Face Off: Organic vs. Conventional
Although some steps that we take to save the planet entail sacrifice (personally, I am getting tired of seeing my breath in my ice-cold house as a result of turning down the thermostat on my gas-burning furnace all winter. But I digress.), more and more evidence is emerging that organic produce is a win-win.
Of course buying organic sends a market signal that leads growers to use fewer pesticides and other agricultural chemicals, not to mention keeps carcinogens and neurotoxins out of your diet. But according to the most comprehensive comparison to date of the nutrient content of organic vs. conventional fruits, vegetables and grains, organics contain higher levels of eight out of 11 important nutrients. Among them: polyphenols (linked to lower risk of lung cancer and heart disease, as well as to greater longevity) and antioxidants (ditto).
Since 2001 more than 40 studies comparing the nutrient content of organic and conventional foods have been published. From those and some earlier studies, the Organic Center identified 236 scientifically-valid head-to-head match ups between an organic food and a conventional one. The nutrients included antioxidants (total phenolics, total antioxidant capacity, quercetin and kaempferol), three precursors of key vitamins (Vitamins A, C, and E), two minerals (potassium and phosphorous) and total protein.
Results: the organic food trumped the conventional one in 145 match-ups, or 61 percent of the cases. Organics came out ahead in polyphenols and antioxidants in about three-quarters of the 59 match-ups of these compounds.
A big exception: Conventional produce usually had more carotenoids. That's what you’d expect: the big jolt of fertilizer applied to conventionally-grown fruits and vegetables leads to what scientists call “photosynthesis on steroids.” The fertilizer increases the production of chloroplasts inside plant cells, which increases the amount of photosynthesis and its production of sugars, which are precursors of carotenoids. As a result, conventional fruits and vegetables generally contain higher amounts of beta-carotene and Vitamin A than the organic version.
This same process means conventionally-grown fruits and vegetables generally have less vitamin C than organics, though. When a plant is flooded with nitrogen fertilizer, it grows like Jack’s beanstalk; by channeling the products of photosynthesis to simple carbohydrates, starch and carotenoids, it makes less of other compounds, notably vitamin C. (The biochemical pathway that makes vitamin C gets turned on only when a plant’s reproductive cycle starts, which in turn occurs only when a plant decides that it doesn’t have to grow any bigger—which happens later or not at all when it is heavily fertilized, as in conventional agriculture.)
“This is the universal point that has not been driven home yet in all the discussion of organic vs. conventional foods,” says Charles Benbrook, chief scientist of the Organic Center. “When you push a plant or an animal to ‘super-animal/plant’ levels of performance, [you] do about the same thing as putting an athlete on steroids: you shift body composition toward a particular type of cell/tissue and dilute/reduce other types.”
That’s what happens with milk. Organic milk contains higher levels of protein, basically because organic cows produce about 20 percent less milk on average than conventional cows, says Benbrook: “There is nutrient dilution. When you feed big Holsteins lots of hot feed (corn), and inject bovine growth hormone, aka somatostatin, in them, yes, they produce more milk. But as the production level increases the milk is composed of more water and less nutrients. The drop in protein is not huge—less than 20 percent—but it is definitely real.”
Next up: the Organic Center is working on a database that will show, veggie by veggie, whether organic or conventional contains more of whatever nutrient you’re interested in.