Coffee
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Coffee is a beverage, served hot or with ice, prepared from the roasted seeds of the coffee plant. These seeds are almost always called coffee beans. Coffee is the second most commonly traded commodity in the world (measured by monetary volume), trailing only petroleum, and the most consumed beverage. In total, 6.7 million tonnes of coffee were produced annually in 1998-2000, forecast to rise to 7 million tonnes annually by 2010. Coffee is one of humanity's chief sources of caffeine, a stimulant. Its potential benefits and hazards have been, and continue to be, widely studied and discussed.

Etymology and History

The word entered English in 1598 via Italian caffè, via Turkish kahve, from Arabic qahwa, meaning "to have no appetite," as in to have no appetite for sleep. Its ultimate origin is uncertain, there being several legendary accounts of the origin of the drink. One possible origin is the Kaffa region in Ethiopia, where the plant originated (its native name there being bunna). Coffee beans were first exported from Ethiopia to Yemen.

Consumption of coffee was outlawed in Mecca in 1511, and in Cairo in 1532, but in the face of the drink's immense popularity, the decree was later rescinded. In 1554, the first coffeehouse in Istanbul opened.

Largely through the efforts of the British East India Company and the Dutch East India Company, coffee became available in Europe no later than the 16th century, according to Leonhard Rauwolf's 1583 account. The first coffeehouse in England was set up in Oxford by one Jacob or Jacobs, a Turkish Jew, in 1650. The first coffeehouse in London was opened two years later in St. Michael's Alley in Cornhill. The proprietor was Pasqua Rosée, the Ragusan servant of a trader in Turkish goods named Daniel Edwards, who imported the coffee and assisted Rosée in setting up the establishment. The coffeehouse spread rapidly in Europe and America after that, with first coffeehouses opening in Boston in 1670, and in Paris in 1671. By 1675, there were more than 3,000 coffeehouses in England.

Women were not allowed in coffeehouses, and in London, the anonymous 1674 "Women's Petition Against Coffee" complained:

"…the Excessive Use of that Newfangled, Abominable, Heathenish Liquor called COFFEE […] has […] Eunucht our Husbands, and Crippled our more kind Gallants, that they are become as Impotent, as Age.

Legend has it that the first coffeehouse opened in Vienna in 1683 after the Battle of Vienna, taking its supplies from the spoils left behind by the defeated Turks. The officer who received the coffee beans, Polish military officer Franciszek Jerzy Kulczycki, opened the first coffee house in Vienna and helped popularize the custom of adding sugar and milk to the coffee (until recently, this was celebrated in Viennese coffeehouses by hanging of picture of Kulczycki in the window). Additionally, another credible story is that the first coffeehouses were opened in Krakow in the 16th or 17th century because of closer trade ties with the East, most notably the Turks. The first coffee plantation in the New World was established in Brazil in 1727 when Lt. Col. Francisco de Melo Palheta smuggled seeds from the French Guiana in a bouquet spiked with seedlings that was to sprout a coffee empire. By the 1800 Brazil’s harvests would turn coffee from an elite indulgence to an everyday elixir, a drink for the people. Brazil, like most other countries cultivates coffee as a commercial commodity, relied heavily on slave labor from Africa for its viability until abolition in 1888. The success of coffee in 17th-century Europe was paralleled with the spread of the habit of tobacco smoking all over the continent during the course of the Thirty Years' War (1618–48).

For many decades in the 19th and early 20th centuries Brazil was the biggest producer and virtual monopolist in the trade, until a policy of maintaining high prices opened opportunities to other growers, like Colombia, Guatemala and Indonesia.

Coffee Bean Types

There are two main species of the coffee plant. Coffea arabica is the older of them. Thought to be indigenous to Ethiopia, it was first cultivated on the Arabian Peninsula. While more susceptible to disease, it is considered by most to taste better than Coffea canephora (robusta). Robusta, which contains about 40-50% more caffeine, can be cultivated in environments where arabica will not thrive. This has led to its use as an inexpensive substitute for arabica in many commercial coffee blends. Compared to arabica, robusta tends to be bitter and has little flavor, with a telltale "burnt rubber" or "wet cardboard" aroma and flavor. Good quality robustas are used as ingredients in some espresso blends to provide a better "crema" (foamy head), and to lower the ingredient cost. In Italy many espresso blends are based on dark-roasted robusta.

