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Effects of Zinc Supplementation in Occurrence and Duration of Common Cold in School Aged Children During Cold Season: a Double-Blind Placebo-Controlled Trial


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Objective: Zinc deficiency is common in children in developing countries due to low intake of animal foods, and high dietary phytate content. Zinc deficiency impairs overall immune function and resistance to infection. The effect of zinc on the common cold is still questionable. To determine whether supplementation of zinc could reduce frequency rate and duration of common cold during cold season in school aged children living in a low socioeconomic suburb of Mashhad (Altimor), north-east Iran. Methods: We designed a randomized double-blind, placebo-controlled efficacy trial. Subjects were 200 grade 2 primary school children who all completed the trial. Intervention supplementation was zinc sulfate tablets (10 mg elemental) and placebo tablets for case and control groups, respectively. Tablets were taken on a daily basis, 6 days a week, for 5 months (November to March). Findings: Among the zinc-supplemented group common cold incidence of 1.37±0.86 episodes per child during the study period was recorded in comparison to 3.15±0.55 cold episodes per child among the placebo group (P<0.001). Mean overall missing days from school was 0.55±1.09 days and 1.35±1.79 days for zinc-supplemented and placebo groups, respectively. The need for administration of antibiotics for bacterial infections (pharyngitis, acute otitis media, sinusitis, pneumonia) were 20 and 47 courses for zinc-supplemented and placebo groups, respectively (P<0.01). Conclusion: This study showed that zinc supplementation has a beneficial impact on the occurrence of common cold.
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* Corresponding Author;
Address: DepartmentofPublicHealthHealthfacultyMashhadUniversityofMedicalsciences,Mashhad,Iran
©2009byPediatricsCenterofExcellence,Children’sMedicalCenter,TehranUniversityofMedicalSciencs, Allrightsreserved.
1. DepartmentofPediatrics,MashhadUniversityofMedicalSciences,Mashhad,Iran
2. DepartmentofPublicHealth,MashhadUniversityofMedicalSciences,Mashhad,Iran
3. ProvinceHealthCenter,MashhadUniversityofMedicalSciences,Mashhad,Iran
4. ImmunologyResearchCenter,MashhadUniversityofMedicalSciences,Mashhad,Iran
Objective:Zinc deficiencyiscommoninchildrenindeveloping countriesduetolowintakeof
animal foods, and high dietary phytate content. Zinc deficiency impairs overall immune
To determine whether supplementation of zinc could reduce frequency rate and duration of
Methods:We designed a randomized double‐blind, placebo‐controlled efficacy trial. Subjects
were200grade2primaryschoolchildrenwhoallcompletedthetrial. Intervention
supplementation was zinc sulfate tablets (10 mg elemental) and placebo tablets for case and
controlgroups,respectively.Tabletsweretakenonadailybasis,6 days a week, for 5 months
Findings:Amongthe zinc‐supplemented groupcommoncoldincidenceof 1.37±0.86 episodes
perchildduringthestudyperiod was recorded in comparison to 3.15±0.55 cold episodes per
child among the placebo group (P<0.001). Mean overall missing days from school was
0.55±1.09 days and 1.35±1.79 days for zinc‐supplemented and placebo groups, respectively.
The need for administration of antibiotics for bacterial infections (pharyngitis, acute otitis
media, sinusitis, pneumonia) were 20 and 47 courses for zinc‐supplemented and placebo
Conclusion:Thisstudyshowedthatzincsupplementationhasabeneficialimpact on the
Original Article
Iran J Pediatr
Dec 2009; Vol 19 (No 4), Pp:376-380
Archive of SID
Iran J Pediatr; Vol 19 (No 4); Dec 2009
growth, development, and immune function.
