IRA FLATOW, HOST:
This is SCIENCE FRIDAY. I'm Ira Flatow. One of the mantras of eating healthy is to eat more fiber, more whole grains. Whole grains may be good for your heart, stave off diabetes. They might even ward off certain cancers. Sounds like good advice. But when you go to the supermarket, your head starts to hurt.
You've got your multigrain cereal, the Nutri-grain bars, the wholegrain Lucky Charms. Do you choose the harvest grain frozen pizza or the wholegrain blend Rice-A-Roni? OK, so you read the label. It says whole wheat bread. But does that mean white flour with some wheat germ added back? And then there's my favorite: stone ground. What does that stand for?
Does it make a difference how you eat your whole grains? If the grains are mostly intact, like brown rice, wheat berries or steel-cut oats, do you get more nutrition than you would from pulverized flour? And can anyone reveal the true identity of couscous? Is it small chunks of grain, or is it a pasta?
Whole grains, that's what we're going to be talking about this hour. Our number is 800-989-8255. You can tweet us @scifri, S-C-I-F-R-I with questions. What would you like to know about what whole grains are, what they mean? Some people who do know are my guests.
Joanne Slavin is professor in the - Joanne Slavin, a professor of the Department of Food Science and Nutrition at the University of Minnesota in St. Paul. She joins us today from Minnesota Public Radio. Welcome to SCIENCE FRIDAY, Dr. Slavin.
JOANNE SLAVIN: Thanks for having me.
FLATOW: You're welcome. David Ludwig is a professor of pediatrics at Boston Children's Hospital. He's also director of the New Balance Foundation Obesity Prevention Center there. Welcome to SCIENCE FRIDAY, Dr. Ludwig.
DAVID LUDWIG: Thank you, Ira.
FLATOW: Joanne Slavin, tell us what - to you what a whole grain means.
SLAVIN: Well, I'm fortunate to live in the grain capital of America. So we've been harvesting grains in Minnesota for a long time, and I think over time people really wanted refined grains. So if you look at the history, we mostly, you know, would have white flour because that made bread that people liked. So a whole grain is where everything goes in.
So you take the grain, and all grains basically have the same anatomy, and you grind up the grain, and in that you get the bran, the germ and the endosperm. And so the concept is actually pretty easy. It's just trying to get it into food that people actually want - to enjoy.
FLATOW: Yeah, David Lustig, how do they make whole wheat flour?
LUDWIG: Just to clarify, I'm oftentimes confused with Rob Lustig, who is of the sugar fame, and I'm David Ludwig.
FLATOW: I'm sorry.
(LAUGHTER)
FLATOW: I'm sorry - we had David Lustig on a few weeks ago, and I...
LUDWIG: That's Robert Lustig.
FLATOW: I just went to his head for a second. I apologize. David Ludwig.
LUDWIG: His book is selling much better than mine.
(LAUGHTER)
FLATOW: Well, not after this show. We'll see. Go ahead. I'm sorry. How do you make whole wheat flour?
LUDWIG: Well, you know, I think as Joanne said, in theory wholegrain flour contains all of the ingredients of the intact kernel, so that's the starchy middle part, the endosperm, that's - starch is just sugar in a long chain. That's where all the calories are, very few nutrients. The bran and the germ are where the fiber, the vitamins and minerals and things called phytochemicals, these antioxidants that promote health, they may support cellular metabolism, maybe even have anti-cancer and other protective factors, that - the bran and the germ have those parts.
Now, in theory a flour, a wholegrain flour has all of those components. But there are three possible problems. First, despite the official requirements, some of the key components of the whole kernel could be lost or degraded in extreme industrial processing, things like food extrusion, where the flour is subjected to high temperatures and high pressures.
And secondly, a wholegrain product may have lots of unhealthful added ingredients, which is typically sugar. You know what you're getting when you eat a bowl of brown rice. But what about a bowl of chocolate Lucky Charms touting whole grains as the first ingredient?
And the third important difference is that when the kernel structure is severely disrupted by intensive food processing, the starch from the grain is released from the fiber in the food structure. So it's digested much more quickly and absorbed more quickly, leading to a surge and crash in blood sugar that may stimulate hunger, drive overeating and maybe increased risk for diabetes.
