Camelia sinensis i.e. Green, Oolong & Black Tea contain a rich source of tannins. Tannins are polyphenolic compounds that have an affinity for proteins. This is why we use them to ‘tan’ animal hides and convert them to leather. The are what give that puckering, astringent sensation in the mouth.
Internally this action helps to reduce absorption of toxins and protect against irritants. Tannins also display anti-microbial properties as well as constriction of blood vessels – making useful for reducing bleeding be it internal or external.
The less fermentation of the type of tea the more antimicrobial action the teas show i.e. Green tea, no fermentation, Oolong slight and Black tea the most fermentation. Green tea showed the strongest antimicrobial action against the following: Bacillus subtilis, Escherichia coli, Proteus vulgaris, Pseudomonas fluorescens, Salmonell sp., Staphylococcus aureus, Yersinia enterocolitica. The amount of tea taken was below ‘cup of tea’ concentrations.
In green tea the antibacterial effects are due to the tannins epigallocatechin, epigallocatechin gallate and epicatechin gallate. In black tea the effects were due to theaflavin and its gallates. A recent review (Hamilton-Miller JM. Anti-carogenic (i.e. stops/lessens tooth decay) properties of tea (Camelia sinensis). J.Med Microbiol 2001; 50(4):299-302 suggest an anticariogenic activity. Stopping S.mutans & S.sobrinus adhering to teeth; inhibition of the enzyme glucosyltransferase thereby limiting the biosynthesis of an adherence factor and the inhibition of human and bacterial amylases.
All in all another good reason for drinking tea!!
