What Are Catechins in Tea and Why Do They Matter?

Tea is one of the most popular beverages worldwide, containing a class of natural compounds known as catechins. These compounds are responsible for some of tea’s characteristic taste and are linked to its reputed health benefits. Understanding what catechins are and how their levels vary among different teas provides deeper insight into this beverage.

Defining Catechins: Nature’s Protective Compounds

Catechins belong to a large family of plant-based compounds called polyphenols and are a type of flavonoid. The tea plant, Camellia sinensis, produces these compounds in its leaves, where they contribute to the plant’s defense mechanisms against environmental stressors. These compounds can make up a significant portion of the dry weight of a fresh tea leaf, sometimes reaching up to 25%.

These molecules are related to tannins, a broader category of polyphenols. This relationship helps explain why teas rich in catechins have a distinctly brisk and sometimes bitter taste. Catechins are part of the tea plant’s natural chemical arsenal, which in turn shapes the sensory experience for the tea drinker.

Key Catechins in Different Tea Types

The leaves of the tea plant contain several types of catechins, with four being primary:

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

Among these, EGCG is the most abundant and the most extensively studied due to its biological activity, often accounting for more than half of the total catechin content.

The concentration of catechins in a finished tea depends on the level of oxidation during processing. Green tea is produced by quickly heating leaves after harvest, which halts oxidation and preserves most of the original catechins. This process gives green tea the highest concentration of these compounds, particularly EGCG.

In contrast, black tea production involves a full oxidation process where enzymes transform most catechins into theaflavins and thearubigins. These compounds give black tea its dark color and robust flavor. Oolong tea is semi-oxidized, with catechin levels falling between green and black tea.

Factors Influencing Catechin Potency in Tea

Beyond oxidation, other variables influence the final catechin content. Agricultural conditions like climate, soil composition, altitude, and sun exposure affect catechin production in the leaves. The age of the tea leaves at harvest is also important, as younger leaves contain more catechins than older, more mature leaves.

Specific processing details further modify catechin levels. For instance, in green tea production, the method used to stop oxidation matters, as Japanese-style steaming can preserve catechins differently than Chinese pan-firing methods. Roasted teas like hojicha, which start as green tea, have lower catechin levels because the high heat of roasting degrades these compounds.

The way tea is prepared by the consumer also impacts how many catechins are extracted. Brewing with hotter water pulls more catechins from the leaves, although excessively high temperatures can cause some degradation. The duration of the steep is also a factor, as a longer brewing time results in a higher concentration of catechins.

The Dual Role of Catechins: Flavor and Physiological Effects

In the cup, catechins are primary contributors to tea’s flavor profile, specifically its astringency. This is a physical sensation of dryness or puckering in the mouth that occurs because catechins bind to proteins in saliva. The main catechins contribute differently to this sensation, with EGCG and ECG providing a stronger bitterness and astringency compared to the milder EC and EGC.

Beyond flavor, catechins are recognized for their antioxidant properties. They can neutralize reactive molecules in the body known as free radicals, which can cause cellular damage. Studies have also suggested that catechins may contribute to cardiovascular health by helping to lower LDL cholesterol and improve the function of blood vessels.

Other areas of investigation include the influence of catechins on metabolism, as some studies indicate they may slightly increase fat oxidation. However, the bioavailability of catechins—how much is absorbed and used by the body—is complex. Absorption can be low and is inhibited by food, especially proteins, meaning consumption on an empty stomach leads to higher absorption.