FLATOW: So you have to be an informed consumer then, when you look on the labels and things like that to know what you're actually getting.
SLAVIN: Well, I would like to just say, you know, that we really want people to eat more whole grains. It has more fiber. And people eat so few. Right now we're in a culture where people eat really less than one serving a day. If you look at kids, an adolescent it's like half a serving. So getting people to eat whole grains and making products they'll actually consume is very helpful.
And if you look at some of the physiological effects of, like, extruded cereal, as far as cholesterol lowering, it does the same as oats that are - you know, the regular oatmeal. So I think that that effect of processing, just because to process foods is how we get those to market and where people can actually consume them.
FLATOW: One of the problems in getting those whole grains, as I say, is the confusing labeling at the supermarket. You have the multigrain, the wholegrain something-or-other, the whole wheat. You're on a scientific advisory board of the Whole Grains Council, which is trying to do something about that, Dr. Slavin. Tell us about what's happening there.
SLAVIN: Yeah, I think what happens so often in labeling is that kind of the interest in the consumer side gets ahead of FDA. And one problem we have is with fiber. We can measure fiber. So it's - and fiber has to be on the label. So if you go to the store, fiber will give you some idea of, you know, how much grams of fiber, and we need more fiber. It's a shortfall nutrient. We can do that.
Whole grains is much harder to analyze. So it's basically a calculated value. So it's really no different than added sugar. If people say how much added sugar is in this, you can't measure that from sugar that comes naturally in foods. We don't have a chemical method. So we're in the same kind of problem with whole grains.
And so when - if you look at what's out on grocery shelves right now, people have to be truthful and not misleading and tell you how many grams of whole grains are actually in the product. And the Whole Grains Council has kind of stepped in, even though they're not the government, and said because consumers are really interested in whole grains, let's try to have some standard, these whole grain stamps, to give people some idea of how much whole grain is in this product.
So I think it's a good effort. I do think you're going to see the government step forward because we want people to eat more whole grains. We need some standards. I think they're going to come along. But for right now the whole grain stamp is probably the best thing for a consumer just because it will tell you how many grams of whole grains are actually in the product.
FLATOW: David...
SLAVIN: I agree with David that a lot of times those products, you know, that's going to tell you just how much whole grain. So there can be sodium, sugar. So you shouldn't immediately say it's a healthy product. It'll just tell you how many grams of whole grains are there.
FLATOW: David, any reaction?
LUDWIG: Yeah, I mean I agree with Joanne that we need to take sometimes small steps first. The - now that trans fat is largely leaving the food supply, refined carbohydrates in general, and I think - well, Rob Lustig would say sugar, but I would broaden that to say refined carbohydrates in general, importantly including refined grain products, are among the least healthful foods in the food supply, where as whole grains are consistently shown to be protective.
So what do we do about a population that's eating a lot more white bread than wheat berries for, you know, for breakfast or for snack and for lunch? I think the first step is to move from highly processed white grains to whole grains that may still be very, very processed, you know, the things that you would find in the chocolate Lucky Charms cereal.
But then the next step is to really think about how the intact food structure, the properties of food that can't be measured just by a number and a nutrient, may affect biology. And there's considerable reason to believe that the intact whole grain is really much better.
For example, we did a study with 12 obese adolescents where we gave them instant oatmeal and compared that to to steel-cut oats. We gave that to them at breakfast. Steel-cut oats is a preparatory method that maintains the structure of the oat kernel intact, just slices it a couple of times so it can cook. It takes 30 minutes to cook instead of instant.
But we found that after the instant oatmeal, blood sugar rose much faster and higher than after the steel-cut oats. A few hours later, the blood sugar crashed, levels of adrenaline, which is a stress hormone released with hypoglycemia, surged, and the teenage participants were much hungrier, eating five or six hundred calories more when offered free food, freely available food, than after the steel-cut oats.
Same calories, same fiber, same grams of carbohydrate, the only difference being the food form.
FLATOW: So if you can keep it in its original form, as it's grown before it's processed, it's more - would the right word be better for you than even if you just rolled the oats...
