It may seem strange, but tea leaves contain more caffeine than coffee beans. However, when brewed, the caffeine in the tea combines with tannins (tannins) to form caffeine tannate. It does not have such a pronounced tonic effect.
“Caffeine tannate, also called theine, has a milder effect (mainly on the heart). It is excreted from the body faster, which prevents its accumulation. And, unlike pure caffeine, it does not have such a bitter taste,” said expert and Doctor of Biological Sciences Mikhail Goncharov.
In addition to caffeine, this drink contains many polyphenols, which are antioxidants. They help neutralize free radicals (reactive oxygen species) that trigger the oxidation process.
Oxidative stress is believed to be linked to the development of cardiovascular disease, cancer, and Alzheimer's disease. Therefore, drinking antioxidant-rich tea can be considered a preventive measure against cancer and dementia.
"Tea contains polyphenols from different groups. These are mainly flavonoids from the catechin group. During fermentation, they can turn into more complex substances: theaflavins and thearubigins. Another group of polyphenols in tea are tannins. This is a compound of catechins with gallic acid. They are what gives tea its tart taste," says the specialist.
A study by the Poznań University of Life Sciences showed that yellow tea contains the most antioxidants, while black tea contains the least.
A study from the University of Texas found that the compound epigallocatechin-3-gallate (EGCG) in green tea inhibits the formation of new blood vessels, which are necessary for the growth of cancerous tumors, and slows the spread of cancer cells throughout the body (metastasis). In addition, the catechins in green tea stop cancer cell division and trigger their programmed cell death.
A 2022 meta-analysis confirmed that this drink affects key cardiometabolic indicators:
– body mass index,
– blood pressure,
– glycemic status,
– lipid profile.
The study authors concluded that those who regularly drink green tea are less prone to obesity, spikes in glucose levels, and elevated levels of “bad” cholesterol.
"The most beneficial for the heart are complexes of tannins with caffeine (caffeine tannate), which dilate blood vessels, relieve spasms, and normalize blood pressure. And also catechins, which strengthen capillaries," says Mikhail Goncharov.
A study by Guilan University of Medicine in Iran found that regular tea consumption (especially green tea) can reduce systolic (upper) blood pressure by 3 mmHg and diastolic (lower) blood pressure by 1 mmHg. However, for a significant effect, the tea must be drunk for more than three months
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