Mild to moderate zinc deficiency can be best
supplementation trials. Zinc supplementation
hasbeen shown tohave a positiveeffect on the
Upper respiratory tract viral infections are
one of the most common reasons for physician
requires medical attention. Statistics indicate
thatmorethan 80% of commoncoldsrequiring
medical attention affect children and
Zinc salts have been found to inhibit
rhinovirus replication invitro, possibly by
has also been suggested that cold symptoms,
Several controlled trials of treatment of
common cold with zinc have been published;
however,there are onlyafewcommunity‐based
longitudinal studies that have been conducted
with zinc supplementation for prevention of
To investigate the effect of zinc supplemen‐
tation on the prevention of occurrence and the
anintervention trial among school aged Iranian
The study was a randomized, double‐blind,
placebo‐controlled, community‐based inter‐
vention trial conducted between November
2004 and March 2005 in Altimor suburb of
approved by the scientific advisory and ethical
committees of Mashhad University of Medical
signed by the parents before including the
children in the study. For ethical reasons and
A total of 200 children (aged 78 to 120
months) were randomly assigned to daily (6
days in week) supplementation with 10 mg
elementalzincasatablet(n=100,50males, and
standardized questionnaire was completed to
obtain family details including basic
demographic and socioepidemiologic data. The
subjects were free of chronic diseases, such as
sickle cell disease, or protein‐energy
malnutrition. All participants were observed on
adaily basis for any medicalsign and symptom
for the detection of any sign and symptom of
common cold and other possible diseases was
These workers were also responsible for
proper administration of the zinc or placebo
tablets. Regular field visits (once a week) for
additionaldata collectionandsupervisionofthe
health workers were made by our physician.
Commoncoldwas defined as thepresence of at
least two of the following symptoms: cough,
headache, hoarseness, muscle ache, nasal
Data were analyzed using statistical software
Prevention,Atlanta, GA) using the χ2 test,t‐test
and ANOVA, P values less than 0.05 was
Table l summarizes the demographic charac‐
Archive of SID
ZincSupplementationandDurationofCommonCold; R Vakili, et al
Mean(SD*) 93.7(7.38) 93.1(7.35) 0.09
members4.7(2.2) 4.5(2.1) 0.7
SmokerParent18 19 0.1
months of study were 0.55±1.09 days (per
student) and 1.35±1.79 days (per student) in
zinc‐supplemented and control groups,
respectively (P<0.001). In the zinc‐
supplemented group, three participants
complained from mild gastrointestinal
Millions of people throughout the world may
limited access to zinc‐rich foods (animal
abundance of zinc inhibitors such as phytate,
Zinc is a key component of the cell
metalloproteinases, oxidoreductase, and
transferase which are involved in protein
synthesis,nucleicacid metabolism, and immune
function[18].Zincdeficiency is commonin young
children in the developing countries and is
associated with reduced immuno‐competence
and increased rates of serious infectious
supplementation has a positive influence on
Community‐based studies conducted among
childrenofdifferentage groups have shown the
beneficialimpact of zinc supplementationinthe
form of reduced diarrhea episodes in children
with zinc deficiency, since this supplementation
maylead toacceleratedregeneration ofmucosa,
increased levels of brush border enzymes,
enhancedcellularimmunity,andhigherlevels of
Table2: Mediancommoncoldoccurrenceneedforantibioticmissingschool
administration20 47 <0.001
Daysmissingschool0.55±1.09 1.35±1.79 <0.001
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Iran J Pediatr; Vol 19 (No 4); Dec 2009
associated with a decrease in the average
occurrence of commoncold duringcold months
of year, among children living in suburbs of
found that supplementation with zinc was
associated with a decrease in the average
Prasad and coworkers showed a beneficial
effectof zinclozenges for reduction of duration
and severity of cold symptoms[7]. They believed
improvement in cold symptoms was related to
the antioxidant anti–inflammatory effect of
However, previous trials failed to show a
cold, perhaps because inadequate doses or
inappropriate formulations of zinc were used,
resulting in lack of bioavailable zinc[11,12]. Three
other double‐blind placebo‐controlled trials
evaluated the prophylactic and therapeutic
first study involving 57 volunteers,
every 2 hours for 4.5 days) started one day
before inoculation with human rhinovirus,
8.2 with placebo[13,14].Inanotherstudy69
randomly allocated to receive either zinc
gluconate lozenges or matched placebo every 2
treatment significantly reduced clinical scores
compared to placebo[15]. Retrospective chart
analysis study by McElroy and coworkers
of zinc in school‐aged subjects with common
cold. They concluded that treatment with zinc
canreducedurationofcoldsigns andsymptoms
and the need for antibiotics, and prophylaxis
[16]. Hulisz
of the onset of common cold may reduce the
duration and severity of symptoms of common
cold[17].According toAmericanFamilyPhysician
of common cold because of these inconsistent
In our study only 20 participants in zinc
supplementation group required antibiotics for
treatment of upper respiratory tract infection
compared to 47 individuals that needed
Recently, Kurugol and coworkers carried out a
the common cold in children. The results of the
study showed that the use of zinc sulphate
significantly reduced the risk of colds andcold‐
with zinc was associated with significant
common cold. In addition, the need for use or
Fortification of more commonly used foods
such as bread with zinc salts may be beneficial.
