When someone says “green tea is healthy,” most people nod along — yet few can explain why. The answer lies in one group of compounds worth remembering: catechins. Natural antioxidants that make Japanese green tea one of the most scientifically studied foods in the world. In this article, we explore what catechins are, how they work in the body, where to find the highest concentrations — and what all of this means for your daily cup of tea.

What Are Catechins and Where Do They Come From

Catechins belong to a large family of compounds called polyphenols — plant-based substances with antioxidant properties. Polyphenols protect cells from damage caused by free radicals, which are naturally produced during metabolic processes but also generated by stress, pollution, or an unhealthy diet.

Within polyphenols, catechins are classified as flavonoids, specifically flavanols. Green tea contains them in exceptionally high concentrations. The reason is straightforward: unlike black tea, green tea does not undergo oxidation (fermentation), and therefore retains a much higher proportion of catechins. While black tea loses catechins through their conversion into theaflavins and thearubigins, green tea — particularly Japanese green tea, processed by steaming (mushisei, 蒸し製) — preserves catechins virtually intact.

The tea plant Camellia sinensis itself produces catechins as a natural defence mechanism. In the wild, they serve as protection against pests and competing plants. For us, however, they are valuable for an entirely different reason.

The Four Main Catechins in Tea

Green tea contains four main types of catechins. Each has slightly different properties, but all share a strong antioxidant potential:

EGCG (epigallocatechin gallate) — the most studied and most abundant catechin in green tea, accounting for roughly 50–60% of all catechins in the tea leaf. EGCG is at the centre of scientific research into cardiovascular health, metabolism, and anti-inflammatory effects.

EGC (epigallocatechin) — the second most abundant catechin, contributing to the body’s antioxidant defence.

ECG (epicatechin gallate) — responsible for the characteristic astringency (shibumi, 渋み) of tea and possessing antioxidant properties of its own.

EC (epicatechin) — the simplest of the four main catechins, yet still with a measurable benefit for the body.

The ratio of these catechins varies depending on the type of tea, cultivation method, harvest timing, and processing — which is why no two green teas are exactly alike.

What Makes Japanese Green Tea Exceptional

Japanese green teas hold one crucial advantage over Chinese and other green teas: steam processing. This method (sencha style) immediately halts the oxidation of the leaves and preserves the maximum amount of catechins. In China, tea leaves are traditionally pan-fired, which is gentler on flavour but less effective at preserving catechins.

Beyond processing, specific Japanese cultivation techniques naturally alter the balance of compounds in the tea leaf:

Shading (kabuse or ooishita) — for teas such as gyokuro or matcha, tea bushes are covered for 2–3 weeks before harvest. Shading causes the plant to produce more L-theanine (an amino acid associated with calm focus) and chlorophyll, while catechin content decreases somewhat. The result is a deeper umami flavour and lower bitterness.

Full sunlight — teas such as sencha or bancha grow in direct sunlight, which stimulates higher catechin production. These teas have a more pronounced astringency and potentially greater antioxidant capacity.

In other words: if you are looking for the highest catechin intake, reach for a quality sencha. If you prefer a balanced ratio of catechins and L-theanine, gyokuro or matcha are an excellent choice.

What Catechins Do in the Body

Research into catechins — and EGCG in particular — is extensive and ongoing. Based on the available evidence, catechins may contribute to several areas of health:

Antioxidant protection. Catechins neutralise free radicals and may help reduce oxidative stress, which is associated with premature cell ageing and a range of lifestyle-related diseases.

Cardiovascular support. A meta-analysis published in Arteriosclerosis, Thrombosis, and Vascular Biology (American Heart Association, 2018) demonstrated that catechins promote vasodilation — the relaxation of blood vessel walls through activation of the NO/cGMP signalling pathway. A clinical study in the Journal of the American College of Nutrition (Potenza et al., 2007) showed that a single 300 mg dose of EGCG improved endothelial function in patients with coronary artery disease. A meta-analysis by Khalesi et al. (2014) in the European Journal of Nutrition, covering 13 randomised controlled trials, also demonstrated a decrease in systolic blood pressure of 2.08 mmHg and diastolic blood pressure of 1.71 mmHg with regular consumption.

Metabolism and energy. A study by Dulloo et al. (1999), published in The American Journal of Clinical Nutrition, found that a combination of catechins (375 mg, of which 270 mg was EGCG) and caffeine (150 mg) increased 24-hour energy expenditure by 4% and raised fat oxidation from 31.6% to 41.5% compared to placebo. Caffeine alone at the same dose did not produce this effect — the synergy with catechins proved essential. Later systematic reviews note that this effect is measurable with acute intake, while results from chronic consumption are less consistent.

Cognitive function. A study published in Nutritional Neuroscience (Haskell et al., 2008) demonstrated that the combination of L-theanine and caffeine — both naturally present in green tea — improved task-switching accuracy and subjective alertness (p < 0.01) compared to placebo. A randomised controlled trial involving 99 older adults (Uchida et al., 2024, published in PLOS One) showed that 2 g of matcha daily for 12 months measurably improved cognitive scores in social perception.

Choosing Your Tea: A Guide by Catechin Content

In Closing: Why Catechins Matter

Catechins are a natural component of the tea leaf that humans have been consuming for thousands of years. Japanese culture understood long before modern science that green tea brings the body balance and support. Today’s research is gradually confirming this traditional knowledge.

Every cup of quality Japanese green tea is a small but consistent contribution to your health. A ritual that makes sense. And that is exactly how we approach tea at Rishe Tea: with respect for Japanese roots and an emphasis on giving every cup its purpose.

Wondering which tea from our range is right for you? Explore our sencha for the highest catechin dose, gyokuro for a balanced experience, or matcha for the full potential of the whole leaf. And if you are unsure — get in touch. We are happy to help.