Iron and Zinc at a cross-road: A trade-off between micronutrients and anti-nutritional factors in pearl millet flour for enhancing the bioavailability

Worldwide, millets are regarded as a nutri-grain; however, they are the least exploited. Pearl millet grain is abundant in health-beneficial nutrients, making it suitable as food and feed; though poor in bioavailability of micronutrients like iron (Fe) and zinc (Zn) due to abundance of anti-nutritional factors causing micronutrient deficiencies (MNDs). Crop biofortification has been used as one of the potential strategies to control micronutrient malnutrition, mainly Fe and Zn in a cost effective manners. Many in vivo and in vitro studies have advocated the negative impact of phytates, fibers and tannins on iron and zinc availability. The interaction between Fe, Zn and other minerals has also adverse impact on the bioaccessability and bioavailability of micronutrients. The efforts have been made to reduce anti-nutritional factors using different processing methods like pre-soaking of seeds, fermentation, heat treatment, snap heat, phytase treatment, etc. to improve the nutritional quality of the flour. Hydrothermal with infra-red treatment has been observed to be most effective in enhancing the availability of minerals. The screening of pearl millet germplasms in many studies indicated presence of sufficient variability for grain iron and zinc. Breeding, molecular and processing approaches should be followed to achieve micronutrient homeostasis and nutrient sustainability. [Display omitted] •Pearl millet flour is rich in macro- and micronutrients required for our balanced diet.•The bioavailability of Fe/ Zn is very low due to abundance of ANFs causing MNDs.•Phytase treatment, germination, fermentation, etc. enhances the bioavailability of Fe and Zn.•Wide-diversity has been observed in ANFs and nutrients in pearl millet germplasm.•Micronutrient homeostasis can be achieved through breeding and processing methods.