A slowly growing field of biological research is uncovering evidence that increasing levels of carbon dioxide in the atmosphere is steadily decreasing the concentration of nutrients in our food supply. Plants metabolize CO2 in the same way we metabolize oxygen, and increases in CO2 levels have proven to boost plant growth, but that increased growth causes the affected plants to pack on more carbohydrates at the cost of taking on nutrients such as vitamins and minerals — effectively turning crops we consider to be healthy dietary choices into junk food.

This finding is being promoted by Irakli Loladze, an associate professor of mathematical biology at Bryan College of Health Sciences, after running into the phenomenon while studying for his PhD at Arizona State University in 1998. The university’s biology department was conducting an experiment where they attempted to increase the growth of zooplankton — microscopic creatures that form the food base for a multitude of larger aquatic creatures — by increasing their food supply, namely algae, by increasing the amount of light made available to the algae.

While the increased light increased algal growth, the more abundant food supply only increased zooplankton to a point, after which the tiny creatures struggled to survive. More algae as food should equal more zooplankton, but that wasn’t what the experiment was seeing. The researchers eventually discovered that during its accelerated growth the algae took up fewer nutrients, effectively turning it into junk food for the zooplankton.

This discovery prompted Loladze to question whether or not this phenomenon could also take place on land, and his research has shown that this is indeed happening, albeit due to an excess of carbon dioxide spurring the increase in plant growth, rather than an increase in light. The decrease in crop nutrients, including minerals, vitamins and protein, has been documented for some time now, but has traditionally been blamed on issues such as the focus of traits for new breeds putting an importance on yields over nutrient density, and farming practices that deplete the soil. However, after isolating these factors, researchers have found that an increased intake of CO2 in staple crops, such as wheat, rice, barley and potatoes, decreases their concentration of minerals, including calcium, potassium, zinc and iron, by an average of 8 percent, with their protein content also seeing similar declines.

Researchers are projecting that this effect could have a major impact on the developing world by 2050, where may people rely on plants as their chief source of protein, especially in countries like India and Bangladesh, where 150 million people could face protein deficiency. Iron deficiencies are also expected to exacerbate an already widespread health problem of anemia. While there have been no studies projecting the potential impact on developed nations such as the U.S. conducted so far, researchers are questioning as to whether or not rising CO2 levels also have a hand in increasing rates of obesity and cardiovascular disease. 

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