Rising CO2 Levels Threaten Rice’s Nutritive Value

An increase in the concentration of CO2 in the atmosphere is responsible for a change in the nutritional qualities of rice, according to a study conducted, among others, by the Chinese Academy of Sciences and the U.S. Department of Agriculture.

By Alexandra Bachot

Fully 18 different varieties of rice were studied in two rice fields, one in Japan and the other in China. Some parts of these fields were covered in plastic tubing inside of which CO2 concentrations were increased. The rice was measured for its exact content of protein, iron and vitamins.

The results showed that over and above contributing to the greenhouse effect, a rise in CO2 levels also made the rice grow faster, but lose some of its nutritional value.

Between now and the end of the century, we will see a 10% decrease in the protein content of rice, whereas its iron content will decrease by 8% and its zinc by 5%. The concentration of vitamins B1 and B2 in rice will fall by between 10% and 30%.

When there is “more carbon in the air, the plant grows higher and produces more seeds, but this comes at a price: the plant’s nutritional value decreases,” explains  Lewis Ziska, one of the authors of the study.

This could have serious effects on public health. Rice constitutes 23% of all calories consumed on the planet. For hundreds of millions of people in Asia rice is their staple food, from which they derive over half their daily calories.

“The effect could be devastating in rice-consuming countries, where 70% of their calories and most of their nutrients come from rice,” says Adam Drewnowski, professor of epidemiology at the University of Washington. Researchers believe that south and south east Asia’s poorest countries, such as Bangladesh, Cambodia and Laos, stand to be hardest hit.

The scientists suggest some solutions to fill the nutritional gap in these countries, including instilling a more balanced diet including vegetables, fruit and other protein sources. But these foods are inaccessible for the poorest Asian nations, for whom rice is a cheap food source. Another solution scientists suggest: the use of hybrid rice varieties, more resistant to the rise in carbon dioxide levels.

First seen in Raymond Viger’s blog July 26th, 2021

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