Inorganic zinc and the intestinal absorption of ferrous iron

Crofton, R. W.; Gvozdanovic, D.; Gvozdanovic, S.; Khin, C.; Brunt, P. W.; Mowat, N. A. G.; Aggett, Peter

doi:10.1093/ajcn/50.1.141

Cited by 56 publications

(28 citation statements)

References 22 publications

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“…The molar ratio of iron and zinc seems to be critical in determining the interactive effects. One study has shown that zinc inhibited iron absorption when the zinc-iron ratio was 1.14:1 (1:1 molar ratio), but not when it was 0.36:1 (0.4:1 molar ratio) [28] . Another study has shown that a zinc-iron ratio of 5:1 significantly reduced iron absorption from an aqueous solution, but did not affect heme iron absorption from a hamburger meal in humans [29] .…”

Section: Discussionmentioning

confidence: 99%

Concurrent repletion of iron and zinc reduces intestinal oxidative damage in iron- and zinc-deficient rats

Bodiga

Krishnapillai²

2007

WJG

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AIM:To understand the interactions between iron and zinc during absorption in iron-and zinc-deficient rats, and their consequences on intestinal oxidant-antioxidant balance. METHODS:Twenty-four weanling Wistar-Kyoto rats fed an iron-and zinc-deficient diet (< 6.5 mg Fe and 4.0 mg Zn/kg diet) for 4 wk were randomly divided into three groups (n = 8, each) and orally gavaged with 4 mg iron, 3.3 mg zinc, or 4 mg iron + 3.3 mg zinc for 2 wk. At the last day of repletion, 3 h before the animals were sacrificed, they received either 37 mBq of 55 Fe or 65 Zn, to study their localization in the intestine, using microautoradiography. Hemoglobin, iron and zinc content in plasma and liver were measured as indicators of iron and zinc status. Duodenal sections were used for immunochemical staining of ferritin and metallothionein. Duodenal homogenates (mitochondrial and cytosolic fractions), were used to assess aconitase activity, oxidative stress, functional integrity and the response of antioxidant enzymes. RESULTS:Concurrent repletion of iron-and zinc-deficient rats showed reduced localization of these minerals compared to rats that were teated with iron or zinc alone; these data provide evidence for antagonistic interactions. This resulted in reduced formation of lipid and protein oxidation products and better functional integrity of the intestinal mucosa. Further, combined repletion lowered iron-associated aconitase activity and ferritin expression, but significantly elevated metallothionein and glutathione levels in the intestinal mucosa. The mechanism of interactions during combined supplementation and its subsequent effects appeared to be due to through modulation of cytosolic aconitase, which in turn influenced the labile iron pool and metallothionein levels, and hence reduced intestinal oxidative damage. CONCLUSION:Concurrent administration of iron and zinc corrects iron and zinc deficiency, and also reduces the intestinal oxidative damage associated with iron supplementation.

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Section: Discussionmentioning

confidence: 99%

Concurrent repletion of iron and zinc reduces intestinal oxidative damage in iron- and zinc-deficient rats

Bodiga

Krishnapillai²

2007

WJG

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“…The first study looking at the effect of Zn on Fe absorption was published by Crofton et al (1989). The authors used the Fe post absorptive curve (AUC) as a surrogate of Fe absorption.…”

