"Would Zinc Lozenges Help With COVID-19?"
Given the current pandemic, the search for potential preventive
and therapeutic antiviral strategies is of particular and urgent interest,
so what about zinc, which is known in some cases
to have antiviral and anti-inflammatory benefits?
I looked into it as a potential treatment after the fact-checking site Snopes
validated that a noted virologist did indeed make
a recommendation back in February to stock up now with zinc lozenges.
He based his supposition on the efficacy of zinc for common colds,
up to 29% of which are caused by coronaviruses.
There's actually a sweet backstory to that:
A 3-year-old girl undergoing chemotherapy for leukemia—
a disease marked by low zinc levels— refused to swallow a zinc supplement.
Immunosuppressed, she had just started getting a cold.
Instead of swallowing the supplement, she just let it dissolve in her mouth
and the cold seemed to disappear within hours. Ok, cute little anecdote,
but this observation led her father, her own father, to conduct
the first randomized double-blind placebo-controlled trial
on zinc lozenges for the common cold.
That's how it all started, but there have since been more than a dozen
randomized controlled trials published, and overall, researchers have found
that zinc is indeed beneficial in reducing both duration
and severity of the common cold
when taken within the first 24 hours of symptom onset.
Zinc lozenges appear to shorten colds by about 3 days
with significant reductions
in nasal discharge and congestion and hoarseness and cough.
The common cold results for zinc are often described as mixed,
but that appears to be because some studies use zinc lozenges
containing added ingredients like citric acid that strongly
sequester zinc, so little or no free zinc is actually released.
They taste better, but what's the point if you don't actually get the zinc?
So what's the best way to take zinc for the common cold?
Lozenges containing around 10 to 15 mg of zinc taken every two waking hours
for a few days starting immediately upon symptom onset, as either
zinc acetate or zinc gluconate, without zinc binders such as
citric acid, tartaric acid, glycine, sorbitol, or mannitol may work best.
Best for the common cold, but what about for COVID-19?
There are a number of purported mechanisms
for the potential protection afforded by zinc.
The first is that it interferes with the attachment of rhinoviruses,
the most common cause of the common cold, to our cells.
This presumably wouldn't help us in the case of COVID-19
since our new coronavirus utilizes a different docking receptor.
Zinc also appears to slow rhinovirus replication, at least in a petri dish.
What about coronaviruses?
Zinc inhibits the coronavirus that causes SARS by interfering
with the virus' ability to replicate its genetic code, but that was
in conjunction with a chemical that ferried zinc inside the cells.
There are natural dietary compounds that may play a similar function,
but even if viral replication were able to be slowed in your throat
where the lozenge is, what we care about most
is stopping replication of the COVID-19 virus in the lungs.
But a third mechanism by which zinc may help seems more promising:
boosting our antiviral immunity. For example, giving zinc pills
to children with severe regular pneumonia
has been shown to be effective in reducing mortality
as much as 3-fold over placebo.
Three times higher death rates in the sugar pill group.
But these studies were done in countries like Uganda, India, and Ecuador
where there may have been pre-existing zinc deficiencies.
So yeah, taking zinc if you're zinc deficient, no wonder that helps, but
it's unclear if similar benefits could be had in higher-income countries
with better population-wide micronutrient status.
Some have suggested that despite the lack of clinical data—
no one has yet put zinc to the test for COVID-19; maybe it could help.
I'm skeptical it would be helpful in well-nourished individuals, but
if taken as directed, it shouldn't hurt, though zinc supplements and lozenges
can cause nausea, especially when taken on an empty stomach,
and some other gastrointestinal symptoms.
And one should never put zinc in their nose.
In the drug store you'll find all sorts of intranasal zinc gels, sprays, and swabs
that have been linked to the potentially permanent loss of one's sense of smell.
Oh, and happy ending: that 3 year-old girl beat the cancer,
never relapsed, and grew up to become a scientist herself.