Arabica coffees were traditionally named by the port they were exported from, the two oldest being Mocha, from Yemen, and Java, from Indonesia. The modern coffee trade is much more specific about origin, labeling coffees by country, region, and sometimes even the producing estate. Coffee aficionados may even distinguish auctioned coffees by lot number.

The largest coffee exporting nation remains Brazil, but in recent years the green coffee market has been flooded by large quantities of robusta beans from Vietnam. Many experts believe this giant influx of cheap green coffee after the collapse of the International Coffee Agreement of 1975-1989 with Cold War pressures led to the prolonged pricing crisis from 2001 to 2004. In 1997 the "c" price of coffee in New York broke US$3.00/lb, but by late 2001 it had fallen to US$0.43/lb. Robusta coffees (traded in London at much lower prices than New York's Arabica) are preferred by large industrial clients (multinational roasters, instant coffee producers, etc.) because of their lower cost.

Coffee beans from two different places, or coffee varietals, usually have distinctive characteristics such as flavor (flavor criteria includes terms such as "citrus-like" or "earthy"), caffeine content, body or mouthfeel, and acidity (black coffee has a pH of around 5). These are dependent on the local environment where the coffee plants are grown, their method of process, and the genetic subspecies or varietal.

Economics of Coffee

Top Ten Green Coffee Producers - 2005 (million metric ton)
Brazil	2.18
Vietnam	0.99
Indonesia	0.76
Colombia	0.68
Mexico	0.31
India	0.28
Ethiopia	0.26
Guatemala	0.22
Honduras	0.19
Uganda	0.19
World Total	7.72
Source: UN Food & Agriculture Organisation (FAO)

Coffee is one of the world's most important primary commodities; it ranks second only to petroleum in terms of dollars traded worldwide, ($70 billion pa). With over 400 billion cups consumed every year, coffee is the world's most popular beverage. Worldwide, 25 million small producers rely on coffee for a living. For instance, in Brazil alone, where almost a third of all the world's coffee is produced, over 5 million people are employed in the cultivation and harvesting of over 3 billion coffee plants; it is a much more labour-intensive culture than alternative cultures of the same regions as soy, sugar cane, wheat or cattle, as it is not subject to automation and requires constant attention.

Coffee is also bought and sold as a commodity on the New York Coffee, Sugar, and Cocoa Exchange. This is where coffee futures contracts are traded, which are a financial asset involving a standardized contract for the future sale or purchase of a unit of coffee at an agreed price. The world's largest transfer point for coffee is the port of Hamburg, Germany.

According to the Composite Index of the London-based coffee export country group International Coffee Organization the monthly coffee price averages in international trade had been well above 100 US cent/lb during in the 70s/80s, but then declined during the late 90s reaching a minimum in September 2001 of just 41.17 US cent per lb and stayed low until 2004. The reasons for this decline included a collapse of the International Coffee Agreement of 1975-1989 with Cold War pressures, which had held the minimum coffee price at USD$1.20 per pound. Moreover, the expansion of Brazilian coffee plantations and Vietnam's entry into the market in 1994 when the United States trade embargo against it was lifted added supply pressures. The market awarded the more efficient Vietnamese coffee suppliers with trade and caused less efficient coffee bean farmers in many countries such as Brazil, Nicaragua, and Ethiopia not to be able to live off of their products, which at many times were priced below the cost of production, forcing many to quit the coffee bean production and move into slums in the cities. (Mai, 2006).

Ironically, the decline in the ingredient cost of green coffee, while not the only cost component of the final cup being served, was paralleled by the rise in popularity of Starbucks and thousands of other specialty cafés, which sold their beverages at unprecedented high prices. According to the Specialty Coffee Association of America, in 2004 16% of adults in the United States drank specialty coffee daily; the number of retail specialty coffee locations, including cafés, kiosks, coffee carts and retail roasters, amounted to 17,400 and total sales were $8.96 billion in 2003. It is important to note that the coffee sold at retail is a different economic product than wholesale coffee traded as a commodity, which becomes an input to the various ultimate end products so that its market is ultimately effected by changes in the ultimate consumption patterns and prices. The market for soft drinks has been steadily climbing, passing the consumption of coffee in terms of mass of product consumed in the early 2000s.

