CO2 and Staple Crop Nutrition

by Brian Rigby, MS, CISSN

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There have been a few articles the past few weeks about the effect of carbon dioxide on the nutritional properties of crops, based on the research of Irakli Loladze, a math doctorate who became interested in a biological puzzle about two decades ago. If you haven’t read on this topic, here’s a good article that overviews it. The long and short, however, is that increased carbon dioxide levels lead to plants both growing faster and having less nutrition, mostly in the form of protein and a few minerals (notably iron). This effect has been dubbed the “junk food effect”, because it increases sugar calories while decreasing nutrition—it brings the nutritional profile of crops closer to “junk food”.

Before I dive into this topic with a skeptic’s eye, let’s all be clear that this is definitely not a good thing. Faster growing crops could be desirable, but when the trade-off is losing vital nutrients, it’s much less desirable; agricultural scientists work hard to improve yield without affecting nutrition. And, as I will write later in this post, this effect is demonstrably bad for certain people, so I’m certainly not trying to downplay its significance!

Why the skepticism, then? Because some folks online are under the mistaken idea that this is just a continuing trend towards the loss of nutrition in the average Westerner’s diet, a trend that began back in the 1940s or 50s when industrial agriculture took over. To these folks, the modern diet is bereft of nutrition, and losing more protein and minerals will only make it even worse.

Fortunately, there’s not a lot of evidence that the modern diet—even the Standard American Diet, which is hardly a paragon of healthy eating—is not nutrient-deficient (it is, in fact, overloaded with caloric nutrients). While surveys like NHANES have suggested (based off 24-hour food recalls) that Americans don’t get enough of certain nutrients, hard tests do not bear that theory out; the nutrients we can test for in the serum are rarely deficient.

This does, of course, make a certain amount of sense. Nutritional deficiencies lead to debilitating problems. To skirt this issue, less-science-inclined nutritionists will often talk about nutritional insufficiencies, a term that conveniently has no official definition and can therefore be used in any situation where a person feels like more of something could be beneficial without any evidence to back that hypothesis up. In more scientific terms, you can be deficient in a nutrient—a state that has measurable negative effects—or you can be sufficient, but “insufficient” is meaningless; you either have enough of a nutrient to perform 100% of the functions you need that nutrient for, or you don’t have enough and your health suffers. RDAs are set based on the amount of a nutrient you need to cover 100% of these essential functions, not just how much you minimally to drag yourself through another day.

In the case we’re discussing now, there will be virtually no effect on our health because Westerners don’t derive the majority of their nutrition from staple crops. The protein and iron we get from wheat isn’t nothing, but it’s also not where we get most of the protein or iron in our diet. If wheat becomes a worse source of protein or iron (or anything else), nobody who eats a diverse diet will suffer or even notice that one component of that diet has grown slightly less healthy.

The issue, then, isn’t really that our crops are becoming more like junk food, which implies that this is a Western problem that will lead to larger waistlines on Westerners—that’s not going to happen, and is an exceedingly narrow (and egotistical) view of the consequences of rising carbon dioxide. The issue is that there are people in the world who do rely on crops like wheat to get a large portion of their protein, iron, etc., and any reduction in that staple crop’s nutritional value could lead to overt deficiencies and disease. As staple crop nutrition declines further, these problems will intensify unless a solution can be figured out.

So do read up on this topic and stay informed, but keep in mind that this isn’t a “junk food” problem, it’s a nutritional sufficiency problem. Westerners are going to suffer far less from the rising levels of carbon dioxide than un- and underdeveloped regions (in more ways than this), and framing worldwide problems as (what amounts to) a vanity issue for the West doesn’t give proper scope to the very real consequences!

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