University Place

cc >> Welcome, everyone, to Wednesday Nite at the Lab. I'm Tom Zinnen. I work here at the UW-Madison Biotechnology Center. I also work for UW Extension Cooperative Extension, and on behalf of those folks and our other organizers, Wisconsin Public Television, the Wisconsin Alumni Association, and the UW-Madison Science Alliance, thanks again for coming to Wednesday Nite at the Lab. We do this every Wednesday night, 50 times a year. Tonight's a rather auspicious event for me, and I hope for many people in Wisconsin, because we're celebrating and commemorating the centennial discovery of vitamins in Wisconsin here at UW-Madison. A paper was accepted in June of 1913, and that paper is the paper that basically was regarded as the discovery of vitamins in general and Vitamin A in particular. It's great to be able to say that line of research continues a hundred years later. I think it will be continuing for many decades into the future. The whole research into vitamins is robust and important, not only for Wisconsin, but for the world. And I think it's one of the great points of pride of being a citizen of Wisconsin and being involved with the University of Wisconsin. Tonight I'm delighted to be able to introduce to you Sherry Tanumihardjo. She is a professor here in the Nutritional Sciences Department. She works on vitamin A in a couple of ways. One is to do analytical analysis and the other is looking at the biological availability. She has three decades of experience with vitamin A and carotenoids. She holds a BS in chemistry, a Master's in biochemistry, and a PhD in nutrition. She's from Mauston, and she got her undergraduate degree at the University of Wisconsin Eau Claire, and her other two degrees I think are from Iowa State. Is that correct? Her research group works with a numbers of animal models, including gerbils, rats, pigs, and monkeys, to answer various questions about issues relating to vitamin A toxicity and bioavailable and deficiency. Not only that, she applies this work to the human model. In particular, her team has conducted studies with humans in the United States, Indonesia, South Africa, Ghana, Burkina Faso, and Zambia. She is a strong advocate for the promotion of nutritionally enhanced staple foods which is one of the things we're going to hear about tonight. Particularly this idea of orange maize as a potential source for vitamin A for millions of people around the globe. This is a remarkable story to me because the whole idea that just three years ago strains of corn were found that had much higher levels of carotenoids, vitamin A precursors in them. In a world where half a million kids go blind every year from vitamin A deficiency, think about what that might mean. And tonight we get to not only think about it, we get to hear about it as Sherry Tanumihardjo presents her work on orange maize and what it might mean for alleviating vitamin A deficiency around the globe. Please join me in welcoming Sherry to Wednesday Nite at the Lab.

