And Lu Yu, the famous Chinese writer who published Cha’ Ching (Classic of Tea) in 780 AD told his readers that tea “tempers the spirits and harmonizes the mind, dispels lassitude and relieves fatigue, awakens thought and prevents drowsiness, lightens and refreshes the body, and clears the perceptive faculties.” So what ingredients are in the tea plant that give it such generous beneficial properties?
Polyphenols, the Natural Ingredients Responsible for Tea´s Flavour
Probably the most important ingredients are what we call polyphenols, natural plant compounds that add flavor and texture to the teas we drink. There are different groups of polyphenols in tea and the largest group are called flavonoids which are formed in sunlight from the amino acids in the leaves.
The most important of these are called catechins which act as antioxidants in the human body and help protect us against age-related diseases such as heart disease, stroke, thrombosis, atherosclerosis, etc.
The most beneficial of the catechins is called epigallocatechin-3-gallate (EGCG), and higher levels of this and other catechins are found in the tender buds and the first one or two leaves on new tea shoots.
Catechins and other polyphenols change during oxidation and so unoxidised teas (green, yellow and ‘silver needle’ white teas) are richer in catechins than oxidized dark oolongs or black teas. The polyphenols in tea account for some of the positive messages about tea’s health properties that have been handed down over the centuries from China.
They certainly help to keep the doctor or apothecary away; and modern research has shown that tea can help protect us not just against problems of our circulation system but also against certain cancers, and against diseases such as Alzheimers since it appears to help protect the brain’s connective tissue.
Tea also contains enzymes, such as polyphenol oxidase (PPO) and peroxidase (POD) that bring about changes in the leaf cells as they break down during manufacture. As the leaves wither and begin to oxidise, the enzymes become involved in changes to the polyphenols, turning the leaves from green to brown and forming theaflavins (responsible for the brightness and quality of the tea’s liquor), and thearubigins (which give tea its rich red color, its depth and its body).
Other flavor and aroma compounds, called volatiles, are also present in the leaves and develop during processing to give the tea its different flavours (grassy, floral, fruity, vegetal, spicy, woody, sweet, etc).
Caffeine and y L-theanine, a combination that improves mood and stimulate mental activity
Traditional wisdom refers again and again to tea’s ability to calm us when we are agitated, wake us up when we are sleepy, help us sleep if we suffer from insomnia, refresh us if we are fatigued.
One poem about tea says the following:
“If you are cold, tea will warm you;
If you are too heated, it will cool you;
If you are depressed, it will cheer you;
If you are excited, it will calm you.”
These somewhat contradictory benefits are the result of caffeine working in harmony with the amino acid L-theanine.
Caffeine is in the tea plant to act as an insecticide and discourage hungry insects from nibbling and damaging the leaves and buds. When we consume drink tea, the caffeine acts as a stimulant to wake us up, increase our stamina, and keep us alert. Too much caffeine absorbed too quickly can make us tremble and feel agitated. But L-theanine in tea slows down the rate at which our bodies absorb the caffeine so that we are less aware of the effects of caffeine and just gradually realise that we feel refreshed, wide awake, and able to concentrate without feeling shaky or anxious.
L-theanine reduces mental and physical stress, reduces blood pressure, and helps us to relax and feel calm. It also has the added benefit of giving tea a wonderful velvety sweetness, and a thick, brothy mouthfeel. When tea grows in sunny conditions, more polyphenols are converted from nitrogen-rich amino acids in the leaf and contribute to the bitterness that we sometimes taste in tea. But if tea is grown under shade or in very misty conditions where the sun barely breaks through the cloud cover, fewer polyphenols form and more amino acids remain in the leaf.
A Source of Vitamins and Minerals
Other beneficial ingredients include fluoride, a natural mineral absorbed from the soil by the plant as it grows and which reduces tooth cavities and decay. Other nutrients include small amounts of manganese, potassium, zinc, beta-carotene, (a precursor of vitamin A, essential for night vision), vitamin B1, B2, B3, B5, B6, B12 (folic acid), Vitamin C and Vitamin E.
The leaves also contain carbohydrates in the form of starches and sugars, saponins (which give tea a bitterness and astringency and have anti-inflammatory and anti-allergy properties), chlorophyll and pigments that determine the colour of the tea. No wonder that the Chinese have a proverb that says: “Better to be deprived of food for three days than tea for one.”