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Colds and flu can be prevented with a common mineral supplement

[Apr. 20, 2023: Staff Writer, The Brighter Side of News]

Zinc is known to be one of the rare things that might help fight off a common cold. Or does it? (CREDIT: Creative Commons)

Hieronymus David Gaubius, a German physician, introduced zinc to the Western scientific community as a promising medication in 1771.

Nowadays, over two centuries later, zinc can be found among the numerous supplements lining pharmacy shelves. While it is reputed to be one of the few remedies that can potentially help to combat a cold, the question remains whether it actually does.


The use of zinc supplements has limited evidence, with mixed results from studies and inadequate investigation into dosage, formulation, and prescription length to date.

However, a recent meta-analysis of 28 randomized controlled trials has reinforced the idea that taking zinc supplements can potentially prevent symptoms and reduce the duration of viral respiratory infections such as the common cold or flu.


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According to Jennifer Hunter, an integrative medicine doctor from Western Sydney University in Australia, the belief that zinc only helps prevent and treat infections in individuals who are deficient in zinc is widely held. However, our research contradicts this idea."

Research from China, involving two large trials, discovered that a zinc nasal spray with a very low dosage lowered the probability of developing clinical illness. In contrast, two smaller trials conducted in the United States, which investigated the preventive impact of oral zinc, excluded individuals with zinc deficiency.


The trials examining the efficacy of zinc in treating the common cold were conducted in populations where zinc deficiency is highly unlikely, according to the available evidence.

In terms of prevention, the analysis showed that taking zinc led to a 28% decrease in the likelihood of experiencing mild symptoms and an 87% decrease in the likelihood of experiencing moderately severe symptoms.

When used as a treatment after contracting the cold, zinc was found to slightly reduce the duration of symptoms, typically by about two days. However, the effect was modest and did not significantly reduce the overall severity of symptoms. Furthermore, zinc was unable to prevent infection if the patient intentionally exposed themselves to the virus.

While this analysis is a promising development, the researchers caution that some of the studies included in the analysis were small, used different dosages, and may have introduced bias in symptom reporting. It is important to remember that the reliability of meta-analyses depends on the quality of the underlying data.


The results are intriguing, but they do not provide significant insights into how zinc can combat viral infections such as the common cold.

Prior to the late 18th century, alchemists sold zinc to address severe seizures. However, Gaubius unveiled the "secret drug" he had discovered, which turned out to be just zinc oxide.

Zinc was used to manage epilepsy for a time in the 19th century, but by the 20th century, it had lost its popularity and was no longer on our radar.

Zinc resurfaced as a potential therapy for zinc deficiencies in the 1960s and for Wilson's disease, an uncommon genetic disorder that causes copper accumulation in vital organs. As an anti-copper agent, zinc has been shown to be effective in treating this neurological illness.

Nonetheless, zinc's potential in fighting viral infections remains largely untapped.


However, despite pending results from randomized control trials, some healthcare workers have already started to use zinc as a treatment for COVID-19. This renewed interest in zinc is due to some health guidelines recommending its use for lower respiratory infections and the recent COVID-19 pandemic.

Prevention of respiratory tract infections (RTIs). Risk of community-acquired RTI, clinical colds from human rhinovirus (HRV) inoculation and non-serious adverse effects from prophylaxis. RoB-2 risk of bias legend: (1) randomisation process, (2) deviations from intended interventions, (3) missing outcome data, (4) measurement of the outcome, (5) selection of the reported result. M-H, Mantel-Haenszel; PEP, post-exposure prevention; PREP, pre-exposure prevention; RoB, risk of bias. (CREDIT: BMJ Open)

Although there are ongoing randomized control trials, healthcare workers have begun using zinc as a COVID-19 treatment. This renewed interest in zinc is due to its recommendation for lower respiratory infections and its potential highlighted during the pandemic.


The risks are low if the patient is screened correctly and the dosage does not get too high. Unless a person has a disorder that allows bodily zinc to filter into the brain, there are almost no serious health effects from taking the supplement.

Symptom severity. Mean symptom severity scores following treatment for community-acquired respiratory tract infections and clinical colds from human rhinovirus (HRV) inoculation. RoB-2 risk of bias legend: (1) randomisation process, (2) deviations from intended interventions, (3) missing outcome data, (4) measurement of the outcome, (5) selection of the reported result. RoB, risk of bias. (CREDIT: BMJ Open)

Some dosages of zinc can, however, come with non-serious side effects, like nausea or, as is common with using too much zinc nasal spray, a loss of smell. And overall, we still don't even know what's the best way to take zinc, either.


"Clinicians and consumers need to be aware that considerable uncertainty remains regarding the clinical efficacy of different zinc formulations, doses and administration routes," says Hunter.

Duration of illness. Risk of remaining symptomatic and mean days duration following treatment for community-acquired RTI or clinical colds from HRV inoculation. (CREDIT: BMJ Open)

"At the moment there just isn't enough research to say whether a zinc nasal spray, versus a nasal gel, versus a lozenge, versus oral zinc is any better or worse than the others. Most of the trials used zinc gluconate or zinc acetate formulations, but that doesn't mean that other zinc compounds are less effective."


The results of the review support the need for further investigation into immuno-nutrition, especially in communities at higher risk of SARS-CoV-2. The researchers suggest that zinc could be a promising treatment based on preliminary research into SARS-CoV-2 and the findings of the review.

It is clear that more research is necessary, a sentiment that Gaubius would likely endorse.

The study was published in BMJ Open.

For more science news stories check out our New Discoveries section at The Brighter Side of News.


Note: Materials provided above by the The Brighter Side of News. Content may be edited for style and length.


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