Are GMOs to blame for the loss of nutrients in our fruits and vegetables?

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We have been losing nutrient content in our food, particularly raw produce. Today’s conventionally grown produce isn’t as healthful as it was decades ago. The decline in the quality of fruits and vegetables was first reported more than 15 years ago by English researcher Anne-Marie Mayer, who looked at the dwindling mineral concentrations of 20 UK-based crops from the 1930s to the 1980s. Other countries, including the United States, face similar disheartening trends.

The usual coalition of anti-GMO and pro-organic activists claim that these losses result from genetically engineered foods. However, the science tells us that this trend predates the introduction of genetic modification, and may even predate the use of fertilizers, pesticides and other methods that ushered in the Green Revolution.

There’s been a lot of data generated pointing to declines in vitamin and mineral content in produce, and there’s also been a lot of blame. For example:

  • A post on Mercola.com claimed that “Cultivation of GE crops may be a major contributor by adversely altering soil’s ecological balance and fertility, possibly irreversibly; DNA from GE organisms is not readily broken down by soil microbes, and this foreign DNA can mix with the DNA of these microbes to create bizarre strains, toxins, and otherwise interfere with the biological system that controls soil’s fertility.”
  • Many anti-GMO activists, like the Lotus Clinic, accused GMOs and glyphosate use for depleting soils, and therefore crops, of nutrients. Other anti-GMO sites similarly juxtaposed soil depletion with “studies” showing (falsely) that organic produce has higher nutritional content than genetically modified foods.
  • The Organic Consumers Association has accused the USDA of doing nothing while nutrients have dropped since the 1970s. These included an enormous 50 percent drop in the amount of calcium in broccoli, for example. Watercress down 88 percent in iron content; cauliflower down 40 percent in vitamin C content-all since 1975.” The culprit? A commercial emphasis on how food looked, which overlooked nutritional content.
  • blog post in Scientific American cited a University of Texas study in 2004 as evidence that nutrient depletion between 1950 and 1999 was the result of soil depletion caused by so-called Big Ag: “The main culprit in this disturbing nutritional trend is soil depletion: Modern intensive agricultural methods have stripped increasing amounts of nutrients from the soiI in which the food we eat grows.”

It’s not the soil and not GM 

But that wasn’t quite what the Texas paper said. A look at the actual study, a statistical analysis of historical USDA nutrient data conducted by UT scientist Donald Davis, shows the researchers reached a different conclusion. It did show nutrient depletion in some vegetables and fruits between 1950 and 1999, but it also showed increases in nutrients in other produce. In addition, while Davis and his group did hypothesize about the role of soil types in depletion, they also focused on genetic variations in plants and the tradeoffs in creating hybrids and cultivars:

Cultivars commonly are selected for yield, growth rate, pest resistance and other attributes, but seldom have they been selected for nutrient content. It is well accepted in agricultural research that selection for one resource-using function may take resources away from other resource-using functions.

So, if you selected for nutrient increases, you’d eventually get them. If you didn’t select for nutrient increases, you likely traded nutrients away in favor of something else.

What is the reason behind nutrient decreases?

Nutrient depletion has clearly been a problem since well before the advent of genetic engineering of crops. But it also may have been a problem as we entered the era of what we consider modern agriculture (at least what the Green Revolution produced starting in the 1960s).

Carbon dioxide gas increases may be one factor in declining nutritional content. In a paper published in Nature in 2014, and international team led by the Harvard School of Public Health found that certain cereals and grasses contained less zinc and iron when grown under increased levels of carbon dioxide. The carbon dioxide levels tested were those predicted to exist by the middle of this century, assuming current trends in global warming/climate change continue. The researchers also found significant variation in nutrient levels among cultivars in the face of greenhouse gases, and concluded that breeding for resistance to carbon dioxide levels could restore zinc and iron levels.

Nutrient decreases may have started at the beginning of the industrial revolution, in the mid-19th century. A British experiment called the Broadbalk Wheat Experiment has been measuring nutrient (nitrogen, potassium, phosphorus, and calcium) content in wheat and straw since 1843. Studies using these data found steady levels of these minerals from 1845 until the 1960s, when nutrient content in plants began decreasing, possibly due to cultivar selection. In contrast, soil content of these same nutrients has remained stable over the past 160 years. Moreover, the soil and plant nutrient content was the same regardless of whether the plants were raised using inorganic fertilizers, no fertilizers, or under organic production rules.

