Efficacy of iron-biofortified crops

Abstract

Biofortification aims to increase the content of micronutrients in staple crops without sacrificing agronomic yield, making the new varieties attractive to farmers. Food staples that provide a major energy supply in low-and middle-income populations are the primary focus. The low genetic variability of iron in the germplasm of most cereal grains is a major obstacle on the path towards nutritional impact with these crops, which is solvable only by turning to transgenic approaches. However, biofortified varieties of common beans and pearl millet have been developed successfully and made available with iron contents as high as 100 mg/kg and 80 mg/kg, respectively, two to five times greater than the levels in the regular varieties. This brief review summarizes the research to date on the bioavailability and efficacy of iron-biofortified crops, highlights their potential and limitations, and discusses the way forward with multiple biofortified crop approaches suitable for diverse cultures and socio-economic milieu. Like post-harvest iron fortification, these biofortified combinations might provide enough iron to meet the additional iron needs of many iron deficient women and children that are not covered at present by their traditional diets. BIOFORTIFICATION OF STAPLE CROPS WITH IRONThe staple crops which have shown the most potential to increase dietary iron intake through traditional or selective plant breeding are common beans, pearl millet, cowpea, chickpea, pigeon pea, and lentils. Plant breeders have successfully developed varieties of these common staples with iron content two to five times higher than typical commercial varieties. Even considering the low iron bioavailability from these staples due to their high phytic acid (PA) content, it has been estimated that the higher iron content in these biofortified pulses and pearl millet can provide an additional 20 to 30% of the estimated average iron requirement for non-pregnant, non-lactating women of reproductive age, and children three to six years of age who consume these as staples [1]. Careful testing of these varieties is underway so that they can ultimately be introduced into food systems with claims of nutritional superiority and agronomic competitiveness.Before new biofortified varieties are released to farmers, their ability to improve iron status in at-risk populations must be demonstrated initially through well-designed and implemented, randomized controlled efficacy trials, and ideally also under market conditions via effectiveness studies. Until now, only three iron-biofortified staple foods, rice (in the Philippines), beans (in Rwanda), and pearl millet (in India), have been tested for nutritional efficacy, and two of these (biofortified beans and pearl millet) have been tested for iron bioavailability. Given the relatively short time that biofortification has been pursued as an intervention strategy, no effectiveness trials have yet been completed for iron-biofortified crops. Bioavailability of Iron-biofortified Staple Foods: Evidence ...

Biofortified crops for tackling micronutrient deficiencies – what impact are these having in developing countries and could they be of relevance within Europe?

“…Furthermore, the impact of polyphenols on bioavailability is not sufficiently straightforward, due to the aforementioned modifying factors, to warrant exclusive use of white beans (Boy et al . ).…”

“…Standard pearl millet can contain ~2 mg iron per 100 g whereas biofortified varieties can contain ~8 mg per 100 g (Boy et al . ). Pearl millet husks are purple in colour due to the presence of tannins, which are thought to inhibit iron absorption.…”

“…Low genetic variability among rice varieties, substantial losses during rice polishing and low iron contents compared to beans and pearl millet restrict the potential usefulness of this crop in enhancing iron status (Boy et al . ).…”

The impact of food fortification on stunting in Zimbabwe: does gender of the household head matter?

“…Several efficacy and impact studies have shown that food fortification in its three forms can have a nutritional impact [7,9,12,14,22]. For example, studies conducted in rural Uganda showed that the introduction of Orange-fleshed sweet potato (OFSP) resulted in increased vitamin A intakes among children and women, and improved vitamin A status among children [19].…”

The impact of food fortification on stunting in Zimbabwe: Does gender of the household head matter?

“…Female headed households are more likely to adopt food fortification than their male counterparts. Several efficacy and impact studies have shown that food fortification in its three forms can have a nutritional impact (Biebinger & Hurrell, 2008;Boy et al, 2017;Finkelstein et al, 2017;Das et al, 2018;Lividini et al, 2018). For example, studies conducted in rural Uganda showed that the introduction of Orange-fleshed sweet potato (OFSP) resulted in increased vitamin A intakes among children and women, and improved vitamin A status among children (Hotz et al, 2012).…”