Thisstudy wassupportedbygrantNo. 83047of
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... Zinc supplementation has been reported to reduce the risk or the effects of URTI such as the common cold or flu. [18][19][20][21] However, several other studies have reported conflicting results that zinc was only beneficial for boys [22] or for children with malnutrition. [23] Larger discrepancies have been reported with Vitamin A supplementation studies. ...
... This is in accordance with several other studies that also reported zinc supplement correlation with lower episodes of AURTIs in a highly mentally and physically stressed population such as the United States Air Force Academy. [20] Moreover, zinc supplement has been associated with decreased duration of cold symptoms and incidences [19] and less need for antibiotics in severe infections. [23] Daily zinc supplementation was found to decrease the incidence of diarrhea and ARIs as early as 6 weeks of age. ...
... Pre efekt liečby je však nevyhnutná skorá aplikácia, a to už v priebehu prvých 12-24 hodín od začiatku prodromálnych príznakov. Odporúča sa aplikácia zvý šenej dávky, minimálne 75 mg zinku denne u dospelého pacienta po dobu 5 dní [21, [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Použitie zinku v liečbe akútnej rinosinusitídy odporúčajú aj medzinárodné smernice na liečbu akútnej rinosinusitídy -European Position Paper on Rhinosinusitis [38,39]. ...
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Zinok má komplexné imunomodulačné, protivírusové, protizápalové a cytoprotektívne účinky, preto patrí medzi efektívne spôsoby liečby a prevencie respiračných vírusových infekcií. Lekárnik je zdravotnícky pracovník, ktorý najčastejšie a ako prvý rieši samoliečbu rôznych respiračných infekcií. Tie sú takmer vždy spôsobené vírusmi. Článok opisuje úlohu zinku pre správne fungovanie imunitného systému, vrátane mechanizmov jeho protivírusového pôsobenia. Lekárnik môže odporúčať zinok v liečbe akútnych infekcií horných dýchacích ciest (napr. prechladnutie), alebo ako doplnkovú liečbu a prevenciu iných respiračných infekcií či chronických respiračných ochorení s predpokladom deficiencie zinku. V článku sa tiež uvádza možné využitie zinku ako súčasti liečby a prevencie ochorenia covid-19. Kľúčové slová zinok – respiračné infekcie – protivírusový účinok – lekárnik Zinc has complex immunomodulatory, antiviral, anti-inflammatory and cytoprotective effects, making it an effective way of treating and preventing respiratory viral infections. Pharmacists are the first-line healthcare professionals frequently handling self-treatment of various respiratory infections, which are almost always caused by viruses. The article describes zinc’s role in the immune system being able to function correctly, including its antiviral mechanisms of action. A pharmacist may recommend zinc to treat acute upper respiratory tract infections, such as the common cold, or as adjunctive therapy, and to prevent other respiratory infections or chronic respiratory diseases with a presumption of zinc deficiency. The article also discusses the possible use of zinc as part of treatment and prevention of covid-19. Key words zinc – respiratory infections – antiviral effect – pharmacist
... Clinical studies using zinc supplementation are primarily limited to rhinovirus infection, and are often grouped with other "common cold" viruses such as influenza and coronaviruses with several studies using zinc lozenges and formulations. The replication of rhinoviruses was potently inhibited by Zinc salts in in vitro experiments and amelioration of clinical symptoms associated with common cold has been reported to occur following increased level of zinc salts in the nasal cavity (Vakili et al., 2009). For instance, the administration of zinc bisglycinate reduced significantly the duration of illness and manifestation of symptoms under experimental conditions (Sanguansak & Lakkana, 2013). ...
