A meta-analysis of 33 prospective intervention trials regarding zinc supplementation and its effects on the growth of children in many countries showed that zinc supplementation alone had a statistically significant effect on linear growth and body weight gain, indicating that other deficiencies that may have been present were not responsible for growth retardation. Other
A Cochrane review stated that people taking zinc supplement may be less likely to progress to age-related macular degeneration. Zinc supplement is an effective treatment for acrodermatitis enteropathica, a genetic disorder affecting zinc absorption that was previously fatal to affected infants. Zinc deficiency has been associated with major depressive disorder (MDD), and zinc supplements may be an effective treatment. Topical use
Topical preparations of zinc include those used on the skin, often in the form of zinc oxide. Zinc oxide can be formulated into a sunscreen to mitigate sunburn. Applied thinly to a babys diaper area (perineum) with each diaper change, it can protect against diaper rash.Chelated zinc is used in toothpastes and mouthwashes to prevent bad breath; zinc citrate helps reduce the build-up of calculus (tartar).Zinc pyrithione is widely included in shampoos to prevent dandruff.Topical zinc has also been shown to effectively treat, as well as prolong remission in genital herpes. Biological role
Zinc is an essential trace element for humans and other animals, for plants and for microorganisms. Zinc is required for the function of over 300 enzymes and 1000 transcription factors, and is stored and transferred in metallothioneins.
Disability and even deaths from excessive use of these products have been claimed.The U.S. Food and Drug Administration (FDA) states that zinc damages nerve receptors in the nose, causing anosmia. Reports of anosmia were also observed in the 1930s when zinc preparations were used in a failed attempt to prevent polio infections. On June 16, 2009, the FDA ordered removal of zinc-based intranasal cold products from store shelves. The FDA said the loss of smell can be life-threatening because people with impaired smell cannot detect leaking gas or smoke, and cannot tell if food has spoiled before they eat it.Recent research suggests that the topical antimicrobial zinc pyrithione is a potent heat shock response inducer that may impair genomic integrity with induction of PARP-dependent energy crisis in cultured human keratinocytes and melanocytes. Poisoning
In 1982, the US Mint began minting pennies coated in copper but containing primarily zinc. Zinc pennies pose a risk of zinc toxicosis, which can be fatal. One reported case of chronic ingestion of 425 pennies (over 1 kg of zinc) resulted in death due to gastrointestinal bacterial and fungal sepsis. Another patient who ingested 12 grams of zinc showed only lethargy and ataxia (gross lack of coordination of muscle movements). Several other cases have been reported of humans suffering zinc intoxication by the ingestion of zinc coins.Pennies and other small coins are sometimes ingested by dogs, requiring veterinary removal of the foreign objects.