The phenolic content in tea refers to the

phenols In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (− O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds ar ...

and

polyphenol Polyphenols () are a large family of naturally occurring phenols. They are abundant in plants and structurally diverse. Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as ...

s, natural plant compounds which are found in

tea Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of '' Camellia sinensis'', an evergreen shrub native to East Asia which probably originated in the borderlands of south-western China and nor ...

. These

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

s affect the flavor and

mouthfeel Mouthfeel refers to the physical sensations in the mouth caused by food or drink, making it distinct from taste. It is a fundamental sensory attribute which, along with taste and smell, determines the overall flavor of a food item. Mouthfeel i ...

of tea. Polyphenols in tea include

catechins Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of comp ...

theaflavin Theaflavin (TF) and its derivatives, known collectively as ''theaflavins'', are antioxidant polyphenols in tea, polyphenols that are formed from the condensation of flavan-3-ols in tea leaves during the enzymatic oxidation (sometimes erroneously re ...

tannins Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widely applied to any large po ...

, and

flavonoids Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

. Polyphenols found in

green tea Green tea is a type of tea made from the leaves and buds of the '' Camellia sinensis'' that have not undergone the withering and oxidation process that creates oolong teas and black teas. Green tea originated in China in the late 1st millenn ...

include, but are not limited to, epigallocatechin gallate (EGCG),

epigallocatechin Gallocatechol or gallocatechin (GC) is a flavan-3-ol, a type of chemical compound including catechin, with the gallate residue being in an isomeric ''trans'' position. This compound possesses two epimers. The most common, (+)-gallocatechin (GC), ...

epicatechin gallate Epicatechin gallate (ECG, (−)-epicatechin-3-gallate) is a flavan-3-ol, a type of flavonoid, primarily found in green tea (''Camellia sinensis''), with smaller amounts in cocoa, grapes, and other plants. It is also reported in buckwheat and in g ...

, and

epicatechin Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids. The name of the catechin chemical family derives from '' catechu'', which is the tann ...

;

flavanol Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of comp ...

s such as

kaempferol Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavonol, a type of flavonoid, found in a variety of plants and plant-derived foods including kale, beans, tea, spinach, and broccoli. It is also found in propolis extracts. Kaempferol i ...

quercetin Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is found in many fruits, vegetables, leaves, seeds, and grains; capers, red onions, and kale are common foods containing appreciable amounts of it. It has a bitter flavor ...

, and

myricitin Myricetin is a member of the flavonoid class of polyphenolic compounds, with antioxidant properties. Common dietary sources include vegetables (including tomatoes), fruits (including oranges), nuts, berries, tea, and red wine. Myricetin is struc ...

are also found in green tea.

Catechins

Catechins include

epigallocatechin-3-gallate Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is the ester of epigallocatechin and gallic acid, and is a type of catechin. EGCG – the most abundant catechin in tea – is a polyphenol under basic research for its ...

(EGCG), epicatechin (EC), epicatechin-3-gallate (ECg), epigallocatechin (EGC), catechin, and gallocatechin (GC). The content of EGCG is higher in

. Catechins constitute about 25% of the dry mass of a fresh tea leaf, although total catechin content varies widely depending on species, clonal variation, growing location, season, light variation, and altitude. They are present in nearly all

s made from ''

Camellia sinensis ''Camellia sinensis'' is a species of evergreen shrub or small tree in the flowering plant family Theaceae. Its leaves, leaf buds, and stems can be used to produce tea. Common names include tea plant, tea shrub, and tea tree (unrelated to ''Me ...

'', including

white tea White tea may refer to one of several styles of tea which generally feature young or minimally processed leaves of the ''Camellia sinensis'' plant. Currently there is no generally accepted definition of white tea and very little international ...