In 2005, however, the coffee prices rose (with the above-mentioned ICO Composite Index monthly averages between 78.79 (September) and 101.44 (March) US Cent per lb). This rise was likely caused by an increase in consumption in Russia and China as well as a harvest which was about 10% to 20% lower than that in the record years before. Many coffee bean farmers can now live off their products, but not all of the extra-surplus trickles down to them, because rising petroleum prices make the transportation, roasting and packaging of the coffee beans more expensive. Prices are expected to either remain constant or rise in 2006. (Mai, 2006)

Coffee is often mentioned along with other primarily agricultural goods and production of primary inputs (like raw minerals) as one of the main government-controlled economic goods under historical regimes of imperialism, mercantilism, and protectionism, (along with attempts at supporting free trade pricing using a country's core government-estimated comparative advantage), within an overall economic pattern in which some developing countries have had a very large investment in one product made primarily for export, and thus become somewhat dependent upon the demand and world market price for coffee. For example, Brasil's government tried at many times to stabilize the national income from coffee production through methods such as regulating new plantations, production levels, imposing tariffs and subsidies, keeping its own stocks, paying a fixed price to farmers, controlling export prices and by controlling currency exchange rates with a long series of complex controls in which the rates were determined with combinations of the free trade rate and statutory rates in tiers depending upon the type of product being sold (for example, to try to favor coffee over sugar or cotton cloth production or vice versa depending upon the current goals of the government). There is much controversy around the idea that these countries are unstable and subservient because of their large dependence on the free trade price of products like coffeee. Much has been done in the late 20th and early 21st Centuries to diversify production in countries like Brasil, and many countries today are much closer to being fully free-trade regimes with coffee and other products.

A number of classifications are used to label coffee produced under certain environmental or labor standards. For instance, bird-friendly or shade-grown coffee is produced in regions where natural shade (canopy trees) is used to shelter coffee plants during parts of the growing season. Organic coffee is produced under strict certification guidelines, and is grown without the use of potentially harmful artificial pesticides or fertilizers; conventional coffee is grown with more pesticides than any other agricultural crop—cotton comes second. The ironically named Fair trade Coffee is produced by small coffee producers; guaranteeing for these producers a minimum price, though with historically low prices, current fair-trade minimums are lower than the market price of only a few years ago. TransFair USA is the primary organization currently overseeing Fair Trade coffee practices in the United States, while the Fairtrade Foundation does so in the United Kingdom.

Health and Pharmacology of Coffee

Coffee is consumed in large part not simply because of taste, but because of the effect it has on those who drink it. The coffee bean itself contains chemicals which are mind-altering (in a way some find pleasing) for humans as a by-product of their defense mechanism. These chemicals are toxic in large doses, or even in their normal amount when consumed by many creatures which may otherwise have threatened the beans in the wild.

Coffee as a Stimulant

Coffee contains caffeine, which acts as a stimulant. For this reason, it is often drunk in the morning and during working hours. Students preparing for examinations with late-night "cram sessions" use coffee to maintain their concentration. Many office workers take a "coffee break" when their energy is diminished.

Recent research has uncovered additional stimulating effects of coffee which are not related to its caffeine content. Coffee contains an as yet unknown chemical agent which stimulates the production of cortisone and adrenaline, two stimulating hormones .

For occasions when one wants to enjoy the flavor of coffee with almost no stimulation, decaffeinated coffee (also called decaf) is available. This is coffee from which most of the caffeine has been removed, by the Swiss water process (which involves the soaking of raw beans to absorb the caffeine) or the use of a chemical solvent such as trichloroethylene ("tri"), or the more popular methylene chloride, in a similar process. Another solvent used is ethyl acetate; the resultant decaffeinated coffee is marketed as "natural decaf" due to ethyl acetate being naturally present in fruit. Extraction with supercritical carbon dioxide has also been employed.

Decaffeinated coffee usually loses some flavor over normal coffees and tends to be more bitter. There are also coffee alternatives that resemble coffee in taste but contain no caffeine (see below). These are available both in ground form for brewing and in instant form.

Caffeine dependency and withdrawal symptoms are well-documented; see Caffeine for more on the pharmacological effects of caffeine.

There have been cases all over the world of people who drink/take too much of the actual coffee bean material (anywhere between 10-50 tablespoon's worth) and have experienced side effects similar to that of the illegal drug cocaine.

Benefits

Coffee increases the effectiveness of pain killers—especially migraine medications—and can rid some people of asthma. For this reason some aspirin producers also include a small dose of caffeine in the pill. Some of the beneficial effects may be restricted to one sex, for instance it has been shown to reduce the occurrence of gallstones and gallbladder disease in men. Coffee intake may reduce one's risk of diabetes mellitus type 2 by up to half. While this was originally noticed in patients who consumed high amounts (7 cups a day), the relationship was later shown to be linear (Salazar-Martinez 2004).

