caffeine

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• Caffeine--Not just a stimulant
• M.Prasad Naidu
• MSc Medical Biochemistry,
• Ph.D.Research Scholar

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• Introduction
• Consideration of the physiological effets of
  caffeine typically are limited to presumptive
  stimulant effects.
• Many of the human responces to caffeine extend
  beyondstimulant effects and evidence of such
  beneficial responces to caffeine consumption is
  abundant.

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Caffeine potentiates postsynaptic
neurotransmission in the sympathetic nervous
system

• Caffeine (1,3,7-trimethylxanthine) is a plant
  alkaloid that increases the excitability of the
  adenosine-sensitive sympathetic nervous
  system.signals originating within the sns produce
  transient increases in the cAMP concentration
  within the postsynaptic cells through which the
  signal is expressed.

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• By acting as a competitive antagonist of
  adenosine,caffeine inhibits the enzymatic
  degradation of cAMP by phosphodiesterase within
  the postsynaptic cell the presence of caffeine
  may increase strength of transmitted signals.

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Caffeine increases resting energy expenditure

• Human 24-h energy expenditure,sleeping metabolic
  rate, resting awake metabolic rate all are
  proportional to the rate of sympathetic nerve
  activity plasma norepinephrine concentration.
• By potentiating sympathetic activity,caffeine
  stimulates lypolysis.

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For Ex.the ingestion of as little as 50 mg of
caffeine by normal-weight,non-excercising,healthy
men produced a significant increase in resting
energy expenditure within 30 min of caffeine
ingestion. The increase persisted for 4 h
produced a significant 6 total increase in daily
energy expenditure. Exercise-associated FA
oxidation is also increased.
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Caffeine increases endurance and enhances
performance

• In addition to effects on energy
  production,caffeine increases serotonin
  concentration in brainstem regions that have
  excitatory projections to spinal motor
  neurons,increasing the self sustained firing of
  the skeletal muscle motor units that are
  innervated by these neurons.
• By potentiating motor unit sensitivity to
  stimulation,caffiene postpones fatigue
  increases human endurance

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• In its definitive 2001 report,the institute of
  medicine food nutrition board committee on
  military nutrition research concluded that 150 mg
  of caffeine enhances physical endurance the
  quality of physical performance...

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Caffeine increases mental energy

• In adition to benefiting physical performance
  endurance,caffeine directly supports the CNS
• MRI evidence shows that cerebral blood flow is
  directly proportional to recent caffiene intake
  the acute consumption of 400mg of caffeine has
  been shown by pulsed trans cranial doppler
  sonography to increase significantly blood flow
  through the middle anterior cerebral arteries.

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In addition, caffeine acutely increases the
functioning efficiency of neuronal networks in
the human cerebral cortex. Such increases in
mental energycan produce increases in the
functional capacity to engage in cognitively
demanding tasks that can be expressed as
increased vigilance,alertness,ability to
concentrate, ability to choose among
alternatives.
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Caffeine enhances cognitive functioning

• In many human studies,caffeine consumption has
  increased alertness,ability to concentrate,problem
  -solving ability,wakefulness, feelings of
  energy.
• The benefits of caffein consumption extend beyond
  wakefulness to other reflections of enhaced
  mental energy.

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• Cognitive functions,including the ability to
  concentrate to solve problems requiring
  reasoning,mental fatigue, vigoralertness,reactio
  n time,accuracy of responces,ability to focus
  attention,working short-term memory,sentence
  varification ability.

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• In its definitive 2001 report(caffeine for the
  sustainment of mental task performance.Formulation
  s for Military Operations),the Institute of
  Medicine Food Nutrition Board Committee on
  Military Nutrition Research concluded that the
  consumption of 150 mg of caffeine enhances
  cognitive performance that these effects can
  persist for as long as 10 h after consumption.

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Caffeine increases neuromuscular coordination,

• In contrast to common misconseptions,moderate
  caffeine consumption contributes to enhanced
  neuromuscular coordination.
• A single dose of caffeine upto 600 mg enhance
  cognitive functioning capabilities
  neuromuscular coordination.

