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Food Becoming More Calorific But Less Nutritious Due To Rising Carbon Dioxide (theguardian.com) 90

Posted by msmash from the troubling-findings dept.
More carbon dioxide in the environment is making food more calorific but less nutritious -- and also potentially more toxic, a study has found. From a report: Sterre ter Haar, a lecturer at Leiden University in the Netherlands, and other researchers at the institution created a method to compare multiple studies on plants' responses to increased CO2 levels. The results, she said, were a shock: although crop yields increase, they become less nutrient-dense. While zinc levels in particular drop, lead levels increase.

"Seeing how dramatic some of the nutritional changes were, and how this differed across plants, was a big surprise," she told the Guardian. "We aren't seeing a simple dilution effect but rather a complete shift in the composition of our foods... This also raises the question of whether we should adjust our diets in some way, or how we grow or produce our food."

While scientists have been looking at the effects of more CO2 in the atmosphere on plants for a decade, their work has been difficult to compare. The new research established a baseline measurement derived from the observation that the gas appears to have a linear effect on growth, meaning that if the CO2 level doubles, so does the effect on nutrients. This made it possible to compare almost 60,000 measurements across 32 nutrients and 43 crops, including rice, potatoes, tomatoes and wheat.
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Food Becoming More Calorific But Less Nutritious Due To Rising Carbon Dioxide More

Food Becoming More Calorific But Less Nutritious Due To Rising Carbon Dioxide

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  • The reason food is becoming less nutritious is that is costs way less to make something full of carbs, stabilizers and preservatives so it lasts forever on the shelves and in the warehouses and sell it as food. Nutritious food is also nutritious to mold and bacteria and tends to oxidize.

    • Re:That's not why (Score:5, Insightful)

      by alvinrod ( 889928 ) on Friday December 19, 2025 @11:53AM (#65869081)
      That's a different unrelated problem. This is a separate issue that plants that receive more CO2 are less nutrient dense. It makes sense if you consider that CO2 is basically food for plants and that they grow more when exposed to it. However if the other molecular components that make up nutrients in those plants don't increase, then it's unsurprising that the nutrition density goes down. Of course that also means that the problem isn't too difficult to fix if the crops can be fertilized with the various compounds or precursors that are used by the plant to form those nutrients.

      • Then can you explain the increase in lead content; that was what surprised me. Calories come from carbon, hydrogen, and oxygen.
           

        • If the study was at 500 ppm and this causes "toxic" shocking amounts of lead then what about greenhouses that run at 1000 ppm? Nothing? Ok.

          • The soil in the greenhouses where enrichment is used may have less lead in it, because it's usually only used for cannabis and that is generally grown in containers when in greenhouses.

          • Re: (Score:2)

            by tragedy ( 27079 )

            If the study was at 500 ppm and this causes "toxic" shocking amounts of lead then what about greenhouses that run at 1000 ppm? Nothing? Ok

            Others have pointed this out already, but adding my two cents anyway. It should be fairly obvious that the soil in greenhouses will often be different than the soil in fields. In nature, the minerals that plants absorb normally come from the slow breakdown of rocks. What kind of rocks can vary a lot by region. I mean, this could be the subject of several chapters from a geology textbook, if not its own entire book, but just a few examples. Soil can be in regions that were glaciated in the last ice age with

            • Gemini:

              "while modern agriculture uses intensive methods because natural mineral replenishment is slow, a substantial portion of the resulting output is lost to systemic waste, household disposal, or economic structures that prioritize production volume over efficient distribution. "

            • No, you are reading too much into a comment

              • Re: (Score:2)

                by tragedy ( 27079 )

                No, you are reading too much into a comment

                You asked a question (in a weird way where you presupposed that no-one had an answer), and you got an answer. That's how that works. I'm not even clear what your "No" in your single sentence response is even referring to.

        • There are a few possibilities that stick out to me. One is that lead is more available and is being uptaken to replace something else that isn't available in the necessary quantities. The human body is good at making some substitutions when some molecules aren't available, so it would not surprise me if other organisms did the same. For example, if humans restrict carbohydrates in their diet, the brain will switch to using ketones in place of glucose. Plants could be using lead in place of something else in

        • Re: (Score:2)

          by tragedy ( 27079 )

          Then can you explain the increase in lead content; that was what surprised me. Calories come from carbon, hydrogen, and oxygen.

