Fascinating video from Veritasium about the potential cause of the decline in our crops’ nutrient content over the last century. Popular theories include soil depletion due to over farming, as well as selective breeding (the only ones I’d heard of prior). But there is evidence to suggest that the decline is also happening in non-cultivated plants and may actually be due to increased carbon dioxide levels in the atmosphere.
There are experiments run by injecting more CO2 into the area where plant crops are grown, and they find that wheat and barley, rice, and potatoes—they will grow faster if there’s more CO2 in the atmosphere. But here’s the thing: they don’t necessarily become more nutritious—they simply put on more carbs.
In other studies conducted in Japan and China, scientists pumped carbon dioxide into rice crops to simulate the kind of CO2 concentrations expected in 50 years time. On average, protein levels fell by 10 percent, iron by 8 percent, and zinc by 5 percent.
And in case it’s not immediately obvious, he notes that plants are not necessarily decreasing in absolute nutritional content. Rather, faster growth leads to an increase in plant size (without a corresponding increase in nutrients), so the nutrients in the plant are simply more diluted.