The Importance of Zinc in Human Nutrition and Estimation of the Global Prevalence of Zinc Deficiency

Abstract

This paper summarizes recent research on the importance of zinc for human health, and reviews available methods of evaluating zinc status in individuals and populations. The lack of generally accepted biomarkers of zinc status has impeded estimation of the global prevalence of zinc deficiency. Although measurement of zinc consumption and/or plasma zinc concentration can be used to assess population zinc status, few countries have collected adequate data to permit estimation of the prevalence of zinc deficiency. An alternative method, described herein, is to estimate the zinc content of national food supplies, using FAO food balance sheets; the assumed bioavailability of that zinc based on phytate:zinc molar ratios; and the relation between absorbable zinc and theoretical requirements according to country-specific demographics. The results of these analyses indicate that nearly half of the world's population is at risk for inadequate zinc intake, suggesting that public health programs are urgently needed to control zinc deficiency.

Use of national food balance data to estimate the adequacy of zinc in national food supplies: methodology and regional estimates

“…In our original calculations of the amount of absorbable zinc available in national food supplies 7 , we applied estimates of the fractional absorption of zinc (FAZ) by using a model proposed by the World Health Organization (WHO), which was based mostly on single-meal studies 14 .…”

“…This paper describes the methods used to achieve these objectives and the resulting estimates of national, regional and global risks of inadequate zinc intake. A preliminary paper describing this approach was published previously 7 , and a brief summary of the results was included in a recent technical document prepared by the International Zinc Nutrition Consultative Group (IZiNCG) 1 . The current paper differs from the earlier presentations in several important ways, as follows:…”

Effect of zinc supplementation on vitamin status of middle-aged and older European adults: the ZENITH study

“…Most of these studies have been performed among hospitalized or institutionalized elderly or focussed mainly on the relationship between zinc status and immune function (Pepersack et al, 2001;Mitchell et al, 2003;Chandra, 2004), while data in elderly free living people are scarce. Results are heterogeneous and conflicting but in agreement with the importance of zinc supplementation in case of deficiency or in case of altered metabolism associated with reduced immune response (Turnlund et al, 1986;Cousin, 1989;McClain and Stuart, 1990;Bales et al, 1994;Sturniolo et al, 1994;Fortes et al, 1998;Brown et al, 2001;Pepersack et al, 2001;Mitchell et al, 2003;Chandra, 2004).…”

Is the Mediterranean diet adequate to satisfy zinc requirements during adolescence?

“…According to Brown et al (7) , the Zn absorbable from the diet may be estimated by calculating the phytate:Zn molar ratio; it is accepted that diets with a phytate:Zn ratio .15 have relatively poor Zn bioavailability, those with a ratio between 5 and 15 have medium Zn bioavailability, and ratios ,5 imply relatively good Zn bioavailability. According to the range of phytate contents reported by Brown et al (7) for the different sources of food and taking into account the food consumption among the participants of the present assay, the phytate:Zn ratio in our study ranged from 2 to 11, which would correspond to a high-moderate Zn bioavailability diet. The maximum value is comparable with the overall range of phytate:Zn molar ratio reported by Wuehler et al (33) for Western Europeans (10?6) and with the mean value of 10?1 observed in Koreans consuming varied diets but rich in vegetables, legumes, grains and cereals (34) .…”

“…This deficiency is mainly due to an insufficient mineral intake or to the consumption of diets with low Zn bioavailability. According to Brown et al (7) , approximately 50 % of the world's population is at risk of inadequate Zn intake. Individuals at risk of low Zn status include those with low absorption, increased losses or increased needs due to growth, heightened by low Zn intake or by a diet with low Zn bioavailability.…”