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Zinc over supplementation can cause copper deficiency

Doctors often incorrectly diagnose zinc deficiency, according to a clinical audit in Scotland, and so induce cases of copper deficiency because misplaced treatment results in too much zinc.

Published in the Journal of Clinical Pathology, a publication from The BMJ, the findings come from an analysis of case notes from 70 patients prescribed zinc supplements at Glasgow hospitals in the decade from 2000-10.

The study found that 62% of patients were prescribed zinc at doses sufficient to cause copper deficiency.

"These findings underline the lack of awareness of zinc-induced copper deficiency," conclude the authors. They continue:

"Zinc is an essential trace element and so clinicians may consider it a safe nutrient rather than a drug carrying potential risk.

"This study offers persuasive evidence of a potential risk of iatrogenic copper deficiency being unwittingly caused by prescribing high doses of zinc."

The authors point out that the zinc requirement for adults is less than 10 mg a day. The dose most commonly prescribed, however, is 135 mg a day - yet "there is no evidence to support the prescription of zinc" at this level.

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12 Replies

I was scratching my head thinking "How on earth can they prescribe 135 milligrams?", but the BNF clearly shows up to three effervescent tablets a day, each of 45 milligrams.

With not even a mention of copper there.

I find it difficult to understand why the BNF lists it without any real guidance as to dose.

The USA's Office of Dietary Supplements does have consumer and professional sheets:


Helvella, the article also states that 45mg is the smallest dose [prescription dose] but my supermarket supplement is 15mg, so smaller doses are available.


Weird indeed as it is known that people who have dentures might end up having sort of zinc poisoning if the paste they use is zinc based.

I have learned that zinc and copper go hand in hand and you need (?) ratio. Always copper taken in morning and zinc before bedtime. Tho recently I have heard that there is supplements that contains both right ratio but that doesn't make sense as they block each other.

Tho this might not be something doctors really know as they seem to know very little about these things. Not even the basics!

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Justina, I read that heavy use of dental glue means a lot of zinc may be ingested and causes copper deficiency.

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Clutter, that stuff was taken off the market.


A ratio of 1:10 copper/zinc.


And Vitamin C uses copper -


I don't know whether this should worry me or not. According to Wikipedia, copper deficiency is very rare, yet I have all of this, to the letter: "The researchers found problems typically associated with zinc-induced copper deficiency: anemia, neutropenia (low white cell count) and/or neurological symptoms developed in 13 patients."

I have low haematocrit anaemia, neutropenia and the neurological condition of trigeminal neuralgia. What's worse, there has never been any explanation of WHY I have neutropenia or low haematocrit, both of which seem to be random and disconnected.

All that said, I see no reason for me to have low copper. I took zinc for many years, through the 80s, 90s, but I haven't taken it since then, so surely it would have corrected itself? The only other thing that MIGHT apply is coeliac disease, which I'm still fighting for the correct testing for, but all the conventional tests have been negative.

Now I don't know if I should risk looking like a (bigger) neurotic fool and ask to have a serum copper test, or this is just too unlikely to be true....


Chancery, it seems worth investigating but from what you've said about your GP I don't suppose he'll embrace the possibility. Still, don't ask, don't get.


Yep. I think it's that sneering long-suffering reception to the idea that is putting me off asking, but it does seem like a dodgy bunch of coincidences to ignore. I'll feel like the village idiot, but I think I'll just have to be a man and suck it up.


Chancery, good luck :)


I'll need it - thanks! (And thanks for posting this, as unthrilled as I may be by the prospect!)


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