Abstract
The inconsistent findings regarding green tea intake and colorectal cancer (CRC) risk in several epidemiological studies might result from variations in lifestyle factors. Therefore, we examined whether increased green tea intake was associated with a decreased risk of CRC and how the risk of CRC was altered by the protective effect of green tea consumption and five health-related factors. A case-control study including 2742 participants (922 cases and 1820 controls) was conducted in Korea. Green tea consumption was assessed using a semiquantitative food frequency questionnaire. The risk of CRC was approximately 40% less in the participants in the highest green tea intake tertile than in participants in the lowest green tea intake tertile. Of the five lifestyle factors examined, high body mass index and physical inactivity were independent risk factors for CRC. Regarding the interactions between tea consumption and lifestyle factors, high green tea consumption was associated with a decreased risk of CRC, with or without considering lifestyle factors. However, moderate green tea consumption increased the risk of CRC among ever-smokers, ever-drinkers and the high-inflammatory diet group. Increased consumption of green tea might be helpful to reduce the risk of CRC in those with an unhealthy lifestyle.
Highlights
A rapid increase in colorectal cancer (CRC) incidence has been observed worldwide; CRC rates nearly doubled between 2002 and 2018 due to a shift in lifestyles and diet [1,2,3,4]
Significant differences were observed depending on the group; the case group was more likely to have a lower prior body mass index (BMI), a higher family history of CRC (p < 0.001), a lower education level (p < 0.001) and to exercise less regularly (p < 0.001) than the control group
No differences were found in age, sex, BMI, alcohol consumption or smoking
Summary
A rapid increase in colorectal cancer (CRC) incidence has been observed worldwide; CRC rates nearly doubled between 2002 and 2018 due to a shift in lifestyles and diet [1,2,3,4]. CRC is the second most prevalent cancer in Asian countries, such as South Korea [5,6]. Beverage intake, including tea, increased threefold over a decade in Korea [7]. Among the variety of teas, green tea may have beneficial effects on CRC due to its polyphenol content [8,9]. Experimental studies have demonstrated that green tea strongly contributes to a decreased risk of CRC, previous epidemiological studies have reported inconsistent results [12,13,14]. A recent meta-analysis of 12 case-control studies and 17 cohort studies with 1,642,007 participants identified an inverse association between the risk of CRC and green tea consumption [12]; there were no such associations in a Chinese prospective cohort
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