There are a lot of reasons behind changes in nutrient content. Farming practices like spacing of rows, seeding, type of amount of fertilizer, irrigation, and other factors like geographic location and weather all play a significant role in how much of a specific nutrient is in a plant. And there has been a lot of variation depending on the breed of plant farmed. Davis’ 2004 study, in fact, found 4-fold variations in beta-carotene, 9-fold variations in one type of Vitamin E, 10-fold variations in y-tocopherol (another Vitamin E subtype) and 2.8 fold in ascorbate, all in 50 broccoli varieties growth together.

In the 2004 study, Davis left us with perhaps a more significant warning. He noted that while refined sugars, processed fats and oils, and white flour and rice have all seen significant reductions in nutrients, they currently constitute half the calories consumed by Americans. Moving away from those foods toward any type of fresh produce, therefore, would be an improvement in nutrition that far eclipses any mineral and nutrient declines seen over the decades.

Andrew Porterfield is a writer, editor and communications consultant for academic institutions, companies and non-profits in the life sciences. He is based in Camarillo, California. Follow @AMPorterfield on Twitter.

  • Garrett Osborn

    Interesting article. With the Broadbalk Wheat Experiment, it is hard to imagine the soil nutrient levels remaining stable over this period of time (as a crop should remove 10% to 20% of its dry weight in soil minerals). This soil has either a rapid nutrient cycle or conditions exist that allow it to retain it’s nutrients.
    The loss of mineral content in food has ramifications on health (ie impaired enzyme function), when also combined with the volume of processed foods consumed in our society (with little to no enzyme content).
    A shift in our “quality” paradigm will have to occur, where farmers are paid for quality based on mineral content or high refractometer reading on fresh crops (which passes on in improved flavor & storability). Much of the produce today is good for making a turd, but has minimal nutritional value. The differences between garden grown produce & commercially soil or hydroponic grown produce are significant.

    • crush davis

      You’re right that crops remove nutrients from soil. But the biggest advocates of restoring “nutrient density” to food through the soil are in the biological farming circles. And they don’t rely on credible, empirical estimates of nutrient removal to develop soil management plans. In fact, they shun university and extension research in favor of whatever pseudoscientific crap they can dredge out of the Acres USA septic tank. Usually that consists of heavy doses of the so-called “Albrecht Method” leavened with Cary Reams’ discredited ideas, seasoned further with such unscientific idiocy as paramagnetic scams. Nor do they acknowledge that crop genetics, breeding and hybridization are critical in food nutrient composition. Joe Mercola is just the biggest mouth–but he’s not out there setting back the production in the field. That’s left to the biological farming fertilizer salesmen and “consultants” who like to use a lot of sciency-sounding language to rip off gullible growers and consumers. The only way crop nutrient levels will improve is if REAL scientists with legit credentials develop models that growers can follow and adapt to restore the nutrients that plants remove, along with optimizing varieties for a combination of desirable traits.

    • Alokin

      Didn’t go behind the paywall to get at the details, but the abstract suggests the addition of fertilizer: “Similarly decreasing trends were observed in different treatments receiving no fertilizers, inorganic fertilizers or organic manure.” http://www.ncbi.nlm.nih.gov/pubmed/19013359

      • crush davis

        Good point. On a related note: in the recent issue of Crops & Soils magazine, a study in the Midwest was reported that showed foliar-feeding micronutrients to soybeans and corn isn’t likely to increase yields, but can increase leaf and grain nutrient concentrations. http://bit.ly/1P1rgcp

        One inference is that declining soil nutrients doesn’t necessarily mean crops cannot have good nutrient levels. Another inference? The biological-farming, “nutrient-density” fertilizer salesguys will ignore much of this research in an effort to push more foliar sprays, even if the economics don’t warrant their use.

        • crush davis

          I have to correct myself: the study was run on soybeans only. Not corn. But more to the point of this original blog: the research in that link also demonstrated that soil and tissue micronutrient tests need to be calibrated to local conditions to be optimized. In short, if the scientists and researchers aren’t confident in making recommendations, growers should be VERY cautious when a fertilizer salesman makes claims, and speaks with the sort of confidence that often comes from not understanding empirical methods and their limitations.

