For the Japanese, who have the highest average life expectancy in the world, hypertension is an unavoidable issue for most. As people age, their blood pressure rises, and the prevalence of hypertension increases from 3.6% in people in their 20s to 42.9% in those in their 50s (※1).
Moreover, in winter, the decrease in temperature causes blood vessels to contract, making it easier for blood pressure to rise. Staying indoors due to the cold and not getting enough exercise can increase the risk of a rise in blood pressure.
Hypertension can lead to severe complications such as cerebral infarction, congestive heart failure, and myocardial infarction.
Over 90% of hypertension cases are primary hypertension, whose cause is not clear. A variety of factors, including excessive salt intake, obesity, smoking, drinking, and genetic predisposition, can trigger it. Therefore, preventing its onset requires strict self-management, such as a regular diet and moderate exercise.
Catechins contained in green tea have been reported to suppress increases in blood pressure.
According to research reports, adults (ages 25–55) with visceral obesity who continued to drink green tea (583mg catechins/340ml) daily for 12 weeks saw their systolic blood pressure decrease from 139.8 to 130.8mmHg, and their diastolic blood pressure decrease from 90.3 to 83.5mmHg (※2).
In trials involving obese children (ages 6–16) as well, continuous daily consumption of green tea (576mg catechins/340ml) for 24 weeks resulted in a decrease in systolic blood pressure (※3).
One of the factors in primary hypertension is a protein called angiotensin II. Angiotensin I in the blood is metabolized in the capillaries of the lungs to become angiotensin II, which promotes the contraction of blood vessels and raises blood pressure.
Catechins suppress the production of angiotensin II, thereby preventing increased blood pressure.
A hot cup of freshly brewed green tea can provide a moment of relaxation. The effects of catechins suppress the rise in blood pressure; as the body warms up and the blood vessels expand, blood pressure decreases. Green tea is perfect for maintaining a calm day without raising blood pressure.
※1 Ministry of Health, Labour and Welfare. National Health and Nutrition Survey 2018, Table 55: Status of Hypertension Patients - Status of Hypertension Patients by Age Group, Number, Percentage - Total, Male, Female, Aged 20 and Over
※2 Nagao, T., Hase, T., Tokimitsu, I. A green tea extract high in catechins reduces human body fat and cardiovascular risks. Obesity (Silver Spring) 2007;15:1473-1483.
※3 Matsuyama, T., Tanaka, Y., Kamimaki, I., Nagao, T., Tokimitsu, I. Catechin Safely Improved Higher Levels of Fatness, Blood Pressure, and Cholesterol in Children. Obesity (Silver Spring) 2008;16:1338-1348.