Coffee can also reduce the incidence of cirrhosis of the liver and prevent colon and bladder cancers. Coffee can reduce the risk of hepatocellular carcinoma, a variety of liver cancer (Inoue, 2005). Also, coffee reduces the incidence of heart disease, though whether this is simply because it rids the blood of excess fat or because of its stimulant effect is unknown. At the annual meeting of the American Chemical Society in Washington, D.C., on August 28, 2005, chemist Joe Vinson of the University of Scranton presented his analysis showing that for Americans, who as a whole do not consume large quantities of fresh fruits and vegetables, coffee represents by far the largest source of valuable antioxidants in the diet.

Coffee contains the anticancer compound methylpyridinium. This compound is not present in significant amounts in other food materials. Methylpyridinium is not present in raw coffee beans but is formed during the roasting process from trigonellin, which is common in raw coffee beans. It is present in both caffeinated and decaffeinated coffee, and even in instant coffee.

Coffee is also a powerful stimulant for peristalsis and is sometimes considered to prevent constipation; it is also a diuretic. However, coffee can also cause loose bowel movements.

Many people drink coffee for its ability to increase short term recall and increase IQ. It also changes the metabolism of a person so that their body burns a higher proportion of lipids to carbohydrates, which can help athletes avoid muscle fatigue.

Some of these health effects are realized by as little as 4 cups a day (24 U.S. fl oz, 700 mL), but others occur at 5 or more cups a day (32 U.S. fl oz or 0.95 L or more).

Some controversy over these effects exists, since by its nature coffee consumption is associated with other more negative behavioral variables. Therefore it has been variously suggested that the cognitive effects of caffeine are limited to those who have not developed a tolerance or to those who have developed a tolerance and are temporarily caffeine-deprived, suggesting that drinking in cycles could be necessary to achieve some effects.

Practitioners in alternative medicine often recommend coffee enemas for "cleansing of the colon" due to its stimulus of peristalsis, although mainstream medicine has not proved any benefits of the practice.

Risks

Many notable effects of coffee are related to its caffeine content.

Many coffee drinkers are familiar with "coffee jitters", a nervous condition that occurs when one has had too much caffeine. Like tea, coffee also causes staining of the teeth. The best way to avoid this is to brush after every coffee drinking. Coffee can also increase blood pressure among those with high blood pressure. Coffee can also cause insomnia in some, while paradoxically it helps a few sleep more soundly. It can also cause anxiety and irritability, in some with excessive coffee consumption, and some as a withdrawal symptom. There are also gender-specific effects: in some PMS sufferers it increases the symptoms; it can reduce fertility in women; it may increase the risk of osteoporosis in postmenopausal women; and there may be risks to a fetus if a pregnant woman drinks 8 or more cups a day (48 U.S. fl oz or 1.4 L or more).

A February 2003 Danish study of 18,478 women linked heavy coffee consumption during pregnancy to significantly increased risk of stillbirths (but no significantly increased risk of infant death in the first year). "The results seem to indicate a threshold effect around four to seven cups per day," the study reported. Those who drank eight or more cups a day (48 U.S. fl oz or 1.4 L) were at 220% increased risk compared with nondrinkers. This study has not yet been repeated, but has caused some doctors to caution against excessive coffee consumption during pregnancy.

Decaffeinated coffee is occasionally regarded as a potential health risk to pregnant women, due to the high incidence of chemical solvents used to extract the caffeine. These concerns have almost no basis, however, as the solvents in question evaporate at 80–90 °C, and coffee beans are decaffeinated before roasting, which occurs at approximately 200 °C. As such, these chemicals, namely trichloroethane and methylene chloride, are present in trace amounts at most, and neither pose a significant threat to unborn children. Women still worried about chemical solvents in decaffeinated coffee should opt for beans which use the Swiss water process, where no chemicals other than water are used, although higher amounts of caffeine remain.

The American Journal of Clinical Nutrition published a study in 2004 which tried to discover why the beneficial and detrimental effects of coffee conflict. The study concluded that consumption of coffee is associated with significant elevations in biochemical markers of inflammation. This is a detrimental effect of coffee on the cardiovascular system, which may explain why coffee has so far only been shown to help the heart at levels of four cups (20 fl oz or 600 mL) or fewer per day.

