When formulated with sucrose and vitamin C, the absorption of the green tea compounds, epigallocatechin (EGC) and epigallocatechin gallate (EGCG) were increased by 200 per cent, suggest findings published in the Food Research International.
The study, led by Mario Ferruzzi from Purdue University’s Department of Foods and Nutrition, taps into growing interest in the formulation of nutritionally enhanced beverages. The health profile of green tea are increasingly known to consumers, with studies reporting a wide range of effects, including a lower risk of certain cancers, improved heart health, weight loss, and protection against Alzheimer's.
Results of in vitro (Caco-2 intestinal cells) and in vivo methods (rats) showed that “the common practice of co-formulating ready-to-drink green tea beverages with sucrose and ascorbic acid may enhance bioavailability of catechins through both pre-absorptive and absorptive mechanisms”, wrote the researchers.
Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent.
The four primary polyphenols found in fresh tealeaves are EGCG, EGC, epicatechin gallate (ECG), and epicatechin (EC).
Dr Ferruzzi and his co-workers formulated a range of green tea products to contain 50 mg of green tea extract. The effects of additional sucrose (1.25 grams), ascorbic acid (10 milligrams) or both on the bioavailability and bioaccessibility of the tea’s catechins were evaluated in Sprague Dawley rats and in intestinal cells.
“The high sucrose level relative to green tea powder utilized in this study was chosen to emulate a typical commercial sweetened ready-to-drink green tea beverage,” explained the researchers. “As beverages may be formulated with other non-caloric and caloric sweeteners using lower or higher usage rates, a more detailed study of the dose-dependent enhancement of catechin absorption by various sweeteners is required to determine if optimum ratios exist.”
According to their findings, formulation with both sucrose and ascorbic acid increased the absorption of EGC and EGCG was “significantly enhanced”, they said, with levels three times higher than that observed in the control tea.
Furthermore, the in vitro digestive recovery was between 51 and 53 per cent for EGC and EC, while EGCG and ECG recovery was less than 20 per cent, and this was “modestly enhanced” in the sucrose-only or sucrose plus ascorbic acid formulations.
“These data suggest that formulation with sucrose and ascorbic acid may improve catechin bioavailability by enhancing bioaccessibility and intestinal uptake from tea,” wrote the researchers.
Tea – the secret to eternal youth?
Recently, scientists from the Chinese University of Hong Kong reported that the cells of regular tea drinkers may have a younger biological age than cells from non-drinkers.
By looking at the length of telomeres, DNA sequences at the end of chromosomes that shorten as cells replicate and age, the Chinese researchers reported that the telomeres of people who drank an average of three cups of tea per day were about 4.6 kilobases longer than people who drank an average of a quarter of a cup a day.
This average difference in the telomere length corresponds to “approximately a difference of 5 years of life”, wrote the researchers, led by Ruth Chan.
Source: Food Research International
Published online ahead of print, doi: 10.1016/j.foodres.2009.08.016
"Formulation with ascorbic acid and sucrose modulates catechin bioavailability from green tea"
Authors: C.M. Peters, R.J. Green, E.M. Janle, M.G. Ferruzzi