Tea contains more caffeine than coffee by dry weight. A typical serving, however, contains much less, since less of the product is used as compared to an equivalent serving of coffee. Also contributing to caffeine content are growing conditions, processing techniques, and other variables. Thus, teas contain varying amounts of caffeine. [231] Caffeine is used as a primary treatment for apnea of prematurity, [40] but not prevention. [41] [42] It is also used for orthostatic hypotension treatment. [43] [42] [44] People with health conditions should talk to their doctor about caffeine as part of any discussion about a healthy lifestyle. What are the health benefits of consuming caffeine?

Chocolate derived from cocoa beans contains a small amount of caffeine. The weak stimulant effect of chocolate may be due to a combination of theobromine and theophylline, as well as caffeine. [237] A typical 28-gram serving of a milk chocolate bar has about as much caffeine as a cup of decaffeinated coffee. By weight, dark chocolate has one to two times the amount of caffeine as coffee: 80–160mg per 100g. Higher percentages of cocoa such as 90% amount to 200mg per 100g approximately and thus, a 100-gram 85% cocoa chocolate bar contains about 195mg caffeine. [221] Tablets No-Doz 100mg caffeine tablets Interestingly, consuming decaffeinated coffee was also linked to a 21% lower risk of diabetes. This indicates that other beneficial compounds in coffee can also protect against type 2 diabetes ( 36). Summary Caffeine does not appear to be a reinforcing stimulus, and some degree of aversion may actually occur, with people preferring placebo over caffeine in a study on drug abuse liability published in an NIDA research monograph. [114] Some state that research does not provide support for an underlying biochemical mechanism for caffeine addiction. [2] [115] [116] [117] Other research states it can affect the reward system. [118] Caffeine also causes the release of dopamine in the dorsal striatum and nucleus accumbens core (a substructure within the ventral striatum), but not the nucleus accumbens shell, by antagonizing A 1 receptors in the axon terminal of dopamine neurons and A 1– A 2A heterodimers (a receptor complex composed of 1 adenosine A 1 receptor and 1 adenosine A 2A receptor) in the axon terminal of glutamate neurons. [169] [164] During chronic caffeine use, caffeine-induced dopamine release within the nucleus accumbens core is markedly reduced due to drug tolerance. [169] [164] Enzyme targets

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Other studies show that drinking 2–4 cups of coffee or green tea per day is linked to a 14–20% lower risk of stroke ( 30, 31). The central ingredient in Alpecin shampoo is caffeine. Studies show that caffeine can stimulate hair follicles and promote new hair growth in people suffering from hair loss and male pattern baldness (androgenic alopecia). activehours:........xxxxxxxx........ - put 24 . or x characters - which indicate from hour 0 to hour 23 of the day. Caffeine will Caffeine, like other xanthines, also acts as a phosphodiesterase inhibitor. [173] As a competitive nonselective phosphodiesterase inhibitor, [174] caffeine raises intracellular cyclic AMP, activates protein kinase A, inhibits TNF-alpha [175] [176] and leukotriene [177] synthesis, and reduces inflammation and innate immunity. [177] Caffeine also affects the cholinergic system where it is a moderate inhibitor of the enzyme acetylcholinesterase. [178] [179] Pharmacokinetics Caffeine is metabolized in the liver via a single demethylation, resulting in three primary metabolites, paraxanthine (84%), theobromine (12%), and theophylline (4%), depending on which methyl group is removed. Urinary metabolites of caffeine in humans at 48 hours post-dose [180]

Koot P, Deurenberg P (1995). "Comparison of changes in energy expenditure and body temperatures after caffeine consumption". Annals of Nutrition & Metabolism. 39 (3): 135–42. doi: 10.1159/000177854. PMID 7486839.a b Downs J, Giust J, Dunn DW (September 2017). "Considerations for ADHD in the child with epilepsy and the child with migraine". Expert Review of Neurotherapeutics. 17 (9): 861–869. doi: 10.1080/14737175.2017.1360136. PMID 28749241. S2CID 29659192. This is more likely to cause side effects, as a full key down/key up is generated. It's included for compatibility with older systems which might need this

Liver protection. Coffee may reduce the risk of liver damage (cirrhosis) by as much as 84%. It may slow disease progression, improve treatment response, and lower the risk of premature death ( 37, 38). The earliest credible evidence of either coffee drinking or knowledge of the coffee plant appears in the middle of the fifteenth century, in the Sufi monasteries of the Yemen in southern Arabia. [249] From Mocha, coffee spread to Egypt and North Africa, and by the 16th century, it had reached the rest of the Middle East, Persia and Turkey. From the Middle East, coffee drinking spread to Italy, then to the rest of Europe, and coffee plants were transported by the Dutch to the East Indies and to the Americas. [250]Some people use caffeine-containing beverages such as coffee or tea to try to treat their asthma. [45] Evidence to support this practice is poor. [45] It appears that caffeine in low doses improves airway function in people with asthma, increasing forced expiratory volume (FEV1) by 5% to 18% for up to four hours. [46] Nehlig A (2010). "Is caffeine a cognitive enhancer?" (PDF). Journal of Alzheimer's Disease. 20 (Suppl 1): S85–94. doi: 10.3233/JAD-2010-091315. PMID 20182035. S2CID 17392483. Archived from the original (PDF) on 31 January 2021. Caffeine does not usually affect performance in learning and memory tasks, although caffeine may occasionally have facilitatory or inhibitory effects on memory and learning. Caffeine facilitates learning in tasks in which information is presented passively; in tasks in which material is learned intentionally, caffeine has no effect. Caffeine facilitates performance in tasks involving working memory to a limited extent, but hinders performance in tasks that heavily depend on this, and caffeine appears to improve memory performance under suboptimal alertness. Most studies, however, found improvements in reaction time. The ingestion of caffeine does not seem to affect long-term memory.... Its indirect action on arousal, mood and concentration contributes in large part to its cognitive enhancing properties. Death from caffeine ingestion appears to be rare, and most commonly caused by an intentional overdose of medications. [144] In 2016, 3702 caffeine-related exposures were reported to Poison Control Centers in the United States, of which 846 required treatment at a medical facility, and 16 had a major outcome; and several caffeine-related deaths are reported in case studies. [144] The LD 50 of caffeine in rats is 192 milligrams per kilogram, the fatal dose in humans is estimated to be 150–200 milligrams per kilogram (2.2lb) of body mass (75–100 cups of coffee for a 70kg (150lb) adult). [145] [146] There are cases where doses as low as 57 milligrams per kilogram have been fatal. [147] A number of fatalities have been caused by overdoses of readily available powdered caffeine supplements, for which the estimated lethal amount is less than a tablespoon. [148] The lethal dose is lower in individuals whose ability to metabolize caffeine is impaired due to genetics or chronic liver disease. [149] A death was reported in 2013 of a man with liver cirrhosis who overdosed on caffeinated mints. [150] [151] Interactions