Zinc gluconate (also called
zincum gluconium) is the
zincZinc , also known as spelter, is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
salt of
gluconic acidGluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH24COOH. It is one of the 16 stereoisomers of 2,3,4,5,6-pentahydroxyhexanoic acid....
. It is an
ionicAn ionic bond is a type of chemical bond that involves a metal and a nonmetal ion through electrostatic attraction. In short, it is a bond formed by the attraction between two oppositely charged ions....
compoundA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
consisting of two moles of gluconate for each mole of zinc. Zinc gluconate is a popular form for the delivery of zinc as a
dietary supplementA dietary supplement, also known as food supplement or nutritional supplement, is a preparation intended to provide nutrients, such as vitamins, minerals, fiber, fatty acids or amino acids, that are missing or are not consumed in sufficient quantity in a person's diet...
.
Gluconic acid is found naturally, and is industrially manufactured by the
fermentationFermentation is the process of deriving energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. This is in contrast to cellular respiration, where electrons are donated to an exogenous electron acceptor,...
of
glucoseGlucose , a monosaccharide also known as - grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology. The living cell uses it as a source of energy and metabolic intermediate...
, typically by
Aspergillus nigerAspergillus niger is a fungus and one of the most common species of the genus Aspergillus. It causes a disease called black mold on certain fruits and vegetables such as grapes, onions, and peanuts, and is a common contaminant of food...
, but also by other
fungiA fungus is any member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. The Fungi are classified as a kingdom that is separate from plants, animals and bacteria...
, e.g.
PenicilliumPenicillium is a genus of ascomycetous fungi of major importance in the environment, food and drug production...
, or by
bacteriaThe bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, e.g.
AcetobacterAcetobacter is a genus of acetic acid bacteria characterized by the ability to convert alcohol to acetic acid in the presence of oxygen...
,
PseudomonasPseudomonas is a genus of gamma proteobacteria, belonging to the larger family of pseudomonads.Recently, 16S rRNA sequence analysis has redefined the taxonomy of many bacterial species. As a result the genus Pseudomonas includes strains formerly classified in the genera Chryseomonas and Flavimonas...
and
Gluconobacter. In its pure form, it is a white to off-white powder. It can also be manufactured by electrolytic oxidation, although this is a more expensive process. The advantages are a lower microbiological profile, and a more complete reaction, yielding a product with a longer shelf life.
Zinc gluconate may interfere with the absorption of
antibioticIn common usage, an antibiotic is a substance or compound that kills or inhibits the growth of bacteria...
s, so combinations may be unsafe.
Zinc and the common cold
Some studies have suggested that zinc gluconate lozenges may shorten the duration of cold symptoms, possibly due to reductions in inflammatory
cytokineCytokines are any of a number of substances that are secreted by specific cells of the immune system which carry signals locally between cells, and thus have an effect on other cells. They are a category of signaling molecules that are used extensively in cellular communication. They are proteins,...
s. However, research has been inconsistent, and a number of studies have failed to find any benefit. A 2000
systematic reviewA systematic review is a literature review focused on a single question that tries to identify, appraise, select and synthesize all high quality research evidence relevant to that question. Systematic reviews of high-quality randomized controlled trials are crucial to evidence-based medicine...
by the
Cochrane LibraryThe Cochrane Library is a collection of databases in medicine and other healthcare specialties provided by the Cochrane Collaboration and other organisations. At its core is the collection of Cochrane Reviews, a database of systematic reviews and meta-analyses which summarise and interpret the...
referred to the evidence of benefit as inconclusive. The Harvard Family Health Guide stated in 2001 that one study suggested that "zinc lozenges have little, if any, beneficial effect on the treatment of the common cold." A 2003 review in the
Journal of American Pharmacists AssociationThe American Pharmacists Association , founded in 1852, is the first-established professional society of pharmacists within the United States.. APhA is made up of more than 60,000 practicing pharmacists, pharmaceutical scientists, student pharmacists, pharmacy technicians, and others interested in...
determined that the majority of studies supported the value of zinc in reducing the duration and severity of symptoms of the common cold when administered within 24 hours of the onset of common cold symptoms. Another systematic review, published in 2006 in
Clinical Infectious DiseasesClinical Infectious Diseases in an academic journal published by the University of Chicago Press which publishes articles on the pathogenesis, clinical investigation, medical microbiology, diagnosis, immune mechanisms, and treatment of diseases caused by infectious agents...
found that many of the studies of zinc in the common cold suffered from methodologic flaws; restricting the analysis to well designed studies, the authors concluded that the therapeutic effectiveness of zinc lozenges has yet to be established.
Safety concerns
Instances of
anosmiaAnosmia is a lack of functioning olfaction, or in other words, an inability to perceive smells. It can be either temporary or permanent. A related term, hyposmia, refers to decreased ability to smell, while hyperosmia refers to an increased ability to smell. Some people may be anosmic for one...
(loss of smell) have been reported with intranasal use of some products containing zinc gluconate. In September 2003,
ZicamZicam is a branded series of cold and allergy remedies whose ingredients include the element zinc. The Zicam name is derived from a combination of the words 'zinc' and 'ICAM-1' ....
faced lawsuits from users who claimed that the product, a nasal gel containing zinc gluconate and several inactive ingredients, negatively affected their sense of smell and sometimes taste. Some plaintiffs alleged experiencing a strong and very painful burning sensation when they used the product. Matrixx Initiatives, Inc., the maker of Zicam, responded that only a small number of people had experienced problems and that anosmia can be caused by the common cold itself. In January 2006, 340 lawsuits were settled for $12 million. No part of the settlement targeted the product's removal from sale, and the nasal gel continues to be available at drug stores throughout the USA.
The U.S.
Food and Drug AdministrationThe Food and Drug Administration is a Government agency of the United States Department of Health and Human Services and is responsible for regulating and supervising the safety of foods, tobacco products, dietary supplements, Medication drugs, vaccines, Biopharmaceutical, blood transfusion,...
(FDA) considers zinc gluconate to be
generally recognized as safeGenerally recognized as safe is an American Food and Drug Administration designation that a chemical or substance added to food is considered safe by experts, and so is exempted from the usual Federal Food, Drug, and Cosmetic Act food additive tolerance requirements.GRAS exemptions are granted...
(GRAS) when used in accordance with good manufacturing practice, although this does not constitute a finding by the FDA that the substance is a useful dietary supplement. On 16 June 2009 the FDA "warned consumers to stop using and discard three zinc-containing Zicam intranasal products. The products may cause a loss of sense of smell. . . . FDA is concerned that the loss of sense of smell may be permanent." Matrixx responded that the FDA's allegations were "unfounded and misleading", citing a lack of evidence from
controlledWhen an experiment is being conducted to investigate the effect of a single variable of interest on a particular system, a scientific control is used to minimize unintended influences on that system. Such unintended influences include researcher bias, environmental changes, and biological variation...
tests that Zicam causes anosmia. In its warning, FDA stated, "This warning does not involve oral zinc tablets and lozenges taken by mouth. Dietary zinc is also not subject to this warning."