to achieve the mood or mind-set you desire.
As you drift asleep, assured of a wonderful night ahead, you might even laugh as you remember back to the 20th century when, along with everyone else, you were an amateur chemist experimenting daily with your brain — for better or worse. Back then you didn't realize how direct the connection was between what you ate and how you felt and thought.
You didn't really understand that a single meal modified the production of your neurotransmitters, the chemicals manufactured by your brain that motivate or sedate, focus or frustrate. Back then, you thought it was some unknown force that shifted your mood and changed your mind.
Implements of Science
The applied science of nutritioneering will have been born out of discoveries made at the dawn of the new millennium. Using nutriments appropriate to an individual's unique genetic profile, metabolism, and environmental circumstances, nutrition scientists eventually learned to more precisely predict and persuade neurotransmitter production. Nutritional supplements evolved into "nutritioneered complements" that were, in effect, true implements of science (rather than magic bullets fired from marketing departments).
Molecules of the Mind
Neurotransmitters are the mantras muttered in the minds of all Earth's creatures, ever since ancient anenomes first imagined them a half-billion years ago. These brain chemicals allowed animals to emerge from the sea and humans to ascend from the primordial gene pool of thoughtlessness. But, what are they? And most importantly, how can our knowledge of them help us continue to be thoughtful and hopeful, helpful and happy — generation after generation?
Neurotransmitters are chemicals that transmit information between your neurons, the hundred billion brain cells that are responsible for the totality of who you are. They are involved on everything from memory and mental performance to mood and movement. Your personality, your performance, your potential, all emanate from the remarkable ability of your neurons to communicate with each other.
A healthy neuron makes thousands — sometimes hundreds of thousands — of intricate connections with of other neurons. This creates a multi-trillion maze capable of performing 20 million billion calculations per second.
Communication within a Neuron — Local Charges
Neurons use two types of communication, local and long distance. Within a neuron, a bioelectric impulse or "action potential" travels to the cell body through an array of nerve fibers called dendrites. The impulse travels away from the cell body through an antennae called the axon.
Dendrite comes from the Latin word for "tree," because they form into many tiny branches that receive information from axons of neighboring neurons. Axon, from the Latin word for "axle" or "axis," is a single insulated fiber that sends the bioelectric current out to its terminal — which can be inches or even several feet away. The size and quality of the axon determines how fast the impulse travels, which can range from 1 to 150 mph.
A neuron's bioelectric impulse originates in the cell membrane at the beginning of the axon near the cell body. Membrane channels and pumps control an extremely rapid exchange of sodium and potassium ions across the membrane. This is what creates and transmits the action potential along the axon.
A Sports Analogy
The ice sport of curling gives an idea of how the nerve impulse is generated in neurons. In this sport, two players with brooms move along the ice and frantically sweep back and forth next to each other. They represent the sodium and potassium ions being pumped in and out of the neuron. Following this sweeping action, a large "stone" slides nearly friction-free along the ice. Similarly, in the wake of the ion dance — this dosido of sodium and potassium — an electric current is generated.
A single one of your neurons produces almost a tenth of a volt, and the total electrical activity in your brain is easily measurable with an EEG. When this activity completely ceases, you are pronounced dead.
Communication Between Neurons — Long Distance Plan
Between neurons, chemical communication is used instead of electrical. Within the cell body of a neuron, many different types of neurotransmitters are manufactured and shipped to the end terminals of the axon. Here they're stored in bubbles called vesicles, where they wait to cross a tiny gap over to the dendrites of other neurons.
Synapses — Meetings in Your Mind
Even though the bioelectric impulse speeds along the axon at up to 150 mph, it does not jump the gap, which is called the synapse (from the Greek word for" junction"). Instead, it signals the vesicles to burst and the neurotransmitters to spill out across the synapse, where they're caught by receptor molecules on the membrane of the target neuron's dendrites.
More than a hundred different neurotransmitter varieties have been identified in the brain, and others are continually being discovered. Our knowledge of the specific functions of neurotransmitters is in its infancy, but it seems that each one probably plays some role in most behaviors. In general, a neurotransmitter is often identified by whether it either excites or inhibits (in various degrees) the nerve impulse in target neurons. This is where receptors come into play.
