121-397: A tea infuser is a device in which loose, dried tea leaves are placed for steeping or brewing, in a mug or a teapot full of hot water; it is often called a teaball (alternatively tea maker or tea egg ). The tea infuser gained popularity in the first half of the 19th century. Tea infusers enable one to easily steep tea from fannings and broken leaf teas. A tea infuser performs
242-607: A natriuresis (increase in saline excretion); it is mediated via proximal tubular adenosine receptor blockade. The acute increase in urinary output may increase the risk of dehydration . However, chronic users of caffeine develop a tolerance to this effect and experience no increase in urinary output. Minor undesired symptoms from caffeine ingestion not sufficiently severe to warrant a psychiatric diagnosis are common and include mild anxiety, jitteriness, insomnia, increased sleep latency, and reduced coordination. Caffeine can have negative effects on anxiety disorders . According to
363-481: A stimulating effect in humans, primarily due to its caffeine content. An early credible record of tea drinking dates to the third century AD, in a medical text written by Chinese physician Hua Tuo . It was popularised as a recreational drink during the Chinese Tang dynasty , and tea drinking subsequently spread to other East Asian countries. Portuguese priests and merchants introduced it to Europe during
484-489: A 2011 literature review, caffeine use may induce anxiety and panic disorders in people with Parkinson's disease . At high doses, typically greater than 300 mg, caffeine can both cause and worsen anxiety. For some people, discontinuing caffeine use can significantly reduce anxiety. In moderate doses, caffeine has been associated with reduced symptoms of depression and lower suicide risk. Two reviews indicate that increased consumption of coffee and caffeine may reduce
605-539: A Persian ending yi . The Chinese word for tea itself was likely ultimately derived from the non-Sinitic languages of the botanical homeland of the tea plant in southwest China (or Burma ), possibly from an archaic Austro-Asiatic root word * la , meaning "leaf". Tea plants are native to East Asia and the probable center of origin of tea is near the source of the Irrawaddy River from where it spread out fan-wise into southeast China, Indo-China and Assam . Thus,
726-437: A bag within a sealed opaque canister may keep for two years. Green tea deteriorates more rapidly, usually in less than a year. Tightly rolled gunpowder tea leaves keep longer than the more open-leafed Chun Mee tea . Storage life for all teas can be extended by using desiccant or oxygen-absorbing packets, vacuum sealing, or refrigeration in air-tight containers (except green tea, where discrete use of refrigeration or freezing
847-531: A better flavour. Two principal varieties are used: Camellia sinensis var. sinensis, which is used for most Chinese, Formosan and Japanese teas, and C. sinensis var. assamica, used in Pu-erh and most Indian teas (but not Darjeeling). Within these botanical varieties, many strains and modern clonal varieties are known. Leaf size is the chief criterion for the classification of tea plants, with three primary classifications being: Assam type, characterised by
968-461: A canister, paper bag, or other container such as a tea chest . Some whole teas, such as rolled gunpowder tea leaves, which resist crumbling, are vacuum-packed for freshness in aluminised packaging for storage and retail. The loose tea is individually measured for use, allowing for flexibility and flavour control at the expense of convenience. Strainers, tea balls , tea presses, filtered teapots, and infusion bags prevent loose leaves from floating in
1089-410: A decrease in performance on their standardized tests, and caffeine causes a significant improvement. When alcohol and caffeine are consumed jointly, the effects of the caffeine are changed, but the alcohol effects remain the same. For example, consuming additional caffeine does not reduce the effect of alcohol. However, the jitteriness and alertness given by caffeine is decreased when additional alcohol
1210-594: A different variety of tea was endemic to Assam and the northeast region of India, which was then hybridized with Chinese small-leaf-type tea. Using Chinese planting and cultivation techniques, the British colonial government established a tea industry by offering land in Assam to any European who agreed to cultivate it for export. Tea was originally consumed only by Anglo-Indians ; however, it became widely popular in India in
1331-542: A distinct diagnostic category, which closely mirrors the DSM-5 's proposed set of criteria for "caffeine-use disorder". Caffeine use disorder refers to dependence on caffeine characterized by failure to control caffeine consumption despite negative physiological consequences. The APA , which published the DSM-5, acknowledged that there was sufficient evidence in order to create a diagnostic model of caffeine dependence for
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#17327919077301452-505: A good tea cannot be fully appreciated. By adding the milk afterwards, it is easier to dissolve sugar in the tea and to ensure the desired amount of milk is added, as the colour of the tea can be observed. Historically, the order of steps was taken as an indication of class: only those wealthy enough to afford good-quality porcelain would be confident of its being able to cope with being exposed to boiling water unadulterated with milk. Higher temperature difference means faster heat transfer , so
1573-511: A higher risk of alcohol-associated injury. Smoking tobacco has been shown to increase caffeine clearance by 56% as a result of polycyclic aromatic hydrocarbons inducing the CYP1A2 enzyme. The CYP1A2 enzyme that is induced by smoking is responsible for the metabolism of caffeine; increased enzyme activity leads to increased caffeine clearance, and is associated with greater coffee consumption for regular smokers. Birth control pills can extend
1694-633: A letter written by Richard Wickham, who ran an East India Company office in Japan, writing to a merchant in Macao requesting "the best sort of chaw" in 1615. Peter Mundy , a traveller and merchant who came across tea in Fujian in 1637, wrote, " chaa – only water with a kind of herb boyled in it". Tea was sold in a coffee house in London in 1657, Samuel Pepys tasted tea in 1660, and Catherine of Braganza took
1815-412: A marked reduction in consumption, a minimum of 3 of these signs or symptoms is required to meet withdrawal criteria: difficulty concentrating, depressed mood / irritability , flu -like symptoms, headache , and fatigue . Additionally, the signs and symptoms must disrupt important areas of functioning and are not associated with effects of another condition. The ICD-11 includes caffeine dependence as
1936-408: A maximum daily caffeine intake of no more than 2.5 milligrams per kilogram of body weight. Based on average body weights of children, this translates to the following age-based intake limits: Health Canada has not developed advice for adolescents because of insufficient data. However, they suggest that daily caffeine intake for this age group be no more than 2.5 mg/kg body weight. This is because
