Nutritional Effects on Performance

Whether you are performing in a sports competition, on the road in a car, at your desk at work or at home with your family, what you consume makes a difference.   Food and drink will either help your performance or hinder it.

HYPOGLYCEMIA SIGNS & SYMPTOMS:  Symptoms associated with hypoglycemia include, fatigue, foggy thinking, shakiness, forgetfulness, drowsiness, exhaustion, depression, crying spells, indecisiveness, incoordination, dizziness, blurred vision, unprovoked anxiety, numbish feeling in hands, arms, face, tingling lips, nervousness, irritability, stomachache or nausea, headache, sweating (cool), rapid heartbeat, confusion or disorientation, weakness, hunger. In more advanced hypoglycemia also includes slurred speech, tremors and loss of consciousness.  Most of this occurs if you miss or delay a meal.  Note that these symptoms are commonly very slow to set in, you may only experience one of the symptoms, and because of this, it may go by unnoticed.

ëEffects on Performance: The brain is highly dependent upon glucose for oxidative metabolism and function.  Hypoglycemia impairs simple brain functions and is associated with task-specific localized reductions in brain activation.   For a task with greater cognitive load, the brain has to recruit other regions in an attempt to limit dysfunction.  However, unlike alcohol effects, you may be somewhat aware of the increased effort required to perform more complex tasks.  Reaction time slows, multitasking diminishes and short term memory deteriorates.  The visual pathways in the brain get effected and spatial perception is altered as well as visual associative function.  Simple visual stimulus during tests showed decreased activation of response in the brain.  Deficits in all relevant areas of cognitive function occurs during hypoglycemia.

ëCauses:  Missed or inconsistent meals.  Or meals made up of coffee, candy bar or pastry.  Diets high in refined carbohydrates such as white rice, potatoes, bread, cereals, grains, beans, legumes and most of your “white” foods along with low protein.  Need especially protein, but also fiber and fats to stabilize it.  Other Causes: Ethanol in alcohol and certain drugs.

ëSolution: The best solution is proper meal planning.  It is suggested that your performance can be affected by both the timing and type of food intake.   Keep a protein bar, trail mix, and/or cut up fruit as a back up in your car or purse. 

ëNOT a solutionAspartame. Signs & Symptoms:  Memory loss, headaches, migraines, blurred vision, blindness, seizures, dizziness, hearing loss, muscle spasms, nausea, heart palpitations, numbness, slurred speech, insomnia, fatigue, severe rashes, anxiety attacks, breathing difficulty, loss of taste and ringing in the ears, pituitary tumors.  It is a dangerous chemical and has no place in your diet!

DEHYDRATION: As little as 2% dehydration results in 50% reduced performance.  This was a study recently completed on military pilots.  2% drop in body water triggers fuzzy, short term memory, trouble with basic math, difficulty with focusing on small fonts or even the computer screen.  Even mild dehydration will slow down your metabolism as much as 3%.  Number one trigger of daytime fatigue. Symptoms of moderate to severe dehydration include fatigue, dizziness and headache.  The absence of these symptoms (which could also apply to other conditions in your body) does NOT mean you are not dehydrated.  It simply means you’re not dehydrated to the point of being symptomatic.  Thirst, is not necessarily a good indicator.  Adequate fluids also helps deter motion sickness.

ëCauses: Not enough water intake (coffee, tea or sodas don’t count towards total water intake).  Also caused by pressurized aircraft, air-conditioned rooms, drinking sodas, coffee or sweetened drinks. 

ëSolution: How much is enough?  1/2 your body weight in ounces per day up to a maximum of 100 ounces.  So if you weigh 120 pounds, you need to drink 60 ounces of water per day in 4oz increments every half hour or so. 

