Zinc in Excess Denture Cream May Cause Neurologic Illness

A cautionary note to gray panthers: take it easy on the denture cream. Zinc in the grippy goo may lead to copper deficiency and associated neurologic illness.*

In this week's Neurology, physicians from the University of Texas Southwestern Medical Center report 4 patients with neurologic abnormalities in the setting of copper deficiency (hypocupremia) and high zinc levels (hyperzincemia). All presented with clinical myeloneuropathy, and all demonstrated low levels of serum copper and high levels of serum zinc. 

Neurologic symptoms followed the excessive use of denture cream, 2 or more tubes per week for several years. In samples of Fixodent (P&G) or PolyGrip (GSK) denture cream, the authors found zinc levels that ranged from 17 to 34 mg/g and identified no other plausible source of zinc or reason for copper deficiency.

Moreover, in the 3 patients who discontinued the use of denture cream, serum zinc levels dropped. Copper supplementation normalized copper levels in all 4 patients and was associated with mild clinical improvement in 2 patients.

The neurologic conditions in these patients are believed to be due to zinc-induced copper deficiency. Excess zinc—either unintentionally or intentionally swallowed by the denture-cream user—acts as a functional copper chelator, by upregulating the production of copper-binding metallothionein. (The metallothionein-copper complex is excreted in the feces, thereby causing copper deficiency.)

Removal of zinc from denture creams may be problematic, because the saliva-activated adhesive is generally a calcium-zinc polymer. Replies to e-mail inquiries sent to P&G and GSK, asking for comment on the Neurology case reports, are pending.

* Clinically similar to subacute combined degeneration associated with vitamin B12 deficiency.

Photo: iStockPhoto.

Addendum: In a formulaic-type e-mail, GSK, maker of Poligrip products, writes, "When someone uses Super Poligrip for their dentures, the vast majority of the zinc in the product remains in the adhesive and is not released into the mouth. Absorption through the gums, if any, is minimal. This is because the pH level of saliva [generally weakly acidic to neutral] in the mouth prevents the zinc from being released." GSK adds, "Swallowing small amounts of denture adhesive when used as directed is not harmful," and notes that there are Poligrip products that do not contain zinc.

9/11/08 addendum: At last, a response from P&G, or really "Fixodent," or really Ruth...

Thanks for contacting Fixodent, Barbara.

We appreciate your patience while we researched. Our products and their ingredients undergo rigorous scientific evaluations and safety testing before going to market. They are manufactured and packaged in accordance with FDA's good manufacturing practices. We meet all local laws and regulations where we sell Fixodent. We also continually monitor the safety of our products once in market.

Fixodent does not contain harmful ingredients and is safe when used as directed. Zinc is essential to good health. The amount of zinc an average denture adhesive user would ingest from daily usage of Fixodent is less than the amount of zinc in a daily multi-vitamin; less than 6 oysters (fried or raw); comparable to 6 oz. beef tenderloin.

I hope this information is helpful.

Ruth

P&G Team