Zinc requirements and the risks and benefits of zinc supplementation.
Level 5 - mechanism / opinion, no new human data
Narrative review without systematic methodology or primary empirical data
PubMed 16632171 · doi:10.1016/j.jtemb.2006.01.006
What was done
This narrative review synthesized existing evidence and physiological estimates regarding human zinc requirements, dietary bioavailability, and the health consequences of inadequate or excessive intake. It examined global risk factors for zinc deficiency, the consequences of over-supplementation, and the limitations of current clinical assessments of zinc nutriture.
What was found
The adult human body contains approximately 2–3 g of zinc, with roughly 0.1% replenished daily. Conservative estimates indicate that 25% of the global population is at risk of zinc deficiency, primarily driven by poverty and diets high in absorption inhibitors or low in bioavailable zinc. In affluent populations, deficiency arises from food choices, while chronic toxicity occurs from excessive zinc supplement consumption, which can induce copper deficiency. The review notes a narrow range between the recommended dietary allowance (RDA) and the reference dose (RfD) for safe intake, compounded by current diagnostic methods that lack sensitivity and specificity.
Why it matters
It highlights the challenge of managing zinc nutrition globally, where widespread deficiency risks in low-resource settings contrast with potential toxicity from over-supplementation in wealthier populations due to a narrow safety margin.
Limits
As a narrative review, it presents broad estimates rather than a systematic synthesis or novel empirical data. The abstract provides no specific quantitative thresholds for toxicity, search criteria, or sample sizes for the cited associations.
Cited by
- contradicts Excess copper intake, such as from copper plumbing pipes, depletes zinc in the body.