2057-521: A maximum daily caffeine intake of no more than 300 mg, or a little over two 8 oz (237 mL) cups of coffee. A 2017 systematic review on caffeine toxicology found evidence supporting that caffeine consumption up to 300 mg/day for pregnant women is generally not associated with adverse reproductive or developmental effect. There are conflicting reports in the scientific literature about caffeine use during pregnancy. A 2011 review found that caffeine during pregnancy does not appear to increase
2178-723: A medical text by the Chinese physician Hua Tuo , who stated, "to drink bitter t'u constantly makes one think better." However, before the Tang dynasty , tea-drinking was primarily a southern Chinese practice centered in Jiankang . Tea was disdained by the Northern dynasties aristocrats, who describe it as inferior to yogurt. It became widely popular during the Tang dynasty, when it spread to Korea, Japan , and Vietnam. The Classic of Tea ,
2299-438: A mild form of drug dependence – associated with withdrawal symptoms such as sleepiness, headache, and irritability – when an individual stops using caffeine after repeated daily intake. Tolerance to the autonomic effects of increased blood pressure and heart rate, and increased urine output, develops with chronic use (i.e., these symptoms become less pronounced or do not occur following consistent use). Caffeine
2420-606: A milligram scale before and after they have been submerged to find out when they don't need to be exposed to more water imbibition. Floating seeds can be inspected when they have to sink inside mesh infusers submerged in transparent containers by shaking them. Seeds who don't absorb water will not germinate and must be modified with further scarification . Also, hot water treatment at 90 degrees C for 90 seconds followed by dip in cold water for 30 seconds can be an effective seed decontamination method against escherichia coli O157:H7 and salmonella . Ball infusers are removed along with
2541-671: A person grows used to it, have a lesser effect on wakefulness. Caffeine acts by blocking binding of adenosine at a number of adenosine receptor types, inhibiting the centrally depressant effects of adenosine and enhancing the release of acetylcholine . Caffeine has a three-dimensional structure similar to that of adenosine, which allows it to bind and block its receptors. Caffeine also increases cyclic AMP levels through nonselective inhibition of phosphodiesterase , increases calcium release from intracellular stores, and antagonises GABA receptors, although these mechanisms typically occur at concentrations beyond usual human consumption. Caffeine
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#17327919077302662-413: A plant to bear seed and about three years before a new plant is ready for harvesting. In addition to a zone 8 climate or warmer, tea plants require at least 127 cm (50 in) of rainfall per year and prefer acidic soils . Many high-quality tea plants are cultivated at elevations of up to 1,500 m (4,900 ft) above sea level. Though at these heights the plants grow more slowly, they acquire
2783-524: A refined setting. One form of Chinese tea ceremony is the Gongfu tea ceremony , which typically uses small Yixing clay teapots and oolong tea. In the United Kingdom , 63% of people drink tea daily. It is customary for a host to offer tea to guests soon after their arrival. Tea is consumed both at home and outside the home, often in cafés or tea rooms . Afternoon tea with cakes on fine porcelain
2904-833: A role in historical events – the Tea Act of 1773 provoked the Boston Tea Party that escalated into the American Revolution . The need to address the issue of British trade deficit because of the trade in tea resulted in the Opium Wars . The Qing Kangxi Emperor had banned foreign products from being sold in China, decreeing in 1685 that all goods bought from China must be paid for in silver coin or bullion. Traders from other nations then sought to find another product, in this case opium, to sell to China to earn back
3025-414: A similar function as a tea bag , a later American invention. The infuser is generally a small mesh or perforated metal container or covered spoon that holds tea leaves, in varying sizes to steep single or multiple servings at once. Common shapes for infusers include spherical, conical and cylindrical. One style of infuser is a split sphere with tong -like handles to open its mesh container. The infuser
3146-458: A study on drug abuse liability published in an NIDA research monograph. Some state that research does not provide support for an underlying biochemical mechanism for caffeine addiction. Other research states it can affect the reward system. "Caffeine addiction" was added to the ICDM-9 and ICD-10. However, its addition was contested with claims that this diagnostic model of caffeine addiction
3267-469: A treatise on tea and its preparations, was written by the 8th century Chinese writer, Lu Yu . He was known to have influenced tea drinking on a large part in China. Through the centuries, a variety of techniques for processing tea, and a number of different forms of tea, were developed. During the Tang dynasty, tea was steamed, then pounded and shaped into cake form, while in the Song dynasty , loose-leaf tea
3388-431: A tree of up to 16 m (52 ft) if left undisturbed, but cultivated plants are generally pruned to waist height for ease of plucking. The short plants bear more new shoots which provide new and tender leaves and increase the quality of the tea. Only the top 2.5–5 centimetres (1–2 in) of the mature plant are picked. These buds and leaves are called 'flushes'. A plant will grow a new flush every 7 to 15 days during
3509-474: A wide range of unpleasant symptoms including nervousness, irritability , restlessness, insomnia , headaches , and palpitations after caffeine use. Caffeine overdose can result in a state of central nervous system overstimulation known as caffeine intoxication, a clinically significant temporary condition that develops during, or shortly after, the consumption of caffeine. This syndrome typically occurs only after ingestion of large amounts of caffeine, well over
3630-464: Is a central nervous system stimulant that may reduce fatigue and drowsiness . At normal doses, caffeine has variable effects on learning and memory , but it generally improves reaction time , wakefulness , concentration, and motor coordination . The amount of caffeine needed to produce these effects varies from person to person, depending on body size and degree of tolerance. The desired effects arise approximately one hour after consumption, and
3751-540: Is a bitter, white crystalline purine , a methylxanthine alkaloid , and is chemically related to the adenine and guanine bases of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). It is found in the seeds, fruits, nuts, or leaves of a number of plants native to Africa, East Asia and South America and helps to protect them against herbivores and from competition by preventing the germination of nearby seeds, as well as encouraging consumption by select animals such as honey bees . The best-known source of caffeine
