Epigallocatechin gallate, or EGCG, is a natural compound that has drawn public attention, particularly due to its prevalence in green tea. This article explores what EGCG is, its origins, and how it interacts within the body.
Defining EGCG
EGCG stands for Epigallocatechin gallate, a specific type of plant compound. It is classified as a catechin, which falls under the broader category of flavonoids. Flavonoids are diverse plant metabolites. EGCG is also an antioxidant, meaning it helps protect cells from damage.
This compound is an ester of epigallocatechin and gallic acid, giving it a unique molecular structure. The presence of multiple hydroxyl groups contributes to its biological actions. EGCG is the most abundant catechin found in tea.
Primary Sources of EGCG
Green tea is the primary source of EGCG. Its dried leaves contain substantial amounts, with concentrations around 7380 milligrams per 100 grams. White tea also contains significant levels, at approximately 4245 milligrams per 100 grams.
Black tea, while derived from the same plant, has lower amounts of EGCG, around 936 milligrams per 100 grams, as its production process converts catechins into other compounds. Small quantities of EGCG are also found in other plant-based foods, such as cocoa products, apples, pears, and prune juice.
How EGCG Interacts with the Body
EGCG’s interactions within the body are largely attributed to its antioxidant function. Antioxidants neutralize free radicals, unstable molecules that damage cells and tissues. This protective action is linked to the phenolic groups in EGCG’s structure, which are susceptible to oxidation.
Beyond its antioxidant capacity, EGCG is also thought to influence various cellular processes. Research indicates it may modulate specific intracellular signaling pathways and gene expression, inhibiting certain enzymes and interacting directly with cell surface membrane proteins. These biological activities contribute to its observed effects, which can vary depending on the specific cell type and the concentration of EGCG present.
Important Considerations for EGCG Consumption
When consuming EGCG, whether through green tea or supplements, understanding its absorption is helpful. EGCG generally has poor oral bioavailability, meaning only a limited amount is absorbed into the bloodstream. Even at high daily intakes equivalent to many cups of green tea, absorption remains low.
Once absorbed, EGCG blood levels typically peak within about 1.7 hours, with an approximate plasma half-life of around 5 hours. The majority of unchanged EGCG is excreted in urine within 8 hours. While generally considered safe in amounts typically consumed through food and beverages like green tea, high doses from concentrated supplements may warrant caution and professional consultation.