Food becoming more calorific but less nutritious due to rising carbon dioxide

One of the researchers at Leiden University said there was a ‘complete shift’ in the composition of our foods. Photograph: Matthew Ashmore/Alamy

More carbon dioxide in the environment is making food more calorific but less nutritious – and also potentially more toxic, a study has found.

Sterre ter Haar, a lecturer at Leiden University in the Netherlands, and other researchers at the institution created a method to compare multiple studies on plants’ responses to increased CO₂ levels. The results, she said, were a shock: although crop yields increase, they become less nutrient-dense. While zinc levels in particular drop, lead levels increase.