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Rice loses nutrients as CO2 increases

A man carries freshly harvested rice in Myanmar, Southeast Asia Commons

Rice could become less nutritious over the coming decades if the amount of carbon dioxide (CO2) in the atmosphere continues to rise at the current rate, risking the health of nearly 2 billion people for whom it is the main food source. Between 2010 and 2014, a group of researchers coordinated by epidemiologist Kristie Ebi, from the University of Washington, USA, grew 18 varieties of rice on farms in China and Japan, in environments with different concentrations of CO2. Atmospheric levels of carbon dioxide increased from 280 parts per million (ppm) before the industrial revolution to the current level of 410 ppm, and could reach 1,200 ppm by 2100 without significant changes to global emissions. Rice exposed to higher concentrations of carbon dioxide contained 10% less protein, 8% less iron, and 5% less zinc than rice grown under current CO2 levels. The amount of B vitamins was also reduced (Science Advances, May 23). High atmospheric levels of CO2 decrease the concentration of nitrogen, essential to the production of B vitamins in plants. These vitamins influence the absorption of other nutrients and the functioning of the immune system. Folate (vitamin B9) is essential to proper development of the central nervous system in fetuses. Reduced nutrient levels in rice could have a major impact on maternal and infant health, especially in poorer countries that depend heavily on the grain, such as Bangladesh and Cambodia, Ebi wrote in an article published on online news outlet The Conversation.