The analysis included 100,902 participants of the China-PAR project2 with no history of heart attack, stroke, or cancer. They were classified into two groups: Those who drank tea three or more times a week—habitual tea drinkers—and those who drank tea fewer than three times a week—non-habitual tea drinkers—and were followed-up with for a median of 7.3 years.
The analyses estimated that 50-year-old habitual tea drinkers would develop coronary heart disease and stroke 1.41 years later and could live 1.26 years longer than those who never or seldom drank tea, according to a press release.
Related: Study: Caffeine May Offset Some Risks of Fat, Sugar Herbs & Botanicals: Trends, Safety, and Traceability 8 Supplements for Detox and Liver HealthCompared with 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. 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. No significant associations were observed for black tea.
Senior Author Dr. Dongfeng Gu, Chinese Academy of Medical Sciences, said in the release: “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.”
The release notes that green tea is heavily favored in East Asia; the small proportion of habitual black tea drinkers may make it difficult to observe significant associations. However, the release also notes that green tea has two advantages: First, it’s a rich source of polyphenols, while black tea is fully fermented, during which process polyphenols are oxidized and may lose their antioxidant effects. Second, black tea is often served with milk, “which previous research has shown may counteract the favorable health effects of tea on vascular function.”
The authors concluded that randomized trials are warranted to confirm the findings and provide evidence for dietary guidelines.