CO2 rises could fuel obesity as plants “carb-load”

By David Burrows

- Last updated on GMT

'It’s like sprinkling every bite you take with starch and sugar,' said Irakli Loladze, an associate professor at Bryan College of Health Sciences and report co-author. © iStock
'It’s like sprinkling every bite you take with starch and sugar,' said Irakli Loladze, an associate professor at Bryan College of Health Sciences and report co-author. © iStock

Related tags: Climate change, Nutrition

The nutritional quality of food will plummet as carbon emissions rise, with every bite delivering less protein, fewer micronutrients and more sugars, according to a report released this week.


In a world where CO2 levels are almost twice those of today, every serving of bread, pasta, fruits and vegetables will deliver less micronutrients – calcium, magnesium, zinc and the like.

Protein levels will also fall, but carbohydrate content will rise – and the increase can be substantial.

The direct effect of rising CO2 on the nutritional value of crops represents a potential threat to human health, notes the US Global Change Research Program (GCRP) in its report, The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment​.

The risk of foodborne illnesses will also rise, whilst rising sea temperatures will likely lead to a greater accumulation of mercury in seafood. Indeed, the assessment focuses on the “less reported aspects”​ of climate change in relation to food – specifically food safety, nutrition and distribution.

Carbs and CO2

This is the first time, for example, that the US has acknowledged the link between CO2 levels and carbs. Given that climate change affects the whole planet, the issues raised are globally significant.

Sceptics of climate change have often argued that more CO2 in the atmosphere will be a good thing for agriculture, boosting yields. But the US GCRP has now recognised the evidence showing that feeding plants more CO2 will see them building more carbs and less protein.

On the carb-to-protein ratio, it highlights how elevated CO2​ tends to increase the concentrations of carbohydrates (starch and sugars) and reduce the concentrations of protein. The overall effect is “a significant increase”​ in the ratio of carbohydrates to protein in plants exposed to increasing CO2​. “There is growing evidence that a dietary increase in this ratio can adversely affect human metabolism and body composition,”​ it concludes.

Irakli Loladze, an associate professor at Bryan College of Health Sciences in the US, once put it like this. “It’s like sprinkling every bite you take with starch and sugar.”

Loladze, who contributed to the report’s chapter on food safety, nutrition and distribution, told FoodNavigator this week that, taken alone and in a single serving, none of the above changes are worrisome. However, the shift in crop quality is pervasive and persists over a consumer's lifetime – and that is concerning.

“The cumulative effect can contribute to obesity and other health problems, especially to those who are already deficient in one more minerals, such as calcium, magnesium or zinc,”​ he told FoodNavigator.

“While fruits and vegetables are and will be important sources of nutrients, they will be less nutritious with respect to key minerals, including calcium, magnesium, copper, and zinc,” ​he added.

Given that most important food crops will be affected by the predicted rises in CO2, the food industry should take note. “The baking quality of bread has been shown to be affected; rice quality/taste are affected as well by high CO2,”​ Loladze explained. Not all aspects of quality go down. “If starch is desirable, then CO2 boosts starch concentrations,”​ he added.

Mark Driscoll, head of food at Forum for the Future, said governments and businesses “need to wake up to these challenges immediately and work together to address the threat that climate change poses to our future food security”.

Food Drink Europe said it has “not gone into the actual measurements of potential loss of nutritive value”.​ Food security and safety are the major concerns for its members in relation to climate change.

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