A new study measuring the effects of Green Tea compounds in the blood stream after digestion, confirmed that the compounds show protective effects for dementia, and could play an important role in protecting the body against cancer.
The researchers investigated whether the protective properties of green tea – which have previously been shown to be present in the undigested, fresh herb – were still ‘active’ after the herb had been digested.
Lead researcher Dr. Ed Okello from Newcastle University, U.K.said “What was really exciting about this study was that we found when green tea is digested by enzymes in the gut, the resulting chemicals are actually more effective against key triggers of Alzheimer’s development than the undigested form of the tea,” explained Dr. Okello
“In addition to this, we also found the digested compounds had anti-cancer properties, significantly slowing down the growth of the tumour cells which we were using in our experiments,” added Dr. Okello.
Dementia
Alzheimer’s disease – the most common form of dementia – is a progressive and irreversible neurodegenerative disorder associated with cognitive dysfunction.
The authors noted that “mounting evidence” suggests that beta-amyloid peptides in conjunction with free radical species (such as hydrogen peroxide) in the brain play a significant role in the development and pathogenesis of Alzheimer’s.
Many previous studies, have suggested that both black and green teas possess protective properties, which have been mainly attributed to their polyphenol content.
Green tea is high in flavan-3-ols, which are believed to be efficient scavengers of highly reactive free radical species, and have been shown to exhibit anti-carcinogenic; hypocholesterolaemic and neuroprotective properties in previous research.
Dr. Okello said that although research has identified certain compounds as beneficial for health, and in many cases has identified foods with high concentrations of such compounds, he explained that “what happens during the digestion process is crucial to whether these foods are actually doing us any good.”
“Flavan-3-ols have been reported to possess properties beneficial to health, [but] they are known to undergo significant metabolism and conjugation in the gastrointestinal tract,” said the researchers.
“It is unknown how such metabolism and conjugation may influence the putative properties of these polyphenols, hence the focus of our study on a digested green tea extract,” they explained.
Digested extract dilute but potent
Green tea extract was subjected to simulated gastrointestinal acids to assess its potential protective benefits after digestion against the damaging effects of hydrogen peroxide and beta-amyloid on neuronal cells in the brain that are believed to play a role in the development of dementia.
The green tea phytochemicals potentially available after upper gastrointestinal digestion were found to contain less than 200 times the concentration of flavan-3-ols found in the pre-digested green tea; yet these compounds were still able to protect brain neurons from both hydrogen peroxide and beta-amyloid toxicity.
Source: Phytomedicine. Published online ahead of print, doi: 10.1016/j.phymed.2010.11.004
“In vitro protective effects of colon-available extract of Camellia sinensis (tea) against hydrogen peroxide and beta-amyloid (Aβ(1–42)) induced cytotoxicity in differentiated PC12 cells”
Authors: E.J. Okello, G.J. McDougall, S. Kumar, C.J. Seal