ALCOHOL:  There is the same amount of alcohol in a 12 oz bottle of beer as there is in 1.5 oz vodka, or 5 oz wine.  Sugar and carbonation increase absorption of alcohol in the body.  Alcohol sometimes replaces water in the cell structure of the brain. Alcohol depresses the central nervous system.   Less than .02% alcohol in the blood causes loss of discrimination, loss of fine motor control, and reduced concentration and memory.  Heavy drinkers lose about 100,000 brain cells per day.  Even if you don’t drink heavily, you are still losing up to 10 times the normal attrition of brain cells.  People are impaired because they cannot think or work quickly in an emergency.  They can’t respond instinctively, quickly or appropriately to given scenarios.  It’s difficult to recognize a problem or assess what the problem is, much less remedy it in an efficient, and timely manner.  Multi-tasking is greatly diminished.  It increases susceptibility to confusion, disorientation and decreased mental alertness.  It also impairs discrimination and perception in the visual and auditory systems, disrupts short and long term memory, the thinking process, and coordinated hand-eye movements.  It lowers inhibitions and increases recklessness.  Higher mental and reflex functions can be affected for 2-3 days after a drink.  Some of the impairments experienced in one study included decreased reaction time, judgment of distances and heights is compromised, visual acuity is diminished and coordination skills are seriously eroded.  The most subjective problem is an inability to think clearly and to make sound decisions.  Generally, you are unaware that your performance is impaired.  Alcohol allows people to do dumb things without even recognizing the seriousness of his or her actions or inactions.  When under the influence of alcohol, the usually conscientious and careful person loses the normal attitude of caution.  The person under the influence will take chances not ordinarily considered when sober.  These deficits can occur with blood levels less than .02% and even 14-24 hours after blood levels return to 0 percent.  Alcohol effects the cardiovascular system for up to 24 hours or more.  Common problems include heart block, extra beats, problems with conduction, rapid heart beat, elevated blood pressure and eventually an enlarged heart. Alcohol is a diuretic.  At some point the kidneys stop diuresing, and start retaining the fluids.  Fluid retention in the brain, causes vaso-dilation which causes headaches.  Alcohol also induces hypoglycemia that can last for hours.  Alcohol itself is a sugar and adds to the highs and lows of blood sugar swings that can cause many problems as mentioned earlier.  Alcohol contributes to fatigue because sleep is impaired, despite the fact that the user appears to be sleeping deeply.

ëHangovers: Foods such as MSG, processed meats/hot dogs/salami/ham and bacon, cheese and chocolate will accentuate a hangover.  Coffee and oxygen do not improve the poor performance symptoms.  It makes the person feel better, but actually is dangerous because it reinforces the person already thinking he’s not impaired.  Withdrawal can be just as dangerous.

ëWithdrawal:  Irritability, irascibility, anxiety, increased heart rate, muscular tremors and sweating, inability to sit still, lapses of attention, noise sensitivity, hallucinations, confusion and memory deficits, irrational behavior, fear and agitation that last up to 48-72 hours later.  Even slight remnants of alcohol degrade performance.  When someone has consumed alcohol, the alcohol stays in the fluid in the inner ear for up to 72 hours. Post-alcohol impairment can last as long as 72 hours.

