Imagine if the people in your family could only travel to the next town if they were escorted by a lady in a pink dress, rode in a blue Ford Mini-Van and were allowed to travel on only one road. Sound like a difficult journey? Amino acids face similar obstacles and requirements in their journey to the brain.

The fact is, if amino acids reach your brain at all, it should be considered a success. Not only do brain cells compete with body cells for amino acids (body cells pull amino acids from the bloodstream more easily), amino acids must pass the protective blood-brain barrier. To top it all off, amino acids must be escorted through the blood-brain barrier by a certain molecule on a certain pathway in a certain “vehicle”.

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The amino acids tryptophan and tyrosine must both cross the blood-brain barrier in the same pathway. If tryptophan crosses the barrier, it will have a calming effect. If tyrosine wins out, then you will be energized and alert.

A high-carbohydrate meal can increase the brain's tryptophan levels, and hence the serotonin that promotes contentment and normal sleep.

Therefore, a carbohydrate-rich meal may be more appropriate for the evening meal.

On the other hand, one can be energized for hours after a morning meal high in protein, because it raises tyrosine levels in the blood and brain – causing neurons to manufacture norepinephrine and dopamine, two 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. Low blood levels of tyrosine are associated with an underactive thyroid gland. (Extreme thyroid deficiency causes severe mental retardation known as cretinism.)

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Protein's networking role is even more dramatic and direct in the developing brain, when nerve cells are migrating from their birthplace. One particular protein acts as a molecular guide, somewhat like a dog herding a flock of sheep. It directs migrating nerve cells to their correct locations, where they link up with each other as they settle in.

This protein guides the cell bodies themselves, as well as the growth of the long axons that extend from nerve cell bodies toward other nerve cells.¹

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Even in the best of times your brain is often malnourished, which is then reflected in your emotions and behavior. Fortunately, your brain can quickly respond to proper nutrition – even from a single meal. Amino acids are the building blocks of proteins. Your body breaks down dietary protein into the amino acids it uses to assemble the 50,000 different proteins it needs to function – including neurotransmitters and chromosomes, hormones and enzymes.

Dietary proteins fall into two groups. Complete proteins contain ample amounts of all eight 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, 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. For example, rice and beans combine to make a complete protein.

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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.

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.

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 neurotransmitter levels, as does impaired digestion and circulation.

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A single one of your neurons can produce almost a tenth of a volt, and the total electrical activity in your brain is easily measurable with an electroencephalogram (EEG). Within a neuron, a bioelectric impulse (action potential) travels toward the cell body through the dendrites, the intricate branches of nerve fibers that receive information from other neurons.

The impulse then travels at a speed of up to 150MPH away from the cell body through its antennae, called the axon. The axon is a single insulated fiber that sends the bioelectric current out to the cell's terminals, which can be several inches (or feet) away. The size and quality of the axon determines how fast the bioelectric impulse travels.

Hippocampal Neurons

Special channels and pumps in the membrane 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.

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Within the cell body of a neuron, many different types of chemical neurotransmitters are manufactured and shipped out to the end terminals of the axon. Here they're stored in bubble-like structures (vesicles), where they wait to cross over the space between neurons, called the synapse (from the Greek word for "junction").

The bioelectric impulse 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.

Find out more about the types of neurotransmitters and what they do.

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Dopamine is the neurotransmitter needed for healthy assertiveness and sexual arousal, proper immune and autonomic nervous system function. Dopamine is important for motivation and a sense of readiness to meet life's challenges.

One of the most vulnerable key neurotransmitters, dopamine levels are depleted by stress or poor sleep. Alcohol, caffeine, and sugar all seem to diminish dopamine activity in the brain. It's also easily oxidized, therefore eat plenty of fruits and vegetables whose antioxidants help protect dopamine-using neurons from free radical damage. More and more healthcare professionals recommend supplementing with vitamins C and E and other antioxidants.

Age-related cognitive decline is associated with dopamine changes in the brain. People whose hands tremble from Parkinson's disease have a diminished ability to synthesize dopamine, which is crucial to fine muscle coordination. Attention deficits are also connected to dopamine.

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Norepinephrine, also called noradrenalin, is the primary excitatory neurotransmitter needed for motivation, alertness, and concentration. Like a hormone, it travels in the bloodstream to arouse brain activity with its adrenalin-like effects.

Your brain requires norepinephrine to form new memories and to transfer them to long-term storage. This neurotransmitter also influences your metabolic rate.