The health risks of decaffeinated coffee have been studied, with varying results. One variable is the type of decaffeination process used; while some involve the use of organic solvents which may leave residual traces, others rely on steam.

A study has shown that cafestol, a substance which is present in boiled coffee drinks, dramatically increases cholesterol levels, especially in women. Filtered coffee contains only trace amounts of cafestol.

A study published in the Journal of the American Medical Association announced the discovery of a gene that regulates the detoxification of caffeine in the liver. Two variations of this gene exist with one variation resulting in slower metabolism of caffeine. The study compared 2,014 people who had survived a heart attack with 2,014 healthy people in the general population. For people with the slow metabolizing variation of the gene, the risk of heart attack for 2-3 cups of coffee a day was increased 36% and for 4 or more cups of coffee a day, the risk went up to 64%. For people under the age of 59, the risk went up 24% for just 1 cup of coffee a day, 67% for 2-3 cups a day, and 133% for 4 or more cups a day. Under the age of 50, the risk for heart attack increased 4 fold. 54% of the people in this study had the slow metabolizing gene.

A Harvard study over 20 years of 128,000 people published in 2006 concluded that there was no evidence to support the claim that coffee consumption itself increases the risk of coronary heart disease. The study did, however, show a correlation between heavy consumption of coffee and higher degrees of exposure to other coronary heart disease risk factors such as smoking, greater alcohol consumption, and lack of physical exercise. The results apply only to coffee filtered through paper filters, which excludes boiled coffee and espresso, for example. Additionally, the lead researcher on this study ackowledged that subsets of the larger group may be at risk for heart attack when drinking multiple cups of coffee a day due to genetic differences in metabolizing caffeine.

An Iowa Women's Health Study showed that women who consumed coffee actually had less cardiovascular disease incidents and lower cancer rates than the general population. For women who drank 6 or more cups, the benefit was even greater. However, this study excluded 35% of its original participants who already had cardiovascular disease and other chronic diseases when the study began. Since participants were all over the age of 55, no good conclusion can be drawn about the long term effect of coffee drinking on heart disease from this study.

Processing and Roasting

Much processing and human labour is required before coffee berries and its seed can be processed into roasted coffee with which most Western consumers are familiar. Coffee berries must be picked, defruited, dried, sorted, and--in some processes--also aged.

Coffee is usually sold roasted, and the roasting process has a great degree of influence on the taste of the final product. All coffee is roasted before being consumed.

Preparation

The processing of coffee typically refers to the agricultural and industrial processes needed to deliver whole roasted coffee beans to the consumer. In order to turn this into a beverage, some preparation is typically necessary. The particular steps needed vary with the type of coffee desired, and with the raw material being worked with (e.g., pre-ground vs. whole bean). Typically, coffee must be ground to varying coarseness depending on the brewing method. The most common method of consuming coffee is called brewing. Boiling water is passed in a slow stream through the ground coffee and a paper filter resulting in a hot flavored drink that gets its flavor, and some nutrients and chemicals, from the coffee beans, without containing the majority of the bean mass (much like tea). The espresso method uses higher technology to force super hot water or even steam through the coffee grounds, resulting in a stronger flavor and chemical changes with more coffee bean matter in the drink. Once brewed, it may be presented in a variety of ways: on its own, with or without sugar, with or without milk or cream, hot or cold, and so on. Roasted arabica beans are also eaten plain and covered with chocolate.

Quick Coffee

A number of products are sold for the convenience of consumers who don't want to prepare their own coffee. Instant coffee has been dried into soluble powder or granules, which can be quickly dissolved in hot water for consumption. Canned coffee is a beverage that has been popular in Asian countries for many years, particularly in Japan and South Korea. Vending machines typically sell a number of varieties of canned coffee, available both hot and cold. To match with the often busy life of Korean city dwellers, companies mostly have canned coffee with a wide variety of tastes. Japanese convenience stores and groceries also have a wide availability of plastic-bottled coffee drinks, which typically are lightly sweetened and pre-blended with milk. Lastly, liquid coffee concentrate is sometimes used in large institutional situations where coffee needs to be produced for thousands of people at the same time. It is described as having a flavor about as good as low-grade robusta coffee, and costs about 10 cents a cup to produce. The machines used to process it can handle up to 500 cups an hour, or 1,000 if the water is preheated.