  • Alokin

    Discussion of same subject over at Neurologica: http://bit.ly/1NFsVPH

    • WeGotta

      Worth the read, thanks.

  • WeGotta

    It seems like in our race for uniformity and ease of production we have taken our eyes off other important factors.

    Decreasing nutrients for our bodies from larger and larger crops of fewer and fewer plant varieties, decreasing “nutrients” for our souls from monoculture of strip malls and consumerism and decreasing “nutrients” for our minds with “standardized testing” and consolidated media spewing the same bland nonsense no matter where you turn.

    • DrGreenThumb

      Plant breeders and farmers are motivated by market forces, which in this case are yield by weight per unit area. When consumers want more for less, you can’t blame breeders and growers for responding by selecting varieties with higher yield. Until we can fact nutritional content into plants in a way the is reflected economically, this is going to be a difficult ship to turn around.

      Interesting, GE may be a useful tool here as it would allow us to increase nutritional content in varieties that are already high yielding. Theoretically, of course, as I am assuming the biochemical pathways and genetic regulation responsible for the biosynthesis of said nutrients is known.

      • WeGotta

        Yes.
        Most people accept (or at least consent by not having an opinion or through ignorance) the prevailing belief that market forces are the “best” solution for pretty much everything.

        This despite current evidence that this isn’t working.
        This despite history and religious teachings which warn us against such faith in false idols and greed.
        This despite the lack of logic in the belief that such a system could ever produce (or even has as it’s goal) lasting peace and security.
        This despite the fact that there’s really no such thing as a “free” market anymore. It’s rigged from the very beginning where the dollar is created.

        So on one hand I don’t “blame” plant breeders and farmers for their decisions and I don’t “blame” consumers for wanting cheap things. I blame all of us for playing along.

        Either we all work together to turn the ship around or we can fight each other as we hurdle toward the inevitable. I’m on the way to a life boat as I try and warn as many people as I can that there’s trouble ahead.

        • DrGreenThumb

          Well, part of turning this ship around might require helping people to understand that GE isn’t dangerous and can actually be beneficial. Alternatively, we could try to come up with some sort of incentive model to increase the profitability of nutrition instead of yield/area only. However, I think engineering existing high yielding varieties may be a faster and more direct approach (assuming the public gets on board, which at this point is a pretty huge assumption and not a safe one).

          • Alokin

            All aboard the good ship Science.

        • Alokin

          Give me an example of a country you think is doing it right, that has turned the ship around.

          • WeGotta

            Sorry. I don’t have near enough knowledge about that to be able to say.
            I do know there are groups of people working on important things in the US and elsewhere but I don’t know of any country that has say, developed an economic model not based on debt creation or one that has committed to peace and understanding rather than the petty self interests of the ruling class.

          • Farmer with a Dell

            “…don’t have near enough knowledge about that to be able to say…”

            …but more than sufficient ignorance to tell us exactly how you think we all should be living.

            The man simply asked for a real world example — a nice honest direct question — just name a couple countries. Odd so simple a request should leave a smug know-it-all standing akimbo with his shorts yanked down around his ankles. Guess that sort of thing will often happen to mouthy folks who think with their posterior and spend all their time talking through their sphincter. Well done, WeGotta. Carry on.

          • WeGotta

            So a detailed knowledge of all the world’s political and social constructs is necessary to have an opinion about my country’s systems?

            You people are the ones telling us “how we all should be living”. Geneticists telling us what we should eat and whether or not we even get to know about what’s been done to our food, farmers trying to tell us that agricultural “advancement” means only things that improve their cash flows, scientists trying to tell us that the world needs more technology in order to fix our greatest problems.
            And worse than that, you all do so in sanctimonious, unscientific, illogical, and mean-spirited ways.

            You say “believe me or you are stupid”.

            I say don’t believe anyone. Look around you and trust yourself to know truth when you see it.
            I say especially don’t listen to those who tell you you’re ignorant if you don’t see the world as they do.
            I say show me proof that your way of seeing the world produces an outcome that fits my belief about what is good, or fair, or smart.

          • Farmer with a Dell

            All I hear is “pfft”

          • WeGotta

            Exactly.

          • Alokin

            “So a detailed knowledge of all the world’s political and social constructs is necessary to have an opinion about my country’s systems?”