Both norepinephrine and dopamine are manufactured from the amino acids tyrosine or phenylalanine in the presence of adequate oxygen, vitamins B3, B6, and C, folic acid, iron, and copper. Food sources of tyrosine include almonds, avocados, bananas, dairy products, lima beans, pumpkin seeds, and sesame seeds.

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Serotonin is the calming neurotransmitter important to the maintenance of good mood. It promotes contentment and is responsible for normal sleep. In addition to the central nervous system, serotonin is also found in the walls of the intestine (the enteric nervous system) and in platelet cells that promote blood clotting.

Serotonin plays an important role in regulating memory, learning, and blood pressure, as well as appetite and body temperature. Low serotonin levels produce insomnia and depression, aggressive behavior, increased sensitivity to pain, and is associated with obsessive-compulsive eating disorders.

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.

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Acetylcholine is the primary chemical carrier of thought and memory. This excitatory neurotransmitter is essential for both the storage and recall of memory, and partly 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. Therefore, the more choline you consume, the more acetylcholine you can produce.

Choline belongs to the B family of vitamins and is a fat-like substance that's 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, 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.

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A receptor is essentially a geomagnetic lock designed to accept only the right key – the neurotransmitter whose molecular shape and polarity are a precise fit.

"The typical receptor is a large molecule, consisting of hundreds of thousands of atoms. The exposed section, the 'lily pad,' floats on the surface of the cell membrane, while the 'roots' extend deep into the cell.

"The exposed end of the receptor, the lily pad, is in truth not so much a pad as a cup, the mirror image (both in geometry and in magnetic properties)" of the molecule it is designed to receive.

"The final critical aspect of the receptor is that it is spring-loaded. When a [neurotransmitter] molecule settles into it, it suddenly and forcefully changes shape. Inside the cell, the roots move. The movement triggers a reconformation in another Tinkertoy molecule, which in turn disturbs another, which in turn disturbs still another. The reaction travels, domino fashion" until it reaches the cell body where it initiates some sort of specific activity.”²

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There are as many kinds of receptors as there are neurotransmitters – hundreds of types – with numerous subtypes of receptor for any given neurotransmitter. Although each receptor is supposed to recognize and accept only a particular neurotransmitter molecule, certain medicines and plant compounds are also able to mate with some receptors.

The neurological effects of many natural and pharmaceutical drugs are due to this tendency of receptors to accept molecules that resemble their corresponding neurotransmitter. These substitute molecules can either imitate a neurotransmitter and create a similar response, or they could simply occupy and block the receptor, making it unavailable to neurotransmitters. Addictive substance interact with the brain's receptors in this manner.

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The neurotransmitter serotonin interacts with at least 15 different receptors in the body. After age 20, one of serotonin's most common receptors starts to decline in the human brain. Known as 5-HT2A, it was shown in one study to vanish at about 15% per decade, which may be why depression commonly appears in middle-age.

When scientists scanned the brains of 21 healthy men and women, 20 to 70 years old, they observed dramatic age-related drops in the density of 5-HT2A receptors in the brain – particularly in the prefrontal cortex and hippocampus – even though none of the participants were suffering from depression.³

Receptors for the neurotransmitter dopamine also decline with age. When dopamine and glucose metabolism were measured in the brains of 37 healthy subjects, researchers saw a 6% per decade decline in dopamine D2 receptors, after age 20. This decrease in receptors and in glucose metabolism translates into decreased brain activity and deterioration of cognitive function.⁴

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People who repeatedly perform ritualistic-type movements may be suffering from obsessive-compulsive disorder (OCD). A type of OCD known as "body dysmorphic disorder" is a characterized by a preoccupation with an imagined or slight defect in appearance. For example, no matter their actual body size, anorexics firmly believe they are too fat. Conversely, "bigorexics" think themselves too small. As a neurotransmitter that helps regulate mood, appetite, and impulse control, serotonin is involved in eating disorders associated with these forms of OCD. 2nd level info
Bigorexia

Dr. Eric Hollander of Mount Sinai School of Medicine says this exaggerated sense that something doesn't look right has a connection with serotonin, because one of this neurotransmitter's functions seems to be involved with turning off brain processes that signal when "things don't fit our conceived notions." Even though nothing is wrong, a mental alarm continues to sound due to abnormally low levels of serotonin.

