The consumption of coffee and black tea and the risk of lung cancer

A systematic review and dose-response meta-analysis of prospective cohort studies on coffee consumption and risk of lung cancer

Studies on the association between coffee consumption and risk of lung cancer have been conflicting. The aim of this study was to systematically review the current evidence on the association between coffee consumption and risk of lung cancer and to quantify this association by performing a meta-analysis. A comprehensive systematic search was performed on online databases up to July 2023 investigating the association between coffee consumption and risk of lung cancer. All prospective cohort studies reporting odds ratios (ORs), rate or risk ratios (RRs), or hazard ratios (HRs) and 95% confidence intervals (CIs) in this context were included. The overall effect size was calculated using the random-effects model and statistical between-studies heterogeneity was examined using Cochrane's Q test and I2. A total of 14 prospective cohort studies were included in this systematic review and meta-analysis. We found a significant positive association between coffee consumption and risk of lung cancer (RR: 1.28; 95% CI: 1.12, 1.47). This association remained significant when we included a pooled analysis paper and excluded 5 cohort studies (RR: 1.37; 95% CI: 1.12, 1.66). We observed no proof of significant publication bias using Egger's test (P = 0.58). Moreover, dose-response analysis showed that each one cup/day increase in coffee consumption was related with a 6% higher lung cancer risk (RR: 1.06; 95% CI: 1.03, 1.09). In conclusion, we found a significant positive association between coffee consumption and risk of lung cancer.

Phytochemical Profiles and Bioactivities of Cake Tea Leaves Obtained From the Same Cultivar: A Comparative Analysis

Cake tea, a traditional beverage of China, has excellent health benefits. Our study investigated the phytochemical profiles, antioxidant, and antiproliferative activities of cake tea leaves, which were obtained from the same cultivar and processed at different intervals. The effects of bioactive compounds and antioxidant activities of 4 cake tea varieties on a human lung cancer cell line (A549 cells) were systematically examined. The content of total polyphenol, an active ingredient of tea, was significantly higher in green cake teas (14.0% ± 0.4a) than their black (4.8 ± 0.3c), yellow (10.0 ± 0.6b), and white (8.8 ± 0.5b) counterparts. Likewise, the content of total free amino acids in green cake tea (3.6% ± 0.5a) was significantly higher than the other tea varieties. Our results indicated that the extent of fermentation of tea leaves could decrease the antioxidant activities of cake tea leaves. Furthermore, the white tea cake variety demonstrated the maximum antiproliferative activity on A549 cells as opposed to other types of cake tea leaves. Such an observation allows future researchers to narrow down their focus on using specific cake tea types (sourced from the same cultivar) that provide the maximum health benefits.

Associations between tea and coffee beverage consumption and the risk of lung cancer in the Singaporean Chinese population

BACKGROUND

Tea and coffee are widely consumed beverages. Tea flavonoids have been shown to inhibit lung tumorigenesis using in vitro and in vivo models. Conversely, coffee contains complex mixtures of biochemically active compounds, some of which may have genotoxic and mutagenic properties. However, previous epidemiologic studies have shown inconsistent results on tea and coffee in relation to lung cancer risk.

METHODS

The Singapore Chinese Health Study is a population-based prospective cohort of 63,257 Singaporean Chinese men and women, with an average of 17.7 years of follow-up. Information on tea and coffee consumption and other lifestyle factors was collected through in-person interviews at baseline. Multivariable Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations with adjustment for potential confounders.

RESULTS

There were 1486 incident lung cancer cases. Compared to non-daily coffee drinkers, HRs (95% CIs) of lung cancer risk for those consuming one, two, and three or more cups of coffee per day were 1.18 (1.02-1.36), 1.21 (1.05-1.40), and 1.32 (1.08-1.62) respectively (P for trend = 0.0034). The highest category of black tea consumption (at least 2 cups per day) was inversely associated with risk of lung cancer [HR (95% CI) = 0.73 (0.53-0.99)], particularly among men [HR (95% CI) = 0.67 (0.47-0.95)], compared to less-than-weekly black tea drinkers, although the interaction by sex was not statistically significant.

CONCLUSIONS

Coffee beverage consumption was associated with higher risk of developing lung cancer. On the other hand, black tea intake was associated with lower risk of lung cancer among men in our cohort, and further studies are needed to confirm this association.