Chemistry and Applications of Green Tea is the progress report of Japanese researchers from the Taiyo Kagaku Co., Ltd., who for the past 10 years have been investigating the properties of green tea components, especially the polyphenols. The book mainly reviews the efficacy of SUNPHENON(R), a commercial preparation containing 60-75 percent green tea polyphenols (manufactured by Taiyo Kagaku), and also provides brief overviews of the chemistry and physicochemical properties (Chapter 3), metabolism (Chapter 5), and uses of green tea polyphenols in the prevention and treatment of disease (Chapters 6-11, 13) and in food preservation (Chapter 4). In addition, there is a single chapter (12) on green tea amino acids that is largely about theanine, an unusual amino acid that relaxes the body and lowers blood pressure. Another green tea amino acid that lowers blood pressure, gamma-aminobutyric acid (GABA), received only a mention in Chapter 2 and could have been treated more fully here.
A wide range of commercial applications for green tea polyphenols is implied or suggested by the research findings presented in this book. Noteworthy are tables (in the Appendix and Chapters 8-11, 13) giving the minimal inhibitory concentrations of polyphenols for the growth of various micro flora. These tables show that polyphenols can inhibit harmful bacteria without affecting beneficial ones. Considering that these minimal inhibitory concentrations are also nontoxic in mammals, the data suggest that polyphenols might safely be added to mouthwash for the prevention of dental caries, gingivitis, and bad breath, or to animal feed for the treatment of certain forms of intestinal diarrhea. In addition, Chapter 7 presents evidence that two daily 200-rag doses of green tea polyphenols (especially epigallocatechin gallate) can increase the clearance of methylguanidine (uremic poison) from hemodialysis patients by an additional 30 percent after only one month of treatment.
These reviewers have one major criticism of Chemistry..., namely, that the book is not written in standard American English. The reader is too often required to backtrack, rearrange the order of presentation, fill in gaps, or simply guess the author's meaning. Fortunately, the illustrations, tables, and figures (with a few exceptions) are well designed and speak for themselves. The authors are evidently of the opinion that a good table or illustration is worth a thousand poorly chosen words.
The editors intended that Chemistry...be used as a reference work by "not only researchers and engineers working in the field of tea science and manufacturing, but also those in pharmaceutical science and chemistry of natural-occurring compounds." Although a great deal of this science is already known to the book's target audience, this book cites a Japanese literature hitherto accessible only to those who could read Japanese. In addition, Chemistry...is probably the only text in "English" dedicated to reviewing the science behind "the many useful properties of green tea." (Another text, Tea: Cultivation to Consumption, edited by Willson and Clifford, is authoritative on tea production, but it contains only a brief section on the chemistry of the green leaf polyphenols and one chapter on their physiological effects.) Thus, the current crop of tea science professionals may find this book a useful addition to their library.
[The authors of this review wrote the literature review on tea published in Herbal Gram No.37]
Article copyright American Botanical Council.
By Robert S. Gutman and Beung-Ho Ryu