-
2013/08
28
-
茶多酚(Tea polyphenols)
收入:本企業網站 推送日期:2013/08/28
CAS No.:84650-60-2
A group of natural phenols called the flavonoids are of popular interest because researchers have found them to have the potential to contribute to better health. Tea has one of the highest contents of flavonoids among common food and beverage products. Catechins are the largest type of flavonoids in growing tea leaves, which include (EGCG), epicatechin(EC), epicatechin-3-gallate(ECg), epigallocatechin(EGC), catechin, and gallocatechin (GC).
Many polyphenolic extracts, for example from grape skin, grape seeds, olive pulp and maritime pine bark are sold as ingredients in , and without any legal health claims. Some of them have self-affirmed status in the US. There are no recommended levels established for polyphenols.
The diverse structures of phenolic compounds prohibit broad statements about their specific health effects. Further, many purported health claims for specific polyphenol-enriched foods remain unproven. Many of the are dietary polyphenols with measurable affinities to , and positive or negative health effects on humans and livestock.
Compared with the effects of polyphenols in vitro, the effects in vivo, although the subject of ongoing research, are limited and vague. The reasons for this are the absence of validated in vivo biomarkers, especially for or ; long-term studies failing to demonstrate effects with a , specificity or efficacy; and 3) invalid applications of high, unphysiological test concentrations in the in vitro studies, which are subsequently irrelevant for the design of in vivo experiments.[57] In rats, polyphenols absorbed in the may be bound in protein-polyphenol complexes modified by intestinal enzymes, allowing derivative compounds formed by ring-fission to be better absorbed.
A review of studies on the of polyphenols published in 2010 found that "definitive conclusions on bioavailability of most polyphenols are difficult to obtain and further studies are necessary.