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I was looking at the information about a zinc supplement product. Its specifications show that each does contains 30 mg of Zinc (as Zinc Picolinate), and that this is 275% of the daily value. Since an adult may consume only about 10 mg of zinc per day, 30 mg of zinc sounds like poison. Am I misreading the meaning of "Zinc (as Zinc Picolinate)"? In the Q&A page someone says that the manufacturer confirmed that 30 mg is the zinc element. But I suspect if the person misunderstood the message from the manufacturer or is just trolling. A company would not sell poison?

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According to the Office of Dietary Supplements of the US National Institutes of Health, the upper tolerable limit for Zinc is as follows:

Table 3: Tolerable Upper Intake Levels (ULs) for Zinc
Age Male Female Pregnant Lactating
0–6 months 4 mg 4 mg
7–12 months 5 mg 5 mg
1–3 years 7 mg 7 mg
4–8 years 12 mg 12 mg
9–13 years 23 mg 23 mg
14–18 years 34 mg 34 mg 34 mg 34 mg
19+ years 40 mg 40 mg 40 mg 40 mg

As the Office of Dietary Supplements notes, the tolerable upper intake level is the

maximum daily intake unlikely to cause adverse health effects.

Thus, 30mg per day is a tolerable dose of zinc as defined by the NIH for males or females age 14 or older.

However, as noted by timeskull in the comments, this daily intake must also include the zinc one receives from other dietary sources. One study from a few decades ago found the average zinc intake of US adults to be 13mg/day (Briefel et al 2000. PMID 10801945). Thus, more than half of the US population would be exceeding the UL by taking a 30mg dose of elemental zinc daily.

Zinc toxicity is rare (Agnew and Slesinger 2022. NBKID 554548). However, chronic doses of 100-150mg/day of elemental zinc have been reported in association with secondary copper defficiency (Plum et al 2010. PMCID 2872358). Higher daily doses have been associated with gastrointestinal symptoms including anorexia, vomiting, and diarrhea (2021 Merck Manual).

As always, individuals should consult with their personal physician before starting any supplement or medication.
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    30 mg in a daily supplement is tolerable as long as the zinc in your diet is < 10 mg. The CDC toxological profile for zinc cites "A typical Italian diet contains about 10.6 mg of dietary zinc per day, where 4.3 mg of zinc comes from meat and meat products (Lombardi-Boccia et al. 2003)." so supplementing that typical Italian diet would be slightly over the recommended limit.
    – timeskull
    May 23 at 15:41
  • @timeskull Great point, I've edited the answer. To be fair, most reports of toxicity seem to be in the 100+ mg/day range.
    – Ian Campbell
    May 23 at 15:46

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