APPLAUSE

>> Thanks, Tom. Evidence for vitamin A. Well, it dates back to Egyptian times. As early as 1500 BC, there were some scribing on a papyrus saying that if you eat roasted ox or blackhawk liver, it will cure you blindness and you would be able to then see at night. And then Hippocrates, a Greek philosopher, suggested that eating raw liver dipped in honey would help you to see better. So then in 1913, as Tom said, there was the discovery of vitamin A right here at the University of Wisconsin campus. And what he discovered was that if there were certain things called lipins that were in the diet that supported growth. And he fed rats semi-purified diets, and these contained either protein, carbohydrates, salt mixtures with and without fat. And the fats that he chose to add were extracts of butter, egg yolk, and olive oil, and what he discovered is that the butter and the egg yolk supported growth. And in that particular year, he was able to publish a paper with a rat. And you can't do that anymore. You need tens of rats in order to do things, and you also have to do a lovely thing called statistics, which in his day was not really a key thing that was used in publishing work such as this. So he stated that a rat of 40 to 50 grams in weight could grow normally for a certain amount of time but then, after a while, the rat would cease to grow. But by adding the substances back into the rat diet, they were able to maintain further growth. And it was from this experimental data that he decided that growth was from purified, you could not just have a purified diet of protein, carbohydrates, fats, and salt. There were other accessory compounds in foods that were necessary for growth, especially after extended periods. So there were some clues. First of all, vitamin A withstood heating, but it did not withstand heating if you added oxygen to the mix. And then he discovered that butter and egg yolk, but not lard or almond oil, could support growth, green vegetables could support growth, and yellow, but not white, corn could support growth. And it's a hundred years later that we're still working on that one little bullet point. So why am I working on that one little bullet point? Well, malnutrition is at the base of 60% of children dying in the world. And this is complicated by a variety of factors. It's not just vitamin A. Although, vitamin A deficiency does cause blindness in a number of children, even today, around the world, but not only that, something called a marginal vitamin A status actually causes decreased immunity. And so, children are dying not just because they're blind, but because they have impaired immunity because of a lack of vitamin A. So this is the vitamin of the hour. This is the 20-carbon molecule that I have spent 30 years on. And so this is called, commonly, retinol in the vitamin A world. As I said, it's important for vision, essential. It is important in epithelial differentiation. It's important for immune function, and also reproduction. So without vitamin A, we would cease to exist as a species. So why am I showing you these fancy molecules? My point to show you this slide is that vitamin A flips around at a certain point. This is the 11th position. And it's that flipping back and forth from the -- to the all-trans that allows us to see. So that simple change in the configuration of that molecule is what sends the nerve impulses back to the brain to make us able to see. So the term associated with vitamin A deficiency that involves the eye is called xerophthalmia, and there are different degrees of xerophthalmia. The mildest is night blindness. If you give children that are night blind a high dose of vitamin A three days in a row, 20 days later it will go away. So it's totally curable. And then there's something called Bitot's spots on the eye, and then corneal xerosis, ulceration, keratomalacia, and then it causes scarring. At that point, it can lead to blindness. So, above that point, all of these other things can be healed with high dose vitamin A. So, here's a schematic of an eye that's beginning to become in trouble. And right here you see these little dry spots, Bitot's spots, and then the surface of the eye begins to break down. So these are live pictures. You see this dry, foamy patch right here, and then another patch that's called cheesy. Totally preventable blindness at this point. Give these children vitamin A, the Bitot's spots go away, and the child does not become blind. However, what happens if they don't get vitamin A? You start to get scarring on the surface of the eye. The ulcers will scar over and then the child will be blind, especially when it covers the pupil, like in these three eyes. This particular child probably can still see. So, what have we done? For a couple of decades now every six months we give children high dose vitamin A capsules. This prevents blindness, and it has shown to be efficacious. It's not effective in all countries, but if they get those high dose capsules every six months, they will not go blind. The problem, however, is it doesn't prevent a marginal deficiency that can occur when the supplement wears off. Like in the rat study, it took a while for those rats to growth falter. Well, it's the same with children. They start out with a high liver value in vitamin A and then they use this over time, but if their diet cannot support that liver value, they cycle. So they go through periods of time, about two months, when they don't have enough vitamin A before they get the next capsule. So WHO says 200,000 every six months for preschool children. And there used to be 400,000 to lactating women and maybe 50,000 to infants at birth. And this was all based on data saying reduced mortality in children, reduced mortality in pregnant women, and then reduced incidence of malaria attacks. But then what happened? More studies came out. And there were two recent Cochrane reviews that said, yes, vitamin A supplementation to children prevents death. And so WHO says, yes, continue. Unfortunately, all of the data in women and in other adults and in newborns say no effect. On what? Mortality. So if mortality is your outcome and it's the only outcome that WHO is using right now, it says just give supplements to children. And so, this is a big deal because there are countries that were gearing up to starting to give lactating women high dose vitamin A capsules. Yet it says does not prevent death. So let's not do it.

