Increasing CO2 threatens human nutrition

• Published in: Nature (London) Vol. 510; no. 7503; pp. 139 - 150
• Main Authors: Myers, Samuel S, Zanobetti, Antonella, Kloog, Itai, Huybers, Peter, Leakey, Andrew D. B, Bloom, Arnold J, Carlisle, Eli, Dietterich, Lee H, Fitzgerald, Glenn, Hasegawa, Toshihiro, Holbrook, N. Michele, Nelson, Randall L, Ottman, Michael J, Raboy, Victor, Sakai, Hidemitsu, Sartor, Karla A, Schwartz, Joel, Seneweera, Saman, Tausz, Michael, Usui, Yasuhiro
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 05-06-2014; Nature Publishing Group
• Subjects: 704/106/694/2739/2807; Air - analysis; Atmosphere - chemistry; Australia; Breeding; C3 plants; C4 plants; Carbon dioxide; Carbon Dioxide - analysis; Carbon Dioxide - pharmacology; Climate change; Corn; Crop diseases; Crops; Crops, Agricultural - chemistry; Crops, Agricultural - drug effects; Crops, Agricultural - metabolism; Cultivars; Diet; Edible Grain - chemistry; Edible Grain - drug effects; Edible Grain - metabolism; Fabaceae - chemistry; Fabaceae - drug effects; Fabaceae - metabolism; food crops; free air carbon dioxide enrichment; Global health; Global Health - trends; Glycine max; Grain; grasses; Human nutrition; Humanities and Social Sciences; Humans; Iron; Iron - analysis; Iron - metabolism; Iron Deficiencies; Japan; Legumes; letter; multidisciplinary; nutrient deficiencies; nutrients; Nutrition; Nutritional Status; Nutritive Value - drug effects; Oryza sativa; peas; people; Photosynthesis - drug effects; Phytic Acid - analysis; Phytic Acid - metabolism; Pisum sativum; Proteins; Public health; Public Health - trends; Rice; Science; Sorghum bicolor; soybeans; statistical models; Triticum aestivum; United States; Wheat; Zea mays; Zinc; Zinc - analysis; Zinc - deficiency; Zinc - metabolism; Australia; United States; Japan
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature13179

Dietary deficiencies of zinc and iron are a major global public health problem. An estimated two billion people suffer these deficiencies causing a loss of 63 million life years annually. Most of these people depend upon grains and legumes as their primary dietary source of zinc and iron. This manuscript reports findings from the analysis of 540 pairs of crop samples grown at contemporary and elevated [CO2] from six different FACE experiments involving six food crops. We tested the nutrient concentrations of the edible portions of rice (Oryza sativa, 18 cultivars), wheat (Triticum aestivum, 8 cultivars), maize (Zea mays, 2 cultivars), soybeans (Glycine max, 7 cultivars), field peas (Pisum sativum, 4 cultivars) and sorghum (Sorghum bicolor, 1 cultivar). In all six experiments, the elevated [CO2] was in the range of 550-584 ppm. Each crop sample grown at elevated [CO2] was paired with an identical cultivar grown under the same conditions but at contemporary [CO2]. Our main outcomes were fractional changes in concentrations of the nutrients between samples grown at elevated and contemporary [CO2] levels, estimated using a linear mixed effects statistical model. We found that elevated [CO2] was associated with significant decreases in the concentrations of zinc and iron in all C3 grasses and legumes. For example, in wheat grains grown at elevated [CO2] compared with contemporary [CO2], zinc decreased 9.6% and iron decreased 5.2%. We also found that elevated [CO2] was associated with lower protein in C3 grasses with a 6.5% decrease in wheat grains and a 7.9% (95% CI: -8.9, -6.9) decrease in rice grains. Elevated [CO2] showed no significant effect on protein in C3 legumes or C4 crops. Response differences between cultivars suggest breeding crops for reduced sensitivity to elevations in atmospheric [CO2]. Such breeding efforts may partly address the new challenges to global health that these findings highlight.