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The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is the etiological agent for the Coronavirus Disease 2019 (COVID‐19). The COVID‐19 pandemic has created unimaginable and unprecedented global health crisis. Since the outbreak of COVID‐19, millions of dollars have been spent, hospitalization overstretched with increasing morbidity and mortality. All these have resulted in unprecedented global economic catastrophe. Several drugs and vaccines are currently being evaluated, tested, and administered in the frantic efforts to stem the dire consequences of COVID‐19 with varying degrees of successes. Zinc possesses potential health benefits against COVID‐19 pandemic by improving immune response, minimizing infection and inflammation, preventing lung injury, inhibiting viral replication through the interference of the viral genome transcription, protein translation, attachment, and host infectivity. However, this review focuses on the various mechanisms of action of zinc and its supplementation as adjuvant for vaccines an effective therapeutic regimen in the management of the ravaging COVID‐19 pandemic. Practical applications The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), the etiological agent for the Coronavirus Disease 2019 (COVID‐19), has brought unprecedented untold hardship to both developing and developed countries. The global race for vaccine development against COVID‐19 continues with success in sight with attendant increasing hospitalization, morbidity, and mortality. Available drugs with anti‐inflammatory actions have become alternative to stem the tide of COVID‐19 with attendant global financial crises. However, Zinc is known to modulate several physiological functions including intracellular signaling, enzyme function, gustation, and olfaction, as well as reproductive, skeletal, neuronal, and cardiovascular systems. Hence, achieving a significant therapeutic approach against COVID‐19 could imply the use of zinc as a supplement together with available drugs and vaccines waiting for emergency authorization to win the battle of COVID‐19. Together, it becomes innovative and creative to supplement zinc with currently available drugs and vaccines.
... This agreed with the study by Rahim et al. [22] who suggested that zinc through its antioxidant effect may improve symptoms of respiratory tract infection. ...
... This agreed with the study by Rahim et al. [22] who suggested that zinc through its antioxidant effect may improve symptoms of respiratory tract infection. ...
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Abstract Background Zinc is an important micronutrient in humans. Globally, pneumonia represents 18% of mortality in children under 5 years of age and the main infectious purpose of early life mortality. There is a higher pneumonia risk in a population with zinc deficiency. The aim of our study is to compare the level of serum zinc in children with pneumonia with age, sex, and nutritional matched healthy controls. Patients and methods Serum zinc level in 90 children admitted with pneumonia was compared with the matched controls. Results The mean level of serum zinc in children with pneumonia (67.5±21.8) is significantly lower than that of controls (91.8±19.94) with (P
... [6][7][8] Further, supplement intake of vitamin E has been found to increase mortality. 24 Zinc supplementation and URTI has been studied in several trials where two studies showed a decreased incidence among children 25,26 and five studies showed a reduction in duration among adults. 11 Nevertheless, high zinc levels may act pro-oxidative, 27 and routine supplementation has shown adverse effects on the immune system. ...
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Background/objectives: Antioxidants and polyunsaturated fatty acids (PUFAs) have a role in the human immune defense and may affect the susceptibility to upper respiratory tract infection (URTI). To examine dietary intake of vitamin C, vitamin E, selenium, zinc and PUFAs in relation to URTI incidence in a prospective cohort study. Subjects/methods: A total of 1533 Swedish women and men aged 25-64 years were followed for nine months during 2011-2012. Information on dietary intake was assessed through a web-based food frequency questionnaire, and events of URTI were self-reported prospectively as they occurred. Cox proportional hazards regression was applied to obtain incidence rate ratios with 95% confidence intervals. Results: The mean number of URTI events was 0.9 among all participants, 1.0 among women and 0.7 among men. In women, the incidence rate ratios (95% confidence interval) for high compared with low intake were 0.69 (0.55-0.88) for vitamin C, 0.77 (0.62-0.96) for vitamin E, 0.57 (0.39-0.83) for docosahexaenoic acid (DHA) and 0.80 (0.65-0.99) for arachidonic acid (AA). No association was found for selenium or zinc among women. In men, an increased URTI incidence was seen with medium vitamin E intake (1.42 (1.09-1.85)) and high zinc intake (1.50 (1.04-2.16)). No association was found for vitamin C, selenium or PUFAs among men. Conclusions: We found an inverse association of URTI incidence among women for vitamin C, vitamin E, DHA and AA intake and a positive association among men for vitamin E and zinc intake. The observed gender differences warrant further investigation.European Journal of Clinical Nutrition advance online publication, 11 January 2017; doi:10.1038/ejcn.2016.261.
