Why organic tomatoes are good for you

I’ve been meaning to blog this for almost a month. R. Ford Denison (a name to reckon with) blogged about some of his own research that summarizes 10 years of research into the flavonoid content of tomatoes grown conventionally and organically. Bottom line is that the organic tomatoes contained almost double the flavonoids of conventionals. I’m not going to go into whether that’s a good thing or not. Instead, I’ll stress the point that Denison himself makes, about Darwinian agriculture.

Why do the organic tomatoes contain more flavonoids? Maybe because flavonoids play a part in combatting herbivory. And they are often produced in response to pest attacks, rather than all the time. So one reason that organic tomatoes contain more of these compounds — which are believed to be good for human health — is precisely because on an organic farm there are a few pests that attack the plants. No pests, no need for defense, no benefits for human health.

This is just one aspect of what Denison calls Darwinian agriculture, a fascinating approach to the whole question of just what is being selected. There is, as someone else wrote, grandeur in this view of life …

12 Replies to “Why organic tomatoes are good for you”

  1. Denison seems to believe not only in Darwinian agriculture, but also in intelligent design!

    He basically says that (human) intelligent design should take the opportunities that evolution has missed, especially by designing more symbiotic, less competitive relations between organisms than nature would.

    The post Jeremy cites says: “some of the natural insecticides plants make, especially when attacked by insects, are likely to be harmful to humans, rather than beneficial.”

    So the organic flavonoid-rich tomato is fine, but I guess that Denison would argue that the next step should be redesigning the tomato to do the same thing for other chemicals?

  2. I have absolutely no problem with Intelligent Design — as long as one defines the intelligence, which Denison does! (And, of course, Darwin did too.)

    Thanks for the link. I look forward to reading it in due course.

    As for redesigning the tomato, I note that people have already tried to boost carotenoids by GM. Getting rid of harmful compounds has also been tried, both by natural artificial selection and by artificial artificial selection (GM). I’m not sure one can generalise about wheter it works.

  3. I think I agree. My main trouble is not with design but with Denison’s idea of evolution. The statement of De Wit (cited in Denison’s article I linked above) that “There is nothing in the process of evolution that has any aspect of community behaviour as a goal” has been proved wrong (I think) by research on plant communication.

    My preference goes to other kinds of biological theorizing in which competition between individuals is not the main force behind evolution (Brian Goodwin is a good starter).

    In any case, Denison is worth reading, as it is definitely thought provoking. Linking biological theory and agricultural practice seems highly relevant to me.

    As for the tomato, I just meant to say that in this case organic horticulture wins, but that in the case of other chemicals that are less beneficial to human health it may not. So Darwinian agriculture is definitely not the same as organic agriculture, as also becomes clear from Denison’s praise of the Green Revolution.

    So my question is: what kind of vision would an alternative biological theory of evolution produce?

  4. I’m afraid we’re just going to have to agree to disagree on the question of locus of selection; what about plant communication suggests selection among populations, rather than a form of kin selection?

    I hope nothing I said equated Darwinian agriculture with organic agriculture. That was certainly not my intention.

    I’m not sure I need an alternative biological theory to imagine alternative forms of agriculture. In fact, the current biological theory of evolution that I hold underpins what I think is valuable about agricultural biodiversity; resilience, stability, adaptability and all that stuff.

  5. Theorizing often occurs after the fact. However, it seems to me that in Denison’s case “Darwinian” theory is used to justify the Green Revolution (as well as some more friendly agricultural innovations).

    The point is not exactly about kin selection (Goodwin actually dislikes the idea, see the link above). This article explains Goodwin’s ideas well and links to agricultural practice.

