The Flavonoid Quercetin Protects Against Macular Degeneration

Friday, May 23, 2008 by: John Cole
Tags: quercetin, health news, Natural News

eTrust Pro Certified

Most Viewed Articles
Popular on Facebook
BACK INTO THE CLOSET: Why U.S. reporters are not allowed to write about rainbow events in nations where being gay is still condemned
Depopulation test run? 75% of children who received vaccines in Mexican town now dead or hospitalized
A family destroyed: Six-month-old dies after clinic injects baby with 13 vaccines at once without mother's informed consent
INVESTIGATION: Three days before Dr. Bradstreet was found dead in a river, U.S. govt. agents raided his research facility to seize a breakthrough cancer treatment called GcMAF
BAM! Chipotle goes 100% non-GMO; flatly rejecting the biotech industry and its toxic food ingredients
BOMBSHELL: China and America already at war: Tianjin explosion carried out by Pentagon space weapon in retaliation for Yuan currency devaluation... Military helicopters now patrolling Beijing
ECONOMIC SLAVERY FOR ALL: While we were distracted with the Confederate flag flap, Congress quietly forfeited our entire economic future via fast-track trade authority
March Against Monsanto explodes globally... World citizens stage massive protests across 38 countries, 428 cities... mainstream media pretends it never happened
GMO crops totally banned in Russia... powerful nation blocks Monsanto's agricultural imperialism and mass poisoning of the population
SCOTUS same-sex marriage decision may have just legalized the concealed carry of loaded firearms across all 50 states, nullifying gun laws everywhere
Nearly every mass shooting in the last 20 years shares one surprising thing? and it's not guns
Vicious attack on Dr. Oz actually waged by biotech mafia; plot to destroy Oz launched after episode on glyphosate toxicity went viral
Holistic cancer treatment pioneer Dr. Nicholas Gonzalez dies suddenly; patients mourn the loss of a compassionate, innovative doctor who helped thousands heal from cancer
Pepsi drops aspartame from diet soda as consumers reject toxic sweetener
Bride of Frankenfood: Hillary Clinton pushes GMO agenda... hires Monsanto lobbyist... takes huge dollars from Monsanto
STATINS RED ALERT: Widely prescribed drugs act as cellular poisons that accelerate aging... deactivate DNA repair... promote diabetes, muscle fatigue and memory loss
Mind control through emotional domination: How we're all being manipulated by the "crisis of the NOW"
Wild eyes and bowl cuts: Why do mass shooters always share the same hair styles and crazed zombie stares?
(NaturalNews) A new study has investigated the protection afforded by the flavonoid quercetin against macular degeneration. The macula is the yellowish, central part of the retina about 1.5 mm in diameter that produces central vision and color vision. Macular degeneration is the gradual, progressive destruction of the macula that results in lowered central visual acuity needed for most everyday activities, like reading this article. It leads to permanent blindness, and is the most common cause of blindness in people 50 to 60 years old and above. Approximately 10 million Americans are believed to suffer vision loss due to age-related macular degeneration (ARMD).

There are two types of ARMD: dry and wet. The dry type is much more common than the wet type and accounts for up to 90% of ARMD. In the dry type, the macula gradually thins with aging. The pigmented retinal epithelium, which is the dark-colored cell layer at the back of the eye essential for vision, is gradually lost. One of the first signs of ARMD is loss of color sensitivity and blurring or haziness while reading.

Previous reports have concluded that eating foods rich in lutein and zeaxanthin can help protect the macula, that obese individuals have lower amounts of macular pigment than non-obese people, and that people with very low body fat levels have a higher amount of carotenoids in their blood, which could lead to more pigment in the macula.

The Background of the Recent Report

The current research report states that oxidative stress plays a central role in macular damage, and that some previous studies have shown that intake of foods with a high level of antioxidants may lead to a lower risk of ARMD; "recommended supplementary antioxidants include vitamin C, vitamin E, beta carotene, and lutein".

