Is Organically Produced Food More Nutritious?
IRA FLATOW, host:
This is SCIENCE FRIDAY, from NPR. I'm Ira Flatow.
When you're in the produce section of your supermarket, you push your little cart toward the organic veggies - you know, the produce that's grown with nearly no synthetic fertilizers and pesticides. Organic farmers might fertilize their fields with, oh, let's say ground up seaweed. It might be fishmeal, slaughterhouse waste instead of chemical fertilizers. Or they might use things like chrysanthemum extract to repel insects instead of the mass-produced insecticides.
So your organic apples and tomatoes may bring fewer chemicals into their kitchen, but are they any more nutritious? Do organic fruits and veggies have more vitamins and antioxidants and all that good stuff that we assume is healthier for us and makes us better? If you're like most folks, I think you think so, and then say that's one of the top reasons that you buy organic. But the scientific jury is out. Still out.
And that's one of the questions one of my next guests set out to answer by comparing organic and conventional strawberries grown out in California - which is better for you? That study appears the journal PLoS One this week.
What do you think? Why do you buy organic? Do you think it's more nutritious? Do you like the taste better? Give us a call. Our number is 1-800-989-8255. 1-800-989-TALK. You can also Tweet us at @scifri, @S-C-I-F-R-I, or go to sciencefriday.com and leave us a comment there on our SCIENCE FRIDAY page.
Let me introduce my guests. John Reganold is a Regents Professor of Soil Science and Agroecology at Washington State University in Pullman. He joins us from KWSU. Welcome to SCI-FRIDAY.
Dr. JOHN REGANOLD (Regents Professor, Soil Science and Agroecology, Washington State University, Pullman, Washington): Hi, Ira. It's a pleasure to be here.
FLATOW: Thank you. Kate Clancy is a food systems consultant and a visiting scholar at Johns Hopkins Center for a Livable Future. She's also a senior fellow at the Minnesota Institute for Sustainable Agriculture, and she joins us from our NPR studios in Washington. Welcome to SCIENCE FRIDAY, Dr. Clancy.
Dr. KATE CLANCY (Food Systems Consultant, Johns Hopkins Center for a Livable Future; Senior Fellow, Minnesota Institute for Sustainable Agriculture): Thank you. It's so nice to be with you.
FLATOW: Dr. Charles Benbrook is the chief scientist for the Organic Center in Boulder, Colorado, and he joins us today by phone. Welcome to SCIENCE FRIDAY, Dr. Benbrook.
Dr. Charles Benbrook (Chief Scientist, The Organic Center): Well, thank you.
FLATOW: John Reganold, tell us about the strawberry study. Did you find any differences between the organic and the regular ones?
Dr. REGANOLD: Yes, we did. And the reason that we did the study is, is that we wanted to look at why consumers buy - or look at the reasoning why consumers buy organic food. And it is, as you said, they do buy it, the top reason is is because they believe it's healthier. They believe it's better tasting, and they believe it's for the planet.
So we thought, okay, healthier food, healthier soil - is that true? And we then thought, well, we got to - you know, what are we going to choose? We chose strawberries because they're popular in the diet. People know what they are. They're high in antioxidants. They're high in vitamin C. They're suitable for a sensory evaluation. They also have a high economic value. And if you're going to look at berries, especially strawberries, the mecca for strawberries is California. They grow about 90 percent of the berries, strawberries in the United States, and about a fourth of those in the world.
So to do this we wanted to represent reality, and we picked 26 commercial farms. These are real, commercial, strawberry farms, and they were in pairs. So there were 13 pairs. And each pair would be an organic farm, and right next to it would be a conventional farm. And what we found when we looked at the berries, when we looked at the nutritional aspects, we found that the strawberries - and this was three varieties, it was over two years, and we sampled the strawberries multiple times during the seven-month production season.
