Stanford researchers caused a minor scandalin natural-foodie circles last fall when they published a meta-study refuting the nutritional benefits of organic produce. The online commentariat quickly divided into two camps—the vindicated (“I told you so!”) and the aggrieved (“You’re missing the point!”)—and web editors gleefully posted story after link-bait story about the findings.
The big footnote to that research, of course, is that the researchers were focused primarily on organic veggies’ nutritional content and not their small environmental footprint or lack of noxious pesticides. There are plenty of reasons to eat organic—c.f. Michael Pollan’s oeuvre—and not all of them have to do with phosphorus and fatty acids.
An article by Brazilian biologists, published recently in PLOS One, makes a compelling case for the nutritional superiority of organic tomatoes, and (nerd alert!) outlines the biochemical processes responsible for their healthfulness.
The biologists wanted to compare the levels of “phytochemicals” in organic and conventional field-grown tomatoes. Phytochemicals—defined by Oregon State University's Linus Pauling Institute as “chemicals from plants that may affect health, but are not essential nutrients”—are a bit of a rage these days, among nutritionists and health nuts alike. The bioactive compounds include resveratrol (the red wine wonder drug), flavonoids (antioxidants found in tea, fruit, and dark chocolate), curcumin (an anti-inflammatory found in turmeric), and carotenoids (such as lycopene, whose proposed anti-stroke properties we’ve written about previously).
Phytochemicals only recently went from being an “unknown unknown” to a “known unknown” in the scientific community, which is to say, they’re the topic of much conjecture and little certainty. Still, there’s mounting evidence that they play an important role in mediating—if not mitigating—chronic illnesses, such as cancer and heart disease.
The Brazilian researchers proposed that, because organic tomato plants are exposed to more field stress—in the form of pests, weeds, and nutrient scarcity—than conventional ones, their fruit would likely be “endowed with enhanced nutritional properties,” a kind of “what doesn’t kill you makes you stronger” theory of life in the plant kingdom. If the goal were to grow not just large tomatoes but healthful ones, might a moderately stressed vine produce more phytochemicals and antioxidants than a carefully tended one?
Indeed, the biologists found that, while conventional tomatoes were 31 percent larger and 60 percent heavier than their organic cousins, they were lacking in phytochemicals. Pesticide-free fruit, grown on stressed vines, had significantly higher levels of flavonoids, phenolics, and vitamin C.
“Until recently, the focus has been mainly on yield”—i.e. size, weight, and quantity of produce—“rather than on gustative and micronutritional quality of fresh plant products,” the authors conclude. “This might be all right for staple food, but, as far as fruits and vegetables are concerned, it may be argued that gustative and micronutritional quality matter more than energy supply. Our observations suggest that, at least for fruit and vegetable production, growers should not systematically try to reduce stress to maximize yield and fruit size, but should accept a certain level of stress as that imposed by organic farming with the objective of improving certain aspects of product quality.”
Put rather less prosaically, the greater the stress, the sweeter (and more antioxidative!) the wine.