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Chapter 11

Caffeine

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Most widely used psychoactive drug

Many individuals use daily

Belongs to a class of chemicals known as xanthines

There is evidence that caffeine:

Can cause dependence

Interfere with normal functioning

Caffeine

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Image source: © Ingram Publishing/SuperStock (Image Ch11_01CoffeeCups)

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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 the Americas

All three played, and continue to play, important cultural and economic roles

Three Main Sources

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Origin of coffee use (Ethiopia)

Legend: Kaldi, a goat herd, and his goats ate coffee berries and danced

The practice then spread to:

1400s: Egypt and other Arabic countries

1500s: Throughout the Middle East

1600s: Europe

Coffee: History

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17th–18th century England: coffeehouses spread

“penny universities”

a location to listen and learn from literary and political figures

England 1674: “The Women’s Petition Against Coffee”

argued against the use of coffee on the grounds that it made men impotent

Coffee: History

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Use increased following taxation of tea and the American Revolution

To drink tea was to be a Tory

Use increased during and after Prohibition

Use Peaked in 1946

Declined perhaps due to increased soft drink consumption

Current annual use is about 23 gallons of coffee per person

Coffee Consumption in the U.S.

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Originally:

individuals chewed on coffee beans or put raw beans in hot water

Later discovered that roasting improved the flavor of the drink

Coffeehouses and individuals originally roasted and ground their own beans

1790 New York: Commercial roasting

1900: Vacuum packing for long-term storage of ground coffee

Coffee Processing and Storage

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1696: Dutch began cultivation in East Indies

Then Latin America became world’s largest producer

Virtually all coffee is made from two species:

caffea Arabica: milder flavor, takes longer to develop after planting and requires a near tropical climate to grow

caffea robusta: stronger and more bitter flavor and a higher caffeine content, used in less expensive blends

Three billion pounds of coffee were imported to the U.S. in 2013

Brazil supplied the most, followed by Vietnam and Colombia

Coffee Growing and Trade

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Processes to remove caffeine from the coffee bean include:

Soaking unroasted beans in an organic solvent removes the caffeine

This is the most common method in the U.S.

Alternative Swiss water process not widely used

It removes more of the coffee’s flavor

Caffeine removed from coffee is used in soft drinks

Coca-Cola owns one of the largest decaffeinating companies

Decaffeinated Coffee

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A large variety of products in the supermarket and coffee shops

Black coffee, espresso, cappuccino, latte, Turkish, half-caf, iced, flavored

The number of specialty coffee shop increased from 200 (1980) to 25,000 (2010)

Variety of Coffee Drinks

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Image source (espresso): © S. Meltzer/PhotoLink/Getty Images (Image Ch11_08EspressoStand)

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Origin of tea (China)

Camellia sinensis: an evergreen

Legend: Daruma, the founder of Zen Buddhism, cut off his eyelids to remain awake while meditating

New plant grew where his eyelids touched the earth

Leaves from that plant made a stimulating drink

AD 350:

Evidence for medicinal use

AD 780:

Evidence for nonmedical use

Tea: History

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Image source: © Spike Mafford/Getty Images (Image Ch11_09TeawithLemon)

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1610: Dutch delivered tea to Europe

17th century: English East India Company

Imported tea from China

Created a monopoly in England

In Britain, major marketing campaigns promoted the switch from coffee to tea

Tea: History

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Before the Revolution, American colonists were committed tea drinkers

Anger over a tax on tea

“Taxation without representation”

“The Boston Tea Party” (1773)

Tea and the American Revolution

Revolution helped tea sales in England

To be a tea drinker was to be loyal to the Crown

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Image Source: Library of Congress Prints and Photographs Division [LC-USZ62-24071]

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One worker = 10 pounds of tea per day

Tea leaves are then

Dried

Rolled to crush the cells in the leaves

Placed in a cool, damp place for fermentation (oxidation)

Tea Production

Tea is grown in:

China, Sri Lanka, India, and Indonesia

Tea leaves are picked by hand

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Black tea

fully oxidized leaves

Green tea

nonoxidized leaves

Oolong tea

greenish-brown and consists of partially oxidized leaves

Varieties of Tea

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Iced tea

85 percent of all tea consumed in the U.S.