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3872-522: Is a cultural stereotype. In southwest England, many cafés serve a cream tea , consisting of scones, clotted cream , and jam alongside a pot of tea. Caffeine Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class and is the most commonly consumed psychoactive substance globally. It is mainly used for its eugeroic ( wakefulness promoter), ergogenic (physical performance enhancing), or nootropic (cognition improving) properties. Caffeine can supposedly, after
3993-899: Is an evergreen plant that grows mainly in tropical and subtropical climates. Some varieties can tolerate oceanic climates and are cultivated as far north as Cornwall in England, Perthshire in Scotland, Washington in the United States , and Vancouver Island in Canada. In the Southern Hemisphere, tea is grown as far south as Hobart in Tasmania and Waikato in New Zealand. Tea plants are propagated from seed and cuttings; about 4 to 12 years are needed for
4114-478: Is associated with reduced perceived exertion. While this effect is not present during exercise-to-exhaustion exercise, performance is significantly enhanced. This is congruent with caffeine reducing perceived exertion, because exercise-to-exhaustion should end at the same point of fatigue. Caffeine also improves power output and reduces time to completion in aerobic time trials, an effect positively (but not exclusively) associated with longer duration exercise. For
4235-468: Is chewed. Tea drinking may have begun in the region of Yunnan , where it was used for medicinal purposes. It is believed that in Sichuan , "people began to boil tea leaves for consumption into a concentrated liquid without the addition of other leaves or herbs, thereby using tea as a bitter yet stimulating drink, rather than as a medicinal concoction." Chinese legends attribute the invention of tea to
4356-514: Is classified by the U.S. Food and Drug Administration (FDA) as generally recognized as safe . Toxic doses, over 10 grams per day for an adult, are much higher than the typical dose of under 500 milligrams per day. The European Food Safety Authority reported that up to 400 mg of caffeine per day (around 5.7 mg/kg of body mass per day) does not raise safety concerns for non-pregnant adults, while intakes up to 200 mg per day for pregnant and lactating women do not raise safety concerns for
4477-579: Is complete. While not common, a French press may be used as a tea infuser. However, most teas are infused only for a limited time and then removed from the water so that the drink does not become bitter. In gōngfu chá (功夫茶), a modern method to infused tea in China, tea can be infused through a gàiwǎn (盖碗), a tea pot (茶壶) or a gōngdào bēi (公道杯). Tea Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of Camellia sinensis , an evergreen shrub native to East Asia which probably originated in
4598-444: Is consumed. Alcohol consumption alone reduces both inhibitory and activational aspects of behavioral control. Caffeine antagonizes the effect of alcohol on the activational aspect of behavioral control, but has no effect on the inhibitory behavioral control. The Dietary Guidelines for Americans recommend avoidance of concomitant consumption of alcohol and caffeine, as taking them together may lead to increased alcohol consumption, with
4719-480: Is estimated to have diverged from Assam tea around 22,000 years ago, while Chinese Assam tea and Indian Assam tea diverged 2,800 years ago. The divergence of Chinese small-leaf tea and Assam tea would correspond to the last glacial maximum . People in ancient East Asia ate tea for centuries, perhaps even millennia , before ever consuming it as a beverage. They would nibble on the leaves raw, add them to soups or greens , or ferment them and chew them as areca nut
4840-750: Is no evidence that coffee stunts a child's growth. The American Academy of Pediatrics recommends that caffeine consumption, particularly in the case of energy and sports drinks, is not appropriate for children and adolescents and should be avoided. This recommendation is based on a clinical report released by American Academy of Pediatrics in 2011 with a review of 45 publications from 1994 to 2011 and includes inputs from various stakeholders (Pediatricians, Committee on nutrition, Canadian Pediatric Society, Centers for Disease Control & Prevention , Food and Drug Administration , Sports Medicine & Fitness committee, National Federations of High School Associations). For children age 12 and under, Health Canada recommends
4961-574: Is no known antidote or reversal agent for caffeine intoxication. Treatment of mild caffeine intoxication is directed toward symptom relief; severe intoxication may require peritoneal dialysis , hemodialysis , or hemofiltration . Intralipid infusion therapy is indicated in cases of imminent risk of cardiac arrest in order to scavenge the free serum caffeine. Death from caffeine ingestion appears to be rare, and most commonly caused by an intentional overdose of medications. In 2016, 3702 caffeine-related exposures were reported to Poison Control Centers in
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5082-541: Is not supported by evidence. The American Psychiatric Association 's DSM-5 does not include the diagnosis of a caffeine addiction but proposes criteria for the disorder for more study. Withdrawal can cause mild to clinically significant distress or impairment in daily functioning. The frequency at which this occurs is self-reported at 11%, but in lab tests only half of the people who report withdrawal actually experience it, casting doubt on many claims of dependence. and most cases of caffeine withdrawal were 13% in
5203-448: Is often consumed with additions to the basic tea leaf and water added during preparation or drinking. Examples of additional processing steps that occur before tea is sold are blending, flavouring, scenting, and decaffeination of teas. Examples of additions added at the point of consumption include milk, sugar and lemon. Tea blending is the combination of different teas together to achieve the final product. Such teas may combine others from
5324-521: Is on the WHO Model List of Essential Medicines . It may confer a modest protective effect against some diseases, including Parkinson's disease . Some people experience sleep disruption or anxiety if they consume caffeine, but others show little disturbance. Evidence of a risk during pregnancy is equivocal; some authorities recommend that pregnant women limit caffeine to the equivalent of two cups of coffee per day or less. Caffeine can produce
5445-399: Is placed in a cup or pot of hot or boiling water, allowing the tea to brew without loose tea leaves spilling into the pot or cup. A rod or chain is commonly attached to the container of the infuser to simplify retrieval from the pot or cup. Infusers with large holes may not catch all the leaves, requiring the use of a tea strainer to remove the remaining pieces. Water imbibition takes half
5566-427: Is poor. 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. The addition of caffeine (100–130 mg) to commonly prescribed pain relievers such as paracetamol or ibuprofen modestly improves the proportion of people who achieve pain relief . Consumption of caffeine after abdominal surgery shortens