LUDWIG: I think the research still is evolving, and, you know, we don't know exactly where to draw the line. But there's reason to believe that grains that look like they came from nature, rather than powders and pastes, that those intact grains, things like brown rice, steel-cut oats, really whole-kernel breads, these are the ones that are consumed oftentimes in Germany or Scandinavia made from whole rye kernels, wheat berries, quinoa, which is a grain-like plant, that, you know, these have protective factors that go well beyond the vitamins and minerals and fiber that we can measure and provide in a highly processed grain.
FLATOW: Joanne, would you agree with that?
SLAVIN: Yeah, I'd like to mention, Ira, I grew up on a farm. So I have a lot of background in grains and what they are - you know, when they're in the field, they're dirty. They absolutely need to be processed. And if I ate oats that came out of the field, they would go straight through me and they would provide no nutrients. They'd be pretty good as far as laxation, I'd be definitely running to the bathroom.
So I think there's a point here where we lose track of that we cannot just eat a grain. We do not have the digestive tract. And it would be bad for our teeth. So grains need to be processed and put into foods that people will actually consume. And I agree with David, there are some good examples of steel-cut oats, wheat berries, there's things that are actually in the food supply. But to get whole grains into the food supply, we can't expect people to cook brown rice for 30 minutes and steel-cut oats.
We know that those, you know, there's a few people that are willing to make that sacrifice, but the average consumer is not consuming any whole grains, and getting whole grains into products that people actually like to consume, and those whole grains will bring fiber, they'll bring other phytonutrients along, that's a great public health step that we need to keep promoting in the U.S. because we're not making as much progress as we should on that goal.
FLATOW: All right, we're going to take a quick break, come back and talk lots more with Joanne Slavin and David Ludwig. Our number is 1-800-989-8255. We'll take your calls. You can tweet us. We're also going to try to answer the very mysterious question of just what is couscous. Everybody has an idea, everybody thinks they know what it is. Maybe we can solve it. Tweet us if you think you know what that is. Stay tuned. We'll be right back after this break.
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FLATOW: This is SCIENCE FRIDAY. I'm Ira Flatow. We're talking about just what is wholegrain products, with Joanne Slavin, professor in the Department of Food Science and Nutrition, University of Minnesota St. Paul, David Ludwig, professor of pediatrics at Boston Children's Hospital. He's also director of the New Balance Foundation Obesity Prevention Center there. Our number is 1-800-989-8255. Let's go to the phones, to Derwin(ph) in Bellaire, Texas. Hi, Derwin.
DERWIN: Hey, how are you doing?
FLATOW: Hi, there.
DERWIN: I have a question. I have a recipe that I use for my bread that is two cups of whole wheat flour, one-and-a-half cups of unbleached flour and a half a cup of wheat bran. Is that enough bran?
SLAVIN: I would - this is Joanne, here. I would say that's a fabulous recipe. And if we could get people to put more wholegrain flour into their products and wheat bran into their products, we'd get more fiber out. And it's good that people are cooking. I think that's - you know, people say: Why do we have to eat processed wholegrain foods? Because people have kind of lost the ability to cook.
So if we could get people like you out making fabulous bread, we'd be making some good strides on getting people to eat more whole grains. So, you know, if you get into kind of is that a whole grain, is it half - you know, like, it's not the big deal. We want people to make any progress towards more wheat bran, more wholegrain flour in the food supply. So that's fabulous.
FLATOW: Good luck...
DERWIN: If you go to the store...
FLATOW: Whoop, we lost him there. 1-800-989-8255 is our number. Yeah, maybe the point he was going to make: If you go to the store, what should you look for on the label? What is the best thing on the label, David, to look for?
LUDWIG: Well, you know, I think Joanne and I agree about 85 percent. The - I'll just focus for the moment on the 15 percent where we might differ, which is - well, first, let me say the 85 percent, we agree that the label - the first ingredient should be whole grain. There's no question about that. And that'll improve the nutritional quality substantially over the traditional highly processed white flours, white grain products.
But we can't tell from a label the processing. And I can tell you - I can show you a number of research studies that suggest that the degree of processing - for example, the difference between wheat berries and highly processed whole wheat flour, same calories, but in one case, blood sugar will rise twice as high. And substantially more insulin will be produced than in the other case.