Social Aspects of Coffee

The United States is the largest market for coffee, followed by Germany. The Nordic countries consume the most coffee per capita, with Finland, Norway and Denmark trading the top spot depending on the year. However, consumption has also vastly increased in the United Kingdom in recent years. Coffee is so popular in the Americas, the Middle East, and Europe that many restaurants specialize in coffee; these are called "coffeehouses" or "cafés". Most cafés also serve tea, sandwiches, pastries, and other light refreshments (some of which may be dunked into the drink). Some shops are miniature cafés that specialise in coffee-to-go for hurried travelers, who may visit these on their way to work as a substitute for breakfast. Some provide other services, such as wireless internet access (thus the name, "internet café"--which has carried over to stores that provide internet service without any coffee) for their customers. The Brazilian Portuguese expression for breakfast is literally translated as "morning coffee".

In some countries, notably in northern Europe, coffee parties are a popular form of entertaining. Besides coffee, the host or hostess at the coffee party also serves cake and pastries, sometimes homemade.

Because of the stimulant properties of coffee and because coffee does not adversely impact higher mental functions, coffee is strongly associated with white collar jobs and office workers. Paul Martin, former prime minister of Canada, drinks 10-15 cups a day. Social habits involving coffee in offices include the morning chat over coffee and the coffee break. Contemporary advertising tends to equate the term "coffee break" with rest and relaxation, despite coffee's stimulant role. Coffee plays a large role in much history and literature because of the large effects the coffee industry has had on cultures where it is produced or consumed. Coffee is often mentioned as one of the main economic goods used in imperial control of trade, and with colonized trade patterns in "goods" such as slaves, coffee, and sugar, which defined Brazilian trade, for example, for centuries. Coffee in culture or trade is a central theme and prominently referenced in much poetry, fiction, and regional history. "Die Reading," by Joey Parks, is a modern novel centered around a New Zealand barista/barrista (and his lifestyle), which is a person who works in a coffeehouse and generally knows the aromas, names, recipies and special effects of espressos and other coffee beverages.

Other Uses

Spent coffee grounds are a good fertilizer in gardens because of their high nitrogen content. Starbucks, and some other coffee shops, have a specific policy of giving away heir used coffee grounds to gardeners. While they tend to be only slightly acidic, they also tend to improve the acidity of garden soil through the same chemical processes which cause sawdust to do the same thing. Coffee grounds raise soil acidity more immediately if they are added fresh, instead of after brewing. Likewise, coffee diluted with four times its volume of water can be used to amend soil acidity, especially useful for tomatos, chili peppers, blueberries, and other plants which like high soil acidity.

The grounds are also used as bait in "Vegas roach traps".

Some use coffee to create art. Latte art involves designs in the foam of espresso-based drinks. Arfé is the use of coffee as a coloring for painting or other visual effects.

Coffee Alternatives

• Yerba Mate
• Pero, a coffee substitute from Switzerland. It is made from malted barley, chicory, and rye.
• Dandelion root
• Teeccino Caffeine-free Herbal Coffee, a blend of herbs, grains, fruits and nuts that are roasted and ground to brew and taste like coffee.
• During wartime, a grain substitute was made from grain, chicory and roasted acorns.
• Soy Coffee (e.g, Soyfee)
• Postum

References

• Chambers, Robert (1869). Chambers' Book of Days for January 27, retrieved February 21, 2006.
• Inoue, Manami et al. (2005). Influence of Coffee Drinking on Subsequent Risk of Hepatocellular Carcinoma: A Prospective Study in Japan. Journal of the National Cancer Institute, Vol. 97, No. 4, 293-300.
• (German) Mai, Marina. "Boom für die Bohnen" in Jungle World Nr. 1, 2006/January 4, 2006. ISSN 1613-0766.
• Pendergrast, Mark. Uncommon Grounds: The History of Coffee and How It Transformed Our World, Basic Books, 1999. ISBN 0465054676
• Salazar-Martinez E, Willet WC, Ascherio A, Manson JE, Leitzmann MF, Stampfer MJ, Hu FB. "Coffee consumption and risk for type 2 diabetes mellitus." Ann Intern Med 2004;140:1-8.
• Wisborg, Kirsten et al. Maternal consumption of coffee during pregnancy and stillbirth and infant death in first year of life: prospective study. British Medical Journal 2003 (326): 420 (22 February). Online copy.
• Koppelstaeter, Florian et al, Influence of Caffeine Excess on Activation Patterns in Verbal Working Memory, conference paper presented at the Radiological Society of North America, November 30, 2005.

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