Receptors — Where Chemistry Meets Physics
A receptor is a large protein molecule riding on a neuron's membrane — like a lotus floating on the green surface of a natural pond. Thousands of atoms give a receptor its unique geometric shape and magnetic configuration. This "geomagnetic lock" is designed to accept only the right key — the neurotransmitter whose molecular shape and polarity fit precisely into the lock. The correct spatial mating of these molecules is at the crux of your entire nervous system.
Like the spaghetti that's ready, neurotransmitters "stick to the wall" — link to the receptors on the receiving neuron. There are as many kinds of receptors as there are neurotransmitters, with numerous subtypes of receptor for any given neurotransmitter.
This extraordinary mating game of neurotransmitter and receptor influences every aspect of your behavior, spanning the gamut of human experience from physics to chemistry to biology to psychology to sociology. And it has everything to do with what you eat.
The Way to Your Brain is Through Your Mouth
The remarkable thing about neurotransmitters is that you influence their levels whenever you eat. That's because most neurotransmitters are made from the amino acids contained in dietary proteins. Proteins are the building blocks of the animal kingdom, and amino acids are the building blocks of proteins. When your body digests protein, it uses those amino acids to manufacture the 50,000 different proteins it needs, including neurotransmitters and chromosomes, hormones and enzymes, antibodies and muscles, hair and nails.
Your body's proteins are made from combinations of just 22 different amino acids, eight of which are considered essential nutrients for humans and must be obtained from food. The others usually can be synthesized from the eight and are called "nonessential," but they are equally vital to life.
Because of the importance of amino acids to all the cells in your body, your brain can be at a disadvantage. If your amino acid levels are low, then brain cells will have to compete with body cells which have an advantage, because they can more easily take up essential amino acids from your bloodstream.
Border Crossings
Neurotransmitters are synthesized within your neurons, so their production depends on which amino acids actually get into your brain. There is a barrier, however, that complicates matters. Not everything you eat is readily available to your brain cells.
To reach your neurons, amino acids must first pass through your blood-brain barrier, and they can only do so by "active transport." In a sense, amino acids must be "driven" across the border in a molecular transport vehicle, because the capillaries in this barrier are like a "Berlin Wall" whose crossing is carefully supervised. In contrast, capillaries in the rest of your body are more like a "U.S.-Mexican border" where elements — desired or not — can readily cross on their own.
To further complicate matters, amino acids are assigned a particular "truck." Amino acids in the same group compete for the limited space in that transport molecule. For example, the amino acids tryptophan and tyrosine both belong in the same category and must enter your brain together. If tryptophan dominates, your neurons will make more serotonin, the calming neurotransmitter that promotes contentment and is responsible for normal sleep. If tyrosine wins out, then you will synthesize more norepinephrine and dopamine, stimulating neurotransmitters that promote alertness and activity.
Tyrosine is crucial to brain power and alertness in another way. It's also needed for your body to make active thyroid hormones. Therefore, low blood levels of tyrosine are associated with an underactive thyroid gland. An extreme deficiency causes severe mental retardation known as cretinism.
Eat Protein for Stimulation, Carbohydrates for Relaxation
Although both tryptophan and tyrosine are derived from protein, a carbohydrate meal will increase your brain's tryptophan, and hence, serotonin levels. That's because the glucose from digested carbohydrates causes your body to secrete insulin. This hormone tells your cells to pull amino acids out of the bloodstream for storage — except for tryptophan. It keeps circulating and becomes predominantly available to your neurons, who use it to make the serotonin that makes you feel satisfied, relaxed, and ready for a nap.
On the other hand, you could be energized for hours after a morning meal high in protein, because it raises tyrosine levels in your blood and brain, causing your neurons to manufacture norepinephrine and dopamine. Unfortunately, after a night's sleep when blood sugar levels are low, you may be tempted to eat a high-carbohydrate breakfast.
Complete and Complementary Proteins
Dietary proteins fall in to two groups. Complete proteins contain ample amounts of all the essential amino acids. Fish and meat, fowl and eggs, cheese and yogurt are complete proteins. On the other hand, grains and legumes, seeds and nuts, leafy green vegetables and a variety of other foods are incomplete proteins, because they provide only some of the essential amino acids.
