Food loses nutritional value as CO₂ levels rise

Potatoes with beans may still make a solid meal today, but that could change quickly. New research from Leiden shows that crops contain fewer nutrients as atmospheric CO₂ continues to rise. And the impact isn’t limited to vulnerable regions. People who currently have plenty to eat may also face deficiencies.

Declining nutrients

What the researchers observe: plants contain less zinc, iron and protein when CO₂ levels increase. The average drop is 4.4%, with peaks reaching 38%. At the same time, the calorie content goes up. That may contribute to weight gain, even though the meal itself looks no different. There are also indications that harmful substances such as lead increase, although more data is needed to confirm this.

Environmental scientist Sterre ter Haar describes the issue clearly. “Vaak denken we bij voedselzekerheid aan de vraag of mensen hun maag kunnen vullen. Met ons onderzoek benadrukken we dat voedselzekerheid ook betekent dat ons voedsel voldoende voedingsstoffen bevat. Daar moeten we meer aandacht aan geven.”

Significant impact across many crops

The Leiden research team compared data from 43 crops, ranging from rice and potatoes to tomatoes and wheat. The data came from multiple studies in which crops were grown under different CO₂ concentrations. Not ideal for direct comparison. Still, it worked because the effect of CO₂ on nutrients turned out to be linear. Doubling CO₂? Then the effect doubles as well. This allowed the researchers to establish a baseline that connects all datasets.

A future already unfolding

The baseline was set at 350 ppm. The team then looked at what happens at 550 ppm, a level they consider achievable within our lifetime. We are currently at 425 ppm. That puts us halfway toward that scenario. Because of this rise, our diet is likely already less nutritious than it was a few decades ago. And it may mean we’ll need to pay closer attention to our food choices to ensure we get enough essential nutrients.

Research into solutions

The researchers hope their work will support further studies. More crops, more climate effects, more insight into how plants can be adapted. Perhaps through new cultivation methods. Or through improved greenhouse strategies.
Ter Haar sees opportunities: “Gelukkig is er veel innovatie in de Nederlandse voedselsector en hebben we sterke onderzoeksinstellingen die hier onderzoek naar kunnen doen. Samen kunnen we echt vooruitgang boeken.”

Universiteitleiden.nl