“Malnourished kids perform worse in school due to reduction in cognitive capacity. This has serious economic consequences.”  — Akinwumi Adesina, President of the African Development Bank & 2017 World Food Prize laureaute

The brain has an extreme appetite. In adults, it only accounts for 2 percent of our body weight but consumes 20 percent of the energy produced by the body. For example, if you consumed 2,000 calories yesterday, about 400 of those calories were used to carry out brain processes. In addition to energy, the brain requires other building blocks and nutrients to perform its functions. One of these is iron.

This is part of what makes iron deficiency is so deleterious for individuals and societies. But in a recent study published in the Journal of Nutrition, we found consuming high-iron biofortified pearl millet improved cognitive function in iron-deficient Indian adolescents. Here, I briefly explain what we mean by cognitive function, how we attributed its improvement to biofortified pearl millet, and what the implications of these findings are.

Iron plays several important roles in the brain. First, iron is an essential cofactor for mitochondrial enzymes involved in producing energy, so the brain wouldn’t be able to produce energy without iron. Second, iron is needed by special cells called oligodendrocytes, which produce myelin, a fatty substance wrapped around neurons like insulation around a wire. Myelin allows cells in the central nervous system to rapidly transmit signals. Third is iron’s role in neurotransmitter synthesis. Neurotransmitters are chemical messengers that convey signals from one neuron to another, allowing the nervous system to communicate across the brain and body.

Since we studied living humans in a field setting, we couldn’t measure the amount of iron or neurotransmitters in the brain. However, we could measure the amount of iron in the blood, and we could measure behavior, a product of how well the brain functions, which is partly due to iron. In our study, we measured behavior by having the students play a set of five “brain games” on the computer that measure attention and memory. We designed the study so that we could attribute improvements in performance—how fast and how well the students played the games—to consuming biofortified pearl millet.

We compared performance for a random group of students who consumed biofortified pearl millet to another random group of students who were the same age at the same school who consumed another variety of pearl millet lower in iron content. The millet was provided in the form of bhakri, a local flatbread, and shev, a savory snack made from extruded pearl millet flour. We measured cognitive function with the computer-based tests before they started eating the pearl millet and again after six months of consumption at daily school meals. By randomly assigning each student to one of the two groups, we tried to reduce differences between the groups that could account for measured differences in cognitive performance.

We found that consumption of biofortified pearl millet raised blood levels of iron faster and improved attention and memory more than the lower iron pearl millet. A note of caution: this tightly-controlled efficacy trial in a single school where pearl millet was provided freely provides proof of concept but is not meant to describe what would happen in the real world. (Any real-world impact would have to be determined in an effectiveness trial.) Assuming farmers in low income countries adopt high-iron biofortified crops and those crops reach iron-deficient individuals (one important avenue in India may be the government’s school feeding program, the Midday Meal Scheme), biofortification could make a meaningful contribution to society’s most fundamental resource—the human mind.