CAFFEINE: Should be considered a drug.  It reduces reaction time, increases heart rate, causes vaso-constriction, decreases coronary circulation, causes an irregular pulse, increases blood pressure in some, contributes to dehydration, effects mental function, causes anxiety, nervousness, restlessness, panic disorders or states resembling panic disorders, irritability and headaches, muscle twitching, rambling flow of thought and speech, periods of inexhaustibility followed by a “crash”, psychomotor agitation, and gastrointestinal disturbance.  Coffee consumption has been shown to be closely linked to bladder, mammary and pancreatic cancer as well as to heart attacks.  Decaf coffee has the presence of homocysteines, which has been considered a strong factor in increasing cholesterol levels and in cardiovascular disease. Even drinking two cups daily raises cholesterol levels, and effects blood pressure. The fluoride and aluminum in black and green teas cause neurological and renal damage. Green tea has been found to decrease cerebrum calcium and increase aluminum levels.  The cerebrum is the portion of the brain where thought and higher function reside.  High brain levels of aluminum as it binds to fluoride ions in water has long been associated with Alzheimer’s Disease.  In the brain, aluminum fluoride causes short term memory loss, smell sensory loss, unsteady gait and loss of structures of the neo-cortex and hippocampus, all symptoms of Alzheimer’s.  Aluminum fluoride is also associated with depressed thyroid function.  The thyroid hormones are extremely important in the regulation of metabolic processes and brain development.  Every cell in the body depends upon thyroid hormones for regulation of their metabolism.  One of the main symptoms of hypothyroidism associated with excess aluminum fluoride is extreme fatigue and marked weakness.  Thyroid disorders can induce disturbances of mood and intellectual function, depressive and manic depressive disorders and rage.  In addition, the acid in coffee eats away the villi of the small intestines, reducing their effectiveness in assimilating nutrients.  As a result, most coffee drinkers are deficient in calcium and many minerals.  Coffee effects the mineralization of the body.  It demineralizes bones, contributing to osteoporosis. Therefore, the acid in coffee causes as many problems as the caffeine does.  Caffeine also disturbs normal sleep rhythms. It reduces Stage 4 and REM.   It can be found in the blood 5 minutes after consumption and half of it is still found in the blood 3 1/2 hours later.  Although coffee is used to keep us energetic and alert, its ability to override feelings of drowsiness and fatigue usually backfires the day after.  Caffeine amps up the adrenals, which is what gives the energy, but then it slams the adrenals as a result.  Long term coffee consumption depletes the adrenals and results in constant fatigue.  For example, people drink coffee or tea frequently as a pick-me-up.  The problem with that is what goes up, must come down. 

ëWithdrawal From Coffee Signs & Symptoms:  Significant fatigue, worsened cognitive performance – especially on vigilance tasks, causes headaches, irritability, nervousness and anxiety, interference with sleep, shakiness, tearfulness, food cravings, constipation, generalized aching and back pain.  Pre-existing symptoms may recur or be exacerbated during withdrawal.  Abdominal pains, cramping and nausea frequently occurs.  Less common symptoms include: chills, diarrhea, nose congestion, sore throat, decreased hearing and even deafness, drowsiness, rage, depression and feeling emotional.  For some the symptoms resemble withdrawal from narcotic drugs or alcohol.  Withdrawal symptoms tend to build in the first day, peaking by day 2 or 3, then diminishing.  Be aware that occasionally the symptoms can be delayed for several days, and then hit.  The more coffee you drink, the worse your symptoms will be.

SODAS: Eating sugar reduces brain fuel.  To burn sugar in the cell’s mitochondria, neurons require extra oxygen and other nutrients.  Oxygen is further reduced to the brain by clogging the arteries with fats.  Contains caffeine and has those associated problems. Displaces calcium and minerals, contributes to osteoporosis and hypoglycemia.

CIGARETTES: Smoking 3 consecutive cigarettes, or 20-30 cigarettes in a 24 hour period of time results in 8-10% hemoglobin saturation in the body.  Not only does this decrease oxygenation resulting in decreased brain function, but also 20% of a smoker’s night vision is lost. Nicotine causes increased physiological arousal, even though the person may feel relaxed.  This gives a false sense of self-confidence in performance of tasks, and he thinks his concentration is better, also false.  It has been demonstrated that a smoker’s reaction time is reduced, complex tasks are performed less efficiently and short term memory is also worse.  These factors are enhanced by concurrent intake of alcohol.  The carbon monoxide released in cigarette smoke has its own problems.  Hemoglobin prefers to bind to carbon dioxide instead of oxygen, so less oxygen is available to the brain.  In addition, due to its effect on the central nervous system, there is loss of visual discrimination and judgment, there is a loss of manual dexterity and memory, and reduction in vigilant task performance. 

ëWithdrawal:  Depression, difficulties in concentration, irritability and frustration. 

