Food on our plates is quietly changing as rising carbon dioxide levels alter the nutritional makeup of crops, according to a new international study. Researchers have found that while higher carbon dioxide concentrations can boost crop yields, they also reduce essential nutrients and may even increase toxic elements, raising fresh concerns about global food security and public health.
Scientists from Leiden University in the Netherlands analysed data from nearly 60,000 measurements across 43 major food crops, including rice, wheat, potatoes and tomatoes. Their findings show that crops grown under higher carbon dioxide conditions tend to become more calorific but less nutrient-dense. Key micronutrients such as zinc, iron and protein decline, while levels of lead increase in some plants.
The study compared plant growth at a baseline carbon dioxide concentration of 350 parts per million, often described as the last relatively safe level, with projected concentrations of 550 parts per million that could be reached by the middle of this century. On average, nutrient levels fell by more than three percent, with some crops experiencing far sharper losses.
Zinc and protein declines raise alarm
One of the most worrying findings relates to zinc, a micronutrient essential for immune function and child development. In chickpeas, zinc levels were projected to drop by as much as 37.5 percent. Staple crops such as rice and wheat also showed significant reductions in zinc, iron and protein content.
Researchers warned that these changes could lead to “hidden hunger,” a condition in which people consume enough calories but lack vital nutrients. This risk is particularly severe in regions where diets already depend heavily on a few staple crops.
The researchers emphasised that the changes observed go beyond simple dilution caused by faster plant growth. Instead, higher carbon dioxide levels appear to trigger deeper shifts in plant chemistry, altering how nutrients are absorbed and distributed within crops.
Carbon dioxide concentrations in the atmosphere have already reached about 425 parts per million, meaning some nutritional decline is likely already occurring. Scientists say this underscores that climate change is no longer a distant threat but one that is already influencing daily life.
Implications for farming and food systems
The findings have significant implications for modern agriculture, especially in countries that rely on high-tech farming systems. In places like the Netherlands, where crops are often grown in carbon dioxide–enriched greenhouses to maximise yields, the nutritional trade-offs may be particularly relevant.
Experts say the study provides a strong foundation for future research into breeding crops that can maintain nutritional quality under changing environmental conditions. However, they caution that carbon dioxide is not the only factor influencing crop nutrition. Fertiliser use, soil health and farming practices also play critical roles.
Researchers stress that the goal is not to create panic but to highlight a growing problem that demands attention. As climate change reshapes ecosystems, food systems must adapt to ensure that increased production does not come at the cost of human health.
The study, published in the journal *Global Change Biology*, adds to a growing body of evidence that climate change is transforming not just how much food the world produces, but also how nourishing that food really is.