You can, however, combine different incomplete proteins to obtain all necessary amino acids. Such complementary proteins have been known for centuries and are part of traditional diets around the world. Rice and beans, rice and lentils, rice and tofu are examples.
Ensuring adequate neurotransmitter levels is crucial for optimal brain heath and fitness, however, poor nutrition is not the only obstacle. Stress, infection, and drugs tend to diminish levels, as do age-related impairment of digestion and cerebral circulation.
Better Living Through Brain Chemistry
As always, it's a matter of balance. Eat foods that provide the full spectrum of amino acids your brain needs for an appropriate harmony of energizing and calming neurotransmitters. Pay attention to what you eat and how you feel afterward. Learn what works best for you, according to your daily activities and need for rest.
Food is your best source of amino acids. Be cautious about trying to manipulate your intake with individual amino acid supplements. These potent metabolic factors have many functions in the body that we are only beginning to understand. They are not to be taken lightly.
Science continues to unravel the neurotransmitter mystery, and it's only a matter of time before that knowledge opens up a new era of "Better Living Through Brain Chemistry."
The Neurotransmitters that Change Your Mind and Shift Your Mood
Serotonin is the calming neurotransmitter important to the maintenance of good mood. It promotes contentment and is responsible for normal sleep. Serotonin is synthesized from tryptophan in the presence of adequate vitamins B1, B3, B6, and folic acid. The best food sources of tryptophan include brown rice, cottage cheese, meat, peanuts, and sesame seeds. Low serotonin levels produce insomnia and depression, aggressive behavior and increased sensitivity to pain.
Norepinephrine, also called noradrenalin, is the primary excitatory neurotransmitter needed for motivation, alertness, concentration, as well as for good mood. It is needed for your brain to form new memories and to transfer them to long-term storage. Norepinephrine also influences the rate of metabolism. Like a hormone, it travels in the bloodstream to arouse brain activity with its adrenalin-like effects.
Dopamine is crucial to fine muscle coordination. People whose hands tremble from Parkinson's disease have a diminished ability to synthesize dopamine. This neurotransmitter is also needed for healthy assertiveness and sexual arousal, proper immune and autonomic nervous system function.
One of the most vulnerable key neurotransmitters, dopamine levels are depleted by poor sleep or stress. Alcohol, caffeine, and sugar all seem to diminish dopamine activity in the brain. It's also easily oxidized, therefore adequate intakes of vitamins C and E are necessary to protect dopamine-using neurons from free radical destruction.
Norepinephrine and dopamine are both important for motivation and a sense of readiness to meet life's challenges. Your neurons manufacture these neurotransmitters from the amino acids tyrosine or phenylalanine in the presence of adequate oxygen, vitamins B3, B6, and C, folic acid, iron, and copper. Sources of tyrosine include almonds, avocados, bananas, dairy products, lima beans, pumpkin seeds, and sesame seeds.
An increased incidence of depression and other mood disorders are associated with low levels of dopamine and norepinephrine, while increasing the levels of these neurotransmitters might improve mood, alertness, mental functioning, and the ability to cope with stress.
Alcohol Depletes Neurotransmitters
Scientists at the Scripps Research Institute in La Jolla, California concluded from animal studies that heavy alcohol consumption depletes the brain's supplies of the neurotransmitters responsible for feelings of pleasure and well-being — dopamine, GABA, and serotonin. Alcohol also promotes the release of corticotropin releasing factor (CRF) and stress hormones that create tension and depression. This creates a persisting chemical imbalance that leaves the alcoholic vulnerable to relapse.
Alcoholics then drink more to try and get back to normal, but the more they drink, the more CRF is produced. This cycle ultimately raises the amount of alcohol it takes to make an alcoholic feel normal. CRF can remain active for as long as four weeks after someone stops drinking. (American Chemical Society, Aug 27, 1999)
Don't Forget Acetylcholine
Acetylcholine is the primary chemical carrier of thought and memory — the Hermes of your mind. This excitatory neurotransmitter is essential for both the storage and recall of memory, and may be significantly responsible for concentration and focus. It also plays a significant role in muscular coordination. A deficit in acetylcholine is directly related to memory decline and reduced cognitive capacity.