So the new guidelines

let's just give it to children who are between the ages of six to 59 months, and this is a strong recommendation, meaning that the evidence is very clear that these doses save lives. So, why do I go around and promote this? Well, vitamin A is compromised, and it's compromised for the mothers too. But the doses that have been used and the high doses, they only raise breast milk for two days. So it's not a long term effect. And also, most sources of vitamin A in the diets of poor people are from plants. And all of these other issues as far as bioavailability of the nutrients, bioconversion to the active form of vitamin A come into play making the story very, very complicated. So, here's a slide that shows you that vitamin A, this is right before they get that dose. A high number is a bad number in this particular test. So these are children that got that vitamin A dose. This is one month later. These are children right before they get the dose. They get the dose, and they converge together. So, this is a happy liver store of vitamin A. But, like I said, it's going to cycle, and those children will again be vitamin A deficient within about four months. So, how do we assess vitamin A status of groups of people? Well, the most common measure is serum vitamin A. What is circulating in the body? However, there are lots of reasons why that's not a good indicator. First of all, it's a static measure. And it is found in the blood bound to a protein. Notice retinol binding protein. That particular protein is something we call an acute phase reaction. So, in children or adults that are having an infection or have inflammation due to a variety of reasons will have a decreased value. And also, it's homeostatically controlled and it may not respond to intervention. There are a lot of things that regulate vitamin A in the blood. Why? Vitamin A is toxic. So the body actually tries to protect itself by shuffling it around in the body on a protein and by storing it as an ester in the liver. And also with certain percentages from recent dietary intake. So, as far as total body stores, it's not a very good indicator. And of course, a lot of the studies that WHO looks at is looking at this particular indicator. This is just an example. This is a study that we did in rats using serum retinol as our indicator, and what do we see? Well, the little dot that I just circled, that particular group is in the lowest group, meaning they have the lowest level of body stores of vitamin A. Yet this is the indicator of choice in many population groups. This is another, this is 300 Indonesian kids before and after a supplement. And you see that serum retinol is the same before and after the intervention. However, this is a difference. This is two groups of Indonesian children across the street from each other. And this particular group had a happy vitamin A status, but not really. The mean is the WHO cutoff for deficiency. So, is it useful? There was a dietary difference between these two groups of kids, Indonesian kids across the street from each other. The group that had the happy vitamin A status, by a different measure, not serum retinol, was actually getting free eggs from the government. That was the only dietary difference. Remember, we said that an egg extract with support growth in the rats? Well, a single little tiny egg every day in these kids made a huge difference in their vitamin A status. Well, how do the carrots feel? Well, the carrots feel very neglected.

LAUGHTER

So the new guidelines

Carrots are a great source of vitamin A. But what is the problem with carrots in the world? Anybody know? It is a cash crop. So, if families are growing them, poor families growing carrots, what do they do? They sell them for income. They do not eat them. So that's why I'm working on maize right now. So dietary diversification can make a difference, but you have to get the people to eat the vegetables. And so, if you teach people how to garden, they do improve their nutrient intakes. But there's all these bio terms. Bioaccessibility of the vitamin A, bioavailability, bioconversion, bioefficacy. And because of all of these bio terms, people are afraid of using plant sources to meet vitamin A requirements. Which is a shame because I feel like we lost at least two, if not three, decades too overly concerned about plant sources of vitamin A. So here is the motto that I live

by

all things in moderation, except vegetables. But also, we may have to genetically modify our kids to eat vegetables.

