Scientists from Guilan University of Medical Sciences have found that regularly drinking green or black tea may help lower blood pressure.
The findings were published in Complementary Therapies in Medicine and reported by Marjan Mahdavi-Roshan and colleagues.
Green tea has long been associated with health benefits across a range of chronic conditions, including certain cancers, cardiovascular disease, and liver disorders.
Many of these effects are thought to be linked to catechins—plant-based compounds that are abundant in tea, as well as in cocoa and berries.
Long-term consumption of green tea has been shown to help counter high-fat-diet–induced obesity and type 2 diabetes and may reduce the risk of heart disease.
Black tea has also attracted attention as a healthier alternative to coffee or sugary energy drinks. It is low in calories and contains naturally occurring micronutrients that provide multiple health benefits.
Like green tea, black tea is rich in catechins and flavonoids—compounds known for their antioxidant and anti-inflammatory properties.
Previous studies suggest that black tea consumption may help protect against the development of several chronic diseases by reducing inflammation and oxidative stress.
High blood pressure is a major risk factor for cardiovascular disease, and many researchers have investigated whether tea consumption could help improve blood pressure control.
In the current review, the researchers aimed to evaluate the effects of green and black tea consumption in individuals with elevated blood pressure—a condition that often progresses to hypertension if left unmanaged.
Elevated and high blood pressure can damage vital organs and increase the risk of serious health problems, including heart attack, heart failure, stroke, and kidney disease.
The research team reviewed five clinical studies published between February 1, 1995, and July 20, 2019, involving a total of 408 participants.
The analysis showed that regular tea consumption was associated with a reduction in systolic blood pressure of 4.81 mmHg and diastolic blood pressure of 1.98 mmHg.
The researchers also found that longer durations of tea intake—particularly beyond three months—were linked to greater reductions in both systolic and diastolic blood pressure.
When comparing tea types, the blood-pressure-lowering effects of green tea were stronger than those observed for black tea. Importantly, none of the reviewed studies reported adverse side effects associated with tea consumption.
Overall, the findings suggest that regular consumption of green or black tea may help lower blood pressure in people with elevated blood pressure.
The researchers note that healthcare professionals, including doctors and other providers, may consider recommending tea consumption as part of a broader lifestyle approach to blood pressure management.
One limitation of the review is that most of the included studies focused on individuals with elevated blood pressure rather than those with diagnosed hypertension.
Future research is needed to determine whether green or black tea can help people with established high blood pressure better manage their condition.