We found that the organic berries had significantly higher concentrations of antioxidant activity, they had more vitamin C and they had more phenolics. And phenolics are some of the main sources of antioxidants that we get - that humans get in their diet. The organic berries did have lower concentrations of phosphorus and potassium.
The interesting thing is that we found the organic berries rotted more slowly. So, people that sell berries, especially in supermarkets, that's a big concern, because they want the berries to rot slowly. They want to keep them on the shelf as long as possible. And we thought that was really - to me, it was a surprise because there are fungicides used in the field, the strawberry conventional fields, which can retard mold. But we were getting mold faster on the conventional berries.
And then we wanted to look at, well, do organic berries or conventional berries actually have more strawberry? Have more flesh? Have more dry matter? And we found that the organic berries had more dry matter. And then we said, okay, that's interesting, but what about the soil? And so we looked at about 31 chemical and biological properties of the soil, and with 15 of those properties, they were significantly - and in some cases dramatically - higher on the organic. None were higher on the conventional, and that was a bit of a surprise.
Then we took soil DNA. And there's, of course, DNA in the soil because it's living. There are bacteria, fungi, other microorganisms. And we used this technology, it's a micro-array technology that molecular biologists use, and it gives you a way of looking, basically, at the abundance of genes. And also, you can from that look at the diversity of genes that are in the soil as well as important microorganisms that carry out these processes in the soil that we need to live on the planet. And so one of those processes, for example, would be pesticide degradation. Another one would be nitrogen fixation, where the...
FLATOW: John. John, I'm going to ask you to speed up, because I'm run...
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Dr. REGANOLD: Oh, I'm sorry. Anyway, the bottom line is...
FLATOW: It's like a PowerPoint presentation at this point.
Dr. REGANOLD: I'm sorry.
FLATOW: It's okay.
Dr. REGANOLD: Anyway, the bottom line was - because most people, I know we want to talk about food. But the bottom line was the soil was more genetically diverse. These, all these processes were...
Dr. REGANOLD: ...are more easily carried out in the organic soil from this data.
FLATOW: Let me ask - Kate Clancy to react. Do you agree with the nutritional claims, then, of this study? How does that impact the consumer?
Dr. CLANCY: Well, the findings that John reports were really very nice in terms of one particular entity that - on which this debate - most of this debate about the difference between conventional and organic nutrition levels swings. And John did report the information about the nutrients on a basically preserving basis - on a fresh-weight, wet-weight basis - so that readers can actually see that the amount that he measured was - they could look at it on a preserving basis, and the amount that he measured that was different actually meets the criteria - comes close to meeting the criteria for being able to make a claim about whether there's more in the organic strawberry than there is in the conventional(ph)...
FLATOW: So are these strawberries more nutritional than the other (unintelligible)?
Dr. CLANCY: Well, for that - for vitamin C, they are. We don't really have a good definition of what's nutritious for a whole food. But the level of vitamin C is higher, and as he pointed out, the level of potassium is lower in the organic.
FLATOW: Uh-huh. Does it make it healthier, then, to eat these strawberries?
Dr. CLANCY: We wouldn't define health by the 10 percent difference in this single nutrient. Health is made up of a number of different categories, including the things that you've mentioned: pesticide residues, whether nitrate levels, nutrients and other kinds of things, like in meat, we would -antibiotics, for example, would not be - treated with antibiotics would not be as healthy as animals treated without antibiotics.
FLATOW: And as far as the vitamin C content being higher?
Dr. CLANCY: Yeah, the Vitamin C content is higher, and it's almost 10 percent higher, which would in fact meet a standard for nutritional significance, not just statistical significance.
FLATOW: Right, and so you do you agree with him then that these are healthier, these are better choices in the supermarket to make - given two choices?
Dr. CLANCY: Well, I'll tell you the number one reason that I think this is a much better choice, because a 10 percent difference in Vitamin C is not a very big difference, it's significant, but it's not very big, is what John found about those soil microorganisms and the much healthier soil that was clearly in those organic strawberry fields. That's why I would want to purchase these berries.
