Is caffeine healthy?
Answers:
Effects of caffeine
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Caffeine is a central nervous system stimulant, and is used both recreationally and medically to restore mental alertness when unusual weakness or drowsiness occurs. Doses of 100-200 mg result in increased alertness and wakefulness, faster and clearer flow of thought, increased focus, and better general body coordination. It also results in restlessness, a loss of fine motor control, headaches, and dizziness.[9] It is important to note, however, that caffeine cannot replace sleep, and should be used only occasionally as an alertness aid.
Mechanism of action
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The caffeine molecule is structurally similar to adenosine, and binds to adenosine receptors on the surface of cells without activating them (a "false transmitter" method of antagonism). This may be relevant in its diuretic properties, since adenosine is known to constrict preferentially the afferent arterioles of the glomerular apparatus; inhibition may cause vasodilation, with an increase in renal blood flow (RBF) and glomerular filtration rate (GFR). In the brain, adenosine binding also causes blood vessels to dilate (presumably to let more oxygen in during sleep).[12] This effect, called competitive inhibition, interrupts a pathway that normally serves to regulate nerve conduction by suppressing post-synaptic potentials. The result is an increase in the levels of epinephrine or adrenaline and norepinephrine released via the hypothalamic-pituitary-adrenal axis[13] Epinephrine, the natural endocrine response to a perceived threat, stimulates the sympathetic nervous system, leading to an increased heart rate, blood pressure and blood flow to muscles, a decreased blood flow to the skin and inner organs and a release of glucose by the liver.
Caffeine is also a known competitive inhibitor of the enzyme cAMP-phosphodiesterase (cAMP-PDE), which converts cyclic AMP (cAMP) in cells to its noncyclic form, allowing cAMP to build up in cells. Cyclic AMP participates in the messaging cascade produced by cells in response to stimulation by epinephrine, so by blocking its removal caffeine intensifies and prolongs the effects of epinephrine and epinephrine-like drugs such as amphetamine, methamphetamine, or methylphenidate.
The metabolites of caffeine contribute to caffeine's effects. Theobromine is a vasodilator that increases the amount of oxygen and nutrient flow to the brain and muscles. Theophylline, the second of the three primary metabolites, acts as a smooth muscle relaxant that chiefly affects bronchioles and acts as a chronotrope and inotrope that increases heart rate and efficiency. The third metabolic derivative, paraxanthine, is responsible for an increase in the lipolysis process, which releases glycerol and fatty acids into the blood to be used as a source of fuel by the muscles (Dews et al. 1984).
With these effects, caffeine is considered an ergogenic: increasing the capacity for mental or physical labor. A study conducted in 1979 showed a 7% increase in distance cycled over a period of two hours in subjects who consumed caffeine compared to control tests (Ivy et al. 1979). Other studies attained much more dramatic results; one particular study of trained runners showed a 44% increase in "race-pace" endurance, as well as a 51% increase in cycling endurance, after a dosage of 9 milligrams of caffeine per kilogram of body weight (Graham & Spriet 1991). The extensive boost shown in the runners is not an isolated case; additional studies have reported similar effects. Another study found 5.5 milligrams of caffeine per kilogram of body mass resulted in subjects cycling 29% longer during high intensity circuits (Trice & Hayes 1995).
Side effects of caffeine
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The minimum lethal dose of caffeine ever reported is 3,200 mg, administered intravenously. The LD50 of caffeine is estimated between 13 and 19 grams for oral administration for an average adult. The LD50 of caffeine is dependent on weight and individual sensitivity and estimated to be about 150 to 200 mg per kg of body mass, roughly 140 to 180 cups of coffee for an average adult taken within a limited timeframe that is dependent on half-life. The half-life, or time it takes for the amount of caffeine in the blood to decrease by 50%, ranges from 3.5 to 10 hours. In adults the half-life is generally around 5 hours. However, contraceptive pills increase this to around 12 hours, and, for women over 3 months pregnant, it varies from 10 to 18 hours. In infants and young children, the half-life may be longer than in adults. With common coffee and a very rare half-life of 100 hours, it would require 3 cups of coffee every hour for 100 hours just to reach LD50. Though achieving lethal dose with coffee would be exceptionally difficult, there have been many reported deaths from intentional overdosing on caffeine pills.
