Tea Consumption and Risk of Cancer: An Umbrella Review and Meta-Analysis of Observational Studies.

Tea is one of the most widely consumed beverages, but its association with cancer risk remains controversial and unclear. We performed an umbrella review to clarify and determine the associations between tea consumption and various types of cancer by summarizing and recalculating the existing meta-analyses. Meta-analyses of observational studies reporting associations between tea consumption and cancer risk were searched on PubMed and Embase. Associations found to be statistically significant were further classified into levels of evidence (convincing, suggestive, or weak), based on P value, between-study heterogeneity, prediction intervals, and small study effects. Sixty-four observational studies (case-control or cohort) corresponding to 154 effect sizes on the incidence of 25 types of cancer were included. Forty-three (27.9%) results in 15 different types of cancer were statistically significant. When combining all studies on the same type of cancer, 19 results in 11 different types of cancer showed significant associations with lower risk of gastrointestinal tract organ cancer (oral, gastric, colorectal, biliary tract, and liver cancer), breast cancer, and gynecological cancer (endometrial and ovarian cancer) as well as leukemia, lung cancer, and thyroid cancer. Only the reduced risk of oral cancer in tea-consuming populations (OR = 0.62; 95% CI: 0.55, 0.72; P value < 10-6) was supported by convincing evidence. Suggestive evidence was found for 6 results on biliary tract, breast, endometrial, liver, and oral cancer. To summarize, tea consumption was shown to have protective effects on some types of cancer, particularly oral cancer. More well-designed prospective studies are needed with consideration of other factors that can cause biases.

Progress and setbacks in socioeconomic inequalities in adolescent health-related behaviours in Brazil: results from three cross-sectional surveys 2009-2015.

OBJECTIVES: Despite some progress, Brazil is still one of the most unequal countries, and the extent of socioeconomic inequalities in adolescent health is unclear. We assessed trends in socioeconomic inequalities in adolescent's health-related behaviours in Brazil between 2009 and 2015. DESIGN: We used cross-sectional data from the Brazilian National Survey of School Health carried out in 2009, 2012 and 2015. SETTING: Brazilian state capitals. PARTICIPANTS: Students attending ninth grade from public and private schools in Brazilian state capitals in 2009 (60 973 students), 2012 (61 145 students) and 2015 (51 192 students). MAIN OUTCOME MEASURE: We assessed 12 health-related behaviours (irregular fruit, vegetables and bean consumption; regular soft drink consumption; irregular physical activity; alcohol, drug and tobacco use; unsafe sex; involvement in gun fights; bullying victimisation and domestic violence victimisation), under the broad domains of lifestyle risk behaviours, engagement in risky activities and exposure to violence. Socioeconomic status was assessed through an asset-based wealth index derived from principal component analysis. Absolute and relative inequalities in these health behaviours and inequalities trends were investigated. RESULTS: From 2009 to 2015, prevalence of certain harmful health-related behaviours increased, such as unsafe sex (21.5% to 33.9%), domestic violence (9.5% to 16.2%), bullying victimisation (14.2% to 21.7%) and irregular consumption of beans (37.5% to 43.7%). Other indicators decreased: alcohol use (27.1% to 23.2%), irregular physical activity (83.0% to 75.6%) and consumption of soft drinks (37.2% to 28.8%). Over the period, we found consistent evidence of decreasing health inequalities for lifestyle behaviours (fruit, bean and soft drink consumption) and alcohol use, set against increasing inequalities in violence (domestic violence, fights using guns and bullying victimisation). CONCLUSION: Socioeconomic inequality increased in the violence domain and decreased for lifestyle behaviours among Brazilian adolescents. Widening gaps in violence domain urge immediately policy measures in Brazil.