To help the brain raise serotonin levels, the researchers used a drug approach that significantly reduced patients' repetitive movements and obsessive preoccupation with perceived flaws. Although not a cure, Hollander said symptoms improved by 25 to 35%. He pointed out, however, there was a significant drop in suicidal thoughts, and an improved ability to function at work or school.

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Another eating disorder associated with a distorted body image is bulimia nervosa, which is characterized by alternate binge eating and purging. When researchers at the University of Pittsburgh School of Medicine used PET scans to study nine women recovering from bulimia, they observed a reduction in serotonin's ability to bind to receptors in certain brain regions.

Lead author Dr. Walter H. Kaye suspects this dysregulation of the serotonin system contributes to both overeating and undereating, two extremes of impulse control. Whether this alteration in serotonin makes some women more vulnerable to developing bulimia – or is a consequence of having bulimia – is not certain, but other data suggests that bulimics experience symptoms of depressive moods in childhood.⁵

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Homocysteine is an amino acid created in the body from the metabolism of methionine, an essential amino acid obtained from animal protein. Because high levels of homocysteine are toxic, it is normally broken down in the bloodstream and converted back into methionine – with the help of folic acid and B vitamins.

Some people have a genetic tendency to build up toxic levels of homocysteine that damages the walls of their blood vessels. Cholesterol then gets deposited in the arteries impaired by homocysteine, which can lead to blockage and stroke or cardiovascular disease.

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Functional MRI (magnetic resonance imaging) studies reveal the brain's innate plasticity – its ability to reprogram itself after stroke. This highly complex organ adapts to injury by redistributing its cognitive workload across established neural networks, and recruiting different brain areas to fill in for lost functions.

Watching the brain at work with a very-high-field MRI scanner, Dr. Keith Thulborn, director of MR research at the University of Illinois, observed a patient suffering from damage to Wernicke's area (the region in the left cortex that controls the understanding of language). Functional MRI showed that the brain initially recouped by allocating speech comprehension to an area on the opposite side of the brain. Then, over time, an adjacent area took on this cognitive task while Wernicke's area remained damaged.

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The head of stroke research at the Wake Forest University School of Medicine, James F. Toole, says the real culprit behind stroke is homocysteine, not cholesterol. Stroke is the third leading cause of death in the U.S. and is a major cause of disability. What's more, stroke prevention may be as simple as taking three B vitamins involved with homocysteine's metabolism.

He is coordinating a large international clinical trial with 57 institutions in North America and Scotland. Since 1997, the Vitamin Intervention for Stroke Prevention (VISP) trial has involved 3,200 participants with high blood levels of homocysteine, who all recently experienced a stroke. They are are being given high or low doses of vitamin B12, B6, and folic acid.⁷

In another study of nearly 500 white and African-American women age 15 to 44, the increased risk for stroke because of homocysteine was similar to that of smoking a pack of cigarettes per day. "We found that younger women who had the highest levels of homocysteine had double the risk of stroke compared to women with lower levels," says Steven J. Kittner, M.D., M.P.H., professor of neurology, epidemiology, and preventive medicine at the University of Maryland School of Medicine.⁸

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Researchers at Ohio State University measured blood homocysteine concentrations in 33 women and 31 men who completed questionnaires gauging hostility and anger expression. "These were healthy people with no known cardiovascular disease or major risk factors, so the levels of homocysteine were still in the normal range even for those with higher levels of hostility," said Catherine Stoney, associate professor of psychology.

In both the men and women, higher levels of hostility were associated with higher levels of homocysteine. "The fact that we found this relationship even among healthy people is significant," she said. "Many studies have shown hostility and anger expression to be potent risk factors for coronary heart disease, but this study is the first to suggest this potential explanation for why they are linked."⁹ In a previous study, Stoney found that psychological stress can temporarily increase homocysteine levels.

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In a Tufts University study with people over 60 years old, those with higher homocysteine levels fared about 30% as well on a memory test as those with lower homocysteine levels.

Furthermore, Dr. Martha Savaria Morris and her colleagues note that the participants with higher blood levels of folic acid showed a better ability to recall a story.¹⁰

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A natural compound found in small quantities in a variety of plants and animals, supplemental TMG is used to lower homocysteine levels, in conjunction with B vitamins.

Homocysteine is converted back into methionine by a process called methylation – when a methyl group (CH3) from a donor molecule is attached to the homocysteine molecule. Trimethylglycine (TMG), also known as anhydrous betaine, has three methyl groups to donate.

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