Unlike other key neurotransmitters, acetylcholine is not made from amino acids. Its primary building block is choline, which doesn't have to compete for entry into your brain, so the more choline you consume, the more acetylcholine you can produce. Choline is a fat-like substance belonging to the B family of vitamins and is necessary to metabolize fats. It is found in lecithin as phosphatidyl choline. Foods high in lecithin include egg yolks, wheat germ, soybeans, organ meats, and whole wheat products.
You can boost your acetylcholine levels by taking supplements of phosphatidyl choline, which is also the form of choline most important to the structure of your neural membranes. Vitamin C and B5 are needed for your brain to synthesize acetylcholine, which it does by attaching an acetyl group to the choline molecule — in the presence of choline acetyltransferase, a key brain enzyme. Acetylcholine levels tend to decline with age, in part because of a decreased ability to synthesize this enzyme.
There also may be an increase in acetylcholinesterase, the enzyme that breaks down acetylcholine. This enzyme depletes the actual amount of usable acetylcholine, thus severely compromising memory. This is especially true for memory disorders, including Alzheimer's.
A 1988 study found that deteriorated acetylcholine receptors allowed the accumulation of beta-amyloid protein deposits in the brain that harden and strangle nerve cells. This amyloid plaque is found to be quite prevalent in Alzheimer's. (Japanese Journal of Pharmacology 48;3: 365-71)
DMAE (dimethylaminoethanol) is a natural substance found most abundantly in various fish such as anchovies and sardines. DMAE easily crosses the blood-brain barrier and promotes increased levels of choline in the brain. This can lead to increased production of acetylcholine. DMAE has been used to sharpen memory in normal adults and to treat attention deficit in adults and children.
A Little GABA Do You
Your brain's primary inhibitory neurotransmitter is GABA (gamma-aminobutyric acid), an amino acid that's made from glutamic acid. It is associated with states of calm mental focus and serenity. It helps combat chronic anxiety by preventing neurons from over firing from too much stimulation. GABA also promotes muscle relaxation, so a severe deficiency can lead to convulsions.
Glutamic acid is a major excitatory neurotransmitter involved in mental activity and learning. It increases the firing of neurons in the central nervous system. It also acts as an alternative fuel source for the brain when blood sugar levels are low. The conversion of glutamic acid into glutamine is the only means by which the brain can dispose of toxic ammonia — a natural byproduct of protein breakdown that even at low levels is irritating to neurons.
Taurine is an amino acid neurotransmitter that stabilizes neuron membranes by preventing erratic electrical activity. Found most in brain tissue, taurine fosters a centered calmness by balancing the action of certain excitatory neurotransmitters. It also has antioxidant properties. Taurine also promotes the excretion of excess sodium, thus preserving potassium and magnesium. (Dr. Atkins' Health Revelations, June 1996)
Magnesium helps control the firing rate of neurons, and along with vitamin B1 is an essential nutrient that supports the reparative process that neurons need to offset the stress from the continual firing of the electrical impulse. Low synaptic levels of magnesium can cause hypersensitivity. Noises will sound too loud and lights will seem too bright. This increases the body's response to stress, and because stress affects the kidneys' ability to recycle magnesium, hypersensitivity will continue to escalate. (Optimal Nutrition Review, February 1990)
Magnesium also activates sodium-potasium ATP-ase, a key enzyme in cell membranes that controls cellular sodium-potassium balance, which is absolutely essential to the electrical activity of neurons as well as to the existence of the neuron itself. Cells would burst if the sodium-potassium ratio gets too far out of balance!
References and Reading
Food and Mood by Elizabeth Somer, M.A., R.D., 1995
Prescription for Nutritional Healing by James F. Balch, M.D. & Phyllis A. Balch, C.N.C., 1997
Eat Right, Be Bright by Arthur Winter, M.D. & Ruth Winter, 1988
Mind Food and Smart Pills by Ross Pelton, Ph.D., 1989
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