Coffee consumption associated with increased green tea and reduced risk of death for the T2D population

“It has been reported that increased intake of green tea due to antioxidant, anti-inflammatory, or antibacterial effects provides health benefits such as prevention of chronic diseases such as diabetes and reduces mortality. “Masu,” the researchers write.

In addition, coffee contains bioactive chemicals that have been reported to affect health through a variety of mechanisms.

To investigate the combined effects of green tea and coffee consumption on mortality, Japanese researchers analyzed data from the Fukuoka Diabetes Registry. This multicenter prospective study included patients who regularly visited a teaching hospital accredited by the Japan Diabetes Society or an accredited diabetes clinic in Fukuoka from April 2008 to October 2010.

Approximately 5,000 people with T2D (N = 4923) were positively followed for a median of 5.3 years. The average age of the patients was 66 years and the majority (n = 2790) were male. Patients reported data on smoking habits, alcohol intake, sleep time, and additional lifestyle behaviors via a self-administered questionnaire. A total of 309 patients died during follow-up.

Researchers used data collected from another self-managed dietary questionnaire to classify patients into four groups by beverage.

1. Green tea: None, 1 cup / day or less, 2-3 cups / day, 4 cups / day or more
2. Coffee: None, less than 1 cup / day, 1 cup / day, more than 2 cups / day

Caffeinated drinks are rare in Japan, so no questions were asked about the consumption of decaffeinated or decaffeinated drinks.

For green tea consumption, the multivariable adjustment HR for mortality from all causes is (P For trends = .002):

• None: 1.0 (referent)
• ≤ 1 cup / day: 0.85 (95% CI, 0.60-1.22)
• 2-3 cups / day: 0.73 (95% CI, 0.51-1.03)
• ≥ 4 cups / day: 0.60 (95% CI, 0.42-0.85)

For coffee, the hazard ratio is (P For trends =. 002):

• None: 1.0 (referent)
• <1 cup / day: 0.88 (95%, 0.66-1.18)
• 1 cup / day: 0.81 (95%, 0.58-1.13)
• ≥ 2 cups / day: 0.59 (95%, 0.42-0.82)

The hazard ratios for the combination of coffee and green tea are as follows:

• No consumption of green tea and coffee: 1.0 (referent)
• 2-3 cups / day green tea and 2 cups / day or more coffee: 0.49 (95% CI, 0.24-0.99)
• ≥ 4 cups / day of green tea and 1 cup / day of coffee: 0.42 (95% CI, 0.20-0.88)
• 4 cups / day or more of green tea and 2 cups / day of coffee: 0.37 (95% CI, 0.18-0.77)

The effect of each beverage on mortality was independent, but a similar trend was seen in the analysis of cardiovascular disease.– –Specific mortality rate. Overall, “The combination of increased consumption of green tea and coffee has significantly reduced the risk of death from all causes by 63%.”

The mechanism that describes the association is not yet understood. Caffeine may contribute to the relationship. However, previous studies have found that consumption of both decaffeinated and decaffeinated coffee is associated with reduced mortality. In addition, the researchers found that “the relative reduction in mortality risk (HR, 0.37) was greater than when consuming green tea alone (HR, 0.72) or coffee alone (HR, 0.76). Therefore, the protection mechanisms for the two beverages can be different. “

Researchers did not analyze data related to education levels or socio-demographic levels, indicating the limits of their studies, as higher education or income levels may be associated with increased coffee consumption. However, Japan also has a universal insurance system, which is said to be available regardless of socio-economic factors.

Note that the ingredients of Japanese green tea may differ from those of other countries, so the author generalizes the findings to other populations.

reference

Yu Komorida, Makoto Iwase, Hideki Fujii et al. Additive effect of green tea and coffee on all-cause mortality of type 2 diabetic patients: Fukuoka diabetes registration. BMJ Open Diabetes Less Care. Published online on October 21, 2020. doi: 10.1136 / bmjdrc-2020-001252