Do you drink it because you like it? Or because you know it’s good for you? Or both?
Green tea has been used in traditional Chinese medicine for many hundreds of years. Tea (Camellia sinensis) still remains the most commonly drunk beverage across the world after water. Tea contains polyphenols (higher levels are found in green tea), potent antioxidants that in the teapot at least have been shown to have potent anti carcinogenic, hypocholesterolaemic and neuroprotective properties.
How does this work to protect our brain?
The brain is highly metabolically active and produces many free radicals (including a substance called hydrogen peroxide) which if unchecked can cause brain cell damage.
In earlier animal studies, green tea polyphenols were shown to ameliorate the effect of these free radicals and improve cognition in cognitively impaired animals.
A study in 2005 of an elderly group of Japanese people showed that drinking green tea over a two-year period provided them with a degree of cognitive protection.
As with many foods that have been identified as containing powerful biochemical substances useful to maintain our health, the question has been “Do these properties persist once we have consumed the foods and they have undergone digestion?”
What is the effect of digestion in altering the bioavailability and effectiveness of these green tea polyphenols?
A team from Dundee and Newcastle in the UK set up a study to answer that. They firstly developed a technology to simulate human digestion and then looked at how this affected a green tea extract passing through, assessing its ongoing ability to protect against the free radical hydrogen peroxide and beta amyloid toxicity.
What they were able to show was that this “digestion” actually appeared to enhance the neuroprotective and anti carcinogenic properties of the green tea.
The next logical step will be to look at this effect in human digestive studies.
Meanwhile for all you green (and black) tea lovers, it appears that drinking your favourite beverage really is good for your brain and well-being.
E.J. Okello, G.J. McDougall, S. Kumar, C.J. Seal. 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. Phytomedicine, 2010; DOI: 10.1016/j.phymed.2010.11.004