"Scientists claim a cup of tea may help cure diabetes," according to the Daily Mirror. They and other news sources (BBC) report on research that found that some constituents of black tea (theaflavins and thearubigins) mimic the action of insulin in the body. For a long time green tea has been believed to have beneficial health properties and it is now suggested that black tea may also have some potential.
What are theaflavins? Theaflavins are a flavonoid found in tea. Theaflavins are considered the active ingredient in the fight against high cholesterol. Theaflavins are produced as green tea ferments into black or oolong tea. In addition to fighting cholesterol, theaflavins also support lipoprotein metabolism. Theaflavin often works with the other polyphenols in tea to protect and enhance the body's functions.
What are thearubigins? Thearubigins are polymeric polyphenols that are formed during the enzymatic oxidation (called fermentation by the tea trade) of tea leaves.
A large concentration of thearubigin is therefore found in black (fully oxidated) teas, and a very low concentration in unoxidized teas such as white and green teas. The health benefits of oxidized teas can be partially attributed to the antioxidant properties of thearubigins.
While unoxidized tea lacks a high concentration of thearubigins, it still has antioxidant properties which are primarily due to its high concentration of catechin type polyphenols. Catechins are converted to theaflavins such as thearubigin during the oxidation process.
Amy Cameron and colleagues from the University of Dundee and University of Edinburgh carried out the research. The study was funded by the Caledonian Research Foundation, the Chief Scientists Office of the Scottish Executive, the Medical Research Council, and scholarships from the Carnegie Trust for the University of Scotland. The study was published in the peer-reviewed medical journal: Aging Cell.
In this controlled laboratory experiment, the researchers investigated if dietary factors could play a role in the chemical pathways in the body that are involved in regulating aging and glucose formation and breakdown.
As tea is one of the most popular drinks consumed globally, and little is known about the actions of polyphenols from black tea (the antioxidants that are believed to protect against cell damage) in humans, the researchers hoped that further research would reveal how age-related metabolic diseases (such as diabetes) can be delayed or prevented.
The rate of ageing in the body is believed to be regulated by a group of molecules known as FOXO transcription factors. Both insulin and insulin-like growth factor-1 (IGF-1) have been found to inhibit FOXOs. The researchers were particularly interested in one type of FOXO molecule ¨C FOXO1a ¨C which is known to prevent glucose production in the liver by suppressing certain genes.
