Thursday Jan 09, 2020
Researchers have discovered that consuming green tea at least three times a week is an assurance to a longer and healthier life.
"Habitual tea consumption is associated with lower risks of cardiovascular disease and all-cause death," the study's first author, Xinyan Wang of the Chinese Academy of Medical Sciences, Beijing, said.
Published in the European Journal of Preventive Cardiology, the study included 1,00,902 participants of the China-PAR project with no history of heart attack, stroke or cancer.
Participants were classified into two groups: habitual tea drinkers (three or more times a week) and non-habitual tea drinkers (less than three times a week) and followed up for a median of 7.3 years.
Compared to non-habitual tea drinkers, habitual tea consumers had a 20 percent lower risk of incident heart disease and stroke, 22 percent lower risk of fatal heart disease and stroke, and 15 percent decreased risk of all-cause death.
Habitual tea drinkers who maintained their habit had a 39 percent lower risk of incident heart disease and stroke, 56 percent lower risk of fatal heart disease and stroke, and 29 percent decreased risk of all-cause death as opposed to consistent non-habitual tea drinkers.
"The protective effects of tea were most pronounced among the consistent habitual tea drinking group. Mechanism studies have suggested that the main bioactive compounds in tea, namely polyphenols, are not stored in the body long-term," said study senior author Dongfeng Gu.
"Thus, frequent tea intake over an extended period may be necessary for the cardio-protective effect," Gu added.
In a sub-analysis by type of tea, drinking green tea was linked with approximately 25 percent lower risks for incident heart disease and stroke, fatal heart disease and stroke, and all-cause death.
However, no significant associations were observed for black tea, the study said.
According to the researchers, two factors may be at play.
First, green tea is a rich source of polyphenols that protect against cardiovascular disease and its risk factors, including high blood pressure and dyslipidemia. Black tea is fully fermented; during this process, polyphenols are oxidised into pigments and may lose their antioxidant effects.
Second, black tea is often served with milk, which previous research has shown may counteract the favourable health effects of tea on vascular function, the study said.