5687-998: Is possible but the evidence is inconclusive. Caffeine may lessen the severity of acute mountain sickness if taken a few hours prior to attaining a high altitude. One meta analysis has found that caffeine consumption is associated with a reduced risk of type 2 diabetes . Regular caffeine consumption may reduce the risk of developing Parkinson's disease and may slow the progression of Parkinson's disease. Caffeine increases intraocular pressure in those with glaucoma but does not appear to affect normal individuals. The DSM-5 also includes other caffeine-induced disorders consisting of caffeine-induced anxiety disorder, caffeine-induced sleep disorder and unspecified caffeine-related disorders. The first two disorders are classified under "Anxiety Disorder" and "Sleep-Wake Disorder" because they share similar characteristics. Other disorders that present with significant distress and impairment of daily functioning that warrant clinical attention but do not meet
5808-479: Is recommended and temperature variation kept to a minimum). Tea is divided into categories based on how it is processed. At least six different types are produced: After picking, the leaves of C. sinensis soon begin to wilt and oxidize unless immediately dried. An enzymatic oxidation process triggered by the plant's intracellular enzymes causes the leaves to turn progressively darker as their chlorophyll breaks down and tannins are released. This darkening
5929-408: Is reduced in pregnancy, especially in the third trimester, and the half-life of caffeine during pregnancy can be increased up to 15 hours (as compared to 2.5 to 4.5 hours in non-pregnant adults). Evidence regarding the effects of caffeine on pregnancy and for breastfeeding are inconclusive. There is limited primary and secondary advice for, or against, caffeine use during pregnancy and its effects on
6050-426: Is still a good-tasting cup of tea, if you like your tea strong and sweet. But let it cool enough to be quaffed and enjoyed, and your lips will be coated with a sticky scum that forms across the surface, which if left undisturbed will become a leathery membrane that can be wound around your finger and flipped away... Canned tea is sold prepared and ready to drink. It was introduced in 1981 in Japan. The first bottled tea
6171-448: Is stopped at a predetermined stage by heating, which deactivates the enzymes responsible. In the production of black teas, halting by heating is carried out simultaneously with drying. Without careful moisture and temperature control during manufacture and packaging, growth of undesired molds and bacteria may make tea unfit for consumption. After basic processing, teas may be altered through additional processing steps before being sold and
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#17327919077306292-491: Is sweetened with either sugar or honey; tea with milk is called a bawarka (" Bavarian style") in Polish and is widely popular. In Australia, tea with milk is known as "white tea". The order of steps in preparing a cup of tea is a much-debated topic and can vary widely between cultures and individuals. Some say it is preferable to add the milk to the cup before the tea, as the high temperature of freshly brewed tea can denature
6413-529: Is the coffee bean , the seed of the Coffea plant. People may drink beverages containing caffeine to relieve or prevent drowsiness and to improve cognitive performance. To make these drinks, caffeine is extracted by steeping the plant product in water, a process called infusion . Caffeine-containing drinks, such as coffee , tea , and cola , are consumed globally in high volumes. In 2020, almost 10 million tonnes of coffee beans were consumed globally. Caffeine
6534-516: Is the world's most widely consumed psychoactive drug . Unlike most other psychoactive substances, caffeine remains largely unregulated and legal in nearly all parts of the world. Caffeine is also an outlier as its use is seen as socially acceptable in most cultures with it even being encouraged. Caffeine has both positive and negative health effects . It can treat and prevent the premature infant breathing disorders bronchopulmonary dysplasia of prematurity and apnea of prematurity . Caffeine citrate
6655-551: Is therefore not generally considered addictive. However, some diagnostic models, such as the ICDM-9 and ICD-10 , include a classification of caffeine addiction under a broader diagnostic model. Some state that certain users can become addicted and therefore unable to decrease use even though they know there are negative health effects. Caffeine does not appear to be a reinforcing stimulus, and some degree of aversion may actually occur, with people preferring placebo over caffeine in
6776-591: Is used for both prevention and treatment of bronchopulmonary dysplasia in premature infants. It may improve weight gain during therapy and reduce the incidence of cerebral palsy as well as reduce language and cognitive delay. On the other hand, subtle long-term side effects are possible. Caffeine is used as a primary treatment for apnea of prematurity , but not prevention. It is also used for orthostatic hypotension treatment. Some people use caffeine-containing beverages such as coffee or tea to try to treat their asthma . Evidence to support this practice
6897-730: The Chronicles of Huayang , it was recorded that the Ba people in Sichuan presented tu to the Zhou king. The Qin later conquered the state of Ba and its neighbour Shu , and according to the 17th century scholar Gu Yanwu who wrote in Ri Zhi Lu ( 日知錄 ): "It was after the Qin had taken Shu that they learned how to drink tea." Another possible early reference to tea is found in a letter written by
7018-641: The Manchus do, and the elite of the Qing Dynasty of the Chinese Empire continued to do so. Hong Kong-style milk tea is based on British habits. Tibetans and other Himalayan peoples traditionally drink tea with milk or yak butter and salt. In Eastern European countries, and in Russia and Italy, tea is commonly served with lemon juice. In Poland, tea is traditionally served with a slice of lemon and
7139-516: The Qin dynasty general Liu Kun who requested that some "real tea" to be sent to him. The earliest known physical evidence of tea was discovered in 2016 in the mausoleum of Emperor Jing of Han in Xi'an , indicating that tea from the genus Camellia was drunk by Han dynasty emperors as early as the second century BC. The Han dynasty work "The Contract for a Youth", written by Wang Bao in 59 BC, contains
7260-552: The 16th century, at which time it was termed chá . The earliest European reference to tea, written as chiai , came from Delle navigationi e viaggi written by Venetian Giambattista Ramusio in 1545. The first recorded shipment of tea by a European nation was in 1607 when the Dutch East India Company moved a cargo of tea from Macao to Java, then two years later, the Dutch bought the first assignment of tea which
7381-565: The 16th century. During the 17th century, drinking tea became fashionable among the English , who started to plant tea on a large scale in British India . The term herbal tea refers to drinks not made from Camellia sinensis . They are the infusions of fruit, leaves, or other plant parts , such as steeps of rosehip , chamomile , or rooibos . These may be called tisanes or herbal infusions to prevent confusion with tea made from
