How micronutrients have shaped human DNA

Micronutrients, minerals that are part of the human diet in small amounts, may have influenced human evolution more than previously recognized. In a new study publishing September 10 in the Cell Press journal The American Journal of Human Genetics, researchers show how human ancestors from around the world developed various genetic adaptations in response to shortages and surpluses of minerals including iron, calcium, and zinc. 

“Different human populations lived in different environments, so they had to adapt to different kinds of environmental pressures, such as disease and diet, that over time can drive trait differences,” says first author Jasmin Rees, who led this study during her PhD at University College London and is now a postdoctoral researcher at the University of Pennsylvania.  

Micronutrients play an important role in metabolism, development, the immune system, and other functions in the human body. However, the authors note, their availability in food depends on their presence in the soil, so it varies widely across countries and continents. Before dietary supplements were available, many populations lived with too little—and, occasionally, too much—key dietary nutrients. For example, some populations living in African rainforests can develop goiter, a swelling in the neck from an enlarged thyroid, because the soil there is low in iodine.  

When deficiencies are severe and long lasting, they can act as selective pressure on human genes, Rees says. To better understand the scope of this genetic influence, the team decided to investigate how micronutrients as a whole have influenced human evolution. 

The researchers focused on 276 genes associated with how our bodies absorb, transport, or use 13 essential minerals, including iron, calcium, zinc, and selenium. They studied the evolution of these genes using the genetic data of more than 900 individuals from 40 different populations worldwide. 

“This is the first study that looks at micronutrient-driven adaptation on a global scale and across this many micronutrients,” says Rees.  

For every mineral studied, the team found evidence for adaptation in the genes of at least one population, and the impact of these micronutrients was evident across the globe. This suggests that each of these micronutrients likely influenced human evolution at some point in history and in some populations. 

Among the 13 minerals analyzed, some stood out. In Central America, the Maya who live in regions with iodine-poor soils show strong evidence of genetic changes in genes indicated in iodine regulation or metabolism, which could reflect adaptation to low levels of iodine in the diet. 

In contrast, in some parts of South Asia where the soil is very high in magnesium, the team found evidence for adaptation in two genes likely related to the level of magnesium uptake in the local populations—a change that the authors speculate might have protected people from magnesium poisoning.  

Understanding how pressure from micronutrient availability shaped human genes can help establish which populations may be most vulnerable to deficiencies as climate change and intense farming continue to deplete nutrients in soils, Rees says. 

“This paper is a first step in understanding which populations might be most at risk,” says Rees. “We hope with more studies, the findings can eventually help inform public health going forward.”  

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This work was supported by funding from the National Institute for Health and Care Research and the Wellcome Trust. 

The American Journal of Human Genetics, Rees et al., “Global impact of micronutrients in modern human evolution” https://www.cell.com/ajhg/fulltext/S0002-9297(25)00315-5

The American Journal of Human Genetics (@AJHGNews), published by Cell Press for the American Society of Human Genetics, is a monthly journal that provides a record of research and review relating to heredity in humans and to the application of genetic principles in medicine and public policy, as well as in related areas of molecular and cell biology. Visit http://www.cell.com/ajhg. To receive Cell Press media alerts, contact press@cell.com.