          The why is not really explained. So we can just speculate. There are a few possible factors. One of them is that it is not the effect of the CO2 on the plants directly that increases lead, but the effect on the moisture in the soil. If it becomes more acidic, both zinc and lead become more soluble and therefore plants can be expected to absorb more of both through their roots. Another possibility is that the bigger, more active plant that is being produced ends up sucking more moisture through its roots tha

      • Re:That's not why (Score:5, Informative)

        by Rei ( 128717 ) on Friday December 19, 2025 @12:43PM (#65869223) Homepage

        I mean, from a horticultural perspective, there is some potential to gain more of other nutrients, in that if you have more energy, you can develop a larger root system, or generally more effectively, better feed mycorrhizal associations (fungal hyphae are much finer than root hairs, so can get into smaller cracks, and fungi can "acid mine" nutrients out of mineral grains - as an example, here's a microscopic image showing what they did to a garnet [researchgate.net])

        That said, yeah, in general if you can provide more energy, you expect the storage of "calories" to grow much faster than the acquisition of other minerals. Also, it's important to note that while more CO2 is generally good for most plants, more heat, or greater periods of drought (land dries out faster, monsoon belts spread) and flooding (atmosphere holds more moisture, monsoon belts spread) are not. In regards to heat as well, there's a lot of details. First off, though we commonly don't think about it, heat management in plants is critical. Their proteins are designed for function within an optimal temperature range, and to maintain it, they have to cool themselves down with transpiration, creating more water stress. Also it's worth noting that C3 plants (most plants) fundamentally don't tolerate heat as well as C4 or CAM plants (there's work to engineer C4 into some common agricultural crops... it's frankly amazing to me that they're getting some success, as it's not a trivial change).

        BTW, the reason that plants grow better with more CO2 isn't what most people might think. The TL/DR is that the protein that sequesters CO2 so that (using ATP and NADPH from photosynthesis) - RuBisCo (the most abundant protein on Earth, something that has been evolving for billions of years) frankly sucks at its job. Something like 20-25% of the time (at normal CO2 levels), instead of binding with CO2, it binds with O2 instead ("photorespiration"), which means not only does it not sequester a carbon, but the plant has to *give up a carbon* to regenerate the RuBisCo. This is disastrous in terms of energy efficiency. And as a side effect, you also have to keep the stomata open more, which means more water loss. But as you increase the CO2 levels, the ratio between binding CO2 and binding O2 improves, and photorespiration waste drops. C4 plants "fix" this problem by instead of having RuBisCo directly bind CO2, they first bind CO2 into malate (with high selectivity), then the malate transports into bundle sheath cells, the CO2 is re-released, and THEN - in a high-CO2 environment - RuBisCo takes it up. This reduces photorespiration, but also introduces some more wasteful chemical conversions. (CAM plants to even further by storing malate inside vacuules - at the cost of even more energy - so that they can store it up during the night, and then use it during the day, which - although even more wasteful - lets them keep their stomata closed during the day to conserve water)

        (BTW, there are some microbes that have developed a more efficient RuBisCo, but it's proving challenging to engineer it into higher plants)

        • Re: (Score:2)

          by tragedy ( 27079 )

          I mean, from a horticultural perspective, there is some potential to gain more of other nutrients, in that if you have more energy, you can develop a larger root system, or generally more effectively, better feed mycorrhizal associations (fungal hyphae are much finer than root hairs, so can get into smaller cracks, and fungi can "acid mine" nutrients out of mineral grains -

          I would think that, in general, it would be a square-cube ratio issue or a set of them combined with other limits. Surface area of root system versus mass of plant, for example. The constraints on the growth of the root system versus the constraints of the growth of the main body of the plant, for example. Or, to grow bigger (and be denser in Calories) the plant may need to suck up more water which, theoretically means more nutrients, but the soil is not some homogeneous reservoir of mineral water. Differen

        • "... Heat management in plants is critical ..."

          Do plants have genetic memories of adaptations to warmer times? Might plants enjoy adapting by themselves?

          Gemini: ... While most 2025 scientists still distinguish between animal sentience (widely accepted) and plant reaction (the current consensus), the historical lesson is that scientific "consensus" on the "unknowable" inner lives of organisms has been proven wrong before.

      • Exactly. It's working to draw all the things it can from the soil - which likely suggests the lead increase, too -- where it can't get Zn, Mn, Fe, etc. it'll take up what it can - which is Pb, no doubt naturally present in the soil and due to leaded gasoline for years, and so on.

  • Interesting (Score:4, Interesting)

    by Geoffrey.landis ( 926948 ) on Friday December 19, 2025 @11:42AM (#65869061) Homepage

    Interesting.

    For much of the world, avoiding starvation is the principle goal, so for these areas, higher crop yields are beneficial despite lower nutrient density.

    For most of the developed world, getting enough calories to avoid starvation is not a big deal, and lower nutrients in food is undesirable.

    Another thing to keep in mind, of course, is that increased carbon dioxide is going to play havoc with existing farms and fields due to climate change, with areas currently producing high crop yields becoming less farmable, and (presumably) other areas not currently farmable due to drought or other climate-related factors becoming more farmable. This will create an unknown amount of economic disruption.

    • For much of the world, avoiding starvation is the principle goal, so for these areas, higher crop yields are beneficial despite lower nutrient density.

      As Slicher Bath remarks in his book about the agricultural history of Western Europe, "Starving people do not eat less. On the contrary." They eat anything they can. It is the nutritional value that is the problem.

      • When people are starving, it is the calorie value that is the problem.

        • There was a reason people in the middle east packed dates along. No only delicious and require no refrigeration, high in calories.