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#17327919077307502-592: The 1930s, with Nestlé introducing the first commercial product in 1946, while Redi-Tea debuted instant iced tea in 1953. Additives such as chai , vanilla, honey or fruit, are popular, as is powdered milk . During the Second World War British and Canadian soldiers were issued an instant tea in their composite ration ("compo") packs. These blocks of instant tea, powdered milk, and sugar were not always well received. As Royal Canadian Artillery Gunner, George C Blackburn observed: But, unquestionably,
7623-663: The 1950s because of a successful advertising campaign by the India Tea Board. The British introduced tea industry to Sri Lanka (then Ceylon) in 1867. Physically speaking, tea has properties of both a solution and a suspension . It is a solution of the water-soluble compounds extracted from the tea leaves, such as the polyphenols and amino acids. Tea infusions are among most consumed beverages globally. Caffeine makes up about 3% of tea's dry weight, which translates to between 30 and 90 milligrams per 250-millilitre ( 8 + 1 ⁄ 2 US fl oz) cup depending on
7744-669: The DSM-5, but they noted that the clinical significance of the disorder is unclear. Due to this inconclusive evidence on clinical significance, the DSM-5 classifies caffeine-use disorder as a "condition for further study". Tolerance to the effects of caffeine occurs for caffeine-induced elevations in blood pressure and the subjective feelings of nervousness. Sensitization , the process whereby effects become more prominent with use, may occur for positive effects such as feelings of alertness and wellbeing. Tolerance varies for daily, regular caffeine users and high caffeine users. High doses of caffeine (750 to 1200 mg/day spread throughout
7865-464: The Himalayan countries and Mongolian steppes. In Mongolia, tea bricks were ubiquitous enough to be used as a form of currency. Among Himalayan peoples, compressed tea is consumed by combining it with yak butter and salt to produce butter tea . "Instant tea", similar to freeze-dried instant coffee and an alternative to brewed tea, can be consumed either hot or cold. Instant tea was developed in
7986-762: The International Classification of Diseases (ICD-11), cases of very high caffeine intake (e.g. > 5 g) may result in caffeine intoxication with symptoms including mania, depression, lapses in judgment, disorientation, disinhibition, delusions, hallucinations or psychosis, and rhabdomyolysis . High caffeine consumption in energy drinks (at least one liter or 320 mg of caffeine) was associated with short-term cardiovascular side effects including hypertension, prolonged QT interval , and heart palpitations. These cardiovascular side effects were not seen with smaller amounts of caffeine consumption in energy drinks (less than 200 mg). As of 2007 there
8107-735: The Portuguese, who traded in Macao and picked up the Cantonese pronunciation of the word. The more common tea form arrived in the 17th century via the Dutch, who acquired it either indirectly from the Malay teh , or directly from the tê pronunciation in Min Chinese . The third form chai (meaning "spiced tea") originated from a northern Chinese pronunciation of cha , which travelled overland to Central Asia and Persia where it picked up
8228-701: 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. The LD 50 of caffeine in rats is 192 milligrams per kilogram of body mass. The fatal dose in humans is estimated to be 150–200 milligrams per kilogram, which is 10.5–14 grams for a typical 70 kg (150 lb) adult, equivalent to about 75–100 cups of coffee. There are cases where doses as low as 57 milligrams per kilogram have been fatal. A number of fatalities have been caused by overdoses of readily available powdered caffeine supplements, for which
8349-542: The amounts found in typical caffeinated beverages and caffeine tablets (e.g., more than 400–500 mg at a time). According to the DSM-5, caffeine intoxication may be diagnosed if five (or more) of the following symptoms develop after recent consumption of caffeine: restlessness, nervousness, excitement, insomnia, flushed face, diuresis , gastrointestinal disturbance, muscle twitching, rambling flow of thought and speech, tachycardia or cardiac arrhythmia , periods of inexhaustibility, and psychomotor agitation . According to
8470-407: The borderlands of southwestern China and northern Myanmar . Tea is also made, but rarely, from the leaves of Camellia taliensis . After plain water, tea is the most widely consumed drink in the world. There are many different types of tea; some have a cooling, slightly bitter, and astringent flavour, while others have profiles that include sweet, nutty, floral, or grassy notes . Tea has
8591-426: The cake using a small knife, and steeping the extracted pieces in water. During the Tang dynasty, as described by Lu Yu, compressed tea was ground into a powder, combined with hot water, and ladled into bowls, resulting in a "frothy" mixture. In the Song dynasty , the tea powder would instead be whisked with hot water in the bowl. Although no longer practiced in China today, the whisking method of preparing powdered tea
8712-403: The connoisseurs' arguments against paper tea bags by way of its three-dimensional tetrahedron shape, which allows more room for tea leaves to expand while steeping. However, some types of pyramid tea bags have been criticised as being environmentally unfriendly, since their synthetic material is not as biodegradable as loose tea leaves and paper tea bags. The tea leaves are packaged loosely in
8833-407: The criteria to be diagnosed under any specific disorders are listed under "Unspecified Caffeine-Related Disorders". Caffeine is reputed to cause a fall in energy several hours after drinking, but this is not well researched. Consumption of 1–1.5 grams (1,000–1,500 mg) per day is associated with a condition known as caffeinism . Caffeinism usually combines caffeine dependency with
8954-606: The day) have been shown to produce complete tolerance to some, but not all of the effects of caffeine. Doses as low as 100 mg/day, such as a 6 oz (170 g) cup of coffee or two to three 12 oz (340 g) servings of caffeinated soft-drink, may continue to cause sleep disruption, among other intolerances. Non-regular caffeine users have the least caffeine tolerance for sleep disruption. Some coffee drinkers develop tolerance to its undesired sleep-disrupting effects, but others apparently do not. A neuroprotective effect of caffeine against Alzheimer's disease and dementia
9075-619: The desired effects of a moderate dose usually subside after about three or four hours. Caffeine can delay or prevent sleep and improves task performance during sleep deprivation. Shift workers who use caffeine make fewer mistakes that could result from drowsiness. Caffeine in a dose dependent manner increases alertness in both fatigued and normal individuals. A systematic review and meta-analysis from 2014 found that concurrent caffeine and L -theanine use has synergistic psychoactive effects that promote alertness, attention, and task switching ; these effects are most pronounced during