And that has effects on our appetite and our physiology for hours after the meal. So, yes, we do want to, you know, begin with the label, but then look at the product itself. If you can actually see particulates from the whole grain - and stone-ground breads have this, the particulate in the flour is larger, more of the structure is maintained. It slows down digestion. That's going to be better than a traditional, like, these white whole wheat breads that are severely processed, have all the ingredients, but are now subject to more oxidation, you know, by exposure to air, and the digestive system can tear it apart so quickly that, you know, it really doesn't - it isn't as filling.
FLATOW: So the idea is if you slowed down the digestion or the processing of - because it's a wholer grain, you slow it down, therefore it takes longer for your blood sugar level to rise.
LUDWIG: That concept's called the glycemic index. And it's not the only important thing to know about grains, but it is one of the key determinants, I think, of the impact of grains on health. The less processed a grain - and yes, we don't want to be foraging through the fields, as Joann mentions, for, you know, raw oat groats, but unprocessed or minimally processed.
So in the case of oats, that's steel-cut oats. In the case of breads, we can actually find flourless breads. Or if you don't like those - I mean, it's an acquired taste. The Germans love them. But look for stone-ground breads that have less severely processed grains.
FLATOW: Joanne, what about popcorn?
SLAVIN: Well, popcorn's actually a whole grain. So it's one way to get your three servings a day. So our recommendation is - the usual is six servings of grains per day, and half of those should be whole grain. The average person only gets one. So, you know, whole wheat bread for lunch, have some oatmeal for breakfast and maybe popcorn for a snack, and you are going to meet your goal.
So I think we have to simplify. I agree with David: In a perfect world, there are some textural things. Some of the whole grains might be slightly better. Glycemic index, though, is just one part of grains. And grains - whole grains have been linked to a lot of - like you lead, Ira, with a lot of other health benefits. So getting people up to the recommended servings of whole grains would be great progress.
FLATOW: I want to just steer the conversation toward a subject that's been tweeting around now for hours, and that is - and everybody has their own version, idea of - and that is: What is couscous? Is it a grain? Is it a pasta? Is it a combination of the two?
SLAVIN: It's two, two in one. You know, all - everything we're talking about are grains. So rice, wheat, those are all grains. Couscous is made from wheat. So - but it's used like rice, more like a pasta. So I think, you know, we have cooking definitions, how do we use it in food, and I think people would substitute it for like a pasta in a recipe, but it's a grain. That's the way I see it.
FLATOW: David, do you agree?
LUDWIG: Well, you know, I'm looking at this more, you know, biologically, which - so both couscous and pasta come from wheat - you know, in fact typically semolina wheat. But pasta is one of the few grains that is traditionally consumed - it's white, highly - it's processed. There's not a lot of fiber in it. It's closer to white bread in its fiber content. But it digests much more slowly because of the very tight structure of the pasta itself.
So if you put a cooked piece of pasta into a glass of water, what's going to happen? It'll just sit there. If you put a piece of white bread into a glass of water, it just melts. And that represents what happens in the digestive tract. That's why pasta tends to be a lower glycemic food. It raises blood sugar more slowly. It may be more filling. Couscous is much closer to the white bread side of things than to the pasta side of things, biologically.
SLAVIN: I would like to note, too, just that in the pasta field, there are whole grain pastas that are out there that are actually higher in fiber. So there's - you know, they really expanded that category. That is not all refined pasta.
FLATOW: David, is it true that if you cook pasta al dente, you know, a little bit chewy, then you get more benefit out of it?
LUDWIG: That's - you know, that's the physiology based on impacts on blood sugar and insulin, the same grams of carbohydrate, the same calories from a pasta cooked al dente versus white bread produces dramatically different metabolic effects in the subsequent four or five hours. And those effects may have important implications to the likelihood of overeating at the next meal and long-term risk for diabetes, heart disease.
FLATOW: What is there about al dente that...
LUDWIG: Well, you know, as long as you don't kill the pasta, you know, with, you know, an hour of cooking - and, again, this differs from, like, the Chef Boyardee pasta in a can. But pasta that you make from the dry noodle, you know, cooked 10 or 15 minutes, that still has - al dente means I think to the tooth, it still has a little bit in it - that's going to take longer to digest.
And, again, it's going to be more filling and more gentle on blood sugar.
FLATOW: Just to tie up a loose end about the couscous, because we keep getting people asking: How is it made? How is couscous made? Is it flour that's ground up and...
