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Week 7 - Caffeine.docx

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Wilfrid Laurier University
Bruce Mc Kay

Caffeine History Three plants containing xanthines have been used by humans for thousands of years. Coffee (from the Middle East) Caffeine Tea (first grown in China)  Theophylline Cacao (from the Americas)  Theobromide Coffee History -1700s-1800s coffee houses When coffee beans were first discovered they were considered a „cure‟ for just about everything Current North American Consumption = 100 litres per year Coffee Varieties -Black -Espresso -Cappuccino… Laurier Data -coffee and tea consumption very similar most drink less than 1 cup a day Tea Varieties Black leaves – fully oxidized leaves Green tea – non-oxidized leaves Oolong tea – partially oxidized leaved A major highlight in the history of tea: The Boston Tea Party Tea and the American Revolution -American colonists were angry about a tax on their tea imposed by Britain -Legal tea sales dropped due to a boycott -Illegal smuggling of tea increased -A special arrangement was made for the English East India Company, angering American merchants -So…the Americans poured all the English tea into the Boston Harbour illegally smuggled tea that they poured into the harbour How much xanthines are in tea? Tea contains caffeine and theophylline Caffeine – tea has about 40 to 60mg 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 Chocolate: History Chocolate originated in Mesoamerica Cortez introduced chocolate into Europe Chocolate drinking spreads slowly Chocolate is bitter – you must add sugarcane to make it sweet Chocolate was / is a “gift of love” TODAY: A mixture of cocoa butter, sugar, and chocolate powder can be formed into slabs or bars How much xanthines are in chocolate? Chocolate contains theobromine and caffeine 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 Laurier students who eat chocolate: -less than 1 per day most common Other sources of caffeine Soft Drinks: Coca-Cola -developing as a nerve tonic in the late 1800s; ingrediants included: Caramel Fruit Flavouring Phosphoric Acid Caffeine A secret mixture called Merchandise No. 5 Up until 1906, the beverage did contain a small amount of cocaine Contains about 30-50mg of caffeine per serving Per capita soft drink consumption today is about 200 litres per year How much cola do WLU students drink each day? Consume coffee, tea, or cola at least once per day: Estimate: 80% Reality: 40% What are the physiological effects of caffeine? Time Course: -rapid absorption if taken orally -peak levels reached in 30minutes -half life is about 3hours Mechanism of action -xanthines block inhibitory receptors for adenosine, therapy having a stimulant effect Why was it okay to drink coffee/smoke when working? -more productive because consuming stimulants Physiological Effects of Xanthines 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 grades… not true at WLU Headache treatment- helps relieve both migraine and non-migraine headaches Hyperactive – high doses may decrease hyperactivity Water excretion – caffeine inhibits anti-diuretic hormone Sobering Up – caffeine does not lower blood alcohol concentration and will not help a person sober up -no cure for a hangover, alcohol concentration dictates how drunk you are not caffeine Does caffeine really increase alertness? Caffeine (40mg) increases alertness and decreases reaction time in university students Can caffeine cause dependence or toxicity? Caffeine tolerance Mostly seen for cardiovascular effects Caffeine Craving Caffeine withdrawal effects Headache one cup of coffee (few) 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 Acute caffeine intoxication: caffeine can help against Parkinson’s any kind of problem with heart should not consume caffeine talk to physician about drinking caffeine first, incase of heart problem Can people get intoxicated by caffeine? <250mg caffeine -only drug that specifies an amount DSM-IV criteria for “Caffeine intoxication” A. Recent consumption of >250 mg caffeine B. 5 or more of the following shortly after caffeine intake ␣Restlessness ␣Nervousness ␣Excitement ␣Insomnia ␣Flushed face ␣Diuresis ␣Gastrointestinal disturbance ␣Muscle twitching ␣Rambling flow of thought and speech ␣Tachycardia or cardiac arrhythmia ␣Periods of inexhaustibility ␣Psychomotor agitation C. Symptoms in B cause impairments in social, occupational functioning, etc D. Not accounted for by some other DSM-IV diagnosis Toxicity – with >5-10 grams get grand mal seizures and respiratory failure resulting in death (need about 50-100cups) Beverages with caffeine typically contain sugar – or ASPARTAME Is aspartame safe? Controversy in approval process: • Pre-1980 – head of FDA says NO to aspartame because of potential toxicity • 1981 – head of FDA fired by new Reagan administration, aspartame immediately approved by new FDA boss Aspartame metabolites: • Methanol / formaldehyde • Phenylalanine • Aspartic acid (NMDA-mediated excitotoxicity) • Aspartylphenylalanine diketopiperazine (long-term breakdown – brain tumours) Beverages with caffeine typically contain sugar – or ASPARTAME Is aspartame safe? 2007 human study: no link between aspartame and cancer 2006 rat study: increase in lymphoma and other cancers; no effect on lifespan This study widely criticized by experts; conflict of interest by experts? 2006 human study (NCI): no link between aspartame and cancer 1996: survey of all “industry” and “independent” studies of aspartame “Industry” – 100% of studies reveal aspartame is „safe‟ “Independent” – 92% of studies reveal aspartame is „problematic‟ But... vast majority of “independent” studies were not peer-reviewed But... “industry” studies are never peer-reviewed Study #1: Give red bull to grad students late at night -Red bull prevents the typical decrease in „social extrovertedness‟ associated with late night fatigue -in normal people as the night goes on you become less engaged -Red Bull prevents the lengthening of reaction times associated with late-night fatigue Study #2: Give Red Bull (2 cans) to sleep-deprived graduate students and test on driving simulator (a real simulator, not GTA) Red Bull decreases number of “incidents” in the driving simulator Study #3: Giv
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