9196-495: The earlier milk is added, the slower the drink cools. A 2007 study published in the European Heart Journal found certain beneficial effects of tea may be lost through the addition of milk. In 1907, American tea merchant Thomas Sullivan began distributing samples of his tea in small bags of silk with a drawstring. Consumers noticed they could simply leave the tea in the bag and reuse it with fresh tea. However,
9317-437: The estimated lethal amount is less than a tablespoon. The lethal dose is lower in individuals whose ability to metabolize caffeine is impaired due to genetics or chronic liver disease. A death was reported in 2013 of a man with liver cirrhosis who overdosed on caffeinated mints. Caffeine is a substrate for CYP1A2 , and interacts with many substances through this and other mechanisms. According to DSST , alcohol causes
9438-493: The exception of the dietary mineral manganese , at 0.5 mg per cup or 26% of the Reference Daily Intake (RDI). Fluoride is sometimes present in tea; certain types of "brick tea", made from old leaves and stems, have the highest levels, enough to pose a health risk if much tea is drunk, which has been attributed to high levels of fluoride in soils, acidic soils, and long brewing. Camellia sinensis
9559-462: The feature of Compo rations destined to be remembered beyond all others is Compo tea...Directions say to "sprinkle powder on heated water and bring to the boil, stirring well, three heaped teaspoons to one pint of water." Every possible variation in the preparation of this tea was tried, but...it always ended up the same way. While still too hot to drink, it is a good-looking cup of strong tea. Even when it becomes just cool enough to be sipped gingerly, it
9680-541: The fetus or newborn. The UK Food Standards Agency has recommended that pregnant women should limit their caffeine intake, out of prudence, to less than 200 mg of caffeine a day – the equivalent of two cups of instant coffee, or one and a half to two cups of fresh coffee. The American Congress of Obstetricians and Gynecologists (ACOG) concluded in 2010 that caffeine consumption is safe up to 200 mg per day in pregnant women. For women who breastfeed, are pregnant, or may become pregnant, Health Canada recommends
9801-434: The fetus or the breast-fed infants. A cup of coffee contains 80–175 mg of caffeine, depending on what "bean" (seed) is used, how it is roasted, and how it is prepared (e.g., drip , percolation , or espresso ). Thus it requires roughly 50–100 ordinary cups of coffee to reach the toxic dose. However, pure powdered caffeine, which is available as a dietary supplement , can be lethal in tablespoon-sized amounts. Caffeine
9922-801: The first hour post-dose. Caffeine is a proven ergogenic aid in humans. Caffeine improves athletic performance in aerobic (especially endurance sports ) and anaerobic conditions. Moderate doses of caffeine (around 5 mg/kg ) can improve sprint performance, cycling and running time trial performance, endurance (i.e., it delays the onset of muscle fatigue and central fatigue ), and cycling power output. Caffeine increases basal metabolic rate in adults. Caffeine ingestion prior to aerobic exercise increases fat oxidation, particularly in persons with low physical fitness. Caffeine improves muscular strength and power, and may enhance muscular endurance. Caffeine also enhances performance on anaerobic tests. Caffeine consumption before constant load exercise
10043-410: The first known reference to boiling tea. Among the tasks listed to be undertaken by the youth, the contract states that "he shall boil tea and fill the utensils" and "he shall buy tea at Wuyang". The first record of tea cultivation is dated to this period, during which tea was cultivated on Meng Mountain ( 蒙山 ) near Chengdu . Another early credible record of tea drinking dates to the 3rd century AD, in
10164-596: The general population of healthy adults, Health Canada advises a daily intake of no more than 400 mg. This limit was found to be safe by a 2017 systematic review on caffeine toxicology. In healthy children, moderate caffeine intake under 400 mg produces effects that are "modest and typically innocuous". As early as six months old, infants can metabolize caffeine at the same rate as that of adults. Higher doses of caffeine (>400 mg) can cause physiological, psychological and behavioral harm, particularly for children with psychiatric or cardiac conditions. There
10285-643: The growing season. Leaves that are slow in development tend to produce better-flavoured teas. Several teas are available from specified flushes; for example, Darjeeling tea is available as first flush (at a premium price), second flush, monsoon and autumn. Assam second flush or "tippy" tea is considered superior to first flush, because of the gold tips that appear on the leaves. Pests that can afflict tea plants include mosquito bugs, genus Helopeltis , which are true bugs and not to be confused with dipterous insects of family Culicidae ('mosquitos'). Mosquito bugs can damage leaves both by sucking plant materials, and by
10406-499: The history of Camellia sinensis 's consumption, there is no high-quality evidence showing that tea consumption gives significant benefits other than possibly increasing alertness, an effect caused by caffeine in the tea leaves. In clinical research conducted in the early 21st century, it was found there is no scientific evidence to indicate that consuming tea affects any disease or improves health. Black and green teas contain no essential nutrients in significant amounts, with
10527-477: The largest leaves; China type, characterised by the smallest leaves; and Cambodian type, characterised by leaves of intermediate size. The Cambodian-type tea ( C. assamica subsp. lasiocaly ) was originally considered a type of Assam tea. However, later genetic work showed that it is a hybrid between Chinese small-leaf tea and Assam-type tea. Darjeeling tea appears to be a hybrid between Chinese small-leaf tea and Assam-type large-leaf tea. A tea plant will grow into
10648-863: The laying of eggs (oviposition) within the plant. Spraying with synthetic insecticides may be deemed appropriate. Other pests are Lepidopteran leaf feeders and various tea diseases . Tea is mainly grown in Asia and Africa, with smaller areas in South America and around the Black and Caspian Seas. The four biggest tea-producing countries are China, India, Kenya and Sri Lanka, together representing 81% of world tea production. Smaller hubs of production include such places as São Miguel Island, Azores , in Portugal, and Guria , in Georgia. In 2022, global production of tea
10769-459: The maximum adult caffeine dose may not be appropriate for light-weight adolescents or for younger adolescents who are still growing. The daily dose of 2.5 mg/kg body weight would not cause adverse health effects in the majority of adolescent caffeine consumers. This is a conservative suggestion since older and heavier-weight adolescents may be able to consume adult doses of caffeine without experiencing adverse effects. The metabolism of caffeine
