Analysis of catechin content of commercial green tea products

Tea (Camellia sinensis) contains numerous polyphenolic flavonoid-derived compounds known as catechins, which have shown interesting protective activity against cancer and cardiovascular disease. Numerous products based on tea are commercially available, many of which claim to contain specific amounts of the bioactive catechins. The catechin content of seven commercial green tea products (encapsulated extracts or tea bags) was quantified by HPLC and, where possible, compared to that claimed on the label. Wide variability was observed in the catechin content between green tea products, even those that appear outwardly similar to consumers. Measured catechin content ranged from 9% to 48% of label claims; all values were significantly lower than those claims (P < 0.05). These results continue to demonstrate the problems that exist with quality control in the dietary supplement and herbal medicine industry and, there, for consumers of nutraceuticals.