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It remains uncertain as to whether nutrient supplementation for the general population considered healthy could be useful in the prevention of RTIs, such as COVID-19. In this systematic review and meta-analysis the evidence was evaluated for primary prevention of any viral respiratory tract infection (RTI) such as SARS-CoV-2, through supplementation of nutrients with a recognized role in immune function: multiple micronutrients, vitamin A, folic acid, vitamin B12, C, D, E, beta-carotene, zinc, iron and long chain polyunsaturated fatty acids. The search produced 15,163 records of which 93 papers (based on 115 studies) met the inclusion criteria, resulting in 199,055 subjects (191,636 children and 7,419 adults) from 37 countries. Sixty-three studies were included in the meta-analyses, which was performed for children and adults separately. By stratifying the meta-analysis by world regions, only studies performed in Asia showed a significant, but heterogeneous protective effect of zinc supplementation on RTIs (RR 0.86, 95%CI 0.7-0.96, I2=79.1%, p=0.000). Vitamin D supplementation in adults significantly decreased the incidence of RTI (RR 0.89, 95%CI 0.79-0.99, p=0.272), particularly in North America (RR 0.82 95%CI 0.68-0.97), but not in Europe or Oceania. Supplementation of nutrients in the general population has either no, or at most a very limited effect on prevention of RTIs. Zinc supplementation appears protective for children in Asia, while vitamin D may protect adults in the USA and Canada. In 10/115 (8.7%) studies post-hoc analyses based on stratification for nutritional status was performed. In only one study zinc supplementation was found to be more effective in children with low zinc serum as compared to children with normal zinc serum levels.
Because of its high prevalence acute respiratory diseases have a significant impact on the population. The focus of this review was the current state of knowledge for the prophylactic efficacy of: zinc, vitamin C, Echinacea preparations, garlic and carrying out physical measures. Furthermore, the benefits of pneumococcal and influenza vaccine were elicited. In the synopsis, the physical measures proved to be the most effective, cost-effective method to prevent infections. The intake of zinc, Echinacea preparations (for example: E. purpurea), vitamin C and garlic showed moderate success in the prevention of infection and must be elicited individually. Pneumococcal and annual influenza vaccines in family practice should be given furthermore accordingly topical STIKO-recommendation. Nevertheless, the prophylactic effect from influenza vaccines on usual cold illnesses is unsettled. © Georg Thieme Verlag KG Stuttgart · New York.
At the age of 1-7 years, the common cold is prevalence among children. It usually happens 6 to 7 times a year among children. An effective and safe drug is needed to reduce the duration of common colds symptoms in children and reduce subsequent complications. In some studies, zinc sulfate has showed an antiviral effect and immune enhancing activity. Therefore, this study was designed to evaluate the efficacy of zinc sulfate in duration of colds’ symptoms in children. In this study, 112 children with common cold who are between 6-7 years old divided into two groups. Case group received zinc sulfate within 10 days and Control group didn’t receive this drug. The symptoms like rhinorrhea and nasal obstruction, cough, sneezing, fever and duration of illness were checked out in both groups by questionnaire. In children with common cold, a significant decrease was observed in the mean duration of rhinorrhea, cough and nasal obstruction. Compared to the group that didn’t receive zinc sulfate, the zinc group had shorter mean duration of sneezing and fever. The mean duration of illness in patients who had received the zinc sulfate was significantly less than the other group. No side effect was observed in subjects received zinc sulfate. Based on our result, zinc sulfate can be administered with other supportive treatments of common cold, for reduction of symptoms duration and complications in children.
