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Rising Atmospheric CO2 Lowers Concentrations of Plant Carotenoids Essential to Human Health: Meta-analysis.

Plant and human tissues (e.g. leaves, retina) share the need for carotenoids to protect against light-induced and other oxidative stresses. While plants synthesize carotenoids de novo, humans must obtain them primarily through plant-based foods. In plants, elevated levels of atmospheric carbon dioxide (eCO2 ) decrease the concentrations of essential minerals, including magnesium and zinc (essential for brain and eye health), but the overall effect of globally rising CO2 levels on carotenoids is unknown. Here, we sought to investigate how eCO2 affects carotenoids in plants. Our meta-analysis of 1026 experimental observations from 37 studies shows that eCO2 decreases plant carotenoid concentrations by 15% (95% CI: -26% to -6%). Our meta-analysis of available gene expression data for Arabidopsis thaliana points to a potential CO2 -induced downregulation of carotenoid biosynthesis (Log2 fold-change -13%, 95% CI: -17% to -9%). We also highlight some other stoichiometric and biochemical mechanisms related to CO2 -induced changes in carotenoids. While overall eCO2 decreases carotenoid concentrations, individual CO2 studies report variable responses, including increases in carotenoid levels, especially in abiotically stressed plants. Our initial assessment raises a novel question about the potential effects of rising CO2 on human health through its global effect on plant carotenoids. This article is protected by copyright. All rights reserved.