        • Re: (Score:3)

          by tragedy ( 27079 )

          When people are starving, it is the calorie value that is the problem.

          Yes and no. Mostly yes and the Calorie value is certainly important. Obviously the body can't run without energy and basically eats itself to try to stay alive without enough Calories. Even in regular starvation though, the lack of micronutrients can exacerbate the health issues. Then there are types of starvation where Caloric intake is high enough to keep the body going, but the lack of other nutrients can cause potentially fatal health problems. One example is so-called "rabbit starvation" (which notably

    • Re: (Score:2)

      by tlhIngan ( 30335 )

      For much of the world, avoiding starvation is the principle goal, so for these areas, higher crop yields are beneficial despite lower nutrient density.

      We do not have a food issue. We make more than enough food to feed everyone in the world right now.

      We only have a distribution issue - if humanity were to regain some humanity and not feed the greed, it would be easy to end world hunger and ensure no one goes hungry again.

      • Indeed, too much food is grown for ethanol to add to fossil fuel for transport - cut that out and there will be plenty more food available
  • "This also raises the question of whether we should adjust our diets in some way, or how we grow or produce our food." If we truly believe in evolution, survival of the fittest, etc then we really shouldn't need to do anything. We will continue to evolve even as our sources of food change.

    • Not if the assorted cancers and heart disease kills the average person after around age 40.

      • Why would that be a problem? Hell, that's already older than the average lifespan of a human for most of our history.

        You can have plenty of kids before the age of 40 and are unlikely to have many after that age. Evolution only cares about reproduction, so...

    • Sure, mankind isn't going extinct over this. But nature operates in a very brutish manner. If I can avoid health problems by popping a multivitamin or something, I want to know that.

    • That's too fast though, it's related to climate change itself when chuds bring out the "oh you think the climate on Earth has never changed?!?" but no regard for time being a thing to consider.

      Some changes will eventually happen for sure but at the current rate the climate will be outpacing those changes, humans are relatively slow to evolve. We've also used the very technology that has changed to climate to insulate ourselves from evolutionary pressures.

      • "chuds bring out the "oh you think the climate on Earth has never changed?!?" but no regard for time being a thing to consider."

        How about margins of error on assertions that this is the fastest ever climate change? How fast did climate change after the famous asteroid impact and did birds weather it?

        • Everything had a hard time after the impact and we shouldn't be trying to replicate that

        • Hey you know what, you got me, the climate change right now is not as bad as the Chicxulub Impact, we can agree on that totally reasonable assertion.

          • Gemini:

            "mammals massively benefited from the asteroid impact that killed the dinosaurs, as the extinction event eliminated their dominant competitors (dinosaurs), opening up vast ecological niches for mammals to rapidly diversify, grow larger, and eventually dominate Earth, leading to the "Age of Mammals". While many mammals also died in the impact, the survivors, often small and adaptable, quickly filled the empty roles, evolving to fill diverse new environments from ground to trees"

            Did you say evolution i

            • Put some timetables on all those events first, anthropogenic climate change we re ticking at 150-100 years so that's the time to beat, in the broad sense that is 4-10-ish generations.

              How fast the mice are able to evolve isn't really relevant, they can do 5 generations in a year.

            • Re: (Score:2)

              by dryeo ( 100693 )

              the survivors, often small and adaptable, quickly filled the empty roles, evolving to fill diverse new environments from ground to trees"

              Quickly in that case is closer to a million years then 100 years.

        • The margins of error must be rather large, considering that assertion is false. The end of the Maunder Minimum saw a larger and faster increase, and it was recorded in real time with actual thermometers, not heavily compressed ice cores.

          But, for assuredly good and sincere reasons, we are supposed to dismiss the Central England data because only England was measuring temperatures. We're supposed to prefer far less granular data that loses the needed resolution after what, a century? Even if it's improv

          • Re: (Score:2)

            by dryeo ( 100693 )

            Except England is one small data point in a large Earth. All it takes is a small change in a certain ocean current to create a large change there.

    • "If we truly believe in evolution, survival of the fittest, etc"  Darwinian evolution is demonstrably wrong. Genetic drift and macro-happenstance ( volcanoes/asteroids/tsunamis etc ) set the evolutionary "path". And that path is semi-Markov. The fittest/strongest/most-fertile/smartest/best-fed  survive with the smallest imaginable preference.  Edge cases do exist, like random-coil bio-polymers becoming rod-like in low-salt solutions.

  • Come back, zinc! (Score:3)

    by TwistedGreen ( 80055 ) on Friday December 19, 2025 @11:52AM (#65869079)

    You said you wanted to live in a world without zinc, Jimmy! Now your bean salad is contaminated with lead!

  • I was always told plants crave CO2.

    • Sure, like people crave sugar. But change the balance of nutrients and you change the body composition.

  • bad things would happen if CO2 levels went up?

  • Then I saw it came from The Guardian and knew it was crap.
  • Commercial greenhouses have long used higher CO2 levels to accelerate growth.

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