FLATOW: Charles Benbrook, your take on this?
Dr. BENBROOK: Well, you know, I think the study confirms something that observant organic farmers over, you know, many years, indeed centuries, have suspected, and that is a healthier soil produces healthier plants; and healthier plants produce healthier food.
So I think it's very reassuring that, you know, the application of the state-of-the-art molecular tools in the soils analysis in this study is actually confirming something that people have suspected for, you know, many, many years and decades but haven't been able to completely nail down.
FLATOW: Kate, what about the antioxidants? We keep hearing that, you know, organic foods have more antioxidants, and we're told, you know, eat more blueberries. There's black rice research out now, things like that. Is that healthier?
Dr. CLANCY: We, nutritionists started suggesting that yes, people need to greatly increase their consumption of fruits and vegetables, and one of the reasons is because of the all the antioxidant, bioactive food compounds in those, in fruits and vegetables.
Whether the and it's not surprising that there is a difference between organic and conventional. Vitamin C itself is a phytochemical. It's an antioxidant. And to find that the antioxidant levels of a number of different antioxidants are higher is not at all a surprise.
What the problem is with phytochemicals, right now, is we don't have any standards, and we don't have we have very little epidemiological data to show us what kind of levels do we need to be shooting for in terms of what should be in our diet.
So we kind of have to hold off on thinking about the antioxidants and the other phytochemicals in the same that we're able to think about nutrients right now.
FLATOW: So you're saying that there may not be that much nutritional difference, but just the fact that the soil is so much richer in organic life there, that may be worth it in itself?
Dr. CLANCY: Absolutely. I mean, one of the most important reasons to support the organic industry is because of the effects that organic production, these really great effects that organic production is having on the soil, which heaven knows, we will need in the future, the most numbers of acres that are the healthiest soils we can think of.
FLATOW: All right. We're going to have to take a break. We're going to come lots of people would like to talk to us. So we'll take the calls, our number, 1-800-989-8255. You can also tweet us, @scifri, @-S-C-I-F-R-I. Go to our Facebook page, our SCIENCE FRIDAY Facebook page, and leave comments there. We'll have a look at those also. Stay with us. We'll be right back after this break.
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FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.
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FLATOW: You're listening to SCIENCE FRIDAY from NPR. I'm Ira Flatow.
We're talking this hour about organic fruits and vegetables. Is there any real nutritional difference among them? What about the antioxidants? They are supposedly greater in organic fruits and vegetables, with my gusts: Kate Clancy, Charles Benbrook and John Reganold.
Our number, 1-800-989-8255 is out number. Let's see if we can get a call or two in here. Let's go to Judith(ph) in Chico, California. Hi, Judith.
JUDITH (Caller): Yes, thank you for taking my call. I am so happy to hear all of this discussion about the soils. And this was part of my question because this is, I would have to say, the first time I've heard people really make this link between speak publicly - about the importance of the quality of the soil, a living environment, and how can you get nutritional foods out of dead soil.
I think of all the huge monoculture going on in this country, with those huge machines going back and forth, crushing, destroying soil structure. So plus the fact that there have to be so many nutrients we still don't know about.
FLATOW: Let me see if I can get our guests to chime in. Charles Benbrook, any reaction?
Dr. BENBROOK: Well, I think the caller is absolutely right. There have been three or four studies in prominent, peer-review journals that have established a clear connection between the improved quality of soils under long-term organic management with higher nutrient levels in the food itself.
And that's a very significant benefit. I mean, you know, as Kate says, there's much we don't understand about antioxidant levels. There's many micronutrients in food that we haven't even discovered.
But in general, I think the science is very clear that consuming more fresh fruits and vegetables and more of these micronutrients does promote good health.
