Written by Dr Sarah Brewer, Medical Director, Healthspan
Zinc is an essential mineral needed by over 200 body enzymes to work properly. It is involved in switching on genes in response to hormone triggers and is vital for growth, repair, healing and fertility. Zinc also plays a key role in protecting against respiratory infections – so much so that the EU has authorised a health claim
that “Zinc contributes to the normal function of the immune system”.
Food sources of zinc include red meat, seafood (especially oysters), offal, brewer’s yeast, whole grains, pulses, eggs and cheese. However, food processing removes much of the zinc present, especially in grains.
Zinc and the common cold
Zinc is a popular remedy for sore throats and the common cold when taken in the form of zinc acetate lozenges, but its effects were only discovered by chance when a 3-year-old girl with leukaemia developed a cold. Her father gave her a zinc tablet and, because she was unable to swallow, she slowly dissolved it in her mouth. Her cold symptoms disappeared within a few hours which prompted her father – a medical researcher – to investigate further.
It’s now known that sucking zinc lozenges inhibits viral replication and also activates infection fighting white blood cells (Tlymphocytes) in the throat.i These cells control and regulate immune responses to help ward off infection and disease.ii T cells are highly dependent on zinc to work properly, however, as are the natural killer (NK) cells and memory T cells which remember a given infection and patrol the body to mount a rapid response if that particular virus or bacteria is encountered again.
Zinc is also involved in how immune responses are reined in once an infection has resolved, to prevent reactions spiralling out of control and causing excessive inflammation, which prolongs symptoms.iii This may explain why sucking zinc lozenges at the onset of a cold appears to reduce its duration so effectively.
Clinical trials show that sucking zinc acetate lozenges significantly reduces symptoms of the common cold compared with placebo, shortening the duration of:
• nasal congestion by 37%
• scratchy throat by 33%
• hoarseness by 43%
• and cough by 46%.
Sucking zinc acetate lozenges also shortened the duration of muscle aching by 54% – equating to 2.94 days.iv
Numerous studies show that, overall, people who use zinc lozenges recover three times faster than those not using them. Studies show that, by the 5th day of a cold, 70% of those taking zinc were fully recovered, compared with only 27% who were using placebo.v
Zinc acetate lozenges work most effectively when started within 24 hours of the onset of symptoms.
Zinc and respiratory infections
Results from 17 studies found that children receiving zinc supplements were 20% less likely to develop a lower respiratory tract infection such as pneumonia than those not taking them.vi However, do not give zinc supplements to a child under the age of 18 except under medical advice.
Zinc and cold sores
Zinc can inhibit the replication of Herpes simplex viruses, which cause cold sores, by up to 90%. In a small study involving 20 people who normally experienced more than 6 episodes of recurrent herpes cold sores per year, taking zinc supplements (22.5mg twice daily for 4 months) more than halved average recurrences to 3 per year. The duration of each episode was also reduced to an average of 5.7 days.vii Applying a zinc oxide cream also helps to shorten the duration of cold sores.viii
Did you know? Zinc plays a role in the sensory mechanisms that detect odours and flavours. Lack of zinc is a common cause of loss of taste and smell.
How much zinc do you need?
For general health, the EU recommended intake (NRV or Nutrient Reference Value) for zinc is 10mg per day. Average dietary intakes of zinc are low, however. National Diet and Nutrition surveys show that women aged 19 to 65 years only obtain around 7.5mg zinc from their diet, for example.ix
To see off upper respiratory tract infections, however, higher doses are needed in the short term.
Safety
The tolerable upper zinc intake for Ireland, derived from the European Food Safety Authority (EFSA), is 25mg per day, but clinical studies involving the use of zinc acetate lozenges suggest that the use of high doses of zinc (up to 90mg per day for no more than ten days) is a safe and effective self-treatment for common cold symptoms.
Clinical studies involving the use of zinc acetate lozenges suggest that the use of high doses of zinc (up to 90mg per day for no more than ten days) is.x Even at these temporary higher doses, there were no significant differences in reported side effects between those taking zinc and those given placebo (dummy) lozenges.
Do not exceed recommended doses, as excess zinc can cause nausea.
If you are taking any prescribed medication, are pregnant or breastfeeding, or have any medical conditions, always consult a doctor or pharmacist before taking any supplements. Do not give to anyone under the age of 18 except under medical advice.
Healthspan’s ImmunoVit Zinc Defence Lozenges contain 10mg ionic zinc per lozenge (as zinc Zinc is an essential mineral needed by over 200 body enzymes to work properly. It is involved in switching on
genes in response to hormone triggers and is vital for growth, repair, healing and fertility. Zinc also plays a
key role in protecting against respiratory infections – so much so that the EU has authorised a health claim
that “Zinc contributes to the normal function of the immune system”.
acetate). Dissolve one lozenge
slowly in your mouth, every
2-3 hours as required, up to a
maximum of nine lozenges daily
(or the dosage advised by your
nutritionist). Use for a period of up
to 10 days; if symptoms persist
consult your doctor.
i Kaltenberg, J., Plum, L. M., Ober-
Blobaum, J. L., et al. (2010). Zinc signals
promote IL-2-dependent proliferation of
T cells. European Journal of Immunology,
40(05). https://www.ncbi.nlm.nih.gov/
pubmed/20201035
ii Shankar, A. H., and Prasad, A. S. (1998).
Zinc and immune function: the biological
basis of altered resistance to infection.
The American Journal of Clinical Nutrition,
68(02). https://www.ncbi.nlm.nih.gov/
pubmed/9701160
iii Ohio State University. (2013). Zinc
helps against infection by tapping
breaks in immune response. Science
Daily. https://www.sciencedaily.com/
releases/2013/02/130207131344.htm
iv Hemila H at al. (2015). The effectiveness
of high dose zinc acetate lozenges on
various common cold symptoms: a metaanalysis.
BMC Family Practice. https://
www.ncbi.nlm.nih.gov/pubmed/25888289
v Hemila H et al. Zinc Acetate Lozenges
May Improve the Recovery Rate of
Common Cold Patients: An Individual
Patient Data Meta-Analysis. Open Forum
Infect Dis. 2017; 4(2): ofx059. https://
www.ncbi.nlm.nih.gov/pmc/articles/
PMC5410113/
vi Agarwal R et al. Role of zinc
administration in prevention of childhood
diarrhea and respiratory illnesses: a metaanalysis
Pediatrics 2007;119(6):1120-
30 https://pubmed.ncbi.nlm.nih.
gov/17545379/
vii Femiano F et al. Recurrent herpes
labialis: a pilot study of the efficacy
of zinc therapy. J Oral Pathol Med
2005;34(7):423-5 https://pubmed.ncbi.nlm.
nih.gov/16011612/
viii Godfrey HR et al. A randomized clinical
trial on the treatment of oral herpes with
topical zinc oxide/glycine Altern Ther
Health Med 2001;7(3):49-56 https://
pubmed.ncbi.nlm.nih.gov/11347285/
ix Official Statistics. Public Health England
and Food Standards Agency. NDNS:
results from Years 1 to 4 (combined)
https://www.gov.uk/government/statistics/
national-diet-and-nutrition-survey-resultsfrom-
years-1-to-4-combined-of-the-rollingprogramme-
for-2008-and-2009-to-2011-
and-2012
x Hemila H, Chalker E. The effectiveness of
high dose zinc acetate lozenges on various
common cold symptoms: a meta-analysis.
BMC Fam Pract . 2015 Feb 25;16:24.
https://www.ncbi.nlm.nih.gov/pmc/articles/
PMC4359576
