Rising CO₂ May Change Wheat Proteins, With Implications For Food Quality And Health: Study

Climate change could affect more than the quantity of wheat harvested. Rising levels of atmospheric carbon dioxide (CO₂) may also alter the composition of proteins in wheat, potentially affecting its nutritional and functional properties, baking quality and, in the long term, its interaction with the human immune system, a new study has found.

Led by researchers at the Leibniz Institute for Food Systems Biology at the Technical University of Munich, the study found that higher CO₂ concentrations changed the levels of several wheat proteins, with the extent of the changes varying across wheat varieties.

The findings raise questions about how climate change could influence the quality of a staple food consumed by billions of people, including millions of Indians who depend on wheat for a substantial share of their daily calories.

The researchers said crop adaptation strategies should look beyond increasing yields to consider the quality and composition of grain under changing climatic conditions.

For the study, the team grew 10 winter wheat varieties under field conditions, exposing some plants to an elevated CO₂ concentration of 546 parts per million (ppm), while others grew under current atmospheric conditions.

The researchers then analysed the harvested grains using a high-resolution mass spectrometry method to examine different proteins, including gluten proteins, amylase/trypsin inhibitors, puroindolines and peptides associated with coeliac disease.

The analysis found that elevated CO₂ generally increased the content of amylase/trypsin inhibitors, while levels of puroindolines, gluten proteins and certain peptides associated with coeliac disease decreased.

The magnitude of these changes depended substantially on the wheat variety, suggesting that different cultivars may respond differently as atmospheric CO₂ concentrations rise.

“Our results also showed that the reduced concentration of gluten proteins was associated with poorer baking quality,” said Sabrina Geisslitz, principal investigator and research associate in Katharina Scherf’s research group at the Leibniz Institute.

Gluten proteins play an important role in determining the elasticity and structure of wheat dough, influencing the texture and quality of bread and other baked products. Changes in their concentration could therefore have implications for food processing and the suitability of different wheat varieties for specific products.

The findings also point to a possible health dimension, although the implications for consumers remain uncertain.

Katharina Scherf, head of the Food Biopolymer Chemistry research group at the Leibniz Institute and professor of Food Biopolymer Systems at the TUM School of Life Sciences, said changes in amylase/trypsin inhibitors and certain coeliac disease-active peptides could be relevant to wheat-related disorders in the long term.

“However, further studies are needed to clarify the actual biological and immunological significance of these differences,” she said.

The study does not establish that wheat grown under higher CO₂ levels will cause more or fewer cases of coeliac disease, wheat allergy or other food-related conditions. Nor does it show that the observed protein changes translate directly into altered disease risk in people.

Coeliac disease is an immune-mediated condition in which gluten triggers damage to the small intestine in genetically susceptible individuals. Wheat allergy and other forms of wheat intolerance involve different mechanisms. Changes in individual proteins or peptides alone cannot establish whether a food will become more or less harmful to people with these conditions.

The findings have particular relevance for India, where wheat is a major staple and an important part of food security. Any climate-related changes in grain quality could have implications beyond farm productivity, affecting flour processing, baking characteristics and the consistency of wheat-based foods.

India's wheat research and breeding programmes will therefore need to consider how different varieties perform under changing environmental conditions, alongside their yield, disease resistance and ability to withstand heat and water stress.

The German study, however, examined 10 winter wheat varieties under specific field conditions. It did not assess Indian wheat cultivars, Indian growing environments or the health effects of consuming wheat produced under elevated CO₂. Its findings cannot be directly extrapolated to Indian wheat without further research.

But as the atmospheric CO₂ levels have risen substantially over recent decades, for India, this could mean strengthening collaboration between agricultural scientists, food researchers and health experts to assess not only how climate change affects the quantity of wheat produced but also its quality and potential implications for consumers.