            No, but if you are going to turn the ship around, it would be helpful to know which direction to travel once you do. What many people don’t seem to understand, many of them young people, is that capitalism drives all of the most prosperous, respected, and fair societies on the planet. Market forces in capitalist economies are the people until government gets involved and tries to manage the economy. Nothing more powerful and fair in my mind than a free people and their economy responding to the demands of the people.

            I think most of the complaints people have about U.S. capitalism should be directed at government instead. Rather than establish a minimum set of rules and standards and a simple tax code, more and more, our government seeks to pick winners and losers and dispense favors. The larger the government becomes, the more that is the case.

          • WeGotta

            All the “most prosperous, respected and fair societies” obtain all this success off the back of poor people just as we have for centuries.
            It’s built in the system. Billions of people in other countries pay the direct price for our comfort.
            They suffer so we can have way more than we need.

            I have no problem with exchange of goods and services for currency. But the currency shouldn’t be based on debt. It shouldnt be given to those at the top of the pyramid. We see what they are doing with it.
            It shouldn’t be based on consumerism. This is not sustainable and is wrecking the planet.
            It’s no longer even working so well in the “prosperous” countries as many are waking up to find that working a crap job most of your adult life in order to buy cheaply made junk that doesn’t last doesn’t bring fulfillment or happiness.

            It’s pretty safe to say that most people don’t even live long enough or have enough health to enjoy retirement. Our food makes us sick and our working for 50 years wrecks our bodies. Any money we have saved is given to the hospitals. So what’s the point anyway?

            What happened to American individualism and strength?
            We seem content to be lemmings these days and let other people do hard work to keep us in this position of semi-comfort and not-so-freedom.

          • WeGotta

            I agree with a lot of what you say.
            The last thing I want is more governance from a distance.

            It’s even worse when the winners that the government picks and those who pick them become the best of friends.
            I like the idea of alternative currencies. The idea of giving essentially free money to those banks who wrecked the economy, gamble with our money and who have committed felonies so that they can turn around and create more free money to lend to us (supposedly) seems so obviously wrong I’m at a loss of word to explain why it still happens.
            The only thing I can think is that it has to be this way or it all comes tumbling down.

          • Alokin

            You don’t have enough knowledge, but you want to turn the ship around. Anything is better than what we have now? How quickly we forget the lessons of failed experiments in socialism.

          • WeGotta

            Yes. If my car is heading toward a tree, I don’t need to know my heading or gps coordinates. I just turn the wheel towards a direction where there is no tree.

            How quickly people offer excuses, and labels and nay saying that only serve to keep us all heading for the tree.

            Here’s an idea. Let’s just do things that make sense for us right now using the best information and technology available right now and we’ll figure out what to call it later.

  • Jim Tomasko

    Mr. Porterfield has produced yet another lopsided article that failed to reference a ton of scientific journal data.

    Glyphosate was originally patented in 1964 by the Stauffer Company as a metal chelator (Patent #3,160,632, Dec 8,1964), not as an herbicide. This is very significant on how glyphosate (GLY) interacts with metal in the soil as well as metals in life forms. The metal chelating activity is also part of why it is so effective as an herbicide (binding up all available manganese with is often deadly to the plant). In addition to being an herbicide, metal chelator, GLY is also a selective fungicide – meaning it will kill some fungus species but not others. Dozens of peer reviewed journal article have been done on how glyphosate interacts with soil microbial communities and mycrrorhizal fungi – which completely debunked the 30 year journal article (biotech sponosed) where they concluded that GLY in no way affects mycrorrhizal fungi. Keep in mind that these essential soilborne bacteria and fungi are hugely helpful to the plant in often allowing the availability of otherwise ‘locked-up’ nutrients to the plant, and increasing disease resistance. A quick summary is that glyphosate kills many beneficial mycorrhizal fungi and soil bacteria, but others thrive in these conditions. Two genera of mycorrhiza that love GLY soils are Fusarium and Pythium, the two most economically damaging forms of root rot in the country. In fact, Fusarium was found to grow back within 24 hours of GLY application. So soils where GMO’s are grown are completely altered by such long term use of herbicides/fungicides – resulting in completely different soil microfauna than previously and a much higher rate of root rot due to large communities of Fusarium/Pythium. And after the plants become a lot more rot prone, they will be dosed with more chemicals fungicide. Do you think that a stressed out plant without beneficial mycrorrhizal or microbial relationships is going to produce food just as nutritious as something that is grown in soil with healthy and diverse bacterial and fungal communities? Soil is one of the most important aspects of horticulture/agriculture, and often one of the most underrated for some strange reason.

