Source:

Common name: Tea plant

Scientific name: Camellia sinensis

Production: From mature leaves with minimal processing (only drying).

Consumed: Green tea makes up around 20% of tea production worldwide, is consumed most often in China, Korea, and Japan.

Active ingredient: Flavonoid (catechins)

 
  

Catechins make up 80%–90% of the flavonoids, and approximately 40% of the water-soluble solids in green tea.

 

Green tea contains four main catechins:

  1. Epicatechin (EC)
  2. Epigallocatechin (EGC)
  3. Epicatechin-3-gallate (ECG)
  4. Epigallocatechin-3-gallate (EGCG).

Health benefits of green tea:  

Green tea is richer in antioxidants compared to other forms of tea. Tea is composed of polyphenols, caffeine, minerals, and trace amounts of vitamins, amino acids, and carbohydrates. 

It provides benefits for a wide variety of ailments, including different types of cancer, heart disease, and liver disease, to treat metabolic syndrome, such as obesity, type II diabetes, and cardiovascular risk factors, reduce the risk of coronary disease.

 

Component

Effect

Catechins
(Astringency component in tea)

        i.            Decreases blood cholesterol

      ii.            Body fat reduction

    iii.            Cancer prevention effect

    iv.            Antioxidant

      v.            Tooth decay prevention,

    vi.            Antibacterial effect

  vii.            Anti-influenza effect

viii.            Inhibits high blood pressure

    ix.            Anti-hyperglycaemic effect

      x.            Bad breath prevention (deodorizing effect)

Caffeine
(Bitterness component in tea)

        i.            Increases alertness
(decreases tiredness and drowsiness)

      ii.            Increases stamina

    iii.            Hangover prevention

    iv.            Mild diuretic

Theanine
(Full-bodied flavour component in tea)

        i.            Neuronal cell protection

      ii.            Relaxation effect (promotes α wave production)

    iii.            Lowering of blood pressure

Vitamins

Vitamin C

        i.            Maintenance of healthy skin and mucus membrane (collagen formation)

      ii.            Antioxidant

Vitamin B2

Maintenance of healthy skin and
mucus membrane

Folic acid

        i.            Prevention of foetal neural tube defects (NTD)

      ii.            Prevention of arterial sclerosis

β-carotene

Maintenance of night-time vision

Vitamin E

Antioxidant

Saponins

        i.            Lowering of blood pressure

      ii.            Anti-influenza effect

Fluorine

Prevention of tooth decay

γ-aminobutyric acid (GABA)

Lowering of blood pressure

Minerals
(Potassium, calcium, phosphorus,
manganese, etc.)

Biological regulators

Why is green tea better than regular/ black tea?

Tea, from the plant Camellia sinensis, is consumed in different parts of the world as green, black, or Oolong tea. Among all of these, however, the most significant effects on human health have been observed with the consumption of green tea.

The amount of catechins in the tea can be affected by which leaves are harvested, how the leaves are processed, and how the tea is prepared. Polyphenols are quickly oxidized after harvesting due to the enzyme polyphenol oxidase. To prevent loss of the polyphenols, green tea leaves are heated rapidly (most commonly by steaming or pan frying) to inactivate polyphenol oxidase. Black tea leaves are dried, then rolled and crushed, which promotes oxidation.

Therefore, black tea has far fewer active catechins than green tea and contains up to three times the amount of caffeine as green tea.

 

Green tea and cancer:

Green tea consumption has also been linked to the prevention of many types of cancer, including lung, colon, oesophagus, mouth, stomach, small intestine, kidney, pancreas, and mammary glands. The antioxidants and polyphenol compounds present in green tea kill/stop the growth of the cancer cells, scavenges the free radical damage and averts the growth of cancer cells. Tea components possess antioxidant, antimutagenic, and anticarcinogenic effects and could protect humans against the risk of cancer by environmental agents.

Green tea and anti-ageing:

Skin aging is a complex process mediated by intrinsic factors such as senescence, along with extrinsic damage induced by external factors such as chronic exposure to ultraviolet (UV) irradiation—A process known as photoaging—Which can lead to erythema, oedema, sunburn, hyperplasia, premature aging, and the development of non-melanoma and melanoma skin cancers. UV can cause skin damage either directly, through absorption of energy by biomolecules, or indirectly, by increased production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Green tea phytochemicals are a potent source of exogeneous antioxidant that could nullify excess endogenous ROS and RNS inside the body, and thereby diminish the impact of photoaging. Green tea supplementation increases the collagen and elastin fibre content, and suppresses collagen degrading enzyme MMP-3 production in the skin, conferring an anti-wrinkle effect.

Green tea as neuroprotectant:

Green tea and its main ingredients, EGCG and L-theanine, can enhance cognition, neuropsychology and brain functions. The active ingredient caffeine though present in minimal amount works well as a stimulant by blocking inhibitory neurotransmitter adenosine and boosts brain functions. Furthermore, amino acid L-theanine can work together with caffeine that improves mood, concentration and memory also reduce stress and tension. The research findings on habitual, daily green tea consumption of at least 100 ml per day suggest that the principle long-term benefits are improved mental facilities, a more relaxed state of mind and a lower risk of dementia.

Green tea and weight loss:

 Green tea is used as aids in weight loss and weight maintenance. Catechins and caffeine, both contained in green tea, are each believed to have a role in increasing energy metabolism, which may lead to weight loss. Green tea preparations appear to induce a small, statistically non‐significant weight loss in overweight or obese adults. Green tea had no significant effect on the maintenance of weight loss. 

Green tea and Heart health:

Evidence strongly proves that green tea has shown to remarkably lower the level of bad cholesterol (LDL), triglycerides and at the same time elevates the level of good cholesterol (HDL). Moreover, green tea is beneficial in controlling blood pressure and lowers the risk of heart diseases.

Green tea and Diabetes:

The goodness of polyphenol compounds in green helps to lower the blood glucose spike. Catechins and EGCG mimic the action of insulin and lowers hepatic glucose output and stabilizes the blood glucose level.

When to consume green tea?

Green tea contains caffeine and L-theanine, both of which can enhance alertness and attention, which is especially beneficial in the morning, but drinking green tea empty stomach in the morning is not recommended as the caffeine and tannins stimulate the production of gastric acids which may lead to acidity, ulcers or upset stomach.

Also, drinking this tea before exercise may increase fat burning and reduce muscle damage. Certain compounds in green tea may inhibit the absorption of iron and other minerals, so it’s best to drink it between meals rather than along with the meals. Plus, the caffeine content can cause sleep disturbances when consumed before bedtime.

 

References:

  1. https://www.mdpi.com/2306-5710/3/1/6/htm
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2855614/
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6412948/
  4. https://www.itoen-global.com/allabout_greentea/components_benefit.html
  5. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD008650.pub2/abstract
  6. https://core.ac.uk/reader/96761506?utm_source=linkout
  7. https://www.netmeds.com/health-library/post/green-tea-is-there-a-perfect-time-to-drink-this-healthy-beverage
  8. https://www.healthline.com/nutrition/best-time-to-drink-green-tea
Green Tea Introduction