FLATOW: Here's a tweet that came in from OrganicMenu(ph), who makes a point, saying that most in the organic movement don't think organics are more nutritious but that they have fewer pesticides. And that's what people are after. I'm assuming that they want to know that they're not eating the pesticides on the fruit.
Dr. BENBROOK: Ira, I just pulled out the 2008 USDA pesticide data on strawberries that we've analyzed in some detail. There were 48 different pesticides and their metabolites found in the approximately 670 samples of strawberries tested that year.
And there were, in fact, an average of five different pesticides per sample of strawberries tested. These are conventional strawberries, of course.
So, you know, strawberries remain a very pesticide-dependent crop and one that also still utilizes a soil fumigant called methyl bromide that's been very much involved in the climate change debate.
FLATOW: John Reganold, they use organic pesticides, don't they?
Mr. REGANOLD: Yes, and the interesting thing is both the convention and organic farmers use organically certified pesticides. But the conventional farmers also use a number of and they have a choice of pesticides. And by pesticides, I'm talking about insecticides, fungicides, herbicides, et cetera.
And these particular farmers, it's interesting. These conventional farmers are really moving more toward middle ground. In other words, if you put organic in one end and conventional on the other, you would have an integrated approach in the middle.
And these growers, by using the organically certified pesticides, that does reduce their use of other synthetic pesticides, and these conventional growers and this was a big surprise they're using a lot of compost because they believe that they want to improve soil quality, and they also know that after they use methyl bromide to fumigate the soil, they then come back in, and they add this dose of compost because they believe it helps bring back the microorganisms.
FLATOW: We've seen some recent studies showing that the herbicides, the chemicals that kill the weeds, we're seeing some resistance developing in some of the food crops to some of these synthetic chemicals. Does that happen with organic pesticides or herbicides also? Do they develop resistance to this?
Mr. REGANOLD: We haven't seen that, and usually the resistance that we hear about is, for example, with, say, Roundup Ready Soybean, you hear about, well, now there's resistance to Roundup or glyphosate.
And there are a number of weeds that become resistant, and that's one of our in many ways, you could argue it's one of our safest conventional herbicides. And so we don't want to jeopardize it.
Organic farmers don't really have a herbicide like that. They it just you know, some may use a little bit of vinegar. It just, it's not that effective. They really have to control their weed biologically or mechanically.
And with strawberries, they're grown on these mounds that are covered in this plastic, and the interesting thing is, you know, when I was out there, we were sampling all the time. You don't see many weeds, and you don't see them on the organic or the conventional. And the conventional growers use almost no herbicides because of this tarp.
FLATOW: Kate Clancy, what about just planting a different type of tomato or a different type of strawberry? Could you get more antioxidants and stuff that way?
Dr. CLANCY: Well, that's why John also did a very nice job of including three different cultivars in his study. And he saw quite different results with three different cultivars, which is not surprising.
One of the things to remember is that there might be a much greater difference in the nutrient content of a different cultivar, a different variety, than a way larger difference than there is between production methods.
So ideally, what farmers should be planting are the varieties that have the, you know, indigenous higher amounts of nutrients in them.
FLATOW: Is there a listing somewhere on the Internet where you can compare, you know, if you want to go shopping, you can find a list of the nutrients in tomatoes, strawberries, peppers, whatever you're buying so I can look for that on the shelf?
Dr. BENBROOK: Well, Ira, we've got a report on antioxidants in food that's available through the Organic Center website. That includes a table that ranks foods by antioxidant intake both per serving and per calorie. And it's very dramatic.
If you, if a consumer selects antioxidant-rich foods like blueberries or raspberries or red cabbage, they can get a full, optimal daily dose of antioxidants with less than 100 calories, so a relatively small drain on their total daily caloric intake.
But if you pick fruits and vegetables that are on the low end, you can have to you'll have to consume quantities of fruits and vegetables equal to 15 or 20 percent of your caloric intake to get up to these levels.