, green tea,

black tea Black tea (also literally translated as red tea from various East Asian languages) is a type of tea that is more tea processing, oxidized than oolong, yellow tea, yellow, white tea, white, and green tea, green teas. Black tea is generally st ...

and

oolong tea Oolong or Wulong (, ; ; , "black dragon" tea) is a traditional semi-oxidized Chinese tea (''Camellia sinensis)'' produced through a process that includes withering the leaves under strong sun and allowing some oxidation to occur before curling ...

. A 2011 analysis by the

European Food Safety Authority The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002 ...

found that a cause and effect relationship could not be shown for a link between tea catechins and the maintenance of normal blood LDL-cholesterol concentration.

4-Hydroxybenzoic acid 4-Hydroxybenzoic acid, also known as ''p''-hydroxybenzoic acid (PHBA), is a monohydroxybenzoic acid, a phenolic derivative of benzoic acid. It is a white crystalline solid that is slightly soluble in water and chloroform but more soluble in polar ...

3,4-dihydroxybenzoic acid Protocatechuic acid (PCA) is a dihydroxybenzoic acid, a type of phenolic acid. It is a major metabolite of antioxidant polyphenols found in green tea. It has mixed effects on normal and cancer cells in ''in vitro'' and ''in vivo'' studies. It is p ...

(protocatechuic acid),

3-methoxy-4-hydroxy-hippuric acid 3-Methoxy-4-hydroxyhippuric acid is one of the main catechins metabolites found in humans after consumption of green tea infusions. See also * Hippuric acid Hippuric acid (Greek language, Gr. ''hippos'', horse, ''ouron'', urine) is a carboxylic ...

and

3-methoxy-4-hydroxybenzoic acid Vanillic acid (4-hydroxy-3-methoxybenzoic acid) is a dihydroxybenzoic acid derivative used as a flavoring agent. It is an oxidized form of vanillin. It is also an intermediate in the production of vanillin from ferulic acid. Occurrence in natu ...

(vanillic acid) are the main catechins

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

s found in humans after consumption of

infusions.

Theaflavins

Catechin monomer structures are metabolized into dimers

s and oligomers

thearubigin Thearubigins are polymeric polyphenols that are formed during the enzymatic oxidation and condensation of two gallocatechins (epigallocatechin and epigallocatechin gallate) with the participation of polyphenol oxidases during the fermentation reac ...

s with increasing degrees of oxidation of tea leaves. Theaflavins contribute to the bitterness and astringency of black tea. The mean amount of theaflavins in a cup of black tea (200 ml) is 12.18 mg. Three main types of theaflavins are found in black tea, namely theaflavin (TF-1), theaflavin-3-gallate (TF-2), and theaflavin-3,3-digallate (TF-3).

Tannins

Tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...

s are

astringent An astringent (sometimes called adstringent) is a chemical that shrinks or constricts body tissues. The word derives from the Latin '' adstringere'', which means "to bind fast". Astringency, the dry, puckering or numbing mouthfeel caused by t ...

, bitter polyphenolic compounds that bind to and

precipitate In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...

organic compounds.

Gallic acid Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6 H2( OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plant ...

conjugates all of the catechins, such as EGCG (

Epigallocatechin gallate Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is the ester of epigallocatechin and gallic acid, and is a type of catechin. EGCG – the most abundant catechin in tea – is a polyphenol under basic research for it ...

), which are

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...

s with

qualities.

Flavonoids

Phenols called

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

s are under preliminary research, as of 2020, but there is no evidence that flavonoids have antioxidant activity in vivo, or affect physical health or diseases. Tea has one of the highest contents of flavonoids among common food and beverage products.U.S. Department of Agriculture, USDA Database for the Flavonoid Content of Selected Foods, Release 2.1, January 2007

Catechins Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of comp ...

are the largest type of flavonoids in growing tea leaves. According to a report released by USDA, in a 200-ml cup of tea, the mean total content of flavonoids is 266.68 mg for

, and 233.12 mg for

Research

A 2020 review found low- to moderate-quality evidence that daily tea consumption might lower the risk for

cardiovascular disease Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheumati ...

and death.

References

{{teas Tea Natural phenols