12 January - 20 June 2016

Enhancing the bioavailability of green tea catechins with vitamin C and xylitol

10 April 13

A study published in the Journal of Food Science has investigated the effects of vitamin C and the sweetener xylitol on the intestinal transport of green tea catechins.  Catechins are the compounds that give green tea it's 'strong antioxidant activity' and are believed to have preventative effects on arteriosclerosis, liver damage and carcinogenesis.  Chung et al from Sejong University have reported that the bioavailability of catechins in humans can be enhanced with vitamin C and xylitol.  Catechins have been found in previous studies to be more stable in acidic conditions hence it has previously been shown that vitamin C and xylitol increase stability thus cellular uptake.  The catechins studied were:  epigallocatechin gallate (EGCG); epicatechin gallate (ECG); epicatechin (EC); and epigallocatechin (EGC).  Mixtures of these catechins were tested with vitamin C only, with xylitol only, and with both, and all in varying concentrations.  The catechin mixture alone was also tested.  The researchers used caco-2 cell cultures which resemble the small intestinal lining.  The permeability of the cells against the catechin mixtures was measured using HPLC analysis.  Chung et al found that without the addition of vitamin C or xylitol, EC was found to have the lowest bioavailability because it is lost to the extracellular space and was not absorbed. They report that for EC, vitamin C was found to be the most effective on intestinal transport.  Results of this study also indicated that the addition of vitamin C at a level of 10ppm, blocks the efflux of EC and enhances intestinal transport by a factor of 8.  Optimum concentrations of 20 ppm vitamin C and 49.5 ppm xylitol approximately doubled bioavailability of ECG, EGC and EGCG.    These results 'provide a potential strategy to enhance the delivery and bioavailability of catechins in humans.'

RSSL's Functional Ingredients Laboratory can analyse green tea for catechins, including epigallocatechin-gallate (EGCG) and epigallocatechin (EGC). For more information please contact Customer Services on Freephone 0800 243482 or email enquiries@rssl.com

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