Minerals shaped human DNA in surprising ways

Minerals might look like small players in our meals, yet they can leave lasting marks in our DNA. A large global analysis now shows that shortages and surpluses of these micronutrients shaped human biology in ways that still influence health today.

A new study examined 276 genes tied to 13 minerals across 40 populations and found clear signs that natural selection responded to local diets and soils. The signals span minerals such as iron, calcium, zinc, iodine, magnesium, and more.

How minerals shaped human DNA

The research was led by Jasmin Rees during his PhD studies at University College London (UCL). The team searched human genomes for footprints of positive selection, a process where helpful genetic changes spread because they improve survival or reproduction.

They looked for two types of evidence and found both local and wider patterns. Some gene changes were shared across many regions, while others were tightly linked to one place and a specific nutrient challenge.

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

Micronutrient availability depends on soil, which can vary a lot even over short distances. Plants take up minerals from the ground, animals eat the plants, and we eat both, so geology quietly shapes what ends up on our plates.

Deficiencies remain common, affecting roughly 2 billion people worldwide. Before modern supplements and fortification, those gaps were even larger and more prolonged.

Genetic adaptations to minerals

The analysis highlighted iodine related genes in some Central American Maya communities that live on iodine poor soils. Iodine shortage can lead to goiter, an enlarged thyroid that signals low thyroid hormone production.

In parts of South Asia, soils carry very high magnesium. The researchers detected signs near genes linked to magnesium handling and proposed that these shifts could have reduced the risk of magnesium overload in those settings.

Zinc stood out for how widespread the signals were across non-African groups. Several zinc transporter genes showed signs of selection, which fits with the importance of zinc in immune function, growth, and metabolism.

Impact on health today

These patterns help explain why the same diet can affect people differently. If a community has many variants that conserve a scarce mineral, moving to a region or diet with plenty could change risk in ways doctors should anticipate.

Climate pressures add another layer. Rising carbon dioxide has been shown to reduce zinc and iron in key crops, which could tighten already narrow nutritional margins for many families.

Public health steps like iodized salt, biofortified staples, and targeted screening remain crucial. Genetic context does not replace nutrition programs, it can help fine tune them.

What the signals mean

Some nutrient-related genes show concentrated selection at a few points in the genome, a pattern called oligogenic adaptation. Others show weaker, dispersed signals across many genes, a pattern often called polygenic adaptation.

The study also estimated when some of these shifts likely happened. Many appear to cluster around migrations into new environments, which tracks with changes in soils and foods rather than any single recent cultural shift.

“Micronutrient deficiencies have likely shaped worldwide human evolution more directly than previously appreciated. This paper is a first step in understanding which populations might be most at risk,” said Rees.

Limitations and future research

Genome scans show where selection likely acted, but they do not prove the exact biological effect of each DNA change. Lab studies are needed to measure how a variant alters transport, storage, or enzyme activity.

Diet data and environmental maps can sharpen the picture. One recent analysis synthesized national intake surveys to estimate inadequate micronutrient intake across countries, pointing to where diet gaps are largest.

Better soil maps would also help, since farmers can fix plant deficiencies that matter for yield, but not always those that matter mainly for human health. That difference matters for elements like iodine and selenium, which are vital for us but not always for the crop.

Population level findings do not define any person. Your health depends on diet, environment, and many genes working together.

These discoveries are tools to make prevention smarter. They can help target fortification, guide supplementation policies, and focus screening where biology and environment intersect.

The study is published in The American Journal of Human Genetics.

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