Potential Health Effects of Tea

Abstract

Brewed tea (from the Camellia sinensis plant) is the second most commonly consumed beverage in the world, and its consumption has been associated with several human health benefits. Tea polyphenols are absorbed in the intestine following consumption and metabolized by both human and microbial systems to yield a mixture of complex metabolites that can be found in circulation and throughout the body. Identification of tea phenolic constituents and their metabolites has served to strengthen the association between tea consumption and specific health benefits, as well as to measure potential differences between tea product forms. The current state of research suggests that long-term consumption of tea and tea polyphenols may provide distinct health benefits, with the strongest associations being the promotion of cardiovascular health, as well as antidiabetic and antiobesity effects. However, much regarding tea and health remains to be discovered. This includes development of a better understanding of the role of abundant oxidized polyphenol forms in oolong and black tea, whose bioavailability and specific role in health benefits remain unknown. This technical summary focuses on tea polyphenol bioaccessibility/bioavailability, discusses potential bioactivity, and highlights studies that link tea consumption and health.

Tea intake and cardiovascular disease: an umbrella review

“…Brewed tea ( Camellia sinensis ) is a major dietary source of flavonoids, in particular flavan-3-ols [ 1 ]. Results of population studies commonly suggest that tea consumption is inversely associated with several health outcomes [ 2 ].…”

“…Tea consumers are shown to have about 20 times the flavonoid intake of non-consumers [ 9 ]. However, the amount of flavonoids and other dietary bioactives present in tea depends on several factors, including (1) their concentration in tea leaves; (2) the quantity of tea leaves used to prepare the infusion; (3) the volume of water used to prepare the infusion; (4) the water temperature, brew time, and agitation used to prepare the infusion; (5) the pH of the water used to prepare the infusion, thermal processing (for commercial preparations), and duration between preparation and consumption; and (6) the volume of tea consumed [ 1 ]. Similarly, the chemical composition of commercial tea extracts can vary greatly depending on the source material, extraction technique (e.g., water, alcohol, other solvent), type of industrial processing, and nature of the finished product.…”

Dose–Response Relation between Tea Consumption and Risk of Cardiovascular Disease and All-Cause Mortality: A Systematic Review and Meta-Analysis of Population-Based Studies

“…Tea is one of the top dietary sources of flavonoids in the U.S. diet and the second most widely consumed beverage worldwide (1,2). Tea is produced from hot water infusion of dried Camellia sinensis to create a flavonoid-rich beverage.…”

“…Following consumption, flavan-3-ols and flavonols can be metabolized by both host and microbial systems to yield a mixture of complex metabolites that can be found in the circulation and throughout the body (1).…”

“…Tea has been investigated (via in vitro, animal, observational, preclinical, and clinical studies) for its potential to reduce the risk and/or progression of various chronic disease outcomes, particularly cardiovascular disease (CVD) and cerebrovascular disease (1,2). Tea flavonoids can act as modulators of enzymes involved in oxidative and inflammatory stress, enhance nitric oxide status, and improve endothelial function, which may in part contribute to potential benefits on cardiovascular health (4).…”