    GLY also does similar things in the intestines when transgenic food is consumed, with GLY residues. GLY has been shown to kill Lactobacillus, Enterococcus, Bifidobacteria spp., but things like E. coli and Salmonella are immune to the effects of GLY in the intestinal gut microfauna. This is one of the newest and a hugely significant contribution to our understanding of the immune system, neurological disorders/disease, muscoskeletal diseases, brain function as well as odds problems like psoriasis/IBS. There are loads of great new articles about intestinal gut microfauna, check it out at your local universities or online science libraries.

    In conclusion, this article is poorly written and referenced, and the author is essentially unable to answer the question posed. Its interesting that Mr. Porterfield ended the article with a comment about a huge increase in consumption of refined sugars. In this country, these are essentially all transgenic, unless organic. And if its sugar, its GM sugarcane which is GLY-resistant with bT GE’d into the crop. And GLY is the only approved chemical ripener of sugarcane in the US since 1972/1975. So they spray the canes with GLY after harvest to stress the plants and concentrate enough sugars into the cane, to make it economically worthwhile to US Sugar Corp, etc.This is done in states like FLA, LA, etc, where it is too wet during harvest period (stress concentrates the sugar, and the GLY accomplishes the stress very well) And if its just ‘sugar’, then its GM sugarbeets with GLY & bT, or high fructose corn-syrup with GLY & bT also. So regardless Mr. Porterfield, you are the winner, you get to have your dessert and get it with both GLY and possibly even bT. Enjoy!

    Here are some references to some of my comments:

    Barrett, K., M. McBride. 2006. Trace Element Mobilization in Soils by Glyphosate. Soil Science Society of America Journal, Vol 70 (6), pp. 1882-1888.

    Barriuso, J. R.P. Mellado. 2012. Glyphosate affects the rhizobacterial communities in glyphosate-tolerant cotton. Applied Soil Ecology 55, p. 20-26.

    Bott, S., T. Tesfamariam, A. Kania, B. Eman, N. Aslan, V. ROmheld, G. Neumann. 2011. Phytotoxicity of glyphosate soil residues re-mobilised by phosphate fertilisation. Plant and Soil, Vol 342 (1-2), p. 249-263.

    Carvalho, F.P., B.P. Souza, A.C. Franca, E.A. Ferreira, M.H.R. Franco, M.C.M. Kasuya, and F.A. Ferreira. 2014. Glyphosate Drift Affects Arbuscular Mycorrhizal Asssociation in Coffee. Planta Daninha. Vol. 32 (4), P. 783-789.

    E. Clair, L. Linn, C. Travert, C. Amiel, G.E. Seralini, J.M. Panoff. 2012. Effects of Roundsup and Glyphosate on Three Food Microorganisms: Geotrichum candidum, Lactococcus lactus subsp. cremoris and Lactobacillus delbrueckii subsp. bulgaricus. Current Microbiology, Vol. 64 (5), p. 486-491.

    M. Druille, M. Omacini, R.A. Golluscio, and M.N. Cabello. 2013. Arbuscular mycorrhizal fungi are directly and indirectly affected by glyphosate application. Applied Soil Ecology, Vol. 72, p. 143-149.

    M.R. Fernandez, R.P. Zentner, P. Basnyat, D. Gehl, F. Selles & D. Huber. 2009. Glyphosate association with cereal diseases caused by Fusarium spp. in the Canadian Prairies. European Journal of Agronomy, Vol. 31 (3), p. 133-143.

    R.L. Glass. 1984. Metal Complex Formation by Glyphosate. Journal of Agricultural and Food Chemistry, Vol. 32, p. 1249-1253.

    J.M. Merilies, S. Vargas Gil, R.J. Haro, G.J. March and C.A. Guzman. 2006. Glyphosate and Previous Crop Residue Effect on Deleterious and Beneficial Soil-borne Fungi from a Peanut-Corn-Soybean Rotation. Journal of Phytopathology, Vol, 154 (9), p. 309-316.

    C.D. Dalley and E.P. Richard, Jr.. 2010. Herbicides as Ripeners for Sugarcane. Weed Science, Vol. 58 (No. 3), p. 329-333.