Flavored teas

mixtures of tea and mint, spices, or other flavors

Herbal teas

contain a mix of plant leaves and flowers but no actual tea

Varieties of Tea

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Pound for pound, tea has more caffeine than coffee, however

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 is another xanthine found in tea

Very small amounts

In high doses, theophylline is used as an asthma medication

Caffeine Content in Tea

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Origin of chocolate (Mesoamerica)

Theobroma means “food of the gods”

Legend: Cacao tree was a gift to humans from paradise from the Aztec god Quetzalcoatl

Aztecs cultivated cacao widely

The cacao bean was an important part of their economy and culture

Chocolate: History

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Image source (cacao tree): © L. Hobbs/PhotoLink/Getty Images (Image Ch11_20CacaoTree)

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Chocolatl

Was a thick, bitter liquid flavored with vanilla

From the Mayan words choc (“warm”) and latl (“beverage”)

16th century: Cortez introduced chocolate into Europe

Chocolate drinking spread slowly

17th century: Chocolate sold alongside coffee and tea in established coffeehouses

Chocolate: History

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Prior to 1828, the traditional Aztec process was 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

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1828:

Dutch patent issued for a process that removes about two-thirds of the fat (cocoa butter) and produces a powder

A mixture of cocoa butter, sugar, and chocolate powder can be formed into slabs or bars

1876:

Milk chocolate introduced by the Swiss

Chocolate Processing

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Theobromine

A xanthine unique to chocolate

Similar to caffeine, but much less potent CNS effects

An average cup of cocoa contains 200 mg

Caffeine

An average cup of cocoa contains 4 mg

Xanthine Content in Chocolate

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Soft Drinks: Coca-Cola

Developed as a “nerve tonic” in the late 1800s; ingredients included:

Caffeine

Cocaine (in small amounts)

Named for two flavoring agents: coca leaves and cola (kola) nuts

Today, the coca leaves are decocainized before being shipped to the Coca-Cola plant

Other Sources of Caffeine

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Image Source: Library of Congress Prints and Photographs Division [LC-USZC4-12222]

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Other soft drinks

U.S. per capita soft drink consumption is about 45 gallons per year

Energy drinks

Now compete with soft drinks for the market

Over-the-counter medications

Example: Vivarin

Other Sources of Caffeine

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Comparison of Caffeine Content

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Comparison of Caffeine Content

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Comparison of Caffeine Content

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Three key xanthines

Caffeine

Theophylline

Theobromine

Time course

Rapid absorption if taken orally

Peak levels reached in 30 minutes

Half-life is about three hours

Dependence

Caffeine can function as a reinforcer

Withdrawal symptoms include headache and fatigue

DSM-5 does not list caffeine under substance use disorders

Pharmacology

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Mechanism of action

Xanthines block adenosine receptors

Adenosine is an inhibitory neurotransmitter that modulates the release of other neurotransmitters

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

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Stimulation

Cognitive/psychomotor performance:

Caffeine partially offsets the effects of fatigue

But it may not improve performance in well-rested individuals

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

Behavioral Effects

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Overall, 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

Causes for Concern

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Heart disease:

High intake of caffeine may increase the risk of heart attack, particularly in people with other risk factors

Moderate use may lower risk

Caffeinism (excessive use of caffeine)

Toxicity is relatively low (fatal dose = 100 cups of coffee)

Unpleasant symptoms do occur:

Nervousness

Irritability

Tremors

Muscle twitching

Insomnia

Flushed appearance

Elevated temperature

Palpitations

Heart arrhythmias

Gastrointestinal disturbances

Causes for Concern

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