According to research by Harvard T.H. Chan School of Public Health, 250ml of green tea contains more than 200 mg of catechin, especially epigallocatechin gallate (EGCG) - an active ingredient that can destroy free radicals 100 times stronger than vitamin C.
EGCG helps stabilize cell membranes, preventing damage caused by oxidative stress, a major factor that makes the body susceptible to cold and chronic inflammation in winter.
A large-scale study in the Journal of Nutrition shows that people who drink at least two cups of green tea a day have a 36% lower risk of flu and a 28% higher chance of immune resilience of T cells than those who do not drink it.
When the temperature drops, peripheral blood vessels often constrict, causing cold hands and feet and increasing the risk of high blood pressure.
According to the European Heart Journal (2023), drinking warm green tea every day helps improve blood circulation and increase vascular dilation by 15-20% thanks to the effects of flavonoids and L-theanine - two compounds that help increase nitric oxide production, naturally dilating blood vessels.
A clinical trial in Japan recorded that the elderly who drank 3 cups of warm green tea/day for 12 weeks had an average reduction of 4.2 mmHg in their blood pressure and significantly improved the feeling of cold hands and feet compared to the control group.
This shows that tea is not only a summer cooling drink but also a "keeping warm from within" therapy in winter.
A comprehensive analysis published in the Journal of Clinical Lipidology (2024) shows that people who drink 2-3 cups of green tea per day have an average LDL reduction of 9%, while increasing "good" cholesterol (HDL) by 4%.
Scientists say that catechin in tea helps activate the enzyme lipoprotein lipase - promoting the conversion of fat into energy, especially useful for people who are less active in the cold season.
According to the Mayo Clinic, you should drink 2-3 cups of warm green tea per day, equivalent to 400-600 ml, for maximum biological efficiency. Tea should be brewed at 80-85°C for 2-3 minutes to retain polyphenols, avoid brewing too hot or leaving too long, causing loss of active ingredients and bitterness.
The 30-minute morning and post-lunch are the ideal time to drink green tea, which helps stimulate metabolism, reduce fatigue and support fat digestion. In the evening, you should limit drinking black tea to avoid caffeine insomnia. People with stomach problems should dilute it more and drink it after meals.
