You may have heard the NPR story this morning about the meta-study from Stanford University, published in the Annals of Internal Medicine, which found "no significant health benefit" to organic food. As physician R Dena Bravata, the study's co-author, told KQED Science's Amy Standen today, when it comes to healthfulness, "there is, in general, not a robust evidence base for the difference between organic and conventional foods."
A 2010 Nielsen study found 76 percent of respondents bought organic because they thought it was healthier. So this seemed to merit a call to the person who convinced me in the first place that it was okay to pay $4.00 for a head of cauliflower: local journalist, professor, and food advocate Michael Pollan, whose book The Omnivore's Dilemma was a major influence in popularizing organic and locally produced food.
JON BROOKS: So is this meta-study a big deal?
MICHAEL POLLAN: I'm not sure it's a big deal. The media's playing it as if there were something new here, but this is not new research, it's a meta-study [a review of previously conducted research], and I've seen the exact same data analyzed in a very different direction. A lot of it depends on how you manage your assumptions and statistical method.
I think we're kind of erecting a straw man and then knocking it down, the straw man being that the whole point of organic food is that it's more nutritious. The whole point of organic food is that it's more environmentally sustainable. That's the stronger and easier case to make.
It's true the body of research around nutrition is really equivocal, and we need to do more studies on that. But the success of organic doesn't stand or fall on that question. This study disputes how significant the differences in antioxidant and nutrient levels are between organic and conventional food. But that's not central to the discussion of why organic is important, which has a lot more to do with how the soil is managed and the exposure to pesticides, not just in the eater's diet but to the farmworker.
JON BROOKS: The meta study did find that 38 percent of conventional produce tested contained pesticide residues, compared to just 7 percent for organic produce. How important is that in and of itself?
MICHAEL POLLAN: It's very important. If you're concerned about pesticide residues in your food, you're much better off buying organic. The study said all these pesticide residues in conventional produce are permissible under EPA rules. They may be, but there's a question of how adequate those rules are. Because there are questions about whether those levels are okay for children and for pregnant women.
There was a very important study, which was mentioned in the meta study, about organophosphates and the link to various cognitive difficulties in children. This is epidemiological, and it's very hard to prove cause and effect, but caution would argue for keeping those chemicals out of your body, and organic produce is one way to do this.
JON BROOKS: Do you think the food industry will consider this meta study a club to hit organic over the head with, or are they participating in organic now to the point where that wouldn't be productive?
MICHAEL POLLAN: Most of the big food companies are now in both businesses, and I don't know that they want to talk too much about pesticides and remind people that this is an active debate, and that there is a lot of pesticide residue in conventional foods. There are various critics of the food movement that will seize on this, and some of those people are backed by agri-business in various ways.
It's great media fodder and it's terrific that people are looking at the issue and debating it. But people should take a hard look. So much of the story depends on what do you mean by "significant health benefit?" The meta study found less pesticide residue, higher levels of anti-oxidants – plant phytochemicals thought to be important to human health; and less antibiotic-resistant microbes in organic meat. But then they say it might not be significant. I don't think they defined signficant.
JON BROOKS: Let's say you're a consumer standing there at your grocery store and you have a choice between an organically grown piece of produce grown far away and a conventionally grown piece grown locally. All things considered, which is the best choice?
MICHAEL POLLAN: It depends on your values. If you're concerned about nutritional value and taste, you might find that the local food, which is more likely to have been picked when it was ripe, is better. Because any food that's traveled a few days to get to you or been refrigerated for a long time is going to have diminished nutritional value. That argues for fresh being more important than organic.
But if you're concerned about pesticides – let's say you're pregnant or have young kids you're feeding – then you might choose organic, because it will have on balance fewer pesticide residues. You may also be concerned with the welfare of the people picking and the farmers growing your produce, or you may be concerned about soil health -- that would argue for organic too.
I tend to favor local food, whether it's certified organic or not. Most of the local food available to us in the Bay Area, though, tends to be grown organically, even if it's not certified. So it is possible to have it both ways. If you're shopping at your farmers' market, you're getting food that's very fresh, probably very nutritious, and probably grown without synthethic pesticides.
JON BROOKS: Anything else?
MICHAEL POLLAN: I would just encourage people to educate themselves and not take headlines at face value. It's a complicated question, and we need to a do a lot more science. The absence of proof means that we either haven't studied it or we haven't found it yet, it doesn't mean we won't. In the meantime, there's a precautionary principle: even though the case isn't closed on low levels of pesticides in our diet, there are very good reasons to minimize them.