Studies evaluate effects of tea, alcohol consumption on long-term health
Consumption of black tea was associated with lower mortality risk over about a decade, while reducing alcohol consumption from heavy levels to moderate or mild is associated with lower rates of overall and alcohol-related cancer.
Drinking two or more cups of black tea a day was associated with a 9% to 13% lower risk for mortality, one study found, while another examined the association between alcohol consumption and cancer risk.
In the first, researchers conducted a prospective cohort study of 498,043 people ages 40 to 69 years in the United Kingdom who completed a baseline questionnaire from 2006 to 2010. Respondents reported their tea intake, which was tallied with all-cause mortality and leading causes of death, such as cancer, cardiovascular disease (CVD), ischemic heart disease, stroke, and respiratory disease. Results were published Aug. 30 by Annals of Internal Medicine.
During a median follow-up of 11.2 years, higher tea intake was modestly associated with lower all-cause mortality. Relative to no tea drinking, the hazard ratios for participants drinking 1 or fewer, 2 to 3, 4 to 5, 6 to 7, 8 to 9, and 10 or more cups per day were 0.95 (95% CI, 0.91 to 1.00), 0.87 (95% CI, 0.84 to 0.91), 0.88 (95% CI, 0.84 to 0.91), 0.88 (95% CI, 0.84 to 0.92), 0.91 (95% CI, 0.86 to 0.97), and 0.89 (95% CI, 0.84 to 0.95), respectively. Inverse associations were seen between tea consumption and mortality from CVD, ischemic heart disease, and stroke. Findings were similar regardless of whether participants also drank coffee. The researchers noted that biologically plausible mechanisms link tea intake to lower cancer risk.
The second study investigated the association between the reduction, cessation, or increase of alcohol consumption and cancer. Researchers conducted a population-based cohort study of adults enrolled in the Korean National Health Insurance Service. Participants age 40 years and older underwent a national health screening in both 2009 and 2011. Results were published Aug. 24 by JAMA Network Open.
Self-reported alcohol consumption was categorized as none (0 g/d), mild (<15 g/d), moderate (15-29.9 g/d), and heavy (≥30 g/d) drinking. Based on changes in alcohol consumption level from 2009 to 2011, participants were categorized as nondrinker, sustainer, increaser, quitter, and reducer. The primary outcome was newly diagnosed alcohol-related cancers (head and neck, esophagus, colorectum, liver, larynx, and female breast). A secondary outcome was all newly diagnosed cancers except for thyroid cancer. Among the 4,513,746 participants, the incidence rate of cancer was 7.7 per 1,000 person-years during a median follow-up of 6.4 years.
Compared with the sustainer groups at each drinking level, the increaser groups had a higher risk of alcohol-related cancers and all cancers. Alcohol-related cancer incidence was increased in all drinking categories compared to nondrinking, with adjusted hazard ratios (aHR) of 1.10 (95% CI, 1.02 to 1.18) for moderate drinkers and 1.34 (95% CI, 1.23 to 1.45) for heavy drinkers. Mild drinkers who quit drinking had a lower risk of alcohol-related cancer (aHR, 0.96; 95% CI, 0.92 to 0.99) than those who sustained their drinking. Moderate and heavy drinkers who quit drinking had higher cancer incidence than those who sustained their levels (aHRs, 1.07 [95% CI, 1.03 to 1.12] and 1.07 [95% CI, 1.02 to 1.12], respectively) but when quitting was sustained, this increase in risk disappeared. Compared with sustained heavy drinking, reducing to mild or moderate levels was associated with significantly decreased overall and alcohol-related cancer risk.
The researchers said physicians should reinforce alcohol cessation and reduction for cancer prevention and highlighted potential biological mechanisms for the association. “Given the well-established dose-response association between the amount of alcohol consumption and several cancer risks, it is likely that reduction in alcohol consumption is a factor in lower risk of cancers,” the authors wrote. “Second, reducing alcohol intake could act as a temporary step toward permanent quitting, and decreased cancer risk among the reducer group could be associated with their increased probability of complete abstinence.”