  6. At the same time, the herbivory causes the plant to upregulate the production of toxic compounds. So going from higher levels of flavonoids to concluding that they are better for you is not straight-forward. You can’t look at one class of compounds in tomatoes and make a broad generalization about the entire tomato. A UC Davis researcher, Carl Winter, concluded in a paper that the organic-healthier connection isn’t justifiable. That’s not to say that they aren’t healthier, but that the evidence we have doesn’t arrive at that conclusion. Here’s a link to an interview that I did with him on my show:

  7. I’m sure that the biochemical profile of organic tomatoes differs from conventional in many more ways than just the flavonoids. So you’re right, it was a generalization. But equally, there’s a generalization involved in using the phrase “toxic compounds”. Dosage is everything, no? and some things that are beneficial in small amounts may be toxic in larger amounts.

    The problem with that is that people develop a notion of safe vs unsafe, or toxic vs harmless, or whatever. That’s a lot easier than actually thinking things through.

    Nice broadcast too!

  8. I don’t get a lot of readers or comments, so it was nice to find this intelligent discussion. I have mixed thoughts about the Green Revolution. High yields mean we can grow the same amount of food on less land, hopefully leaving some land for nature. But 1) that isn’t always what actually happens, and 2) the lower competitiveness of Green Revolution cultivars tend to lock us in to systems with good weed control. Sometimes it seems like we’re painting ourselves into a corner. Anyway, I just got a book contract with Princeton University Press, so I’ll be developing these ideas in more detail.

  9. I’m sure that the biochemical profile of organic tomatoes differs from conventional in many more ways than just the flavonoids.

    Agreed. What I think we (society) need to do when it comes to health claims based upon food is ask where is the specific evidence of that health claim itself. Before making health claims, they should couple research on flavonoids and other compounds in organic vs conventional tomatoes with a study on differences in how our bodies treat each one. As Ford Denison points out, there is a difference between the varieties being grown in each system – which I might add doesn’t necessarily mean that the way it is grown accounts for the difference, although it probably accounts for some.

    For a great example of coupling a nutritional study with a healthier variety of carrots, see this.

    Theres a renewed interest in the healthfulness of produce on the plant genetics end, because now more than ever, we have the ability to track these kinds of changes during breeding. And knowing what factors affect the absorption of certain nutrients can help us figure out how to enhance our foods in a way that makes a difference. Interestingly, I learned last week from a carrot breeder (arguably the carrot breeder, Phil Simon, that breeding efforts over the last few decades have enhanced the carotene content of carrots almost threefold. (This was done by crossing the carrot with wild relatives)

    It’s a luxury to be able to talk about making foods healthier for ourselves or the environment, because prior to the Green Revolution, the issue was whether or not there would be enough food to eat in the first place. Norman Borlaug and the GR are credited with saving the lives of over a billion people.

    There’s no question that there have been drawbacks to the GR, but hunger is such a socially and environmentally-destabilizing force. What makes me optimistic about this field is that with a cushion of relative food security (not to gloss over current problems), we can address these problems and sustain interest in them.

    Thanks for the comment about the show, I recently started it up again. On the toxic compounds issue, I meant compounds toxic to us – and the point of bringing it up was to say that we don’t know whether or not those changes are bad or benign.
    Bottom line: just eat your veggies!

  10. Here’s a short version:
    Our ancestors who delayed reproduction when environmental cues predicted famine were more likely to survive to reproduce after the big die-off. Delaying reproduction therefore increased relative representation in the smaller post-famine gene pool. Biological responses inherited from those ancestors are still triggered by cues that predicted past famines, such as eating less or eating “famine foods.” These responses can therefore extend lifespan, with a decrease in potential fertility as a side-effect. But most of us don’t want to achieve our maximum possible family size anyway.

    I guess I should have said that if you click on my name in the comment above, it goes to a longer explanation. I’ve mentioned this work elsewhere on your blog, where Penny corrected my simplifying assumption that “famine foods” are necessarily bitter.

    Also, Amazon.uk is taking preorders for my book on Darwinian Agriculture, which seems a bit premature, as I haven’t finished writing it.

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