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Food Stories · Episode 16 · Why does...?

Zinc and Colds: What the Research Says (and Doesn't)

A sourced look at zinc: what it does in the body, where the zinc lozenge idea came from, what trials and a 2024 review found, and safety warnings.

Major Orange and Princess Punch in the Food Stories episode "Zinc: The Case of the Disappearing Cold"Video coming soon
A still from the episode. The video is coming soon to YouTube @wonderadeusa; the full transcript is below.

The short answer

Zinc is a mineral the body needs every day; about one in ten human proteins holds zinc, and it plays a part in growth, healing, taste and smell. Some trials in adults found zinc lozenges started early shortened colds, but a 2024 Cochrane review rated the overall evidence as low certainty. Zinc should never be put in the nose, too much zinc can lower copper, and for children the advice is to ask a doctor or pharmacist. This article is general information, not medical advice.

  • Dr. Ananda Prasad first described human zinc deficiency in 1961, in young men in Iran who had stopped growing.
  • In a pooled analysis of three adult trials, 70% on zinc acetate lozenges had recovered by day five versus 27% on placebo.
  • A 2024 Cochrane review of 34 trials called the evidence uncertain.
  • The FDA warned in 2009 that nasal zinc products were linked to loss of smell, sometimes permanent.
  • Foods with zinc include oysters, beef and pumpkin seeds.

The story (transcript)

Narration from the episode, as it is spoken.

Princess Punch woke up sniffly, three days before her big game. So Detective Major Orange took the case: can a metal shorten a cold?

The suspect: zinc. Romans made brass with its ore, and medieval India made tons of it. Its disguise today? Pennies, mostly zinc under a copper coat.

Clue one: zinc's day job. About one in ten of your proteins holds zinc, and it helps you grow, heal, taste and smell.

When an egg starts a new life, it even shoots out zinc, filmed as flashes of light. Zinc sparks!

Clue two: young immune cells train at a camp called the thymus, and they need zinc.

Without it? In nineteen sixty-one, Doctor Ananda Prasad described young men in Iran who had stopped growing. Their flatbread diet lacked zinc.

Then, an eyewitness. George Eby's little daughter let a zinc tablet melt in her mouth, and her cold seemed to fade. In nineteen eighty-four, he tested it.

Three later trials gave adults with new colds zinc lozenges or placebos. By day five, seventy percent on zinc had recovered, versus twenty-seven percent on placebo. Colds were about forty percent shorter.

How? Maybe zinc blocks the virus at its doorway into cells. But that's just a theory.

Then, the cross-examination. A twenty twenty-four review called the evidence uncertain. Those trials were adults only, the form and dose mattered, and lozenges can taste bad.

The fine print: never put zinc up your nose. It has taken away people's sense of smell, sometimes for good. Too much zinc pushes out copper. For kids, ask a doctor or pharmacist.

The verdict: case partly closed. Princess Punch rested up, and felt better by game day.

And zinc? Not a magic cure, but an everyday hero you need a little of, from foods like oysters, beef and pumpkin seeds.

Brought to you by Wonderade, the juice you wish you had when you were growing up.

Questions people ask

Does zinc help with colds?
The evidence is mixed. Some trials in adults found zinc lozenges started early shortened colds, but a 2024 Cochrane review rated the evidence low certainty. Ask a doctor or pharmacist before using zinc, especially for children.
Is too much zinc harmful?
Yes. The NIH sets upper limits by age, and too much zinc can lower copper levels. Zinc should never be used in the nose; the FDA linked nasal zinc products to loss of smell.
What foods have zinc?
Oysters have the most per serving. Beef, crab, pumpkin seeds and cheese also provide zinc, according to the NIH Office of Dietary Supplements.

Sources

Each source is listed with the facts we took from it.

Lozenges and colds

How we checked this

What we simplified, hedged or left out, and why.

  • The story frame. Princess Punch gets better by resting, not by zinc, and she never takes a lozenge or tablet. The verdict says "partly closed" and the takeaway says "not a magic cure", so the strong trial result is never the last word. "Felt better by game day" is story, not a claim about how long colds last.
  • "About forty percent shorter" is the acetate figure (33% for acetate and gluconate together; Cochrane 2024 about 2.4 days, low certainty). It is followed at once by the theory caveat and the 2024 review saying "uncertain".
  • Nasal zinc. "Sometimes for good" follows FDA's "long-lasting or permanent" (2009, Zicam intranasal products).
  • Zinc sparks. "When an egg starts a new life" covers the human egg-activation study and the mouse/monkey fertilization work; the egg-quality claim stays out.
  • Prasad. "Described young men in Iran who had stopped growing" (index case 1958, report 1961). "Their flatbread diet lacked zinc" simplifies phytate-rich bread plus clay-eating; the zinc cause was confirmed in Egypt.
  • Pennies. "Its disguise today? Pennies, mostly zinc under a copper coat" means the cents in pockets now (post-1982 copper-plated zinc, 97.5% Zn). Circulating production ended in November 2025; the line doesn't say they're still being made.

This article is general information, not medical advice. For anything about a child's health, ask a doctor or pharmacist.

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