Because of its high prevalence acute respiratory diseases have a significant impact on the population. The focus of this review was the current state of knowledge for the prophylactic efficacy of: zinc, vitamin C, Echinacea preparations, garlic and carrying out physical measures. Furthermore, the benefits of pneumococcal and influenza vaccine were elicited. In the synopsis, the physical measures proved to be the most effective, cost-effective method to prevent infections. The intake of zinc, Echinacea preparations (for example: E. purpurea), vitamin C and garlic showed moderate success in the prevention of infection and must be elicited individually. Pneumococcal and annual influenza vaccines in family practice should be given furthermore accordingly topical STIKO-recommendation. Nevertheless, the prophylactic effect from influenza vaccines on usual cold illnesses is unsettled. Akute respiratorische Erkrankungen (ARE) gehören zu den häufigsten Erkrankungen in den industrialisierten Staaten. Symptome divergieren in Dauer und Intensität. Sie schränken den Patienten in seinem Allgemeinbefinden oft derart ein, dass eine Arbeitsunfähigkeit resultiert. Um für die Patientenberatung eine aktuelle Übersicht zu haben, wurde eine Literaturrecherche zum Thema „Infektprophylaxe“ durchgeführt.
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Effervescent lozenges containing 10 mg of zinc acetate were evaluated as a treatment of upper respiratory tract infections in a double-blind randomized trial by using a placebo which was indistinguishable to most observers in taste and appearance from the active material. Of the 70 treatment courses used by 55 individuals in 34 families, 63 (33 zinc and 30 placebo) were considered evaluable, in that the volunteer used the medication at least four times daily for at least 3 days, the average utilization being 5.4 days at an average dose of six lozenges daily. Six users of zinc reported nausea (versus no placebo users), and eight reported an unpleasant taste or aftertaste (versus one placebo user). No benefit was observed among the users of zinc acetate. The mean duration of symptoms in users of the zinc was 12.1 days, compared with 7.7 days in those who used the placebo. Nor was any beneficial effect of zinc evident among the four zinc-treated versus the two placebo-treated individuals from whom rhinovirus was grown.
Zinic ions rapidly inhibit virus production in HeLa cells infected with human rhinovirus type 1A and lead to the accumulation of human rhinovirus type 1A precursor polypeptides. The degree to which cleavage of these precursors is inhibited is directly dependent on the quantity of cell-associated zinc. Proteolysis resumes after the removal of zinc-containing medium, and the accumulated viral precursors are cleaved predominantly to stable virus polypeptides. The precursors stabilized at the lowest zinc levels are those that contain capsid protein sequences. Furthermore, added zinc is bound to human rhinovirus type 1A capsids and prevents them from forming crystals. Zinc-resistant mutants display antigenic alterations in coat proteins. These results suggest that zinc complexes with rhinovirus coat proteins and alters them so that they cannot function as substrates for proteases or as reactants in the assembly of the virus particles.
