A study published in the Environmental Health and Preventive Medicine journal in March 2025 found that women who drink green tea daily have a significantly lower mortality rate from chronic kidney disease compared to those who do not. The research, conducted by epidemiologists from the University of Tsukuba, analyzed data from a Japanese cohort of over 100,000 individuals aged 40 to 79, who were followed for nearly twenty years. The study found that women who consumed three or more cups of green tea daily had a 45% lower risk of dying from chronic kidney disease compared to those who drank less than one cup. One to two cups of green tea per day showed a trend toward reduced risk, but no additional benefit was observed beyond five cups per day. Men, however, showed no association between green tea consumption and mortality from kidney disease, regardless of the number of cups consumed. The study highlights that the protective effects of green tea may be due to its catechins, antioxidants that may help protect the small blood vessels responsible for filtering blood. However, the researchers note that men in the cohort tended to smoke and drink more, which may have masked any potential benefits of green tea. No clinical trials have tested this hypothesis, and the study does not prove causation, as observational data cannot establish direct cause-and-effect relationships. Other factors, such as differences in lifestyle, diet, or follow-up habits among green tea drinkers, could have influenced the results. The study also notes that other research, such as the Spanish PREDIMED-Plus cohort, found a slightly faster decline in kidney filtration among tea drinkers. The authors emphasize that green tea should not replace water and that concentrated extracts are not equivalent to the cups measured in the study. For individuals with advanced kidney disease or those on a potassium-restricted diet, the amount of green tea should be discussed with a healthcare provider. The study acknowledges its limitations, including the fact that drinking habits were self-reported only once at the beginning of the study and not monitored over the 20-year follow-up period. Additionally, the study only counted deaths where kidney disease was the primary cause, not all kidney-related deaths. For kidney health, the researchers note that controlling blood pressure and blood sugar remains more critical than tea consumption. Limiting the use of anti-inflammatory medications without medical advice and monitoring kidney function through a simple creatinine test during annual blood tests are also recommended.