Tea drinkers live longer
January 9, 2020
European Society of Cardiology
Drinking tea at least three times a week is linked with a longer and healthier life, according to a study published today in the European Journal of Preventive Cardiology, a journal of the European Society of Cardiology (ESC).
"Habitual tea consumption is associated with lower risks of cardiovascular disease and all-cause death," said first author Dr. Xinyan Wang, Chinese Academy of Medical Sciences, Beijing, China. "The favourable health effects are the most robust for green tea and for long-term habitual tea drinkers."
The analysis included 100,902 participants of the China-PAR project2 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 never or non-habitual tea drinkers (less than three times a week) and followed-up for a median of 7.3 years.
Habitual tea consumption was associated with more healthy years of life and longer life expectancy.
For example, the analyses estimated that 50-year-old habitual tea drinkers would develop coronary heart disease and stroke 1.41 years later and live 1.26 years longer than those who never or seldom drank tea.
Compared with never or non-habitual tea drinkers, habitual tea consumers had a 20% lower risk of incident heart disease and stroke, 22% lower risk of fatal heart disease and stroke, and 15% decreased risk of all-cause death.
The potential influence of changes in tea drinking behaviour were analysed in a subset of 14,081 participants with assessments at two time points. The average duration between the two surveys was 8.2 years, and the median follow-up after the second survey was 5.3 years.
Habitual tea drinkers who maintained their habit in both surveys had a 39% lower risk of incident heart disease and stroke, 56% lower risk of fatal heart disease and stroke, and 29% decreased risk of all-cause death compared to consistent never or non-habitual tea drinkers.
Senior author Dr. Dongfeng Gu, Chinese Academy of Medical Sciences, said: "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. Thus, frequent tea intake over an extended period may be necessary for the cardioprotective effect."
In a subanalysis by type of tea, drinking green tea was linked with approximately 25% 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.
Dr. Gu noted that a preference for green tea is unique to East Asia. "In our study population, 49% of habitual tea drinkers consumed green tea most frequently, while only 8% preferred black tea. The small proportion of habitual black tea drinkers might make it more difficult to observe robust associations, but our findings hint at a differential effect between tea types."
Two factors may be at play. First, green tea is a rich source of polyphenols which protect against cardiovascular disease and its risk factors including high blood pressure and dyslipidaemia. Black tea is fully fermented and 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.
Gender-specific analyses showed that the protective effects of habitual tea consumption were pronounced and robust across different outcomes for men, but only modest for women. Dr. Wang said: "One reason might be that 48% of men were habitual tea consumers compared to just 20% of women. Secondly, women had much lower incidence of, and mortality from, heart disease and stroke. These differences made it more likely to find statistically significant results among men."
She added: "The China-PAR project is ongoing, and with more person-years of follow-up among women the associations may become more pronounced."
The authors concluded that randomised trials are warranted to confirm the findings and provide evidence for dietary guidelines and lifestyle recommendations.
https://www.sciencedaily.com/releases/2020/01/200109105508.htm
Drinking tea improves brain health
September 12, 2019
Science Daily/National University of Singapore
A recent study led by researchers from the National University of Singapore (NUS) revealed that regular tea drinkers have better organised brain regions -- and this is associated with healthy cognitive function -- compared to non-tea drinkers. The research team made this discovery after examining neuroimaging data of 36 older adults.
"Our results offer the first evidence of positive contribution of tea drinking to brain structure, and suggest that drinking tea regularly has a protective effect against age-related decline in brain organisation," explained team leader Assistant Professor Feng Lei, who is from the Department of Psychological Medicine at the NUS Yong Loo Lin School of Medicine.
The research was carried out together with collaborators from the University of Essex and University of Cambridge, and the findings were published in scientific journal Aging on 14 June 2019.
Benefits of regular intake of tea
Past studies have demonstrated that tea intake is beneficial to human health, and the positive effects include mood improvement and cardiovascular disease prevention. In fact, results of a longitudinal study led by Asst Prof Feng which was published in 2017 showed that daily consumption of tea can reduce the risk of cognitive decline in older persons by 50 per cent.
Following this discovery, Asst Prof Feng and his team further explored the direct effect of tea on brain networks.
The research team recruited 36 adults aged 60 and above, and gathered data about their health, lifestyle, and psychological well-being. The elderly participants also had to undergo neuropsychological tests and magnetic resonance imaging (MRI). The study was carried out from 2015 to 2018.
Upon analysing the participants' cognitive performance and imaging results, the research team found that individuals who consumed either green tea, oolong tea, or black tea at least four times a week for about 25 years had brain regions that were interconnected in a more efficient way.
"Take the analogy of road traffic as an example -- consider brain regions as destinations, while the connections between brain regions are roads. When a road system is better organised, the movement of vehicles and passengers is more efficient and uses less resources. Similarly, when the connections between brain regions are more structured, information processing can be performed more efficiently," explained Asst Prof Feng.
He added, "We have shown in our previous studies that tea drinkers had better cognitive function as compared to non-tea drinkers. Our current results relating to brain network indirectly support our previous findings by showing that the positive effects of regular tea drinking are the result of improved brain organisation brought about by preventing disruption to interregional connections."
Next step in research
As cognitive performance and brain organisation are intricately related, more research is needed to better understand how functions like memory emerge from brain circuits, and the possible interventions to better preserve cognition during the ageing process. Asst Prof Feng and his team plan to examine the effects of tea as well as the bioactive compounds in tea can have on cognitive decline.
https://www.sciencedaily.com/releases/2019/09/190912100945.htm