10890-419: The moderate sense. Moderately physical dependence and withdrawal symptoms may occur upon abstinence, with greater than 100 mg caffeine per day, although these symptoms last no longer than a day. Some symptoms associated with psychological dependence may also occur during withdrawal. The diagnostic criteria for caffeine withdrawal require a previous prolonged daily use of caffeine. Following 24 hours of
11011-547: The mythical Shennong (in central and northern China) in 2737 BC, although evidence suggests that tea drinking may have been introduced from the southwest of China (Sichuan/Yunnan area). The earliest written records of tea come from China. The word tú 荼 appears in the Shijing and other ancient texts to signify a kind of "bitter vegetable" ( 苦菜 ), and it is possible that it referred to many different plants such as sow thistle , chicory , or smartweed , as well as tea. In
11132-618: The natural home of the tea plant is considered to be within the comparatively small fan-shaped area between Nagaland , Manipur and Mizoram along the Burma frontier in the west, through China as far as the Zhejiang Province in the east, and from this line generally south through the hills to Burma and Thailand to Vietnam . The west–east axis indicated above is about 2,400 km long extending from longitude 95°-120°E. The north–south axis covers about 1,920 km, starting from
11253-616: The northern part of Burma, latitude 29°N passing through Yunnan , Tongkin , Thailand, Laos and on to Annan, reaching latitude 11°N. Chinese (small-leaf) type tea ( C. sinensis var. sinensis ) may have originated in southern China possibly with hybridization of unknown wild tea relatives. However, since there are no known wild populations of this tea, its origin is speculative. Given their genetic differences forming distinct clades , Chinese Assam-type tea ( C. sinensis var. assamica ) may have two different parentages – one being found in southern Yunnan ( Xishuangbanna , Pu'er City ) and
11374-408: The other in western Yunnan ( Lincang , Baoshan ). Many types of Southern Yunnan Assam tea have been hybridized with the closely related species Camellia taliensis . Unlike Southern Yunnan Assam tea, Western Yunnan Assam tea shares many genetic similarities with Indian Assam-type tea (also C. sinensis var. assamica ). Thus, Western Yunnan Assam tea and Indian Assam tea both may have originated from
11495-481: The potential of this distribution and packaging method would not be fully realised until later. During World War II, tea was rationed in the United Kingdom. In 1953, after rationing in the UK ended, Yorkshire -based tea manufacturer Tetley launched the tea bag in the UK, and it was an immediate success. The "pyramid tea bag" (or sachet), introduced by Lipton and PG Tips/Scottish Blend in 1996, attempts to address one of
11616-507: The presence of polyphenols . These are the most abundant compounds in tea leaves, making up 30–40% of their composition. Polyphenols in tea include flavonoids , epigallocatechin gallate (EGCG), and other catechins . Although there has been preliminary clinical research on whether green or black teas may protect against various human diseases, there is no evidence that tea polyphenols have any effect on health or lowering disease risk. Although health benefits have been assumed throughout
11737-413: The pressure in various muscles, including the eyelids . Acute ingestion of caffeine in large doses (at least 250–300 mg, equivalent to the amount found in 2–3 cups of coffee or 5–8 cups of tea) results in a short-term stimulation of urine output in individuals who have been deprived of caffeine for a period of days or weeks. This increase is due to both a diuresis (increase in water excretion) and
11858-406: The proteins found in fresh milk, similar to the change in taste of UHT milk, resulting in an inferior-tasting beverage. Others insist it is better to add the milk to the cup after the tea, as black tea is often brewed as close to boiling as possible. The addition of milk chills the beverage during the crucial brewing phase, if brewing in a cup rather than using a pot, meaning the delicate flavour of
11979-494: The results of observational studies, suggests that women who consume large amounts of caffeine (greater than 300 mg/day) prior to becoming pregnant may have a higher risk of experiencing pregnancy loss. Caffeine in coffee and other caffeinated drinks can affect gastrointestinal motility and gastric acid secretion. In postmenopausal women, high caffeine consumption can accelerate bone loss . Caffeine, alongside other factors such as stress and fatigue, can also increase
12100-410: The risk of congenital malformations , miscarriage or growth retardation even when consumed in moderate to high amounts. Other reviews, however, concluded that there is some evidence that higher caffeine intake by pregnant women may be associated with a higher risk of giving birth to a low birth weight baby, and may be associated with a higher risk of pregnancy loss. A systematic review, analyzing
12221-450: The risk of depression. Some textbooks state that caffeine is a mild euphoriant, while others state that it is not a euphoriant. Caffeine-induced anxiety disorder is a subclass of the DSM-5 diagnosis of substance/medication-induced anxiety disorder. Whether caffeine can result in an addictive disorder depends on how addiction is defined. Compulsive caffeine consumption under any circumstances has not been observed, and caffeine
12342-707: The same cultivation area or several different ones. The aim is to obtain consistency, better taste, higher price, or some combination of the three. Flavoured and scented teas are enhancements of the base tea. This can be accomplished through directly adding flavouring agents, such as ginger , cloves , mint leaves , cardamom , bergamot (found in Earl Grey ), vanilla , and spearmint . Alternatively, because tea easily retains odours, it can be placed in proximity to an aromatic ingredient to absorb its aroma, as in traditional jasmine tea . The addition of milk to tea in Europe
12463-468: The same parent plant in the area where southwestern China, Indo-Burma, and Tibet meet. However, as the Indian Assam tea shares no haplotypes with Western Yunnan Assam tea, Indian Assam tea is likely to have originated from an independent domestication. Some Indian Assam tea appears to have hybridized with the species Camellia pubicosta . Assuming a generation of 12 years, Chinese small-leaf tea
12584-633: The silver they were required to pay for tea and other commodities. The subsequent attempts by the Chinese Government to curtail the trade in opium led to war. Chinese small-leaf-type tea was introduced into India in 1836 by the British in an attempt to break the Chinese monopoly on tea. In 1841, Archibald Campbell brought seeds of Chinese tea from the Kumaun region and experimented with planting tea in Darjeeling . The Alubari tea garden
12705-471: The tax on tea, thereby eliminating the smuggling trade, by 1785. In Britain and Ireland, tea was initially consumed as a luxury item on special occasions, such as religious festivals, wakes, and domestic work gatherings. The price of tea in Europe fell steadily during the 19th century, especially after Indian tea began to arrive in large quantities; by the late 19th century tea had become an everyday beverage for all levels of society. The popularity of tea played