LAUGHTER

by

It is true. Kids don't necessarily like the bitter taste of vegetables. And in fact, a lot of adults don't. So the bottom line is you have to start early with these different foods, including vegetables. So let's talk about fortification for just a minute. A very quick minute. Fortification is where you add preform vitamin A to staple foods. You could add it to maize; you could add it to sugar or flour or rice or wheat. But you know what happens when you do that? Use the preform vitamin? People go toxic. Very, very quickly. In a week I'm going to Guatemala And why? Because we have to find out to what degree are they toxic. They've been putting vitamin A in sugar for decades. And guess what? They're eating more sugar than they thought they would be eating. The vitamin A is more stable than they thought it was going to be. And for all of these reasons, the population is now vitamin A toxic. So, is that a good thing or is that a bad thing? Well, the flip side would be that they would be vitamin A deficient. So it's like a balancing act, right? We don't want them to be vitamin A deficient, but vitamin A toxicity is not a good thing either. And in fact, one year after they introduced vitamin A fortified sugar in Nicaragua, one of the neighboring countries, nine out of 21 children were vitamin A toxic. Just one year after. The bottom line is if you look at this number,.57 micromoles vitamin A per gram liver, guess what? They're not even deficient to begin with. My liver value is.3, half of what theirs is. So they didn't even need to put vitamin A in the sugar to begin with. They based it on serum retinol, but I told you that's a bad indicator. So, my new buzz word, another bio term, is biofortification. It comes from the Greek word bios, which means life, and the Latin word fortificari, which means make strong. So, make life strong. So what is it? Is it a new methodology? Let's go back to one of my

favorite vegetables

carrots. Originally, carrots were purple and yellow, not orange. About 400 years ago, a carrot was domesticated that was orange. And around the same time, red and white carrots showed up. This is all traditional domestication of vegetables. Thirty years ago, Phil Simon came up with a glow-in-the-dark orange carrot which had five times the amount of beta-carotene just by breeding for higher amounts of beta-carotene. And then in 2005, I said, hey, Phil, can you make me a carrot that's purple, orange, and red, and in 2007 he delivered it on my doorstep. A purple and orange/red carrot all done with traditional breeding methods. But why did I change from working constantly on carrots to maize? Well, that's where the money was. Truth be told. Lost my carrot money. But also, more people eat staple foods not carrots. 80% of energy intakes in Bangladesh are from rice. And what's the bottom line? People around the world are not very rich. Most people are poor. And poor people have poor diets. It's a fact. And the bottom line is poverty can lead to under- and over-nutrition, and this will lead to nutrient deficiencies, hidden hunger, and obesity. We are seeing obesity epidemics not because they're eating too much food necessarily, it's because they're eating poor quality foods. They have diets that are high in staple foods. Why? Because those particular foods fill the stomach. So, what are the advantages of biofortification? It's for people who eat lots of staple foods, the rural poor. It is cost-effective. We can do research in a central location and then multiply that research in different countries. Most of my current efforts have

