People who drink tea regularly have an 11% lower risk of developing vascular disease, according to a new study. Because the research was observational, however, it does not prove that drinking tea causes the lower risk.
Researchers at the School of Health Policy and Management of the Chinese Academy of Medical Sciences and Peking Union Medical College recently published their analysis of tea consumption and vascular health in the Journal of Internal Medicine. The team tracked 485,934 people for an average of 9.05 years. During that period, 14,863 participants developed vascular conditions including cardiovascular disease, cerebrovascular disease, cor pulmonale and peripheral artery disease.
The analysis found that regular tea drinkers faced an 11% lower overall risk of vascular disease than those who did not drink tea. Risk was lowest among those who drank six to eight cups a week. Among people who drank tea regularly, did not smoke and were highly physically active, the risk was about 45% lower. That figure reflects the combined effect of all three habits, not tea consumption alone.
By type, black tea was associated with a larger reduction in risk than green tea. Drinking tea at a moderate temperature tended to correspond with lower risk, while drinking it very hot was associated with higher risk. Antioxidant compounds in tea such as polyphenols and flavonoids are known to improve the function of the vascular endothelium and to reduce oxidative stress and inflammation.
Similar findings have been reported before. In August 2022, researchers at the U.S. National Cancer Institute said that among 498,043 participants in the U.K. Biobank tracked for a median of 11.2 years, those who drank two or more cups of tea a day had a 9% to 13% lower risk of death from any cause than non-drinkers. About 89% of the tea drinkers in that study favored black tea. That research was also observational, meaning randomized clinical trials would be needed to establish causation. A literature review published in 2011 similarly concluded that the evidence for recommending tea consumption to the general public remains uncertain, citing conflicting results and the possible influence of confounding factors such as lifestyle.
Caffeine warrants attention. Drinking large amounts of green or black tea can push caffeine intake above recommended levels. Per 100 milliliters, green tea contains 25 to 50 milligrams of caffeine and black tea 20 to 60 milligrams. The Ministry of Food and Drug Safety sets the recommended daily caffeine limit for adults at 400 milligrams or less. Average daily intake among Korean adults was 78.0 milligrams, or about 20% of the limit, according to a ministry survey conducted from 2015 to 2017, though caffeine from coffee and other drinks must be counted as well. Excessive intake can cause anxiety, insomnia and gastrointestinal problems.