MEDICATIONS:  No drug is safe.  Painkillers and anti-inflammatories are some of the worst.  Not just strong medications such as vicodin or darvocet, but also ibuprofen and aspirin have detrimental effects to performance.  Ibuprofen is taken by many for headaches, but can also CAUSE headaches, and severe ones at that.  Aspirin can cause ringing in the ears, vertigo and partial or total hearing loss.  Concurrent use of Vitamin C with aspirin slows the excretion of aspirin from the body, causing a toxic buildup, exposing you to higher levels than you think you may have.   Antibiotics: The penicillin family has substantial evidence of the ability to cause convulsions.  Streptomycin causes measurable hearing loss in 15% of people who ingest it, damaging delicate vestibular structures.  The result is vertigo and spatial disorientation.  Neomycin and vancomyin adversely effect hearing.  Antihistamines and decongestants effect performance.   Drowsiness is one of the main symptoms, but also depression, dizziness, impaired visual acuity, rapid heart rate and decreased coordination.  Decongestants tend more to make you jittery or nervous, while cough suppressants can have a similar effect as alcohol and tend to make you drowsy as well.  A few types of antihistamines and decongestants have more serious side effects such as blurred vision, vertigo, increased blood sugar, decreased coordination, and increased heart rate or blood pressure.  PPA’s (phenylpropanolamine) found in both decongestants and diet pills cause restlessness, headache, dizziness, disorientation, confusion, agitation and even hallucinations. 

PROTEIN: The average man breaks down and synthesizes about 400 gms protein each day.  Fortunately we recycle much of it, however, much needs to be replaced on a daily basis.  The main function of protein after adolescence is to repair wounds, replace and maintain body tissues such as muscles, blood, skin, body organs and connective tissue.   Amino acids, the broken down version of proteins are needed to make enzymes and hormones that regulate most body processes (insulin is one of them).  It is needed to make the enzymes to digest fats, protein and carbohydrates.  It is critical to the immune system.  The antibodies that ward off infections are proteins in of themselves.  Many proteins transport nutrients such as sodium and potassium in and out of cells, while others, ferry substances in the blood.  Hemoglobin is a protein that carry’s oxygen to the brain, lungs and other tissues.   Proteins also play a role in maintaining the body’s water balance.  If protein levels in the blood plasma fall too low, fluid accumulates in the tissues (called edema).    Proteins act as buffers to regulate the acid-base balance (pH) of the body fluids.  If you’re consuming soda’s you especially need more protein as well as more water!  Protein can also be used for energy.  However, fats and carbohydrates are better energy sources, but if they are not available, the body strips protein being used for other vital functions and uses it instead.   In a study done on mental disorders, protein deficiency was identified as one of the causative factors.  Severe protein deficiency is called Kwashiorkor.  While there are several symptoms, the ones that apply to us include immunodeficiency, pathological changes in the liver, mental apathy, anemia, pancreatic atrophy, and GI disorders.  I mention it here because these symptoms will occur in lesser degrees with lesser deficiencies.

ëProblems: A diet too high in protein increases magnesium needs.  It also overstress the kidneys and liver, increases the risk of dehydration (because it requires extra water to rid the body of the by-products of protein metabolism) and contributes to illnesses such as Gout.  High protein diets tend to diminish brain function.  The main fuel of the brain and nervous system is glucose, which is broken down from carbohydrates.  On a high protein diet, less carbohydrates are available and the body has to strip either fats or protein from delicate organs to supply the brains’ needs.  In the body’s attempt to not break down all its own tissues, it starts to partially burn down the fatty acids (called Ketones).  This results in ketosis.  Ketosis makes the blood more acidic which can cause potentially serious side effects such as headache, dizziness, fatigue and if severe enough for long enough it can cause death.  So too much protein is not much better than a deficiency is.  Single amino acid supplements can cause imbalances that may also interfere with normal absorption of food-derived amino acids.  They are generally classified as “unsafe” by the FDA. 