• Zinc deficiency occurs in individuals and populations whose diets are low in sources of readily bioavailable zinc such as red meat, and high in unrefined cereals that are rich in phytate and dietary fibers. Dietary zinc deficiency was described nearly three decades ago among the poor of the Middle East. It is now known to occur in children and adolescents from widely diverse areas including Egypt, Iran, Turkey, China, Yugoslavia, Canada, and the United States; and among pregnant women from Iran, Turkey, the United Kingdom, Australia, and the United States. Major manifestations include retarded growth and development and an increased incidence of pregnancy complications. Other manifestations may include suppressed immunity, poor healing, dermatitis, and impairments in neuropsychological functions. Precise information as to the numbers of people affected by dietary zinc deficiency is not available. Even so the nature of diets associated with zinc deficiency suggests that mild deficiency is common in some populations. (AJDC. 1991;145:853-859)
Following a tolerance study, double-blind placebo controlled trials were conducted to determine the prophylactic effect of zinc gluconate lozenges on rhinovirus challenge and, in a third study, their therapeutic efficacy when given at the start of colds caused by virus inoculation was tested. In the prophylaxis study a total of 57 volunteers received lozenges of either zinc gluconate (23 mg) (29 volunteers) or matched placebo (28 volunteers) every 2 h while awake during a period of four and a half days. They were challenged with 10² tissue culture infecting dose (TCID50) of human rhinovirus 2 (HRV-2) on the second day of medication, and were monitored daily for symptoms and signs of colds and laboratory evidence of infection. Zinc reduced the total mean clinical score from 8.2 in the placebo group to 5.7 and the reduction of the mean clinical score was statistically significant on the second day after virus challenge. In the therapeutic study 69 volunteers were inoculated with 10² TCID50 of HRV-2 and those who developed cold symptoms were randomly allocated to receive either zinc gluconate lozenges (six volunteers) or matched placebo lozenges (six volunteers) every two hours they were awake for six days. Treatment of colds with zinc reduced the mean daily clinical score and this was statistically significant on the fourth and fifth day of medication. Similarly, medication also reduced the mean daily nasal secretion weight and total tissue count and these reductions were statistically significant on days two and six for nasal secretion weights and days four to six of medication for tissue counts when compared with placebo. There were also statistically significant reductions in the mean total nasal secretion weights and total tissue counts. Zinc, however, had no significant effect on the rate or amount of virus excreted by volunteers. We conclude that zinc gluconate lozenges are reasonably well tolerated and that they have a significant effect on the signs and symptoms of colds caused by rhinoviruses, although the mechanism of action remains obscure.
Zinc is essential for all species. Human zinc deficiency related to diet was recognized 30 yr ago among adolescents in Iran and Egypt. Subsequent factorial calculations, balance studies, and tracer studies of bioavailability and turnover established the amounts of zinc needed for equilibrium and dietary factors that impair retention. Comparison of dietary intakes of zinc with requirements suggested many women and children are at risk of deficiency. Epidemiological studies associated low plasma levels of zinc with abnormal pregnancy outcomes and controlled intervention trials showed that zinc repletion improved pregnancy outcomes. Low iron nutriture, a common phenomenon in women, was shown to be associated with low zinc nutriture. Thus the hypothesis that zinc deficiency is a public health problem appears to be true.
Clinical studies have shown that ionic zinc (Zn2+) dissolved in the mouth shortened manifestations of the common cold significantly, by an unknown mechanism. The observed immediate effect on symptoms is consonant with osmotic transport of Zn2+, placing a temporary chemical clamp on critical nerves. It is proposed that transient elevation of Zn2+ concentration in and around the nasal cavity facilitates Zn2+ complexation with known intercellular adhesion molecule binding sites on rhinovirus surfaces which prevents rhinovirus binding to cells and interrupts infection. The crystallographically determined surface of rhinovirus-14 has been found to contain binding sites for at least 360 Zn2+. Such binding of Zn2+ would be stabilized by numerous histidine, methionine, tyrosine and carboxyl/carboxylate groups known to line the HRV-14 surface canyons. The resulting blockage of HRV docking with intercellular adhesion molecule binding sites is proposed to be responsible for the observed reduction of the duration of colds by statistically significant and clinically meaningful times.
Due to dietary modifications including the intake of cereals, vegetables and the frequent use of soy milk instead of breast milk, children in developing countries with diarrhea frequently suffer from zinc deficiency. Furthermore, diarrhea leads to excess zinc losses. Beside low energy intake zinc deficiency contributes to continued diarrhea, which in turn accounts for half of the deaths from diarrhea in children. Zinc supplementation leads to accelerated regeneration of the mucosa, increased levels of brush-border enzymes, enhanced cellular immunity and higher levels of secretory antibodies. In addition, in stunted children zinc supplementation results in enhanced catch-up growth via higher levels of insulin-like growth factor-I. Growth retardation is closely related to the risk of diarrheal diseases in children. These pathophysiological conclusions are supported by several controlled clinical traits which have provided evidence that zinc supplementation results in significant reduction in the risk of continued diarrhea. However, it remains to be clarified whether these benefits are attributable to pharmacological effects or if they can be related to the correction of an underlying deficiency state.