Even if you can get folks to begrudgingly admit that organic foods tends to contain fewer pesticide residues than conventional  (and that this might even impact a person’s health or the way a child develops), they’ll dig in their heels when it comes to the nutritional content. And why shouldn’t they? Organic isn’t really about getting more vitamins, minerals, or other nutrients; it’s always been about getting vitamins, minerals, and other nutrients without the conventional pesticides, herbicides, and fungicides that so often accompany conventional produce. The presupposition that proponents of organic produce claim it contains more nutrients is a bit of a straw man, as that claim is rarely – if ever – made.
But what if that mythological claim actually held a kernel of truth? I mean, now that they’ve mentioned it and let that monkey out of its cage, let’s explore a bit to find out, starting with the Stanford study  that sparked this whole topic.
If you take the Stanford meta-analysis at its word, you’ll conclude that “published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods.” Yet critics of the study argue that mistakes were made and that certain nutrients were overlooked, or undervalued, by the authors. One such critic, Dr. Kirsten Brandt, an agricultural scientist who specializes in how growing conditions impact the nutritional density and composition of produce, conducted a similar meta-analysis of the literature that covered much of the same literature as the Stanford study and came to a slightly different conclusion.
Brandt’s review covered more nutrients than the Stanford review. She found it puzzling  that the Stanford researchers chose to “include [nutrients] where the difference was smallest to begin with” while omitting others “that were just as well-described in the papers they included.” They also wrote that there was no difference in total flavanol content, which directly contradicted Brandt’s findings, but a closer look showed that they’d merely misspelled flavonol – an honest mistake, albeit one that cloaked a major benefit of organic produce.
Contrary to the recent paper, Brandt’s analysis  found that organic produce tended to provide significantly more vitamin C and “secondary metabolites.” Secondary metabolites, or bioactive compounds that aren’t directly involved in the plant’s growth, maturation, or reproduction, include the antioxidant compounds  – the polyphenols, the flavonoids, and all the other phytonutrients – that make fruits and vegetables so uniquely healthful and which the evidence suggests is the primary explanation for the association of produce consumption with increased health . Although these secondary metabolites provide health benefits to those who eat them, for the plants, they are self-defense mechanisms . And without copious amounts of conventional agricultural chemicals doing the protecting, plants grown organically must manufacture more of their own protective compounds  to stay alive, particularly if they’re subjected to stressors (like physical trauma, at least in the case of sweet potatoes ). This is good for us. It’s as if growing plants organically trains them to be better and more beneficial.
Other papers suggest nutritional differences as well, also primarily in terms of secondary metabolites and other “minor” antioxidant compounds:
A 2010 study  examining the fruit quality of three varieties of organic and conventional strawberries found some pretty important differences. First, organic strawberries  tended to win the blind taste tests. They were smaller, but denser. They were brighter, which correlated with increased levels of phenolic compounds and other antioxidants. Organic strawberries also had more vitamin C, lasted longer on the shelf, and were more resistant to fungus (despite having no anti-fungals applied).
Another review (PDF ) found that, by and large, organic produce had greater levels of secondary metabolities and tended toward more magnesium, vitamin C, iron, and phosphorus. Interestingly, the author also found that differences existed between newly-organic farms and more “mature” organic farms; the longer soil was worked using organic methods, the more nutrient-rich its produce. Thus, it’s possible that many of the studies showing little to no difference between conventional and organic were using “young” organic farms that had yet to reach their potential.
Most of these secondary metabolites aren’t going to show up in a nutritional database. They won’t help you pad your MyFitnessPal stats. They aren’t “essential” to health like vitamin D, vitamin C, or protein are and thus won’t register as very important in most meta-analyses, but they certainly make life a whole lot better (and longer, and healthier, and possibly even less cancer-y ).
What about minerals?
Seeing as how the mineral content of produce depends on the mineral content of the soil in which the produce was grown, most studies find little difference between the mineral content of organic and conventional stuff. The biggest general determinant of mineral density in food appears to be geographical location , since different regions have different soil compositions. Even members of the same vegetable variety from different areas of the country can have wildly different levels of certain minerals depending on the mineral level of the soil. That said, one study  found that organic crops had higher levels of magnesium, iron, vitamin C, and phosphorus, with lower levels of nitrates. It’s not that getting ordained by the organic gods magically increases the amount of magnesium in your soil; if organic chard has more magnesium, it may be that the organic chard farmer was just really dedicated to soil maintenance. From talking to the farmers at the farmers markets, I get the sense that this is probably the case.
My personal hunch? The food I buy from the farmers market from people with dirt under their fingernails is more nutritious than the food I get from the grocery store. It certainly tastes better. The odd-looking winter squash with orange knobby protrusions that the farmer says tastes like a cross between kabocha and butternut, or the pale butternut squash from Trader Joe’s? The dry-farmed early girl tomato that weighs twice as much as the same-sized store-bought conventional tomato? The room temp broccoli that’s never seen a fridge before laid out in the Santa Monica sunshine, or the bushel of Costco broccoli florets languishing in the industrial refrigerator? All that flavor, that weight, and that density can’t just be handwaved away as ephemera without a nutritional corollary. Nutrients – no matter how micro they are – occupy physical space. They have mass. If this tomato weighs a quarter pound more than that tomato, there is something qualitatively different about it, and it’s probably got something to do with the nutritional content (with it, ya know, being food and all).
Plus, the “organic” produce I get – whether it’s unofficial organic or proudly displays the emblazonment for all to see – tastes better to me and my family. The strawberries are firmer, sweeter, and more tart; if it’s the increased vitamin C content coupled with more robust intracellular plant matrices (yep, made that up), I don’t really care. The kale’s more bitter and pleasantly pungent; if that’s the increased polyphenol content, good for it. I like the taste. The increased micronutrient density (if it exists, and it looks like it probably does) is just a welcome addition.
Still, the research appears to say that, contrary to what the latest study would have you believe, organic produce tends to be more nutritious, particularly if you count something like a plant pigment with antioxidant qualities or a flavonoid as a “nutrient.” I definitely do, but I can see why someone who lives and dies by a standard nutritional database would overlook them. Vitamins and minerals are vital and all, but they aren’t everything.
What do you think, folks? I realize that you’ve probably never ordered micronutrient testing for your organic baby bok choy and compared it to the stuff from the supermarket, but have you noticed any qualitative differences between produce from different sources? What about that most important of qualities – taste? Let me and everyone know in the comment section!
Thanks for reading.