Habitual tea drinkers live longer and healthier, Chinese study highlights
09 Jan 2020 --- Drinking tea at least three times a week can improve life expectancy and health, a new Chinese study has revealed. Two surveys found that habitual tea drinkers who maintained their habit had a lower risk of incident heart disease, stroke and all-cause death compared to people who do not regularly consume tea. This research comes as adults’ concerns surrounding heart health continue to rise, alongside a booming consumer demand for natural, clean label health solutions.
“Tea has attracted great interest from both the public and scientific researchers due to its potential benefits for the cardiovascular system and people’s general health. According to our results, habitual tea consumption could reduce the risks of cardiovascular diseases (CVD) and all-cause mortality,” senior author Dr. Dongfeng Gu of the Chinese Academy of Medical Sciences in Beijing, tells NutritionInsight.
Habitual tea drinkers who maintained their habit in both surveys found that people who drank tea more than three times a week 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 compared to consistent never or non-habitual tea drinkers.
Tea is one of the most popular beverages globally, Dr. Gu affirms.The inverse association between tea and health outcomes might originate from the effects of cardioprotective compounds in tea, Dr. Gu’s research discovered. “Tea, especially green tea, is a rich source of flavonoids, including mainly epicatechin, catechin, and epigallocatechin-3-gallate (EGCG). Previous mechanism studies have revealed that these bioactive compounds can attenuate oxidative stress, relieve inflammation, enhance endothelial and cardiomyocyte function.”
Earlier observational studies and random controlled trials have also explored using tea as a dietary supplement, which found that the bioactive compounds in tea could ameliorate CVD risk factors including hypertension and dyslipidemia. However, these studies were limited in evidence and further studies are still warranted, Dr. Gu affirms.
Research parameters
The first analysis included 100,902 participants with no history of heart attack, stroke or cancer. Participants were grouped into a set of habitual tea drinkers (three or more times a week) and those who drank less than three cups a week. After an average period of around seven years, the researchers followed up on the health of the participants. In the subsequent survey, 14,081 participants were assessed under the same groupings 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.
The study’s findings hint at a differential effect between tea types, Dr. Gu states. Green tea is a rich source of polyphenols, which protect against CVD and its risk factors, including high blood pressure and dyslipidaemia. Black tea, however, is fully fermented and during this process polyphenols are oxidized into pigments and may lose their antioxidant effects. Black tea is often served with milk, which previous research has shown may counteract the favorable health effects of tea on vascular function.
The regional differences in tea consumption make researching tea's health benefits difficult.Milk and sugar?
Although the researchers took milk and sugar added to tea into consideration, they were unable to produce coherent results on these ingredients due to regional differences in their usage. In addition, when milk or sugar are added into tea, extra calories are also added, which may have adverse health effects. Thus, people would get the most benefit when drinking tea plain, Dr. Gu maintains.
“We could not provide evidence on the influence of adding milk or sugar in the current study population because the Chinese tea drinkers seldom added other ingredients in tea. Previous studies from Western countries could provide a hint,” he continues. For example, black tea was associated with lower risk of heart disease and stroke in the Netherlands, Finland and Sweden, where less milk was added into tea.
“While there were no associations observed for black tea in the UK, where tea is often served with milk and/or sugar, scientists from Germany published their results in European Heart Journal in 2007 and found that milk counteracted the favorable health effects of tea on vascular function, in both human and animal studies,” he elaborates.
Commenting on the study's results, Registered Dietitian and spokesperson for the British Dietetic Association Jodie Relf states that “we need to be mindful of is that drinking tea alone is not going to improve our health. It is merely another tool to add to our belts. We cannot continue to eat high fat foods, live a sedentary lifestyle and expect tea to solve all our problems.”
In the future, the researchers aim to investigate the health benefits of tea drinking on other outcomes, such as cancer by following up on the current study populations. They also endeavor to discover the reasons for the gender differences in the link between tea drinking and CVD, as well as refine the health effects of different types and amounts of tea.
By Anni Schleicher
