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 After a few weeks, the mental impairments of withdrawal had subsided, and I could once again think in a straight line, hold an abstraction in my head for more than two minutes, and shut peripheral thoughts out of my field of attention. Yet I continued to feel as though I was mentally just slightly behind the curve, especially when in the company of drinkers of coffee and tea, which, of course, was all the time and everywhere. Children under 18 years should consume less than 3mg for each kilo of body weight a day. For a 40kg child, this is about 120mg a day, or 2 cans of cola (375mL). There is evidence that amounts greater than this can cause increased anxiety. 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 In 1827, M. Oudry isolated "théine" from tea, [264] but in 1838 it was proved by Mulder [265] and by Carl Jobst [266] that theine was actually the same as caffeine.

a b American College of Obstetricians and Gynecologists (August 2010). "ACOG CommitteeOpinion No. 462: Moderate caffeine consumption during pregnancy". Obstetrics and Gynecology. 116 (2 Pt 1): 467–8. doi: 10.1097/AOG.0b013e3181eeb2a1. PMID 20664420. a b c d Poleszak E, Szopa A, Wyska E, Kukuła-Koch W, Serefko A, Wośko S, Bogatko K, Wróbel A, Wlaź P (February 2016). "Caffeine augments the antidepressant-like activity of mianserin and agomelatine in forced swim and tail suspension tests in mice". Pharmacological Reports. 68 (1): 56–61. doi: 10.1016/j.pharep.2015.06.138. PMID 26721352. S2CID 19471083. Lieberman HR, et al. Daily patterns of caffeine intake and the association of intake with multiple sociodemographic and lifestyle factors in U.S. adults based on the NHANES 2007-2012 surveys. Journal of the American Academy of Nutrition and Dietetics. 2019; doi:10.1016/j.jand.2018.08.152. There is some evidence that people who drink a moderate amount of caffeine regularly might have a lower risk of: Mate is a drink popular in many parts of South America. Its preparation consists of filling a gourd with the leaves of the South American holly yerba mate, pouring hot but not boiling water over the leaves, and drinking with a straw, the bombilla, which acts as a filter so as to draw only the liquid and not the yerba leaves. [234]Instead of F15, the shift key is used. This solves some of the issues with the above apps, but may cause the shift key to become "unpressed" sometimes Around noon, my compulsiveness began to subside, and I felt ready for a change of scene. I had yanked a few plants out of the vegetable garden that were not pulling their weight, and decided to go to the garden centre to buy some replacements. It was during the drive that I realised the true reason I was heading to this particular garden centre: it had this Airstream trailer parked out front that served really good espresso. Gout prevention. Regularly drinking 4 cups of coffee per day may reduce the risk of developing gout by 40% in men and 57% in women ( 50, 51). The effect of caffeine on your health is complex. It can cause some health problems, but it can also reduce your chances of having others. Because caffeine is a stimulant, it can make you feel more alert and energetic. This causes a relative increase in other signaling molecules, such as dopamine and norepinephrine ( 5, 6).

Caffeine's biological half-life– the time required for the body to eliminate one-half of a dose– varies widely among individuals according to factors such as pregnancy, other drugs, liver enzyme function level (needed for caffeine metabolism) and age. In healthy adults, caffeine's half-life is between 3 and 7hours. [8] The half-life is decreased by 30-50% in adult male smokers, approximately doubled in women taking oral contraceptives, and prolonged in the last trimester of pregnancy. [126] In newborns the half-life can be 80hours or more, dropping very rapidly with age, possibly to less than the adult value by age 6 months. [126] The antidepressant fluvoxamine (Luvox) reduces the clearance of caffeine by more than 90%, and increases its elimination half-life more than tenfold; from 4.9hours to 56hours. [187] 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 a b c Burchfield G (1997). Meredith H (ed.). "What's your poison: caffeine". Australian Broadcasting Corporation. Archived from the original on 26 July 2009 . Retrieved 15 January 2014. The earliest evidence of cocoa bean use comes from residue found in an ancient Mayan pot dated to 600 BCE. Also, chocolate was consumed in a bitter and spicy drink called xocolatl, often seasoned with vanilla, chile pepper, and achiote. Xocolatl was believed to fight fatigue, a belief probably attributable to the theobromine and caffeine content. Chocolate was an important luxury good throughout pre-Columbian Mesoamerica, and cocoa beans were often used as currency. [251]O'Callaghan F, Muurlink O, Reid N (7 December 2018). "Effects of caffeine on sleep quality and daytime functioning". Risk Management and Healthcare Policy. 11: 263–271. doi: 10.2147/RMHP.S156404. PMC 6292246. PMID 30573997. The short-term effects of caffeine typically happen about 30 minutes after consumption. They can last up to 6 hours, depending on the individual. Is your kid over-caffeinated? Academy of Nutrition and Dietetics. https://www.eatright.org/food/nutrition/healthy-eating/is-your-kid-over-caffeinated. Accessed Feb. 1, 2020. In general, dark-roast coffee has very slightly less caffeine than lighter roasts because the roasting process reduces caffeine content of the bean by a small amount. [229] [230] Tea Mathe

