Tea leaves are a treasure; you wouldn't know if you don't drink them.
The benefits and health preservation effects of tea leaves are summarized comprehensively for everyone today.
Tea can reduce the risk and mortality rate of cardiovascular diseases.
A recent study reported that Japanese researchers have been tracking over 40,000 individuals aged between 40 to 79 years old since 1994. Compared to those who drink less than one cup of tea a day, men who drink more than five cups of green tea daily have an average risk of death from cerebral vascular disease reduced by 22%, while women see a decrease of 31%. The reduction is most notable in cases of cerebral infarction, with a drop of 42% for men and a significant 62% for women. According to the UK's Daily Mail, a new study found that drinking three cups of tea a day can lower the risk of myocardial infarction by 70%. Studies from Finland and France also show that drinking two to three cups of tea a day can reduce the risk of stroke.
Tea can lower cholesterol and blood pressure.
Researchers at Hong Kong University discovered that drinking tea can reduce total blood cholesterol levels by 25%. Another study on the relationship between drinking tea and hypertension incidence found that the incidence of hypertension in non-tea drinkers was 10.55%, whereas regular tea drinkers had a rate of 6.95%, indicating that tea does indeed have some effect in lowering blood pressure.
Tea helps prevent early-onset dementia.
Tea protects brain cells and can effectively slow down brain degeneration, helping maintain the health of cerebral vessels. Recent studies show that drinking more tea can improve memory and prevent early-onset dementia.
Tea has stress-relieving and anti-anxiety effects.
Fast-paced modern life and work often cause anxiety, tension, irritability, depression, and other mental symptoms. Green tea contains L-theanine, a relaxant without sedative effects, which can help the brain increase production of gamma waves. These gamma waves can help control anxiety, improve attention, and enhance mental state and overall function. Typically, 3-4 cups of green tea contain 100-200 milligrams of L-theanine, making green tea effective in relieving stress and anxiety.
Tea can boost the immune system.
If there's a flu outbreak, drink more tea. Researchers at Harvard University found that people who drank five cups of tea daily for two weeks produced ten times more antiviral interferon than non-tea drinkers. This protein, which can resist infection, can enhance the body's immunity and effectively help the body fight off the flu.
Other health benefits of tea.
Tea can also eliminate fatigue, refresh the mind, improve vision, aid digestion, promote diuresis and detoxification, prevent dental caries, eliminate bad breath, and it is an alkaline beverage that can help correct acidic constitution. Tea truly deserves its title as the healthiest beverage of the 21st century.
It is undeniable that tea plays a significant role in human health. However, before the 19th century, no one could clearly explain why tea possesses so many functions. From the 1960s and 1970s onwards, the ancient and mysterious field of tea welcomed scientific exploration, with extensive scientific research conducted on the internal components of tea leaves, opening up this wondrous door for us.
As seen from the figure, tea leaves contain 75% water, which scientifically explains the saying “4 pounds of leaves for 1 pound of tea.” Water-soluble substances in tea leaves account for 30-48%, and their main chemical components include polyphenols, alkaloids, amino acids, sugars, organic acids, etc., which form the quality and flavor of tea.
Polyphenolic Compounds
Polyphenolic compounds are widely present in nature, and well-known ones include tea polyphenols, apple polyphenols, grape polyphenols, etc. Due to their excellent antioxidant properties, they are widely used in cosmetics, pharmaceuticals, and other fields.
Tea polyphenols are one of the main components that give tea its color, aroma, and flavor, and are also one of the primary components with health-preserving properties. They are abundant, widespread, and change significantly, having the most significant impact on the quality of tea. Tea polyphenols include catechins, anthocyanins, flavones, flavonols, and phenolic acids, among which catechins are the highest in content and the most important. Studies show that after drinking a cup of tea, the antioxidant capacity (the ability to combat free radicals) in the blood increases by 41-48% within half an hour and remains high for one and a half hours.
Polyphenolic compounds make up about one-third of the dry matter in fresh tea leaves and three-quarters of the total extractable substances in tea infusion. They are extremely reactive and can undergo a series of chemical reactions under external conditions, generating new chemical substances that influence the quality of various types of tea. Therefore, the degree of oxidation of tea polyphenols is one of the main criteria for classifying different tea types.
Schematic diagram of the degree of polyphenol oxidation in different tea types.
Polyphenolic compounds are the primary water-soluble pigments in tea, determining the color of tea infusion and contributing to the color of dried tea. At the same time, the main components responsible for the astringent taste in tea are polyphenolic compounds, their oxidation products, aldehydes, iron, etc., with catechins playing a particularly important role.
Tea Amino Acids
The main amino acids in tea include theanine, glutamic acid, aspartic acid, and over 20 others. Theanine is an essential component that contributes to the fragrance and freshness of tea, accounting for over 50% of free amino acids in tea. Its water-soluble substances mainly impart a fresh and sweet taste, which can inhibit the bitterness and astringency of tea infusion. Japan approved the use of theanine as a food additive in 1964.
In addition to extraction from tea leaves, theanine can also be synthesized through biological or chemical means. Due to its properties of reducing blood pressure, calming the mind, improving sleep, and promoting brain function, theanine is used as a raw material for health foods and pharmaceuticals.
How Should Different Populations Choose Their Tea?
1. Green tea is suitable for those who use their brains frequently. Reports suggest that green tea helps prevent cancer, lowers blood lipids, and prevents arteriosclerosis. It is recommended for individuals frequently exposed to harmful substances or living in heavily polluted environments, as the active components in green tea can provide protective effects. It is also beneficial for smokers and drinkers, aiding in detoxification and sobering effects. It is suitable for young adults experiencing rapid growth