The Truth About Tea

The Truth About Tea The Antibacterial Effects of Green Tea: Bottled vs. Brewed

Background Research • Green tea has been shown to help with heart disease, oral health, arthritis, weight loss, stress, flu, food poisoning, colds, and other bacterial illnesses • It can also help promote helpful bacteria in the intestines • Sweetened, flavored, bottled, and old green teas have been shown to retain less antibacterial effects as they are very processed • Escherichia coli (E. coli) • Gram negative • Bacteria found in intestines of warm blooded animals and people • Causes food poisoning and can be from consuming undercooked or raw meat and vegetables, water, or anything that comes in contact with animal manure • Can cause diarrhea and eventually HUS/kidney failure • Most documented outbreak of O157:H7 • Similar to Salmonella • Streptococcus mutans • Gram positive • Bacteria found in teeth and mouth area • Creates acid which causes tooth decay, and also damages gums and roots • Feeds on refined carbohydrates in milk, sugar, fruit, etc.

Question • Which type/brand of green tea has the most antibacterial effects?

Hypothesis • The brewed green tea made from Chinese tea leaves will have the most antibacterial effects.

Materials (1) • Twenty-four sterile paper disks • Six Petri dishes with tryptic soy agar • Six empty Petri dishes • Streptococcus mutans purchased from a catalog • Escherichia coli purchased from a catalog • Ruler (in centimeters) • Sterile tweezers • Incubator • Sterile swabs • Goggles • Lab coat • Gloves • Permanent marker • Tape

Materials (2) – Green Teas • Brewed Chinese green tea • Trader Joe’s unsweetened bottled green tea • AriZona sweetened honey ginseng bottled green tea • Just Tea unsweetened bottled green tea • Gold Peak sweetened bottled green tea • Sterile water

Procedure • Petri dishes with agar were labeled with three tests for each type of bacteria, and type of tea on outside • Empty Petri dishes were each filled with one of the types of tea and sterile water, and the sterile disks were put in to soak • Freeze dried E. coli and strep mutans cultures were hydrated using sterile technique, and the bacteria was incubated for approx. 24 hours • Sterile swabs were used to spread E. coli over three Petri dishes, and strep mutans over three Petri dishes • One disk soaked in each type of tea was placed into each of the dishes • The Petri dishes were incubated at 37 °C for approx. 48 hours, then the zones of inhibition were observedfor both types of bacteria

Variables • Independent • The types of green tea; the types of bacteria • Dependent • The size of the zones of inhibition • Control • The sterile water tests • Constants • The two different types of bacteria, the types of green tea and water, the length of incubation

Data (1)

Data (2)

Data (3)

Possible Sources of Error • For the E. coli test, the time between when the brewed green tea was made and when it was tested was larger than in the strep mutans test • In the strep mutans test, the zones of inhibition were very faint and may have been inaccurately measured for any of the teas

Continuations • What other bacteria are green tea effective on? • Does green tea really help other, non-bacterial illnesses? (ex: cancer, arthritis, etc…) • Do other green tea products besides the actual tea have antibacterial effects? (ex: lotions, body washes, food, etc…) • Are other alternative medicines more antibacterial than green tea?

Conclusion • All teas except for AriZona had at least a small amount of antibacterial effects • The two sweetened teas (AriZona and Gold Peak) appeared to have the least health benefits, although the error bars are large • The flavored, sweetened, more processed teas had less effects • Because of the range of data for brewed green tea, it can’t be said whether it had a greater effect than any others except AriZona • The hypothesis was rejected – Trader Joe’s had the most effects overall and was very consistent in the data • Unsweetened, unflavored bottled green tea or brewed green tea from loose leaves are still the best choices

Works Cited • About E. coli. (2011). Retrieved from Marler Clark LLP, PS website: http://www.about-ecoli.com/ • All about antioxidants. (n.d.). Retrieved from AriZona Beverage Co. website: http://www.drinkarizona.com/‌index_national.html#health_anti_ox • Baker, S. L. (2010, August 17). Scientists discover how polyphenols in green tea may protect health of diabetics. Retrieved from Natural News Network website: http://www.naturalnews.com/‌029496_polyphenols_green_tea.html • Bottled green tea and canned drinks: Why more harmful than healthy. (2006-2010). Retrieved from http://www.amazing-green-tea.com/‌bottled-green-tea.html • Chinese tea health benefits. (2005-2010). Retrieved from http://www.goldenteahouse.com/‌health_benefits.php#bac • Cold tea vs hot tea health benefits: How long can you keep or steep? (2006-2010). Retrieved from http://www.amazing-green-tea.com/‌cold-tea.html • Compestine, Y. C. (2000). Introduction. In Cooking with green tea (pp. 2-3). New York, NY: Avery Books. • Cup of green tea to keep the bacteria away. (2007, January 16). ScienceDaily. Retrieved from http://www.sciencedaily.com/‌releases/‌2007/‌01/‌070116132946.htm • Green tea. (2007). In B. Baver (Ed.), Mayo clinic book of alternative medicine (p. 56). New York, NY: Time. • Herbal remedies. (2010). Retrieved from Resort health products website: http://www.resorthealth.com/‌herbs/‌green_tea.html • Lash, R. (2007). The legend of green tea keeps a-growin. Discover. Retrieved from http://discovermagazine.com/‌2007/‌oct/‌the-legend-of-green-tea-keeps-a-growin/‌?searchterm=health%20&%20medicine%20nutrition%20te • Learn all about the history of green tea. (2010). Retrieved from Adagio Teas website: http://www.green-teas-guide.com/‌history-of-green-tea.html • LIPTON® green tea with citrus flavor. (2010). Retrieved from Unilever website: http://www.liptont.com/‌our_products/‌iced_tea/‌ice_green_citrus.aspx • Strep mutans. (2010). Retrieved from http://www.dentist.net/‌strep-mutans.asp • Tai, J. (2006-2010). The truth about tea: A t-volution is quietly steeping away. Retrieved from http://www.amazing-green-tea.com/‌index.html Thank you!

The Truth About Tea