A 2011 review found that increased caffeine intake was associated with a variation in two genes that increase the rate of caffeine catabolism. Subjects who had this mutation on both chromosomes consumed 40mg more caffeine per day than others. [192] This is presumably due to the need for a higher intake to achieve a comparable desired effect, not that the gene led to a disposition for greater incentive of habituation.

EFSA Panel on Dietetic Products, Nutrition and Allergies (2015). "Scientific Opinion on the safety of caffeine". EFSA Journal. 13 (5): 4102. doi: 10.2903/j.efsa.2015.4102. Myers RL (2007). The 100 Most Important Chemical Compounds: A Reference Guide. Greenwood Press. p. 55. ISBN 978-0-313-33758-1 . Retrieved 17 June 2018. Caffeine in coffee and other caffeinated drinks can affect gastrointestinal motility and gastric acid secretion. [86] [87] [88] In postmenopausal women, high caffeine consumption can accelerate bone loss. [89] [90] Until recently, the Seventh-day Adventist Church asked for its members to "abstain from caffeinated drinks", but has removed this from baptismal vows (while still recommending abstention as policy). [282] Some from these religions believe that one is not supposed to consume a non-medical, psychoactive substance, or believe that one is not supposed to consume a substance that is addictive. The Church of Jesus Christ of Latter-day Saints has said the following with regard to caffeinated beverages: "... the Church revelation spelling out health practices (Doctrine and Covenants 89) does not mention the use of caffeine. The Church's health guidelines prohibit alcoholic drinks, smoking or chewing of tobacco, and 'hot drinks' – taught by Church leaders to refer specifically to tea and coffee." [283] It is recommended that healthy adults can safely consume around 400mg of caffeine a day. This is the same as:

In addition to its activity at adenosine receptors, caffeine is an inositol trisphosphate receptor 1 antagonist and a voltage-independent activator of the ryanodine receptors ( RYR1, RYR2, and RYR3). [167] It is also a competitive antagonist of the ionotropic glycine receptor. [168] Effects on striatal dopamine Some beverages combine alcohol with caffeine to create a caffeinated alcoholic drink. The stimulant effects of caffeine may mask the depressant effects of alcohol, potentially reducing the user's awareness of their level of intoxication. Such beverages have been the subject of bans due to safety concerns. In particular, the United States Food and Drug Administration has classified caffeine added to malt liquor beverages as an "unsafe food additive". [246] Theobromine (12%): Dilates blood vessels and increases urine volume. Theobromine is also the principal alkaloid in the cocoa bean ( chocolate).

See also

Caffeine can also interact with other stimulants such as cocaine and methamphetamine. It can increase your risk of problems such as an abnormal health rate or heart rhythm. How can I reduce my caffeine intake? Birth control pills can extend the half-life of caffeine, requiring greater attention to caffeine consumption. [158] Medications We do know that many regular coffee drinkers become dependent on caffeine. Regular heavy use of caffeine, more than 600mg a day, can cause: Supercritical carbon dioxide extraction: Supercritical carbon dioxide is an excellent nonpolar solvent for caffeine, and is safer than the organic solvents that are otherwise used. The extraction process is simple: CO 2 is forced through the green coffee beans at temperatures above 31.1°C and pressures above 73 atm. Under these conditions, CO 2 is in a " supercritical" state: It has gaslike properties that allow it to penetrate deep into the beans but also liquid-like properties that dissolve 97–99% of the caffeine. The caffeine-laden CO 2 is then sprayed with high-pressure water to remove the caffeine. The caffeine can then be isolated by charcoal adsorption (as above) or by distillation, recrystallization, or reverse osmosis. [207]