Thursday, August 30, 2007

Science Daily and Zinc

On August 28th, Science Daily featured a zinc study published in the April 2007 Experimental Eye Research Journal. A team of scientists, including three researchers at George Mason University, found that the mineral zinc could play a role in the development of macular degeneration.

These findings are and were viewed as extremely important because the 2001 Age-Related-Eye-Disease (ARED) study results suggested that high doses (80 mg) of supplemental zinc oxide, when combined with vitamin antioxidants and copper, slowed the progression of macular degeneration.

Many nutrition-trained eye care professionals and most biochemists have adamantly disagreed with the long-term daily consumption of 80 mgs of zinc oxide, which is included in the ARED formulation.

Imre Lengyel, PhD, senior fellow at the Institute of Ophthalmology in London and this zinc study chief investigator, found unexpectedly high concentrations of zinc in drusen and sub-retinal pigment epithelium (RPE) post-mortem maculae of eyes with AMD. He has been quoted as saying, "Although supplemental zinc has been found to enhance the immune system, excessive amounts may play a role in the advancement of macular degeneration."

We reported on this study in the March 23, 2007 Friday Pearl.

The Academy of Medicine's published safe upper limit (UL) of supplemental zinc is 40 mg per day.


Jeffrey Anshel, OD said...

While we don't know if this is CAUSATIVE, it's certainly a good idea to err on the side of caution when recommending zinc. And let's not forget about the prostate cancer issue- too much zinc is linked to this all-to-common disease.

James Waugh, MD said...

Urology scientists from the University of Wisconsin found that hospital admission in patients taking 80 mg of zinc oxide were much higher than previously reported.

This study was published in the Feb 2007 journal of Urology.

Anonymous said...

Why does the retina specialist community continue to blow-off high-dose zinc science?

Ellen Troyer, MT MA said...

Great question! One guess might be that they fear they could be held accountable for defending the results of the poorly designed ARED study and recommending the high-dose zinc PreserVision formulation to their AMD patients.

Some dentists continue to defend mercury fillings for similar reasons.

Anonymous said...

I think it is great that your company supplies this much needed information. I have been taking the Macula Complete by your company for a while now and I noticed that the amount of zinc was lowered, is this study one of the reasons why?

Ellen Troyer, MT MA said...

The study being discussed it important, but we do not change formulations based on a single study.

Zinc has proven to be a major player in cellular protection, but a number of high-dose zinc toxicity studies supported our reasons for lowering the amount of zinc in our multiples, Oculair, and Macula Complete.

Janet Kellar said...

Is it true that high-does zinc supplementation is also linked to the amyloid brain plaques associated with Alzheimer's?

Ellen Troyer, MT MA said...

Intresting question Janet.

Amyloid beta research, as it pertains to Alzheimer's seems to be leaning toward a loss of metal homeostasis and oxidative damage within the brain. That includes both copper and zinc. A study published this month in Biometals reported that both copper and zinc are able to bind with amyloid beta-peptides at physiological concentrations in vitro.

This study made me immediately think of the over-priced Paul Harvey Radio Show AMD formulation (Premier Formula for Ocular Nutrition) that includes 8 mg of copper and 60 mg of zinc.

A number of the same genes are associated with Macular Degeneration and Alzheimer's

Angela Ward said...

My eye doctor took me off PreserVision (the ARED formula by B&L) because he said it contained too much zinc. I checked and it contains 69.6 mg in the four tablets per day. That does seem too much.

Why are doctors prescribing so much zinc if they know it can cause trouble?

Don said...

Angela, consider yourself lucky.
Your eye doctor obviously tracks more nutrition science than the ARED study.

Spencer Thornton, M.D. said...

Angela, to answer your question, some people (even doctors) are slow to learn. Physicians hear more about the problems of zinc deficiency like hair loss, skin lesions, decrease in appetite, and abnormalities of taste, smell and vision.

Zinc is an essential mineral, but too much is not beneficial. In some studies, it has been implicated
in prostate cancer and Alzheimer’s, as has been noted in comments above, and we know that an excess of zinc can interfere with other minerals in the body, particularly iron and copper.

Toxicity may occur in children who swallow pennies minted since 1983 (a zinc wafer coated with copper) or using too much zinc oxide as in diaper rash cream. Zinc toxicity may present with loss of appetite, anemia, vomiting, red urine and eventual kidney failure.

The bottom line: a little is good – and necessary, but an excess may be risky.

Anonymous said...

"Even doctors" are slow to learn.

I hope for your sake you meant "including doctors" are slow to learn.

Spencer Thornton, M.D. said...

To Anonymous:
I'm impressed with your sharp catch. You are right, it should have read "even some" - or "a few".
I'm glad to see someone with a critical eye to proper grammar.

Anonymous said...

Hard to believe Dr. Thornton; you absolutely missed my point. It was NOT about proper grammer!

It was about YOUR having too good of an opinion about doctors willingness and ability to learn vs. the rest of the educated world.