The Health Benefits of Green Tea

What Components Are Found in Green Tea?

  • Water-Soluble Components - Catechins (tannins), caffeine, amino acids, theanine, organic acids, saponins, water-soluble pectin, flavonols, vitamin C, etc.
  • Insoluble Components - β-carotene, vitamin E, chlorophyll, lipids, essential oils, etc.
  • Water-Soluble and Insoluble Components - Minerals (such as calcium, phosphorus, potassium, manganese, magnesium, zinc), proteins, and dietary fiber.

Approximate composition: catechins (~15%), lipids (~5%), caffeine (~3%), proteins and amino acids (~25%), ash/minerals (~5%), and dietary fiber (~40%).

Catechins: A Key Health Component in Green Tea

Catechins are crucial chemical compounds in green tea, responsible for many of its health benefits. The main types, in descending order of abundance, are:

  • Epigallocatechin gallate (EGCG)
  • Epigallocatechin
  • Epicatechin gallate (ECG)
  • Epicatechin (EC)

Catechin Content by Tea Type

In general, sencha contains more catechins than gyokuro. This is because sencha is usually grown in full sunlight, while gyokuro is shade-grown, reducing catechin content due to lower sun exposure.

Japanese Tea vs. Global Teas

Compared to global teas, Japanese tea has a higher catechin content. As oxidation increases (e.g., in oolong and black tea), catechins decrease due to oxidation and polymerization into tannins. Though black tea has high tannin content, its catechin and vitamin C levels are much lower.

Health Benefits of Green Tea

Tea has long been enjoyed as a healing beverage. Even before scientific validation, it was valued for its health benefits. Today, research is increasingly confirming its positive effects.

  • Antioxidant Effects - Catechins and vitamin C in green tea act as water-soluble antioxidants. Vitamin E in tea leaves (insoluble) also contributes if leaves are consumed directly.
  • Cancer Prevention - Research shows green tea catechins inhibit mutations and the growth of mutated cells. Its antioxidant and anti-metastatic properties contribute to cancer prevention.
  • Prevention of Arteriosclerosis - Catechins help suppress the rise of HDL cholesterol in the blood and slow cholesterol absorption in the digestive tract.
  • Blood Pressure Control - Catechins are thought to inhibit the activity of renin, an enzyme involved in blood pressure elevation.
  • Blood Sugar Control & Anti-Obesity Effects - Catechins inhibit sugar-decomposing enzymes like amylase and sucrase and help boost liver fat metabolism.
  • Anti-Allergy Effects - Methylated catechins, especially effective against hay fever and allergic rhinitis, have double the anti-allergy activity of EGCG. Cultivars like Benifuuki and Kanayamidori are rich in these compounds.
  • Relaxation Effect - Theanine in green tea promotes relaxation and improves sleep quality—explaining the soothing effect of drinking tea.

Green tea also has antibacterial and antiviral properties. Combining health benefits and flavor, it's an exceptionally appealing beverage.

The Health Benefits of Green Tea