been in one country

Zambia. And it's sustainable. The investments are front loaded and they have low recurrent cost. What do I mean by that? Well, how much do you think it costs to give out vitamin A supplements every six months? There's about 14 countries that are continuing to do that. $500 million every six months. That's a lot of money when you think about it. $500 million for research might be available. That's a lot of research money, if you think about it. It's an interdisciplinary approach. Biofortification has to involve plant breeders, molecular biologists, food technologists, human nutritionists, extensionists, experts in food marketing, communication experts, and economists. And so it's a very intense research effort to include all of these folks. We started biofortification efforts with sweet potato. Guess what? People like white flesh sweet potato. Not necessarily in the United States, we've had the orange flesh around for quite a while, but on a daily basis, many folks were eating white fleshed. So we did a study in South Africa where we fed half the children orange sweet potato and half of the children white sweet potato. We used the sensitive test to measure liver stores of vitamin A, and what we saw that after five months of feeding, the children that were in the orange flesh sweet potato group had better liver stores than the group that was fed white sweet potato. Then there was something called effectiveness studies. Vines of sweet potato were released in Mozambique. There were two agricultural cycles that occurred, and then they discovered that children that were in the orange sweet potato group ate more sweet potato, it was in their backyard, and they did have higher serum retinol concentrations. But, again, 40% were below that WHO cutoff for deficiency. They should have used a better marker. There were taste evaluations that occurred at the village level where they compared white right against orange. And then they taught them how to put sweet potato flour in bread. Wheat flour is very expensive. By replacing just 40% of the flour with sweet potato flour, not only did they cut their cost but they had a more nutritious product. So, orange sweet potato was a success story in Africa. There was active behavior change. People were changing from white to orange. They had farmer participation, seed systems were developed, and there was market development. So then our research group moved on to something called pumpkin nshima. So, we replaced white maize with orange maize in the diets of preschool children. But before we did that, we did animal work. I must admit that I was pretty skeptical because I didn't think that this hard maize that the vitamin A, that provitamin A would be bioavailable. I didn't think that the gerbils, we first fed it to these little guys, these are Mongolian gerbils, could actually get the vitamin A out of that hard maize core. So we had different groups where we compared the maize to a beta-carotene equalized supplement and vitamin A. And lo and behold, the maize was as good as a beta-carotene supplement. Of course, vitamin A had two and a half times, but then again, regulation of vitamin A is not as protected as that of provitamin A carotenoid. So this is the body's way of saying, hey, I have enough vitamin A, I don't need to make any more. Whereas, with the vitamin A supplement, they just keep storing it away in the liver until when? Until they become toxic. And these gerbils probably would have become toxic because a gerbil liver is about two and a half grams, and here we see that these guys were already 1.5 micromoles and toxicity is at one micromole. And then the more vitamin A we put in that maize, the better off the liver vitamin A store was. Here's our typical yellow maize. Just like a hundred years ago, it was giving vitamin A to these animals, but orange maize gave even more vitamin A to these animals. So then we went to Zambia. We worked with a local seed company to develop the seeds and grow the maize. We worked with the National Food and Nutrition Commission to coordinate and mobilize the community. We worked with the local research institute to take our blood, be our vampires, and then the UW came in and we did randomization field coordination and we used very unique biochemical markers to get at liver stores of vitamin A. We did something called a process of sensitization. If you can imagine, you just can't set up shop in the middle of an African village and do a study. You have to involve all different kinds of players. You have to involve the provincial health offices, the permanent secretary, the district health office, and you have to continue to have coordination meetings. You also have to involve the village chiefs. Yes, they still have chiefs in African tribes. We hired a facilitator to help with the community engagements. If you can imagine every African province has their own language. And so, only a few people outside of the tribe can speak these local languages. So we hired a retired nurse/midwife in the first trial, and then in the second trial we hired a nutritionist from the first study. So we've done two intervention studies with orange maize in Zambian preschool children. We had meetings with the community, the headmen, church leaders, and volunteers. We did social mobilization activities, and these included drama, remember many of the folks, mothers of the children in our studies are not literate, and then we had open discussions. We listed villages within the study sites. And in our first study we had six villages, and in our second study we had four of the same villages. And then we confirmed potential child participants in the villages by household. This is a picture of our nutritionist from the first study. Guess which ones belong to my research group?

LAUGHTER

been in one country

And then we, like I said, we hired local nutritionists to lead the study sites every day. This particular woman was our facilitator in the second study, Selena. And it was very nice because she was already well known within our study site. In our first study, we assessed 223 children for eligibility. In our second study, we assessed 143. We excluded some children along the way, and then at the end of the day we had 92 children in one group and 88 children in another group. Overall in our first study, it was children that were 36 to 71 months, and our second study they were the same kids, some of them. We actually moved our age range to 72 months and above. Our first study was 70 days, and our second study was 90 days. And then we recruited from the same eastern province in Zambia. Our feeding groups, we had orange maize versus white maize. So in our first study, it was a simple study design, just two

arms

white maize and orange maize. In the second study, we made it more complicated. We had white maize, we had white maize and a vitamin A supplement, and then we had orange maize. So we had three different groups that we were feeding maize to. In our first study, it's typical study in a village. You start out with orange maize, and you're feeding, feeding, feeding and then you're sitting at a stop light in Madison and you're study coordinator calls you on your cell phone and she says we're running out of maize. I said, really? So I stopped by agronomy. At that time, my maize breeder was actually in agronomy. His name was Kevin Pixley. I said, Kevin, we're running out of maize. He goes, oh. I said, we still have a month of study left. He said, oh.

