Combining genetic and agronomic fortification is essential to meet human health targets for zinc, iron, and protein concentrations in rice grains: A meta-analysis

Rice, consumed by half of the world’s population, is inherently low in zinc (Zn), iron (Fe), and protein. We synthesized data from 245 studies across 34 countries to evaluate the impact of genetic, agronomic, and processing interventions on rice grain Zn, Fe, and protein concentrations. Zn-biofortified cultivars had 9.8% higher grain Zn concentrations than non-biofortified cultivars, while Fe-biofortified cultivars did not exhibit a significant improvement in Fe content. The probabilities of achieving the breeding target concentrations of Zn (28 mg kg ^–1 ) and Fe (15 mg kg ^–1 ) in polished rice were only 4.0% and 10.5%, while Zn and Fe fertilization increased the probability to 41.3% and 67.7% for Zn and Fe, respectively. Milling and polishing of brown rice grains reduced Zn, Fe, and protein concentrations by 21%, 70%, and 6.5%, respectively. Our findings emphasize the need for combined use of genetic and agronomic fortification, and consumption of parboiled rice to attain desired health impacts.