Climate change could affect more than how much wheat farmers grow. New research suggests rising carbon dioxide levels can also change the wheat itself, potentially affecting the flour used to make bread and other everyday foods.
In a study published in Food Chemistry, researchers found that wheat grown under higher carbon dioxide (CO₂) levels generally contained less protein and produced smaller loaves of bread. The findings suggest that changes in the atmosphere could affect not just how much food we produce, but its quality, too.
Researchers in Germany grew 10 varieties of winter wheat in outdoor test plots, exposing some plants to higher CO₂ levels similar to those projected for the coming decades. The others grew under conditions closer to today's atmosphere.
Nine of the 10 varieties had lower protein levels under elevated CO₂, with reductions ranging from 1.9% to 10.3%. The remaining variety actually experienced a small increase, showing that not all wheat responds the same way.
The researchers also found changes in gluten, the protein that gives bread dough its stretch and helps it rise. Wheat grown under higher CO₂ generally contained less of several gluten proteins important for baking.
That difference showed up in the finished product. In standardized baking tests, loaves made from wheat grown under elevated CO₂ had an average of 4.1% less volume than those made from wheat grown under the lower levels.
The study also examined proteins that may play a role in wheat allergies and sensitivities. Some increased under elevated CO₂, while certain gluten components associated with celiac disease decreased.
However, those findings don't tell us whether wheat grown under higher CO₂ is more or less likely to cause health problems. The researchers didn't study people or measure immune responses, and the results don't suggest that wheat is becoming safer for people with celiac disease.
Katharina Scherf, a professor at the Technical University of Munich and a senior researcher on the study, emphasized that more research is needed to understand the potential health implications.
“However, further studies are needed to clarify the actual biological and immunological significance of these differences,” Scherf said.
The experiment also has limitations. It took place at one location during a single growing season, so researchers still need to determine how different wheat varieties respond under other growing conditions.
One promising finding was that some varieties held up better than others. That could help plant breeders develop wheat better suited to future conditions while maintaining the qualities that make it valuable for food production.
As atmospheric CO₂ levels continue to rise, the findings suggest that growing enough wheat may be only part of the challenge. Preserving the quality of that wheat could matter just as much.
The study was funded by Germany's Federal Ministry of Food and Agriculture through the Federal Office for Agriculture and Food, with additional support from the European Union through a European Research Council grant.