Potential for improving micronutrient supply and environmental sustainability by using underutilized crops in China

Rice and wheat provide the bulk of calories in diets globally. However, foods made from these cereals are commonly in refined forms and are low in micronutrients and dietary fiber. Increasing the consumption of more nutrient-dense, underutilized cereals and beans (UCBs), such as millet, sorghum, mung bean, along with unrefined rice and wheat, could improve diet quality. Compared with rice and wheat, UCBs are generally cultivated using less intensive methods, resulting in a lower environmental impact, though their productivity is generally lower. This study explores how reallocating rice and wheat areas to UCBs, either alone or combined with greater use of unrefined rice and wheat, could potentially enhance micronutrient supply (iron, thiamin, riboflavin, calcium, zinc), while reducing water use and greenhouse gas emissions in China. A strategy combining area reallocation and greater use of unrefined rice and wheat increased micronutrient supply and dietary fiber by 12–82%, reduced environmental impact by 11–12%, and slightly increased energy supply (3%). These outcomes were achieved by reallocating 7.9 million hectares (Mha) of rice area (26% of the current total) and 1.7 Mha of wheat area to sorghum (+5.5 Mha), millet (+2.5 Mha), beans (+1.4 Mha), and oats (+0.2 Mha). As a result, the supply of UCBs and unrefined rice and wheat products increased, supporting healthier diets. Reallocating only 5% of the rice area would still yield improvements, especially for dietary fiber and iron ( > 27%). These findings offer insights for rethinking the value of UCBs and supporting their integration into future food system strategies.