# Grain zinc, iron and protein concentrations of contemporary wheat cultivars fall short of targets for human health

## TL;DR

Modern wheat varieties have lower zinc, iron, and protein levels than needed for human health, and even with improvements, meeting targets remains challenging.

## Contribution

A global meta-analysis reveals the decline in wheat nutrients and evaluates the effectiveness of biofortification strategies.

## Key findings

- Most modern wheat cultivars fail to meet zinc and iron nutritional targets.
- Zinc and iron fertilizers significantly boost grain nutrient concentrations.
- Combining genetic and agronomic approaches is key to improving wheat nutrition.

## Abstract

Grain zinc (Zn), iron (Fe) and protein concentrations have declined in wheat cultivars released since the 1960s. Here we conducted a meta-analysis of field studies to provide a global synthesis of how genetic, environmental and agronomic factors influence grain Zn, Fe and protein concentrations. The probability of achieving the Zn target (38 mg kg−1) was 38.9% across bread wheat and 42.7% of durum wheat grain samples, but only 28.5% of released bread wheat cultivars met this target. The probability of achieving the Zn target was 44.7% with Zn-biofortified cultivars but only 24% with non-fortified cultivars. The likelihood of achieving the Fe target (59 mg kg−1) was <8% across bread and durum wheat grain samples. Relative to nitrogen, phosphorus and potassium fertilizers, co-application of Zn and Fe increased grain Zn, Fe and protein concentrations by 27%, 41% and 25%, respectively. Combining agronomic and genetic biofortification is essential for improving grain nutrient concentrations and addressing micronutrient deficiencies.

A synthesis of 243 field studies shows that grain zinc, iron and protein concentrations in modern wheat cultivars have declined since the 1960s, with most varieties falling short of recommended nutritional targets. While agronomic and genetic biofortification can improve these traits, the likelihood of reaching target nutrient levels remains low, highlighting the need for integrated strategies.