ch11.ppt

Chapter 11 Caffeine © 2008 McGraw-Hill Higher Education. All rights reserved. Caffeine Most widely used psychoactive drug Average American intake is 200 to 250 mg/day Some people regularly consume much more Can cause dependence and interfere with functioning Belongs to a class of chemicals known as xanthines History Three plants containing xanthines have been used by humans for thousands of years: Coffee?from the Middle East Tea?first grown in China Cacao?from Mesoamerica All three played important cultural and economic roles Coffee: History Coffee originated in Arabia Legend of its discovery by an Arabian goatherd, Kaldi, who noticed unusually boisterous activity in his goats after they consumed the berries Arabian medical book (900 AD) suggested many medical uses Coffee use spread throughout the Muslim world and was later introduced into Europe Coffee: History Coffee consumption in the United States Use increased following taxation of tea and the American Revolution Use also increased during and after Prohibition Per capita U.S. coffee consumption Peaked in 1946 Declined as soft drink consumption increased Current = about 24 gallons of coffee per year Coffee: Preparation Originally: people chewed on coffee beans or put raw beans in hot water Roasting improves the flavor, aroma, and color of the drink made from the beans Coffeehouses and individuals originally roasted and ground their own beans 1790: Commercial roasting 1900: Vacuum packing for long-term storage of ground coffee Coffee Growing and Trade Introduced into the East Indies and then Latin America About half of American coffee comes from Latin America, the rest from Vietnam, Indonesia, and Thailand Variations in coffee characteristics Different varieties of the coffee tree Different growing and processing conditions 1892: First commercial blended coffee introduced at the Maxwell House hotel Price variations over time: when coffee prices go up Quality of coffee decreases People drink less coffee Coffee Varieties Decaffeinated coffee Soaking unroasted beans in an organic solvent removes the caffeine Alternative Swiss water process not widely used It removes more of the coffee?s flavor Caffeine removed from coffee is used in the manufacture of soft drinks Coffee Varieties Black Espresso Cappuccino Latte Turkish Half-caf Iced Flavored and many more Coffee and Caffeine The caffeine content of coffee depends on how it is prepared Type Average caffeine content Brewed, drip (5 oz) 115mg Brewed, percolator (5 oz) 80 Instant (5 oz) 65 Espresso (2 oz) 90 Cappuccino (2 oz) 90 Tea: History Tea (Camellia sinensis) originated in China Legend of its creation by Daruma, the founder of Zen Buddhism, who cut off his eyelids to remain awake while meditating A new plant grew from the spot where his eyelids touched the earth, with leaves that made a brew that would keep a person awake AD 350: Chinese manuscript describes many medicinal uses AD 780: Nonmedical cultivation and use of tea Tea: History 1610: Dutch delivered tea to Europe English East India Company First imported primarily spices but later expanded its imports of tea from China Most tea sold in coffeehouses In Britain, major marketing campaigns promoted the switch from coffee to tea After the American Revolution, to be a tea drinker was to be loyal to the Crown Tea: History Tea and the American Revolution American colonists were big tea drinkers Anger over a tax on tea that they had not helped formulate ?Taxation without representation? Legal tea sales dropped due to a boycott Illegal smuggling of tea increased Tea: History Tea and the American Revolution A special arrangement was made for the English East India Company, angering American merchants The result was ?The Boston Tea Party? of 1773 Tea Production Camellia sinensis bushes are regularly pruned to aid in harvesting new growth Tea leaves are picked by hand, about every 6 to 10 days Preparation: tea leaves are Dried Rolled to crush the cells in the leaves Placed in a cool, damp place for fermentation (oxidation) Tea Varieties Black tea is fully oxidized leaves Green tea is nonoxidized leaves Oolong tea is greenish-brown and consists of partially oxidized leaves Tea Varieties Iced tea accounts for 75 percent of all tea consumed in the U.S. Flavored teas are mixtures of tea and mint, spices, or other flavors Herbal teas contain a mix of plant leaves and flowers but no actual tea (see right) Tea Xanthines Caffeine Pound for pound, tea has more caffeine than coffee BUT 1 pound of tea leaves = 200 cups of tea 1 pound of coffee = 50 to 60 cups of coffee Tea has