12826-400: The tea and over-brewing. A traditional method uses a three-piece lidded teacup called a gaiwan , the lid of which is tilted to decant the tea into a different cup for consumption. Tea bricks or compressed tea are produced for convenience in transport, storage, and ageing. It can usually be stored longer without spoilage than loose leaf tea. Compressed tea is prepared by loosening leaves from
12947-412: The tea leaves from the pot. Snap ball tea strainers are automatically sealed with the force of the end of the handle that is circulated like a spring . The spring handle requires more metal to manufacture, thus they are usually a bit more expensive than regular infuser balls. The handle in snap ball tea strainers make them more practical: Shut-off infusers are left in the pot after the brewing process
13068-467: The tea plant. The etymology of the various words for tea reflects the history of transmission of tea drinking culture and trade from China to countries around the world. Nearly all of the words for tea worldwide fall into three broad groups: te , cha and chai , present in English as tea , cha or char , and chai . The earliest of the three to enter English is cha , which came in the 1590s via
13189-546: The tea-drinking habit to the English court when she married Charles II in 1662. Tea, however, was not widely consumed in the British Isles until the 18th century and remained expensive until the latter part of that period. English drinkers preferred to add sugar and milk to black tea, and black tea overtook green tea in popularity in the 1720s. Tea smuggling during the 18th century led to the general public being able to afford and consume tea. The British government removed
13310-460: The time for material that floats with half its area above the water surface when they are submerged with an infuser. Seeds are often pre-treated before sowing in order to verify that they will sprout. Imbibition of water through the membrane of the seed shell is the first step in the germination process in most seeds. Seeds can be submerged with an infuser, including hot water scarification treatment for tolerant species. Seeds can be weighed with
13431-409: The time to recovery of normal bowel function and shortens length of hospital stay. Caffeine was formerly used as a second-line treatment for ADHD . It is considered less effective than methylphenidate or amphetamine but more so than placebo for children with ADHD. Children, adolescents, and adults with ADHD are more likely to consume caffeine, perhaps as a form of self-medication . Caffeine
13552-427: The type, brand, and brewing method. A study found that the caffeine content of one gram of black tea ranged from 22 to 28 mg, while the caffeine content of one gram of green tea ranged from 11 to 20 mg, reflecting a significant difference. Tea contains small amounts of theobromine and theophylline , which are xanthines and stimulants , similar to caffeine. The astringency in tea can be attributed to
13673-539: Was 29.8 million tonnes , led by China with 49% and India with 20% of the world total. Kenya , Sri Lanka , and Turkey were secondary producers. Storage conditions determine the shelf life of tea; that of black teas is greater than that of green teas. Some, such as flower teas, may last only a month or so. Others, such as pu-erh, improve with age. To remain fresh and prevent mold, tea needs to be stored away from heat, light, air, and moisture. Tea must be kept at room temperature in an air-tight container. Black tea in
13794-452: Was developed and became popular. During the Yuan and Ming dynasties, unoxidized tea leaves were first stirred in a hot dry pan, then rolled and air-dried, a process that stops the oxidation process that would have turned the leaves dark, thereby allowing tea to remain green. In the 15th century, oolong tea, in which the leaves are allowed to partially oxidize before being heated in the pan,
13915-459: Was developed. Western tastes, however, favoured the fully oxidized black tea , and the leaves were allowed to oxidize further. Yellow tea was an accidental discovery in the production of green tea during the Ming dynasty, when apparently careless practices allowed the leaves to turn yellow, which yielded a different flavour. Tea was first introduced to Western priests and merchants in China during
14036-546: Was first mentioned in 1680 by the epistolist Madame de Sévigné . Many teas are traditionally drunk with milk in cultures where dairy products are consumed. These include Indian masala chai and British tea blends. These teas tend to be very hearty varieties of black tea which can be tasted through the milk, such as Assams, or the East Friesian blend. Milk is thought to neutralise remaining tannins and reduce acidity. The Han Chinese do not usually drink milk with tea but
14157-726: Was from Hirado in Japan to be shipped to Europe. Tea became a fashionable drink in The Hague in the Netherlands, and the Dutch introduced the drink to Germany , France , and across the Atlantic to New Amsterdam (New York). In 1567, Russian people came in contact with tea when the Cossack Atamans Petrov and Yalyshev visited China. The Mongolian Khan donated to Tsar Michael I four poods (65–70 kg) of tea in 1638. According to Jeremiah Curtin , it
14278-591: Was introduced by an Indonesian tea company, PT. Sinar Sosro in 1969 with the brand name Teh Botol Sosro (or Sosro bottled tea). In 1983, Swiss-based Bischofszell Food Ltd. was the first company to bottle iced tea on an industrial scale. In many cultures, tea is consumed at elevated social events, such as the tea party . Tea ceremonies have arisen in different cultures, such as the Chinese and Japanese traditions, each of which employs certain techniques and ritualised protocol of brewing and serving tea for enjoyment in
14399-716: Was opened in 1856, and Darjeeling tea began to be produced. In 1848, Robert Fortune was sent by the East India Company on a mission to China to bring the tea plant back to Great Britain. He began his journey in high secrecy as his mission occurred in the lull between the First Opium War and the Second Opium War . The Chinese tea plants he brought back were introduced to the Himalayas , though most did not survive. The British had discovered that
14520-585: Was possibly in 1636 that Vassili Starkov was sent as envoy to the Altyn Khan . He was given 250 pounds of tea as a gift to the tsar. Starkov at first refused, seeing no use for a load of dead leaves, but the Khan insisted. Thus was tea introduced to Russia. In 1679, Russia concluded a treaty on regular tea supplies from China via camel caravan in exchange for furs. It is today considered the de facto national beverage. The first record of tea in English came from
14641-457: Was transmitted to Japan by Zen Buddhist monks, and is still used to prepare matcha in the Japanese tea ceremony . Chinese pu-erh is often distributed in the form, as other teas may sometimes be. Compressed tea was the most popular form of tea in China during the Tang dynasty. By the beginning of the Ming dynasty, it had been displaced by loose-leaf tea. It remains popular, however, in
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