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• Approved the inclusion of Caffeine in dietary
  supplements intended to promote
  alertness,wakefulness,enhanced cognitive
  performance,endurance,decrease of
  fatigue,enhanced motor performance.
• The Recommended intakes of caffeine are 100 to
  200 mg, every 3 to 4 h, upto five times daily.

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Caffeine elevates mood and relieves anxiety

• Improvement in cognitive functioning capabilities
  are accompanied by improved mood,self image, and
  overall happiness and less anxiety.
• The cognitive emotional benefits of caffeine
  consumption increase in magnitude as the amount
  of acutely consumed caffeine increases,persist
  for 6 h after consumption.

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Caffeine consumption is safe

• Moderate intakes of caffeine pose no health
  risks.
• Daily consumption of up to 400 mg of caffeine
  significantly decreased(by10)the risk of dying
  from any cause.
• Study demonstrated that even more than six cups
  of caffeinated coffee(equivalent to about 1000 mg
  of caffeine) daily had no risk for developing
  coronary heart disease.

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• A Health Professionals Follow-Up Study with
  type-2 diabetes,there was no relation between
  habitual coffee consumption risk for developing
  cardiovascular disease.
• Another study indicated that the risks for dying
  prematurely from any cause specifically from
  cardiovascular disease risk of developing a
  stroke also were significantly inversely
  proportional to chronic daily coffee consumption.

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• Lowa Womens Health Study on Postmenopausal women
  demonstrated that any amount of habitually
  consumed caffeinated coffee decreased the risk of
  death from cardiovascular disease by 15 to 25
• Consistent with these findings,the 10-y
  prospective Framingham Study of menwomen
  initially 65 to 96 y old found that the
  consumption of coffee halved the risk for heart
  valve disease from death from CAD

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Regular intake of caffeinated coffee does not
increase the risk of hypertention

• The US Food Drug Administration has concluded
  that individuals who habitually consume coffee
  develop Tachyphylaxis-a dimnishment of a response
  after the repetative consumption of a
  pharmocologically active substance.
• Based on published scientific evidence that any
  acute pressor effects of caffein consumption
  cease after 1 to 2 wk of daily consumption,USFDA
  concluded that the available evidence shows that
  cronic use of caffeine has no effect on bloob
  pressure that persists beyond 2 weeks.

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• The risk of developing GOUT,the most common
  inflammatory arthtitis in men, was approx.halved
  by the daily consumption of six or more cups of
  caffeinated coffee.
• Postmenopausal women also showed a 12 decrease
  in risk of developing breast cancer.
• Study indicated that the risk for developing
  Diabetes decreases as habitual caffeine intake
  increases in men women.
• The safety of caffeine during pregnancy remains
  contraversial.

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• The potential for habitual caffeine consumption
  to be associated with the neurologic phenomen of
  dependence,tolerence,withdrawl might suggest the
  presence of a relation between caffeine
  consumption psychiatric sequlae.
• A 21 y study of initially middle aged men
  women(the Cardiovascular Risk Factors,Aging
  Dementia CIADE study)found that compared with
  subjects routinely consuming less than 300mg of
  caffeine daily,those subjects routinely consuming
  400 to 650mg daily showed a significantly lower
  incidence of clinical dementia parkinsons
  disease.

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CONCLUSIONS

• The foregoing publicly available scientific
  evidence substantiates the conclusions that the
  consumption of moderate amounts of caffeine
• Increases energy availability
• Increases daily energy expenditure
• Decreases fatigue
• Decreases the sense of effort associated with
  physical activity
• Enhances physical performance

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• Enhances motor performance
• Enhances cognitive performance
• Increases alertness,wakefulness,and feelings of
  energy
• Decreases mental fatigue
• Quickens reactions
• Increases the accuracy of reactions,
• Increases the ability to concentrate focus
  attention
• Enhances short-term memory

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• Increases the ability to solve problems requiring
  reasoning
• Increases the ability to make correct decisions
• Enhances cognitive functioning capabilities
  neuromuscular coordination,and
• In otherwise healthy non-pregnant adults is safe.

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