about 40 to 60 mg of caffeine per cup depending on the type and strength of the brew Theophylline Tea contains a very small amount of theophylline In high doses, theophylline is used as an asthma medication Tea Consumption Annual per capita tea consumption 5.5 pounds in the United Kingdom 1 pound in the United States 70 percent of tea that comes to America is grown in Sri Lanka, India, or Indonesia Chocolate: History Chocolate originated in Mesoamerica Legend: Cacao tree was a gift to humans from paradise from the Aztec god Quetzalcoatl Linnaeus named the cacao tree Theobroma, meaning ?food of the gods? Aztecs cultivated cacao widely, and the cacao bean was an important part of their economy and culture Chocolate: History Chocolatl?from the Mayan words choc (?warm?) and latl (?beverage?)?was a thick, bitter liquid flavored with vanilla Cortez introduced chocolate into Europe Chocolate drinking spread slowly Chocolate was often sold alongside coffee and tea in established coffeehouses Chocolate: Processing Prior to 1828, the traditional Aztec process was still used Cacao pods were dried in the sun, then roasted to remove the husk Kernels were ground to obtain a thick liquid (baking chocolate) Chocolate: Processing 1828: Dutch patent issued for a process that removes about two-thirds of the fat (cocoa butter) and produces a powder 1876: Milk chocolate introduced by the Swiss Chocolate: Processing A mixture of cocoa butter, sugar, and chocolate powder can be formed into slabs or bars Properly manufactured true chocolate melts at body temperature Chocolate Xanthines Theobromine Chocolate contains the unique xanthine theobromine It acts in a parallel fashion to caffeine, but it is much less potent in its CNS effects Caffeine An average cup of cocoa contains about 4 mg of caffeine Other Sources of Caffeine Soft Drinks: Coca-Cola Developed as a nerve tonic in the late 1800s; ingredients included: Caramel Fruit flavoring Phosphoric acid Caffeine A secret mixture called Merchandise No. 5 Named for two flavoring agents: coca leaves and cola (kola) nuts Up until 1906, the beverage did contain a small amount of cocaine Other Sources of Caffeine Other soft drinks All types of soft drinks are popular U.S. per capita soft drink consumption is about 50 gallons per year Energy drinks Over-the-counter medications Caffeine Content Item Caffeine Content (mg) Serving Brewed coffee 40-180 5 oz Instant coffee 30-120 5 oz Decaffeinated coffee 1-5 5 oz Tea 20-110 5 oz Cocoa 5-20 5 oz Diet Coke 45 12 oz Pepsi One 55 12 oz Mountain Dew 55 12 oz Jolt 71 12 oz Red Bull 80 8.3 oz Milk chocolate bar 1-15 1 oz Dark chocolate bar 5-35 1 oz Vivarin stimulant 200 1 dose Pharmacology Three key xanthines Caffeine Theophylline Theobromine Time course Rapid absorption if taken orally Peak levels reached in 30 minutes Half-life is about 3 hours Dependence Reinforcing properties Withdrawal symptoms include headache and fatigue Pharmacology Mechanism of action Xanthines block inhibitory receptors for adenosine, thereby having a stimulant effect Physiological effects Stimulates the CNS and skeletal muscles Causes sleep disturbances Elevates mood Constricts blood vessels in the brain May explain the ability of caffeine to reduce migraine headaches Pharmacology: Effects Stimulation Caffeine partially offsets the effects of fatigue on both mental and physical tasks, but it may not improve performance in well-rested individuals High caffeine consumption among college students is associated with lower academic performance Headache treatment: Helps relieve both migraine and nonmigraine headaches Hyperactivity treatment: High doses may decrease hyperactivity Sobering up? Caffeine does not lower blood alcohol concentration and will not help a person sober up Causes for Concern There is no clear evidence that moderate caffeine consumption is dangerous Cancer: Caffeine is not a risk factor in human cancer Reproductive effects: High consumption of caffeine reduces a woman?s chances of becoming pregnant and slows the growth of the fetus Research is mixed on whether caffeine increases the risk of miscarriage Heart disease: High intake of caffeine may increase the risk of heart attack, particularly in people with other risk factors Causes for Concern Caffeinism (excessive use of caffeine) Toxicity is relatively low It would require about 100 cups of coffee to receive a fatal dose from oral caffeine Unpleasant symptoms do occur: Nervousness Irritability Tremors Muscle twitching Insomnia Flushed appearance Elevated temperature Palpitations Heart arrhythmias Gastrointestinal disturbances