So picking these dark-colored fruits and vegetables like tomatoes and the berries, that's where you get your biggest antioxidant benefit per calorie consumed.
FLATOW: But Kate, as you say, we really don't know what levels of antioxidants are going to make any difference, do we?
Dr. CLANCY: Well, we certainly know that, at least for some disease conditions, fruits and vegetables make a difference. We're being surprised every day with new information about, for example, where they don't seem to make a difference, but they make a difference for a lot of the chronic diseases we're worried about.
So it and I agree with Chuck that no matter how they're produced, choosing those best sources or excellent sources of the fruits and vegetables is the way to go.
FLATOW: Let's go to Fred(ph) in I'm sorry, go ahead. Did you want to jump in there?
Mr. REGANOLD: Yeah, this is John Reganold. I just want to make one comment. You had asked about you know, Kate mentioned about the varieties of strawberry, and different varieties have different amounts of antioxidants. When we buy strawberries in the store, the grocery store, we don't know what that variety is.
We know in that clamshell that it's one variety, but we dont know what it is, and they don't tell us that, and most people aren't as concerned.
But I think in the future, we're going to see more and more of that. When we go to the store, we know that we're getting, say, a Golden Delicious apple, or we know we're getting a Fuji apple. That hasn't happened yet with strawberries, and I think that might be something down the road.
Dr. CLANCY: I agree.
FLATOW: Very interesting. Let me now go to Frederick(ph) in Harper's Ferry. Hi, Fred.
FREDERICK (Caller): Hey, how are you guys doing?
FLATOW: Go ahead.
FREDERICK: I just wanted to say that there's a class aspect to organic foods that I believe is being overlooked. Only now are these studies coming out that are showing that there are some possible advantages to organic farming and nutrition over non-organic or traditional techniques.
And people have said that they have chosen organic for so long because of the possible health benefits, but that really is, you know, you can't trust people to self-report what their emotions truly are.
Isn't it more likely that it's a status symbol to eat organic food, rather than any health or environmental aspect, specifically when, you know, even more land has to be put under cultivation to have a similar amount of productivity? So it's not very environmental in that you reduce you increase the amount of land that's under cultivation for the same amount of food.
FLATOW: Who wants to tackle that one?
Dr. CLANCY: Well, let me tackle just the first part of it. It's not really true from at least a lot of, not necessarily reported studies, but a lot of anecdotal information about low income families and especially moms. When they're interviewed, and there's been quite a number of these, they have no less interest in purchasing organic foods for their families if they find them affordable in the market, and sometimes they do and sometimes they don't.
So I don't - you know, what gets a lot of the press is very fancy restaurants serving organic food. But it really - I think the concern about pesticide residues, about health, about children's health particularly, goes throughout the population.
FLATOW: All right. Thanks for calling. 1-800-989-8255. Let's see. A lot of people would like to talk about it. Where is the best place? Is it your site, Charles, that's best for finding out everything you wanted to know about organic food?
Dr. BENBROOK: Our website, which is www.organic-center.org, has a number of studies that focus on the consumer health benefits of organic food, both those that involve nutrient content and taste, but also the food safety aspects, which would be pesticide residues in food and mycotoxins and the like. And all of our reports are available, both the - a full scientific version as well as short versions, and they're all free of charge.
FLATOW: I want to thank you all for taking time to be with us today, and I wish you all a good holiday weekend. John Reganold is regents professor of soil science and agroecology at Washington State University in Pullman. Kate Clancy, food systems consultant and visiting scholar at Johns Hopkins Center for a Livable Future. She's also a senior fellow at Minnesota Institute for Sustainable Agriculture. Charles Benbrook is the chief scientist for the Organic Center up there in Boulder, Colorado. Thank you all for taking time to be with us today.
Dr. BENBROOK: Thanks.
Dr. CLANCY: Thank you.
FLATOW: You're welcome.
Dr. REGANOLD: Thank you.
Dr. CLANCY: Pleasure.