Increased amount of carbon dioxide in the atmosphere is not just associated with climate change. Findings of a new study have revealed it may also affect the nutritional value of food.

Rice Becomes Less Nutritious With Higher Carbon Dioxide Concentration

Researchers found reduced levels of B vitamins, as well as iron, zinc, and protein in rice grown under conditions with higher carbon dioxide concentration.

In the study published in the journal Science Advances on May 23, researchers examined 18 rice varieties grown in experimental rice paddies in which the plants were subjected to atmospheric carbon dioxide concentrations of 568 to 590 parts per million, the anticipated concentration of carbon dioxide in the second half of the century.

Researchers found that at high carbon dioxide concentrations, vitamins B1, B2, B5, and B9 in rice all declined.

B1 levels (thiamine) dropped by 17.1 percent, B2 levels (riboflavin), were reduced by 16. 6 percent, and B5 levels (pantothenic acid) were reduced by 12. 7 percent. B9 levels (folate) saw the largest drop, declining by 30.3 percent. Folate is particularly crucial for maternal and child health.

"There's been studies over the past hundred years for the importance of these B vitamins," said study researcher Kristie Ebi, from the University of Washington in Seattle.

"One that declines with higher CO2 concentrations is folate. And we know that folate deficiencies in pregnant women can result in children that have various birth anomalies."

Researchers also observed declines in iron, zinc, and protein.

Risk Of Malnutrition In Countries That Depend On Rice For Energy And Protein

Ebi and colleagues raised concern that more malnutrition may occur in population with the highest consumption of rice and lowest gross domestic product as the nutritional value of rice and other low-cost staple food declines.

Apparently, 600 million people primarily in Indonesia, Cambodia, Bangladesh, Lao People's Democratic Republic, Vietnam, Madagascar, and Myanmar get at least 50 percent of their daily energy and/or protein from rice.

"Declines of protein and minerals essential for humans, including iron and zinc, have been reported for crops in response to rising atmospheric carbon dioxide concentration, [CO2]. For the current century, estimates of the potential human health impact of these declines range from 138 million to 1.4 billion, depending on the nutrient," the researchers wrote in their study.

The researchers nonetheless found that not all varieties of rice responded to higher concentration of atmospheric carbon dioxide in a similar manner so future studies may help find varieties that can remain nutritious amid changes in the atmosphere.