How can staple crops be biofortified to fight hidden hunger?

Many people eat enough calories but too little iron, zinc or vitamin A. Breeding or engineering the staple crops they already eat to carry more of these nutrients, called biofortification, can reach them cheaply, provided the nutrients are absorbed and the crops are grown.

Question

What techniques and methods can raise the nutritional value of staple crops to produce biofortified foods? Routes include conventional breeding, genetic engineering and gene stacking, and agronomic biofortification such as micronutrient fertilisation, judged by whether the nutrients reach and benefit the people who eat the crops.

Background

The question is in the theme "advancing cultivation methods" of the 100 essential questions for the future of agriculture, compiled from 419 questions submitted worldwide in 2022, among questions on crop nutrient-use efficiency. Elsewhere the authors note that millions of people suffer from deficiencies of energy, protein and micronutrients such as vitamin A, iron and iodine [1].

What is known

• Since 2003, HarvestPlus and its partners have shown that biofortification through plant breeding works [2]. By the end of 2024, biofortified foods were enough to feed an estimated 360 million people, including 115 million who ate what they grew, and over 23 million smallholder households were growing biofortified crops [3].
• "Golden Rice 2", which carries a maize gene for phytoene synthase, accumulated up to 23 times more carotenoids than the original Golden Rice, mostly as β-carotene [4].
• In a randomised controlled feeding trial with 195 young Rwandan women, most of them iron-deficient at the start, eating iron-biofortified beans for 128 days significantly improved iron status [5].
• Micronutrient deficiency, or hidden hunger, affects about one third of the world's population; stacking several traits by combining conventional breeding with metabolic engineering has been proposed to multiply the impact of biofortification [6].

What would count as progress

No single result settles a question like this; contributions like these would move it forward:

• Multi-nutrient lines (for example iron, zinc and provitamin A together) with yields matching the best conventional varieties, tested across environments.
• Efficacy and effectiveness trials that measure nutrient status and health outcomes in target populations, reporting bioavailability and losses during storage and cooking.
• Adoption studies that track how many households grow and eat biofortified varieties, and why or why not.

References

1. Hu, Y. et al. (2023). 100 essential questions for the future of agriculture. Modern Agriculture 1(1), 4–12.
2. Bouis, H. E. & Saltzman, A. (2017). Improving nutrition through biofortification: a review of evidence from HarvestPlus, 2003 through 2016. Global Food Security 12, 49–58.
3. HarvestPlus (2025). Key Metrics 2024. HarvestPlus, updated May 2025.
4. Paine, J. A. et al. (2005). Improving the nutritional value of Golden Rice through increased pro-vitamin A content. Nature Biotechnology 23(4), 482–487.
5. Haas, J. D. et al. (2016). Consuming iron biofortified beans increases iron status in Rwandan women after 128 days in a randomized controlled feeding trial. The Journal of Nutrition 146(8), 1586–1592.
6. Van Der Straeten, D. et al. (2020). Multiplying the efficiency and impact of biofortification through metabolic engineering. Nature Communications 11, 5203.

Source

Imported from 100 essential questions for the future of agriculture, question 47, curated by Hu et al. Listed as open in the source (2023) and still an active research question as of 2026-10-20. The statement above is written in our own words; see the source for the original wording, history and discussion.