Improving wheat as a source of iron and zinc for global nutrition

Abstract

Wheat is the staple food crop in temperate countries and increasingly consumed in developing countries, displacing traditional foods. However, wheat products are typically low in bioavailable iron and zinc, contributing to deficiencies in these micronutrients in countries where wheat is consumed as a staple food. Two factors contribute to the low contents of bioavailable iron and zinc in wheat: the low concentrations of these minerals in white flour, which is most widely consumed, and the presence of phytates in mineral‐rich bran fractions. Although high zinc types of wheat have been developed by conventional plant breeding (biofortification), this approach has failed for iron. However, studies in wheat and other cereals have shown that transgenic (also known as genetically modified; GM ) strategies can be used to increase the contents of iron and zinc in white flour, by converting the starchy endosperm tissue into a ‘sink’ for minerals. Although such strategies currently have low acceptability, greater understanding of the mechanisms which control the transport and deposition of iron and zinc in the developing grain should allow similar effects to be achieved by exploiting naturally induced genetic variation. When combined with conventional biofortification and innovative processing, this approach should provide increased mineral bioavailability in a range of wheat products, from white flour to wholemeal.

Winter Wheat Grain Quality, Zinc and Iron Concentration Affected by a Combined Foliar Spray of Zinc and Iron Fertilizers

“…Crude fiber was increased remarkably by combined solution with a 60% Zn + 40% Fe ratio as well as other ratios. This could be possibly linked with a significant accumulation of Zn and Fe in aleurone, endosperm, and embryo [22,27] when these micronutrients are supplied to wheat, as discussed in different literature [13,22,74]. It can also be a result of assimilates remobilization in which process Zn and Fe have a greater role.…”

“…Recently, it was reported that in the UK, the Zn intake of about a quarter of adolescents is below the lower reference nutrient intake (LRNI) and the Fe intake of over half of all adolescent girls and over a quarter of adult women is below the LRNI [13,14]. Nutrient-deficient food and diet related problems are the main cause of death on Earth, and this can be prevented by supplying nutrients in a sustainable manner, and finding solutions to malnutrition [4].…”

“…Plant breeding (e.g., genetic biofortification) and application of Zn and Fe fertilizers (e.g., agronomic biofortification), are two important agricultural tools to improve the grain concentration of Zn and Fe [22]. Even though genetic engineering opens more doors to increase dramatically the bioavailability of Zn and Fe in grains, its acceptability by consumers and regulatory bodies is very limited, and genetically modified crop cultivation and marketing are not likely to be relaxed in the near future [13]. Agronomic biofortification is achieved by applying micronutrients to the soil and/or directly to the leaves of the crop [45].…”

The Impact of Phytases on the Release of Bioactive Inositols, the Profile of Inositol Phosphates, and the Release of Selected Minerals in the Technology of Buckwheat Beer Production

“…Phytic acid (myo-inositol 1,2,3,4,5,6-hexakisphosphate, InsP 6 ) is the main phosphorus reservoir in plant tissues, which, in the form of phytate salts, complexes with proteins and carbohydrates, and is considered as an antinutritional factor [10,11]. Phytate, as the compound that reduces the bioavailability of minerals, protein, and starch, may exert a negative effect on mashing and fermentation processes.…”

“…Phytate, as the compound that reduces the bioavailability of minerals, protein, and starch, may exert a negative effect on mashing and fermentation processes. It decreases starch degradation and the available spectrum of fermentable sugars mainly by chelating Ca 2+ and lowering α-amylases activity, inhibits protease, and reduces free amino acid release, as well as chelates cofactors like Mg 2+, Zn 2+ ions, which are crucial for proper Saccharomyces cerevisiae fermentation [9,10,12]. Only limited phytate dephosphorylation may occur by means of thermal hydrolysis, e.g., during cooking, and therefore, enzymatic decomposition seems to be the only effective treatment.…”