Study Shows Increasing Levels of CO2 Leads to Risk of Nutritional Deficiencies in Millions

According to a new study led by Harvard T.H. Chan School of Public Health, the increasing levels of carbon dioxide (CO₂) from human activity are making staple crops such as wheat and rice less nutritious, which could result in 175 million people becoming zinc deficient and 122 million people becoming protein deficient by 2050.

The research also discovered that over 1 billion women and children could lose a great amount of their dietary iron intake, placing them at a greater risk of anemia and other diseases.

Our research makes it clear that decisions we are making every day - how we heat our homes, what we eat, how we move around, what we choose to purchase - are making our food less nutritious and imperiling the health of other populations and future generations.

Sam Myers, Lead Author and Chief Research Scientist at Harvard Chan School

The research was reported online on August 27^th, 2018 in Nature Climate Change.

Currently, over two billion people globally are estimated to be deficient in one or more nutrients. Mostly, humans tend to get a major portion of the key nutrients from plants: 63% of dietary protein originates from vegetal sources, as well as 81% of iron and 68% of zinc. It has been revealed that higher atmospheric levels of CO₂ lead to less nutritious crop yields, with concentrations of protein, zinc, and iron being 3%-17% lower when crops are grown in environments where CO₂ concentrations are 550 parts per million (ppm) compared with crops grown under present atmospheric conditions, in which CO₂ levels are just over 400 ppm.

For this new research, scientists aimed to develop the most strong and accurate analysis of the universal health burden of CO₂-related nutrient shifts in crops in 151 countries. To achieve that, they developed a unified set of assumptions covering all nutrients and used more comprehensive age- and sex-specific food supply datasets to enhance estimates of the impacts across 225 different foods. The research built on earlier analyses by the scientists on CO₂-related nutritional deficiencies, which studied at fewer foods and fewer countries.

The research revealed that by the middle of this century, when atmospheric CO₂ concentrations are expected to touch about 550 ppm, 1.9% of the world’s population - or approximately 175 million people, based on 2050 population estimates - could become deficient in zinc and that 1.3% of the worldwide population, or 122 million people, could be dealing with protein deficiency. Furthermore, 1.4 billion women of childbearing age and children under the age of 5 who are presently at high risk of iron deficiency could have their dietary iron intakes lowered by 4% or more.

The scientists also highlighted that billions of people presently living with nutritional deficiencies would probably see their conditions deteriorate as a result of less nutritious crops.

According to the research, India would have to handle the greatest burden, with an estimated 50 million people dealing with zinc deficiency, 38 million dealing with protein deficiency, and 502 million women and children becoming susceptible to diseases linked with iron deficiency. Other countries in Southeast Asia, Africa, South Asia, and the Middle East would also be greatly impacted.

“One thing this research illustrates is a core principle of the emerging field of planetary health,” said Myers, who directs the Planetary Health Alliance, co-housed at Harvard Chan School and Harvard University Center for the Environment. “We cannot disrupt most of the biophysical conditions to which we have adapted over millions of years without unanticipated impacts on our own health and wellbeing.”