SLAVIN: Yeah. I mean, that's my impression of it. It's, you know, it's - there's ways to make bread. Couscous is really, you know, similar ingredient. It's just a different structure of how you put it together. And it's more like rice, and that's the way it gets used in the field is - and remember, you know, like, our recommendation is 45 to 65 percent of our calories need to come from carbohydrates.
So most diets are based on some starch, grain base, whether it's corn, rice, wheat. And every culture decides. You know, we can't eat protein 100 percent of the day. It's too expensive. So picking that grain base - and so couscous in African countries, in certain countries, it's a big part of that grain base that people consume every day.
LUDWIG: But Joanne raises an interesting - I mean, at least tangentially, Joanne raises an interesting point, which is that grains are a choice culturally, and are typically required for a large population to, you know, to get enough calories. But the biological requirement for grains is zero.
And, of course, we ate no grains, or virtually no grains until domestication of grain products 8,000, 10,000, 12,000 years ago in some populations, and very much more recently in others.
SLAVIN: But our recommendation in the U.S., if we're going to get 50 percent of our calories from carbohydrate, I don't know - I think if you want low glycemic, you'd go with sugar. But otherwise, I don't think we're going to recommend sugar instead of grains as a carbohydrate base, and also from a cost standpoint.
LUDWIG: The tradeoff is with healthy oils - as the New England Journal of Medicine Mediterranean diet study just came out by increasing healthful fats, risk for heart cardiovascular disease plummeted, even without a change in body weight.
FLATOW: Let me get one last question in here from Cail(ph) in Columbia, South Carolina. Hi, Cail.
CAIL: Hello.
FLATOW: Hi there.
CAIL: Yes. I wanted to just tell you what - you know, well, it is kind of a question. You touched upon the - how the price works. I used to - when I was single back in 2008, I used to buy a lot of whole wheat products, the stone-ground pasta from Buy-Low, cereal - Total, bread - Nature's Own. And the bread used to cost about three dollars. Again, this was five years ago. Cereal used to cost about five dollars each. Pasta used to cost almost five dollars.
So what I'd like to ask is, you know, I think it's great for someone that's single, making at least maybe 30,000 a year that can afford it, maybe for a wealthy family making above-average income with two children. But what about - what do you say to an average family with two children? You know, how much...
FLATOW: How are they going to afford it? Yeah.
CAIL: Right. How can they afford it? That's it.
FLATOW: Yeah. Joanne, what do you say?
SLAVIN: I would say food security is a huge problem in our country. And a lot of our recommendations, we don't think about that. So I totally agree with our caller that whole-grain products cost more, and that's unfortunate.
But for people that - you know, grain products - there's not a lot of health detriment. We want to get half of our calories from grain. So I would say whatever your cultural base is, whether it's corn, wheat, rice, don't feel bad about making that the base of your diet. That's actually recommended eating habits.
FLATOW: David, do you agree?
LUDWIG: Well, I actually disagree that there's an evidence base for making grain 50 percent of our calories. And I think there's...
SLAVIN: Carbohydrates or, you know, grains or sugar.
LUDWIG: Carbohydrates, yeah, of which grains typically are the main part of that. I think that there's - there is evidence that substantial reductions in refined grains, and possibly total carbohydrates, can have important health benefits on the metabolic syndrome, and this is a, you know, an exciting, evolving area...
FLATOW: Yeah. OK.
SLAVIN: I would just want to point out, though, this is for healthy people, and it is the dietary reference intake, so it is the basis, the Institute of Medicine's recommendation that 45 to 65 percent of our calories should come from carbohydrate.
FLATOW: All right. We're going to end the discussion there. You know, I'm sure it's not over. Michael Pollan is coming on in a few weeks, so we'll have more to talk about. But I want to thank Joanne Slavin, professor in the Department of Food Science and Nutrition, University of Minnesota in St. Paul; David Ludwig, professor of pediatrics at Boston Children's Hospital, also director of New Balance Foundation Obesity Prevention Center there. Thank you both for taking time to be with us today.
LUDWIG: Pleasure.
SLAVIN: Thanks for being on. Bye-bye.
FLATOW: Bye-bye. I'm Ira Flatow. This is SCIENCE FRIDAY from NPR. Transcript provided by NPR, Copyright NPR.