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Study Finds Drinking Green Tea
Could Reduce Glaucoma Risk
Phytochemicals Naturally Present In Green Tea
Are Valuable For Supporting Healthy Eyes
Green tea catechins could help protect against glaucoma and other
eye diseases, according to a new research which found that the
ingredients travel from the digestive system into the tissues of the eyes.
The results of the study from researchers based at the Chinese University
of Hong Kong and the Hong Kong Eye Hospital were published in the
Journal of Agricultural and Food Chemistry and indicate that green tea
consumption could benefit the eye against oxidative stress.
The scientists analyzed eye tissue from laboratory subjects that drank
green tea and found that the lens, retina and other tissues absorbed
significant amounts of green tea catechins. Although many antioxidants
have been studied in the eye, this demonstates how distribution of
individual catechins after ingestion of green tea extract and to evaluate
their in vivo antioxidative effects in various parts of the eye.
The researchers explained that oxidative stress causes biological
disturbances such as DNA damage and activation of proteolytic
enzymes that can lead to tissue cell damage or dysfunction and
eventually many ophthalmic diseases. “Photo-oxidative stress can
inactivate catalase in the lens to initiate cataract formation, while
long-term effects of reactive oxygen intermediates could damage
retinal tissue cells retinal pigment epithelium, and choriocapillaries.
Oxidation is also associated with primary open angle glaucoma
(POAG),” they explained.
Green Tea’s Nutritive Health Benefits...
Other reported benefits for green tea have been risk reduction
in terms of educing the risk of Alzheimer’s and certain cancers,
improving cardiovascular and oral health, as well as aiding in
weight management.
Green tea contains between 30 and 40 per cent of water-extractable
polyphenols, and the four primary polyphenols found in fresh tea
leaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC),
epicatechin gallate ECG), and epicatechin (EC).
The Laboratory-Controlled Study...
Green tea extract (GTE) in supplement form was suspended in
0.5 mL of water. Susequent analysis of eye tissues in the laboratory
demonstrated that eye structures absorbed significant amounts of
individual catechins, reported the researchers. And the time of
maximum concentration of the catechins varied from 30 minutes
to around 12 hours, they continued.
The authors found that catechins were differentially distributed in eye
tissues as follows: The retina absorbed the highest levels of gallocatechin,
while the aqueous humor tended to absorb epigallocatechin.
Significant reductions in 8-epi-isoprostane levels were found in
the compartments except the choroid-sclera or plasma, indicating
antioxidative activities of catechins in these tissues, concluded the team.
Source: Journal of Agricultural and Food Chemistry (Published online)
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