View Full Version : Green tea could help combat diseases of the eye

02-23-10, 12:17 PM
February 23, 2010
lifeextension.org e-letter

Green tea catechins are able to penetrate eye tissue, which may help protect against glaucoma and other eye diseases, according to Hong Kong researchers.
In the introduction to their article published online on January 19, 2010 in the Journal of Agricultural and Food Chemistry (http://pubs.acs.org/journal/jafcau?cookieSet=1), Chi Pui Pang of the Chinese University of Hong Kong and associates explain that oxidative stress causes DNA damage and activation of proteolytic enzymes which lead to the tissue damage observed in the development of eye diseases such as cataract and glaucoma. The antioxidant properties of polyphenols contained in green tea make the widely-consumed beverage a good candidate for eye protection, yet the delivery of green tea catechins to various areas of the eye had not previously been evaluated.
Using 9 week old rats, Dr Pang and colleagues orally administered a green tea extract that provided the following beneficial catechin compounds: epigallocatechin gallate (EGCG), epicatechin gallate (ECG), gallocatechin gallate (GCG), epicatechin (EC), epigallocatechin (EGC), gallocatechin (GC) and catechin. Catechin and 8-epi-isoprostane (a marker of oxidative stress) levels were measured in the animals' eye tissues at varying time points up to 20 hours following green tea extract administration.
The team found varying distribution of catechins throughout the animals' cornea, lens, retina, choroid-sclera, vitreous humor, and aqueous humor. Gallocatechin was present at the highest concentration in the retina, and EGC in aqueous humor. Maximum catechin concentration varied from one half to 12.2 hours. Although many studies have focused on ECGC, eye tissue levels of other catechins were found to be higher in the current investigation. A significant reduction in 8-epi-isoprostane rapidly followed green tea administration and was well maintained in all tissue and fluid examined with the exception of the choroid-sclera, demonstrating the antioxidant activity of catechins absorbed by these areas.
"To the best of our knowledge this is the first paper to show distribution of individual catechins after ingestion of green tea extract and to evaluate their in vivo antioxidative effects in various parts of the mammalian eye," the authors announce. "Our dosage reduced oxidative stress in some eye tissues for up to 20 hours. Our results indicate that green tea consumption could benefit the eye against oxidative stress," they conclude.

02-23-10, 12:18 PM
from the same source:

Glaucoma (http://www.lef.org/protocols/prtcl-053.shtml?source=eNewsLetter2010Wk9-1&key=Body+Health+Concern)

The premise of taking actions to maintain youthful health and vigor is based on findings from peer-reviewed scientific studies that identify specific factors that cause us to develop degenerative disease. These studies suggest that the consumption of certain foods, food extracts, hormones, or drugs will help to prevent common diseases that are associated with normal aging.
The inability to efficiently extricate the fluid from the eye causes an increase in intraocular pressure (IOP). The tiny, delicate nerve fibers that make up the optic nerve at the back of the eye are slowly destroyed. Because the optic nerve relays visual messages from the eye to the brain, where seeing actually takes place, the health of this nerve is essential to sight. Restricting the free flow of aqueous humor, as seen by narrowing, hardening, or constriction of the exit channels, can be a purveyor of glaucoma.
Fortunately, history provides significant therapeutics in regard to managing glaucoma. Conventional medications and interventions are the most widely used methods of treatment, but nutritional protocols have produced convincing evidence of benefit.
Vitamin C is an effective adjunct in stabilizing IOP. Some individuals respond to as little as 2 grams a day of vitamin C, although others respond to only extremely high doses, for example, 35 grams a day. Because of the variance in the amount of vitamin C required to exert a positive effect, careful monitoring by a physician is required.


02-23-10, 12:41 PM
Tea is something i am conflicted over.

I have sensitivity to fluoride & have only recently learned how many things have fluoride hidden in them & are never disclosed. Tea is one that is listed in the "hidden fluoride" area. I've assumed it had to do with how it is processed (using fluoridated water?) but i don't know.

It is so hard to know, given how many things in our world are chemically contaminated, how to find a balance between what is good for us & where the chemicals (such as hidden fluoride) tip the balance.

02-23-10, 01:46 PM
Katee, I've heard various explanations for the fluoride in green tea so I did a little googling. Here is a site that seem to have careful, balanced information:

Wikipedia is more comprehensive, but you might be more interested in the bibliography at the end of the article:

I drink 2 cups of green tea a day because my well water has no fluoride and I think the health benefits of the catechins outweigh the fluoride risk — for me. Others will need to experiment to see what works for them. One article I read suggested brewing your tea with bottled water if your municipal water supply is fluoridated.

02-23-10, 04:21 PM
Fluoride in tea comes from the tea leaves ability to concentrate fluoride. Even tea grown in areas not using fluoridated water have substantial fluoride. It is probably not a major problem if you use unfluoridated water to prepare the tea and keep consumption at a few cups per day.

Using tea leaves vs tea bags will slightly lessen fluoride as will using a high quality tea. Quality teas use younger leaves and buds so haven't concentrated as much fluoride. White tea has the least of any tea, followed by green, etc. I think your brick teas are the highest.

Again, I think it all comes down to quantity consumed. Drinking a liter a day made with fluoridated water is probably going to cause problems with the thyroid and bones. Drinking a few cups/day made with unfluoridated water probably won't.

I think, the less processed foods you eat, the less your overall exposure to fluoride so that needs to enter into your decision also.

There are green tea extracts available that don't contain fluoride. One place that carries that is www.bodyecology.com and I believe Mercola also carries it.

If you have hypothyroidism and are not treating with medication, then it might be a good idea to drink tea sparingly. Also, fluoride contributes to osteoporosis.

So, moderation.

02-23-10, 04:26 PM
Thank you both. I'll check out the links.

Water in our area is NOT fluoridated (at this time - they seem to be convincing more municipalities to do so). We use a filter on the shower head & on the sink for cold water - cooking mostly. We buy RO water at 25 cents/gal for drinking. I use it some for cooking too. So i'm covered there, but i seem to have such a reaction to fluoride in general that i want to limit my exposure.

Thank you again.