VITAMINS & MINERALS: Every mental state is affected by brain chemistry, from sleep to euphoria, and from depression to anxiety.  Supplying ourselves with brain nutrients, and eliminating harmful foods and substances, is an excellent way to enhance and improve our own performance. Elevated copper/zinc ratios, depressed sodium, potassium, manganese, magnesium and abnormal calcium, is found in patients exhibiting violent behavior, poor stress control and academic underachievement.  Deficiencies in copper, zinc and manganese as well as elevated sodium, potassium, iron, calcium, & magnesium (also with heavy metals) causes impulsivity, irritability, drowsiness and depression.  Minerals, vitamins and amino acids are essential to making neurotransmitters such as serotonin, dopamine and norepinephrine needed to balance emotional behavior.  Iron & zinc keep the brain sharp.  Declining iron levels results in decreased attention span and decreased ability to concentrate.  Decreased levels of zinc decreases the ability to recall specific words.  In addition to being high in salt, Antacids deplete this critical iron and zinc, and also depletes calcium, folic acid, Vitamin D and Vitamin B12.  Many other medications also deplete either iron or zinc and more.  Symptoms of depression include deep sadness, poor concentration, feeling out of control, frustration, helplessness, lethargy, nervousness and self-recriminations.  Depression is linked with biochemical imbalances in the brain of neurotransmitters, particularly Dopamine, Serotonin and norepinephrine.  For example, deficits in Serotonin can generate feelings of fatigue, despair and nervousness, and too much norepinephrine can give rise to mania.   Amino acids, vitamins and minerals play a role in encouraging neurotransmitter synthesis and many studies have shown that nutrients are as effective as drugs in producing beneficial results.  Effective nerve functioning requires a continuous supply of glucose, oxygen, calcium, magnesium, sodium, and potassium to fire the nerve impulses.

ëFunction: Keep in mind that the following are only the functions that will directly effect performance at the moment.  It does not consider the many other health issues each vitamin and mineral effects:

Vitamin A: Is especially needed for night vision.  Deficiency: loss of visual acuity, night blindness, fatigue, poor digestion. Malaise, proneness to infections & slow wound healing.

Vitamin E: Is needed to help with blood flow to heart & brain.  Severe Deficiency: Neuromuscular impairment, diminished vibratory sense, loss of reflexes, gait disturbance, paralysis of eye muscles.

Vitamin B’s: Seen as a whole complex is needed for proper nerve and brain function, helps learning, vision, healthy digestion, stress, needed for energy, controls blood mineral levels, cellular oxidation and utilization of fats.  Deficiency:  Fatigue, irritability, nerve degeneration, nerve and nervous disorders, shortness of breath, slow heart beat, weakness, depression, headaches, muscular weakness, adrenal exhaustion, hypoglycemia, premature aging, behavioral changes, dizziness, convulsions, learning disabilities, walking and speaking difficulties, diminished oxidation of cells, heart disease and insomnia.

Inositol: Is needed for: Brain cell nutrition & formation.  Deficiency: High Cholesterol.

Vitamin C: Is essential for: Vascular health and to protect the heart.  Deficiency: Headaches, lowered energy due to adrenal exhaustion, anemia (fatigue).

Calcium: Is needed for mineral and vitamin metabolism, nerve and muscle response, normal behavior and mental alertness, proper heart contractibility, reduces fatigue.  Deficiency: Muscle cramps, heart palpitations, joint pain, insomnia, nervousness, numbness in extremities.

Copper: Critical for resistance to stress, cell health. Deficiency: Fatigue, breathing difficulties.

Iodine: Is the main functional mineral for thyroid health, energy production, fat metabolism.  Deficiency: Slowed mental reactions, irritability, rapid pulse, hardening of arteries, heart palpitations, sluggish metabolism, and diminished thyroid dysfunction.

Iron: Needed for: Synthesis of phospholipids needed for brain health.  Deficiency: General weakness, impaired respiration.

Magnesium: Needed to make brain tissue, needed for calcium and Vitamin C metabolism.  Deficiency: Brain and body exhaustion, disorientation, confusion, irritability, muscle twitching or tremors, poor circulation.

