Zinc gluconate is the
zincZinc , or 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 formed through an electrostatic attraction between two oppositely charged ions. Ionic bonds are formed between a cation, which is usually a metal, and an anion, which is usually a nonmetal. Pure ionic bonding cannot exist: all ionic compounds have some...
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 supplement the diet and provide nutrients, such as vitamins, minerals, fiber, fatty acids, or amino acids, that may be missing or may not be consumed in sufficient quantities in a person's diet...
.
Zinc gluconate is the
zincZinc , or 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 formed through an electrostatic attraction between two oppositely charged ions. Ionic bonds are formed between a cation, which is usually a metal, and an anion, which is usually a nonmetal. Pure ionic bonding cannot exist: all ionic compounds have some...
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 supplement the diet and provide nutrients, such as vitamins, minerals, fiber, fatty acids, or amino acids, that may be missing or may not be consumed in sufficient quantities in a person's diet...
.
Gluconic acid is found naturally, and is industrially manufactured by the
fermentationFermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...
of
glucoseGlucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a 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 a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
, e.g.
PenicilliumPenicillium is a genus of ascomycetous fungi of major importance in the natural environment as well as food and drug production. Members of the genus produce penicillin, a molecule that is used as an antibiotic, which kills or stops the growth of certain kinds of bacteria inside the body...
, or by
bacteriaBacteria are a large domain of prokaryotic 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 ethanol to acetic acid in the presence of oxygen. There are several species within this genus, and there are other bacteria capable of forming acetic acid under various conditions; but all of the Acetobacter are...
,
PseudomonasPseudomonas is a genus of gammaproteobacteria, belonging to the family Pseudomonadaceae containing 191 validly described species.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...
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
antibioticAn antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s, so combinations may be unsafe.
Zinc and the common cold
A 2011 systematic meta analysis of studies conducted by the
Cochrane CollaborationThe Cochrane Collaboration is a group of over 28,000 volunteers in more than 100 countries who review the effects of health care interventions tested in biomedical randomized controlled trials. A few more recent reviews have also studied the results of non-randomized, observational studies...
indicates that zinc lozenges definitively shorten the duration and severity of cold symptoms but offers no recommendations as to dosage. Many over the counter zinc medications may be less effective or ineffective because they do not contain the optimum mix of ingredients. This variety of formulations has also been implicated in the prior lack of success in determining the effectiveness of zinc medicines. Methodological weaknesses are also thought to have contributed to the mixed results of previous studies (see below). The 2011 Cochrane review is widely regarded as the most authoritative assessment to date of the effectiveness of zinc as a treatment for the common cold. It is suspected that
zinc acetateZinc acetate is the chemical compound with the formula Zn2, which commonly occurs as a dihydrate Zn22. Both the hydrate and the anhydrous forms are colorless solids that are commonly used in chemical synthesis and as dietary supplements. Zinc acetates are prepared by the action of acetic acid on...
lozenges shorten the duration of
coldThe common cold is a viral infectious disease of the upper respiratory system, caused primarily by rhinoviruses and coronaviruses. Common symptoms include a cough, sore throat, runny nose, and fever...
symptoms by reducing inflammatory
cytokineCytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...
s.
Before 2011, research on the zinc and the common cold 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 research 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 summarize 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....
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 a peer-reviewed medical journal published by Oxford University Press covering research 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 odors. Anosmia may be either temporary or permanent. A related term, hyposmia, refers to a 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 products marketed for cold and allergy relief whose original formulations included the element zinc. The Zicam name is derived from a combination of the words "zinc" and "ICAM-1" . It is marketed as an "unapproved homeopathic" product.Zicam was invented by Charles B...
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.
The U.S.
Food and Drug AdministrationThe Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
(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.-History:On January 1, 1958,...
(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
controlledScientific control allows for comparisons of concepts. It is a part of the scientific method. Scientific control is often used in discussion of natural experiments. For instance, during drug testing, scientists will try to control two groups to keep them as identical and normal as possible, then...
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."