One Out, One In #6: daily cheap zinc → food, or a short course

One you drop. One you take instead.

Zinc is essential. The Australian adult RDI is 14 mg men / 8 mg women. The US is 11 / 8. The upper level from food plus pills is 40 mg, set on copper status. Food almost never gets you to 50 mg. A Chemist Warehouse “immune” tablet can.

The products we checked are not mostly oxide. Don't invent an oxide bottle.

B6 in those stacks is next week's problem. This week, it's zinc: there's no end date, and it's sold as an immune tonic.

The NIH Office of Dietary Supplements (NIH ODS), January 2026, says using 50 mg of zinc or more for weeks can interfere with copper absorption, drop immune function, and lower HDL. So that's the opposite of an immune tonic. The NIH ODS copper fact sheet says even about 60 mg of zinc a day for up to 10 weeks has reduced a copper enzyme in red cells. That's why the UL is 40 mg.

The textbook copper-wipeout cases are uglier things: 135 mg of medical zinc, or old zinc denture cream by the tube. The mechanism is real. Don't pretend a 30 mg tablet is one of those cases. Don't pretend a 30 mg zinc tablet with no end date is food.

Cold lozenges are not the IN. Cochrane 2024 says zinc may shorten an existing cold by about two days (low certainty; studies are all over the place). There's little or no prevention. Taste changes and stomach upset are more common. The authors won't firm-recommend it. A short lozenge course isn't a year-round 50 mg zinc tablet, and it isn't a disease claim we'll print.

Park the daily immune zinc if you bought it to “not get sick.” Keep taking that zinc only if a clinician is running a documented-deficiency course, or an ophthalmologist has you on AREDS.

Oysters are the joke serving: ~30 mg in 85 g. After that come beef, crab and dairy. Phytate in legumes and whole grains lowers absorption. Vegetarian and vegan readers often sit lower. They may need a modest conversation with a GP or dietitian, not a 50 mg immune tablet, and not “you don’t need zinc.”

If the GP finds you short, healthdirect describes a clinician-guided 50 mg zinc course and a blood test at two months, then stop the course when replete. That course sits above the UL. It’s their protocol, not this letter’s.

Copper footnote: if someone is truly taking high-dose zinc long term, copper is why AREDS added 2 mg cupric oxide next to 80 mg zinc. That ratio is 40:1, a studied eye formula, not a supermarket 8:1 gospel. There is no NIH 8:1 tablet. Don't recast this issue as a zinc-for-copper swap. Do not add copper if the diagnosis is Wilson disease.

AREDS: keep the formula. Don't strip the zinc. 80 mg versus 25 mg is ophthalmology, not us.

“I’ve been taking zinc every day. Should we check whether I actually need it, and is my dose high enough to run down copper?”

If you're on AREDS:

“I’m on an AREDS / macular zinc formula. Can we confirm this is still the right product for my eyes, and that copper is in it on purpose?”