Too much caffeine, especially over an extended period of time, can lead to a number of physical and mental conditions. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) states: "The 4 caffeine-induced psychiatric disorders include caffeine intoxication, caffeine-induced anxiety disorder, caffeine-induced sleep disorder, and caffeine-related disorder not otherwise specified (NOS)."
An overdose of caffeine can result in a state termed caffeine intoxication or caffeine poisoning. Its symptoms are both physiological and psychological. Symptoms of caffeine intoxication include: restlessness, nervousness, excitement, insomnia, flushed face, diuresis, muscle twitching, rambling flow of thought and speech, paranoia, cardiac arrhythmia or tachycardia, and psychomotor agitation, gastrointestinal complaints, increased blood pressure, rapid pulse, vasoconstriction (tightening or constricting of superficial blood vessels) sometimes resulting in cold hands or fingers, increased amounts of fatty acids in the blood, and an increased production of gastric acid. In extreme cases mania, depression, lapses in judgment, disorientation, loss of social inhibition, delusions, hallucinations and psychosis may occur.[14]
It is commonly assumed that only a small proportion of people exposed to caffeine develop symptoms of caffeine intoxication. However, because it mimics organic mental disorders, such as panic disorder, generalized anxiety disorder, bipolar disorder, and schizophrenia, a growing number of medical professionals believe caffeine-intoxicated people are routinely misdiagnosed and unnecessarily medicated. Shannon et al (1998) point out that:
"Caffeine-induced psychosis, whether it be delirium, manic depression, schizophrenia, or merely an anxiety syndrome, in most cases will be hard to differentiate from other organic or non-organic psychoses..The treatment for caffeine-induced psychosis is to withhold further caffeine." A study in the British Journal of Addiction declared that "although infrequently diagnosed, caffeinism is thought to afflict as many as one person in ten of the population" (JE James and KP Stirling, 1983).
Because caffeine increases the production of stomach acid, high usage over time can lead to peptic ulcers, erosive esophagitis, and gastroesophageal reflux disease.[citation needed] Furthermore, it can also lead to nervousness, irritability, anxiety, tremulousness, muscle twitching, insomnia, heart palpitations and hyperreflexia.[15]
It is suggested that "slow metabolizers" who carry a variant of polymorphic cytochrome P450 1A2 (CYP1A2) enzyme have an increased risk of nonfatal myocardial infarction
Other Answers:
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noI get a huge blood vessel when I get an erection?
thats a definete NO!In moderation, it is not bad for you; however, too much of anything can be dangerous. Moderation is the key.
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it depends on what week it is. doctors and health pros change their mind on a regular basis.i beleive that caffine, as with most things is fine in moderation.
Please Help: How come this doesnt hurt?
certainly NOT.how can any stimulant be safe???
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A little quantity a day in your coffe reduces the risk of heart disease and hypertension.No, it's bad for the brain. Though if you're and adult, the damage is less. If your a child, NEVER DRINK TOO MUCH. A sip is ok.
coffee is actually a very effective anti oxidant..
its better than tea.
so if you do drink coffee, drink moderately..
1 or 2 cups a day will be safe..
After my shower i feel like a muscle spasm or air on my upper back feels like a sharp stab?
It depends on your health caffeine is very healthy for certain individuals others not so healthy depends on the individual people with heart plantations and other medical conditions should check with their doctor before consuming caffenated beverages chocolate is also high in caffeine, I am a person who suffers from heart palputations my doctor recommends that I steer clear of the caffeine due to the fact it triggers heart palputaions.Source(s):
my heart doctor
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