Marija Knez

How Much Nutritional Iron Deficiency in Humans Globally Is due to an Underlying Zinc Deficiency

This chapter recounts the impact of the green revolution (1960–1980) on subsequent world food supplies and its consequences in terms of human nutrition and health via its impact on the micronutrient status of staple foods and of diets generally. Micronutrient deficiency disorders now occur in over half of the total human population. This chapter then reviews the recent medical literature on the molecular physiology of the human gut in relation to micronutrient absorption from food and the regulation of nutrient balance from diets heavily based on cereals that are relatively poor in micronutrients. Weaving these two literatures together leads to the conclusion that basing the green revolution on low micronutrient-dense cereals to replace the lower yielding but more nutrient-dense pulses and other dicotyledonous food crops is the probable cause of the epidemics of micronutrient deficiencies in the burgeoning human population in the years since 1980. There are lessons in this for the implementation of new efforts to increase food production in the face of even further increases in population forecast to 2050, especially the new effort starting in Africa, and for improving primary health care generally in resource-rich as well as resource-poor countries. We conclude that while complete nutrient balance in our diets is the only satisfactory aim of a sustainable food strategy, we focus attention on zinc deficiency and its alleviation as the most extensive and urgent problem among several that arose as an unforeseen side effect of the first green revolution.

New Perspectives on the Regulation of Iron Absorption via Cellular Zinc Concentrations in Humans

abstract Iron deficiency is the most prevalent nutritional deficiency, affecting more than 30% of the total worlds population. It is a major public health problem in many countries around the world. Over the years various methods have been used with an effort to try and control iron-deficiency anemia. However, there has only been a marginal reduction in the global prevalence of anemia. Why is this so? Iron and zinc are essential trace elements for humans. These metals influence the transport and absorption of one another across the enterocytes and hepatocytes, due to similar ionic properties. This paper describes the structure and roles of major iron and zinc transport proteins, clarifies iron-zinc interactions at these sites, and provides a model for the mechanism of these interactions both at the local and systemic level. This review provides evidence that much of the massive extent of iron deficiency anemia in the world may be due to an underlying deficiency of zinc. It explains the reasons for predominance of cellular zinc status in determination of iron/zinc interactions and for the first time thoroughly explains mechanisms by which zinc brings about these changes.

The Impact of Micronutrient Deficiencies inThe Impact of Micronutrient Deficiencies in Agricultural Soils and Crops on the Nutritional Health of Humans

Cereal crops underpin the food supply for peasant farmers in developing countries, a situation that has persisted since the green revolution of the decades of the 1960s and 1970s greatly increased their productivity; indeed yields more than doubled. Ever since, the modern high-yielding, disease-resistant cereals that also show greater tolerance to environmental stresses like drought and heat have dominated the diets of subsistence farmers and urban poor alike.

The influence of food consumption and socio-economic factors on the relationship between zinc and iron intake and status in a healthy population

OBJECTIVE To examine Zn and Fe nutritional status of a healthy population by means of anthropometric, dietary and biochemical measurements and to investigate the relationship of usual Zn and Fe dietary intakes to Zn and Fe status. In addition, to examine the impact of food choices and socio-economic factors on Fe and Zn dietary intakes and status with the aim to identify groups at risk of dietary deficiency and suggest factors that may influence the status of these nutrients. DESIGN Food consumption was assessed by 24 h recall questionnaires. Twenty biochemical parameters were measured, of which Hb, haematocrit, erythrocyte count and plasma concentrations of Fe and Zn were directly related to Fe and Zn nutrition. The prevalence of study participants with inadequate micronutrient intakes was calculated using the Estimated Average Requirement cut-point method. SETTING Serbia, Europe. SUBJECTS Apparently healthy adults (25-65 years of age). RESULTS Mean daily Zn and Fe intakes were 9·1 mg and 11·6 mg for males and 7·3 mg and 9·4 mg for females, respectively. Five per cent of the study population had inadequate dietary Fe intake and 15-25 % had inadequate Zn intake. Lower Hb concentrations were measured in women with lower Zn intakes. No differences in Fe and Zn intakes and status among various socio-economic groups were observed, except for Fe intake between the low-income and affluent groups. CONCLUSIONS Regular follow-ups are needed to ensure that potential deficiencies of Zn and Fe do get recognized and addressed in a timely manner.

Linoleic Acid:Dihomo-γ-Linolenic Acid Ratio Predicts the Efficacy of Zn-Biofortified Wheat in Chicken (Gallus gallus)

The amount of Zn absorbed from Zn-biofortified wheat material has been determined using an in vivo model of Zn absorption. The erythrocyte linoleic:dihomo -γ-linolenic acid (LA:DGLA) ratio was used as a biomarker of Zn status. Two groups of chickens (n = 15) were fed different diets: a high-Zn (46.5 μg Zn g-1) and a low-Zn wheat-based diet (32.8 μg Zn g-1). Dietary Zn intakes, body weight, serum Zn, and the erythrocyte fatty acid profile were measured, and tissues were taken for gene expression analysis. Serum Zn concentrations were greater in the high Zn group (p < 0.05). Duodenal mRNA expression of various Zn transporters demonstrated expression upregulation in the birds fed a low Zn diet (n = 15, p < 0.05). The LA:DGLA ratio was higher in the birds fed the low Zn diet (p < 0.05). The higher amount of Zn in the biofortified wheat resulted in a greater Zn uptake.

The Linoleic Acid: Dihomo-γ-Linolenic Acid Ratio (LA:DGLA)—An Emerging Biomarker of Zn Status

Zinc (Zn) deficiency is a common aliment predicted to affect 17% of the world’s population. Zinc is a vital micronutrient used for over 300 enzymatic reactions and multiple biochemical and structural processes in the body. Although whole blood, plasma, and urine zinc decrease in severe zinc deficiency, accurate assessment of zinc status, especially in mild to moderate deficiency, is difficult as studies with these biomarkers are often contradictory and inconsistent. Hence, as suggested by the World Health Organization, sensitive and specific biological markers of zinc status are still needed. In this review, we provide evidence to demonstrate that the LA:DGLA ratio (linoleic acid:dihomo-γ-linolenic acid ratio) may be a useful additional indicator for assessing Zn status more precisely. However, this biomarker needs to be tested further in order to determine its full potential.

Alterations in the Gut (Gallus gallus) Microbiota Following the Consumption of Zinc Biofortified Wheat (Triticum aestivum)-Based Diet

The structure and function of cecal microbiota following the consumption of a zinc (Zn) biofortified wheat diet was evaluated in a well-studied animal model of human nutrition ( Gallus gallus) during a six-week efficacy trial. Using 16S rRNA gene sequencing, a significant increase in β- but not α-microbial diversity was observed in the animals receiving the Zn biofortified wheat diet, relative to the control. No significant taxonomic differences were found between the two groups. Linear discriminant analysis revealed a group of metagenomic biomarkers that delineated the Zn replete versus Zn deficient phenotypes, such that enrichment of lactic acid bacteria and concomitant increases in Zn-dependent bacterial metabolic pathways were observed in the Zn biofortified group, and expansion of mucin-degraders and specific bacterial groups able to participate in maintaining host Zn homeostasis were observed in the control group. Additionally, the Ruminococcus genus appeared to be a key player in delineating the Zn replete microbiota from the control group, as it strongly predicts host Zn adequacy. Our data demonstrate that the gut microbiome associated with Zn biofortified wheat ingestion is unique and may influence host Zn status. Microbiota analysis in biofortification trials represents a crucial area for study as Zn biofortified diets are increasingly delivered on a population-wide scale.