Section: Effect Of Zn Given In Saline or Aqueous Solutions Or As A Sumentioning

confidence: 99%

Acute inhibition of iron bioavailability by zinc: studies in humans

et al. 2012

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Iron (Fe) and zinc (Zn) deficiencies constitute two of the most important nutritional and public health problems affecting developing countries. Combined supplementation or fortification with Zn and Fe are strategies that can be used to improve the Zn and Fe status of a population. However, there is concern about potential negative interactions between these two micronutrients due to a competitive binding to DMT1 and Zip14 transporter. Studies performed in humans have shown an inhibitory effect of Zn on Fe absorption when both minerals are given together as a solution in fasting conditions. We found that at low doses of iron (0.5 mg) the threshold for the inhibition of iron bioavailability was at a Zn:Fe wt/wt ratio ≥5.9:1, whereas at higher doses of Fe (10 mg) this inhibition occurred at 1:1 Zn:Fe wt/wt ratio. This differential response could be explained by the variation in the abundance of both cations as they compete for a limited number of shared transporters at the enterocyte. Conflicting results have been obtained when this interaction was studied in different food matrices. A negative interaction was not observed when Fe and Zn were provided in a composite hamburger meal, premature formula, human milk, or cow milk. A decrease on Fe absorption was observed in only 1 of 3 studies when Fe and Zn were supplied in wheat flour. The possibility of a negative interaction should be considered for supplementation or fortification programs with both microminerals.

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“…A recent study has shown that zinc impaired the intestinal absorption of iron in humans (241). Mahloudji A high level of zinc supplementation may also affect iron storage.…”

Section: Interactions With Other Metalsmentioning

confidence: 99%

Zinc: Health Effects and Research Priorities for the 1990s

Walsh¹,

Sandstead²,

Prasad³

et al. 1994

Environmental Health Perspectives

156

225

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This review critically summarizes the literature on the spectrum of health effects of zinc status, ranging from symptoms of zinc deficiency to excess exposure. Studies on zinc intake are reviewed in relation to optimum requirements as a function of age and sex. Current knowledge on the biochemical properties of zinc which are critical to the essential role of this metal in biological systems is summarized. Dietary and physiological factors influencing the bioavailability and utilization of zinc are considered with special attention to interactions with iron and copper status. The effects of zinc deficiency and toxicity are reviewed with respect to specific organs, immunological and reproductive function, and genotoxicity and carcinogenicity. Finally, key questions are identified where research is needed, such as the risks to human health of altered environmental distribution of zinc, assessment of zinc status in humans, effects of zinc status in relation to other essential metals on immune function, reproduction, neurological function, and the cardiovascular system, and mechanistic studies to further elucidate the biological effects of zinc at the molecular level. - There is considerable evidence that zinc deficiency in humans is a serious worldwide problem and outweighs the potential problem of accidental, self-imposed, or environmental exposure to zinc excess. Acute deficiency (1) and chronic deficiency (2) are well-known entities in human populations and are probably much more common than generally recognized. The importance of zinc for human health was first documented in 1963 (3) Telephone (617) (617) 638-4329. E-mail: ctwalsh~bu.edu renal disease, and other chronically debilitating diseases are now known to be predisposing factors for zinc deficiency in humans (4).Zinc deficiency is reflected in clinical syndromes which affect men and women of all ages and all socioeconomic and cultural classes in the United States. It is neither prevalent in any specific area of the United States nor associated with any specific or definitive biochemical marker, which can make its identification difficult and confusing. Its presence is manifested by a wide spectrum of symptoms, from acute, life threatening problems to mild subclinical or marginal disorders which may only vaguely disturb well being. The acute problems are often seen in profoundly ill patients treated in hospitals, whereas subclinical problems may be so vague that patients seek assistance outside traditional medical practice.Based upon clinical data and using traditional, epidemiologic techniques, Henkin and Aamodt (5) have reclassified zinc deficiency into three syndromes; these are a) acute, b) chronic, and c) subacute zinc deficiency. Acute zinc deficiency is relatively uncommon and follows parenteral hyperalimentation or oral L-histidine administration. Chronic zinc deficiency is more common, usually resulting from chronic dietary lack of zinc. Subacute or latent zinc deficiency is the most common of these syndromes. It is estimated that there are 4...

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Inorganic zinc and the intestinal absorption of ferrous iron

Cited by 56 publications

References 22 publications

Concurrent repletion of iron and zinc reduces intestinal oxidative damage in iron- and zinc-deficient rats

Concurrent repletion of iron and zinc reduces intestinal oxidative damage in iron- and zinc-deficient rats

Acute inhibition of iron bioavailability by zinc: studies in humans

Zinc: Health Effects and Research Priorities for the 1990s

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