Micronutrient ancestry: How availability shaped genes and influenced uptake

A new study finds that micronutrients may have influenced human evolution more than previously thought, shaping metabolism, development, and the immune system. The availability of minerals, such as iron, calcium, and zinc, in soils varies across continents, prompting genetic adaptations in response to shortages and surpluses. 

The publication in The American Journal of Human Genetics reveals that historic micronutrient levels throughout populations’ diets have brought on selective pressures on human genes, which led to genetic changes. It examined 276 genes linked to the absorption, transportation, or use of 13 essential minerals.

The researchers posit that knowing how micronutrient availability is shaped can help understand which populations might be most vulnerable to deficiencies. It is especially relevant as climate change and agricultural farming are depleting nutrients in soils.

“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 and study lead Jasmin Rees, Ph.D., University College London, UK, who is now a postdoctoral researcher at the University of Pennsylvania, US.

Nutrients shaping genetics

Micronutrients are essential for bodily functions but their availability in food relies on their presence in the soil. This is why it varies across countries. Before supplements were available, people depended on food and lived with too little and sometimes too much nutrients, say the researchers.

(Image credit: Jasmin Rees).

For instance, people living in African rainforests could develop a thyroid swelling in the neck (goiter) because iodine levels were too low, researchers note. Plus, Mayans in Central America also lived in regions with little iodine in the soil. However, genetic changes in regulation or metabolism show that they adapted to this deficiency.

Additionally, in some parts of South Asia, researchers found evidence of adaptation in two genes influencing magnesium uptake in local populations. This micronutrient is very high in soils in those areas. The researchers think this genetic change could have protected people from magnesium poisoning.

Extensive sampling

The researchers investigated how micronutrients as a whole influenced human evolution, using genetic data of over 900 people from 40 populations worldwide. “This is the first study that looks at micronutrient-driven adaptation on a global scale and across this many micronutrients,” says Rees. 

The researchers say that for each mineral analyzed, they found evidence of genetic adaptation within at least one population. Furthermore, its influence was “evident” worldwide, suggesting the likelihood that levels of minerals had influenced evolution at some point in history. 

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

Previous research emphasized the importance of considering race and ethnicity in health care. Nutrition Insight recently interviewed the study author, who called for more detailed and comprehensive data collection and reporting in health care systems, which currently limit prevention and treatment efforts. Racialized and Indigenous communities in Europe, North America, and Central America face a higher risk of cardiovascular disease.