Phosphorus: Needed for nerve transmission, fat metabolism.  Deficiency: Mental and physical fatigue, irregular breathing, nervous disorders.

Potassium: Necessary for neuromuscular contraction.  Deficiency: Poor reflexes, nervous disorders, insomnia, general weakness, impairment of neuromuscular function, slow, irregular heartbeat.

Sodium: (Not NaCl – table salt): Is needed for Elimination of CO2, formation of digestive juices, keeps blood minerals soluble, necessary for proper muscular contraction, nerve impulses and regulates water.  Deficiency: Muscle shrinkage and cramping, diminished fat metabolism, Adrenal exhaustion, dehydration.

Zinc: Is needed to keep the brain sharp, maintains body’s resistance, normalizes sugar metabolism, normalizes heart action.  Deficiency: Hypoglycemia, diabetes, fuzzy thinking, low immune system.

Chromium: Necessary for glucose metabolism, increases effect of insulin, fat synthesis.  Deficiency: Hypoglycemia, diabetes, artherosclerosis, heart disease.


ëFunction:  Essential fats are what the structure of the brain cell is made of.  Your body doesn’t make them. EFA’s increase stamina and endurance, improve protein and amino acid utilization to help maintain lean mass, decrease recovery time and inflammation after exercise and competition and speed healing of injuries, decrease fat storage and production and increase metabolic rate so we can burn more calories.  It improves oxygen uptake and utilization, optimizes glandular function, improves circulation and immune function.  They help promote sleep and elevates mood, heightens reflexes and concentration, decreases arthritic joint pain and strengthens bones. Every bodily function, either directly or indirectly is dependent upon Essential Fatty Acids. It is the main structural component of every cell membrane, is necessary for cell growth and division, and regulates vital cell activity.  Makes red blood cells more flexible and that helps them to receive nutrients and oxygen more easily.  They protect the skin, hair and nails from dehydration, they reduce cravings, and they ease the withdrawal symptoms from foods that were weaned (like coffee).  It reduces inflammation in the tissues, improves bowel flora, and helps prevents PMS.  They lower high triglycerides protecting us from heart attack or stroke.  It helps lower blood pressure by making the vascular walls more flexible.  It helps the kidney’s remove excess water, protects the DNA from damage, helps kill fungus and is needed for wound healing.  Our immune cells use Essential Fatty Acids to make oxygen “bullets” to kill infectious foreign invaders.  It is needed to transport and metabolize minerals.  It is required for protein metabolism.

ëFound in:  Avocados, salmon, mackerel, sardines, tuna, RAW nuts (not roasted) and seeds and in trace amounts in green leafy vegetables and whole grains.

ã2002 Holly A. Carling, O.M.D., L.Ac., Ph.D.

Dr. Holly Carling

Dr. Holly Carling

Dr. Holly Carling is a Doctor of Oriental Medicine, Licensed Acupuncturist, Doctor of Naturopathy, Clinical Nutritionist and Master Herbologist with nearly four decades of experience. Dr. Carling is a “Health Detective,” she looks beyond your symptom picture and investigates WHY you are experiencing your symptoms in the first place. Dr. Carling considers herself a “professional student” – she has attended more than 600 post-secondary education courses related to health and healing. Dr. Carling gives lectures here in the U.S. and internationally and has been noted as the “Doctor’s Doctor”. When other healthcare practitioners hit a roadblock when treating their patients nutritionally, Dr. Carling is who they call. Dr. Carling is currently accepting new patients and offers natural health care services and whole food nutritional supplements in her Coeur d’ Alene clinic.

Medical/Health Disclaimer:

The information provided in this article or podcast should not be construed as personal medical advice or instruction. No action should be taken based solely on the contents of this article or podcast. Readers/listeners should consult appropriate health professionals on any matter relating to their health and well-being. The information and opinions provided here are believed to be accurate and sound, based on the best judgment available to the author, but readers/listeners who fail to consult appropriate health authorities assume the risk of any injuries.

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