Title	Low level Evidence about Tea Consumption and Oral Cancer Incidence
Clinical Question	In adults, aged 18-65, does high consumption of a caffeinated drink (1 or more cups a day) such as tea result in higher or lower oral cancer incidence?
Clinical Bottom Line	Research on consumption of caffeinated drinks such as tea has shown inconclusive results as to whether tea affects oral cancer incidence; more research is needed.
Best Evidence
PubMed ID Author / Year Patient Group Study type (level of evidence) 14519824 Lambert/2003 Populations from Shanghai, Miyagi, Netherlands Systematic Review Key results This systematic review examined the proposed health benefits and effectiveness of tea as a cancer preventive agent. The review encouraged future intervention studies, as the current research has demonstrated inconclusive results, to examine the bioavailability of tea constituents, such as polyphenols (epicatechin, epigallocatechin, epicatechin-3-gallate, etc.), as well as their mechanism of action within the oral cavity. 19002670 Yang/2008 Populations from China and Japan Systematic Review Key results In animal models, the antioxidative and anti-carcinogenic activities of tea polyphenols have been clearly demonstrated in oral, esophageal, stomach, intestinal, colon, skin, liver, bladder, prostate, and breast cancer, but have not been consistently observed in human studies. 19588362 Boehm/2009 51 Studies, more than 1.6 million participants (majority from Asia). Systematic Review Key results Green tea consumption was 3 to 5 cups per day (up to 1200 mL/day) with a minimum of 250 mg/day of catechins (a type of polyphenol found within tea). The results of these studies demonstrated insufficient and conflicting evidence relating tea consumption to cancer prevention whether esophageal, gastric, colon, rectum, oral, or pancreatic cancer.
Evidence Search	“Tea and Incidence of Oral Cancer” using Systematic Reviews as a filter
Comments on The Evidence	The evidence presented in these studies appears valid through animal models and has demonstrated the potential value of tea consumption for purposes of its anti-oxidant nature and potential to reduce cancer risk. However, more research is required to apply towards human models and to elucidate the possible cancer preventive mechanisms of tea polyphenols.
Applicability	The evidence presented in these studies is low level at this time because despite many of the animal studies involving rats showing positive results in reducing carcinogenesis, the studies have yet to demonstrate the mechanism of action of certain polyphenols within tea in reducing carcinogenesis in human populations.
Specialty	(Public Health) (General Dentistry) (Dental Hygiene)
Keywords	Oral cancer, Tea
ID#	2491
Date of submission	07/11/2013
E-mail	louiec@ohsu.edu
Author	Christopher Alex Louie
Co-author(s)
Co-author(s) e-mail
Faculty mentor	Ronald Sakaguchi, DDS, MS, PhD, MBA & Eli Schwarz, DDS, MPH, PhD
Faculty mentor e-mail	sakaguch@ohsu.edu; schwarz@ohsu.edu
Basic Science Rationale (Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?) None available
Comments and Evidence-Based Updates on the CAT (FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs) None available