Another group of antioxidants that may be protective are the bioflavonoids: "the large group of polyphenolic compounds that provide much of the color and flavor of plant foods". The most-studied bioflavonoid is quercetin, which is well known to be present in apples and onions, and has already been shown to have anti-allergic, anti-inflammatory, anti-carcinogenic, anti-viral, and anti-thrombotic properties. It is a strong antioxidant and free-radical scavenger.

The Experiments

The study used cultured human cells of the retinal pigmented epithelium treated with hydrogen peroxide as the oxidative stress agent. Oxidative damage was measured using a special histochemical staining procedure.

Cells treated with hydrogen peroxide alone (the control group) suffered significantly more damage than cells treated with hydrogen peroxide and quercetin. Intracellular glutathione (one of the body's intrinsic antioxidants) was not altered by hydrogen peroxide treatment or by quercetin (glutathione was measure as reduced GSH only in this study), showing that quercetin's protective effects might be independent of glutathione. (However, previous studies, which measured different forms and ratios of glutathione, have shown increased intracellular glutathione after addition of quercetin.)

The protective mechanisms of quercetin were demonstrated to be related to its ability to reduce the activity of caspase-3 and level of caveolin-1, both of which were induced by hydrogen peroxide.

Not too low, Not too high

Healthful circulating levels of quercetin (0.1 to 1 micromole) can be achieved by consuming 100 to 200 grams of onion a day. Other foods containing ample quercetin are listed as capers, ancho peppers, cranberries, fennel, cocoa, black currants, buckwheat, black tea, spinach, and wild greens.

Very high concentrations, 100 micromoles or higher, have been suggested in laboratory studies to induce chromosomal damage or cytotoxicity. So, "like many other especially lipid-soluble antioxidants, excessively elevated serum levels of quercetin may cause cellular injury." (These very high levels were produced in laboratory experiments, but could also probably result from taking too many supplements.)


Although this was an in vitro (test-tube) study, based on the present study's results and past findings, the authors conclude, "quercetin appears to be a candidate as food supplement in the prevention of early pathologic changes" in ARMD.

Journal, Research Facility

The study, reported in Investigative Ophthalmology & Visual Science, was carried out at the Department of Ophthalmology, Ludwig-Maximilians-Universitat, Munich, Germany.

Background Information

1. macula: (http://www.answers.com/macula?cat=health&y=0...)

2. macular degeneration (LEF):

3. macular degeneration (AnswersDotCom):

4. mole (micromole): (http://www.answers.com/mole?cat=technology&y...)

About the author

John H. Cole has been editing medical manuscripts for publication in mainstream U.S. and European medical journals for the past 15 years in Japan. He also has a small English school in Gifu City, Japan. He believes that natural foods, superfoods, herbs, exercise, sunshine, good sleep, and avoidance of pollution are the answers to most people's health problems. He is a friend of nature.

Follow real-time breaking news headlines on
Quercetin at FETCH.news
Join over four million monthly readers. Your privacy is protected. Unsubscribe at any time.
comments powered by Disqus
Take Action: Support NaturalNews.com by linking back to this article from your website

Permalink to this article:

Embed article link: (copy HTML code below):

Reprinting this article:
Non-commercial use OK, cite NaturalNews.com with clickable link.

Follow Natural News on Facebook, Twitter, Google Plus, and Pinterest

Colloidal Silver

Advertise with NaturalNews...

Support NaturalNews Sponsors:

Advertise with NaturalNews...


Sign up for the FREE Natural News Email Newsletter

Receive breaking news on GMOs, vaccines, fluoride, radiation protection, natural cures, food safety alerts and interviews with the world's top experts on natural health and more.

Join over 7 million monthly readers of NaturalNews.com, the internet's No. 1 natural health news site. (Source: Alexa.com)

Your email address *

Please enter the code you see above*

No Thanks

Already have it and love it!

Natural News supports and helps fund these organizations:

* Required. Once you click submit, we will send you an email asking you to confirm your free registration. Your privacy is assured and your information is kept confidential. You may unsubscribe at anytime.