Bioavailability of zinc citrate is comparable to that from zinc gluconate and higher than from zinc oxide
According to new research published online in The Journal of Nutrition*, zinc citrate showed superior absorption compared to zinc oxide and was on pair with the nutritional benchmark zinc gluconate.
Despite of the benefits of zinc citrate over soluble zinc salts concerning zinc content and more neutral taste, no human absorption data was available to date.
The randomised, double-blind, three-way cross-over study was lead by Rita Wegmüller and Richard Hurrel of the ETH Zurich. 15 healthy young adults received 10 mg of elemental zinc as a supplement without food via zinc citrate, zinc gluconate or oxide zinc and absorption was measured using the double isotope tracer methodology.
Median fractional absorption of zinc from zinc citrate was 61.3% and was not different to that from zinc gluconate with 60.9%, but absorption from zinc oxide was at 49.9% significantly lower than from both other supplements (P < 0.01). Interestingly, three subjects had little or no absorption from zinc oxide. This might be explained by the fact that zinc oxide is an insoluble compound which may not be dissolved sufficiently by people with low gastric acid production.
The authors conclude that “…zinc citrate could be a useful compound for zinc supplementation. At the present time, WHO recommends the use of the water soluble compounds zinc sulfate, zinc acetate or zinc gluconate in the form of syrups or dispersible tablets in the management of diarrhea. Zinc citrate might be a useful addition to this list and be especially suitable for chewable/crushable tablets since it has better sensory properties …”
The study was supported by Jungbunzlauer International AG, Basel, Switzerland and the publication can be downloaded for free here. Zinc citrate is produced in Jungbunzlauer’s plant in Pernhofen, Austria and supplied to food, dietary supplement and pharmaceutical industries worldwide.
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Dr. Gerhard Gerstner
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*Rita Wegmüller, Fabian Tay, Christophe Zeder, Marica Brnić, Richard F. Hurrell: Zinc absorption by young adults from supplemental zinc citrate is comparable to that from zinc gluconate and higher than from zinc oxide. First published ahead of print 20 November, 2013 in The Journal of Nutrition as doi: 10.3945/jn.113.181487