USDA Questions Quality of Green Tea Supplements8 years, 1 month ago
Posted on May 03, 2011, 6 a.m.
Analysis of commercially available green tea dietary supplements reveals that the manufacturing process leads to degradation of the health-promoting catechin.
A chemical analysis of 20 commercially available green tea-based dietary supplements suggests that it is far better to drink green tea than opt for supplements. Researchers at the US Department of Agriculture's Agricultural Research Service found that the supplements contain higher levels of compounds associated with a degradation of the beneficial compounds catechins and flavonol glycosides. Results also showed that intake levels varied significantly between products, as did the quality. Furthermore, some contained unlabelled non-tea ingredients, such as fenugreek and sucrose. On the whole, solid green tea supplements were more chemically similar to green tea than liquid supplements. "Although there are some good green tea dietary supplement products, there is no way for the consumer to know the qualities of the green tea dietary supplement products from reading the labels," concluded the researchers. "The claim that a green tea dietary supplement is a good alternative for tea leaves is questionable from a chemical composition point of view."
Jianghao Sun, Pei Chen, Long-Ze Lin, James M. Harnly. A Non-targeted Approach to Chemical Discrimination Between Green Tea Dietary Supplements and Green Tea Leaves by HPLC/MS. J AOAC Int. 2011;94:487-497.