LAUGHTER

arms

He looks at the calendar and he says, well, harvest is coming. I'm like, praise God. And so the bottom line is we had fed our nicely stored orange maize for the first 35 days of the study, then we fed the maize that was not stored very well, it was kept out of the freezer, and then we had fresh maize. Freshly harvest maize. You know what? This was data ready to be analyzed at the bottom line because we had maize that we started with, then we had icky maize, and then we had fresh maize. Guess what? People like eating fresh maize. Bottom line. In fact, they liked the orange fresh maize that we fed the last month of our study better than the white maize that was growing locally. So that was actually an a-ha moment for me. It's like, wow, maybe we can change the color of the food people eat if it tastes good. Bottom line. So here was our project menu. We fed porridge with brown nuts, so maize porridge with Zambian peanuts, porridge with milk, and nshima, nshima is the stiff porridge that I showed you a picture of. In our first study it was 350 grams at lunchtime. And then they had a snack before they went home. In our second study, what we did is we fed three meals a day. So very similar foods except we fed 300 grams of nshima at lunchtime and 300 grams at dinnertime instead of a snack. Here is a man grinding the maize. So this was that orange maize being ground in the local mill. You see white maize dust all over here, right? So we were interfering with the white maize of the mill. Here we set up kitchens. Well, one thing about kitchens in Zambia, most of them don't have electricity. So we had to work during the daylight hours. We had a battery operated scale. All food was weighed before and after the meals, after the children finished eating. We hired the mothers of the children to cook the maize. Here you see them cooking the white maize, and here they're cooking the orange maize. These are the nutritionists tearing the scale and making sure that all of the items are weighed. Making nshima is an art, and it requires a lot of upper body strength. And so here they're sifting through and adding a little more maize to get the right texture. Here's the orange maize. They stir and they stir and they stir. This whole process takes about a half hour to 45 minutes to make a pot of nshima about this big. Here we have them weighing out the porridge, pouring it into the bowl that the child will get. Here they're scooping out the nshima. So I hope you can appreciate the difference in the textures between these two staples. Here you see the children happily eating their orange maize or eating their white maize and their nice big serving of green leafy vegetables. They do eat green leaves in Zambia. Here you see a woman cleaning up the mess. One thing I learned, you know what? Sand makes a really good scouring powder. And so I was watching these women, here we have bleach in this water, by the way, and then you see this woman picking up this sand and cleaning off the coal from the bottom of the pot. Wow. Resourceful. Resourceful. And we have been cleaning up the mess and cleaning up the data for a couple of years now on the first study. The bottom line was that we needed to run into the second study, and I really haven't had time to sit down and write the first paper. But what did we find? We found that the children grew like crazy in our first study. And why was that? Well, we fed these kids probably better diets than they had eaten their entire life. And so they continued to grow very, very well during our study. Intake data. Maize intakes increased with time, and also there was an interaction by group and by week. And also relish intakes consistently increased over time, and snack they ate no matter what. They like their little biscuits and tea at the end of the day. So the bottom line is these kids were growing and they were eating more as time went on. And this shows you these upward trends for the porridge, upward trend for the relish, the upward trend for the nshima. So what about our maize transitions? So the bottom line here is, remember I told you the orange maize one and the orange maize two was the old maize? Once we switched to this fresh, nice, tasty, newly harvested orange maize there was a significant increase in maize intakes. So that was sort of exciting for us. So can maize change vitamin A status? This is our bottom line. We made some predictions from animal and human studies. Remember I told you that sugar, yeah, within a year vitamin A toxicity. So these are data extrapolated from that study. Here you have bioconversion with maize. What happens here? Here they're eating about 100 grams, here they're eating 150 grams, and then what happens? Once their liver says, oh, I have enough vitamin A in my liver, they down regulate the amount of provitamin A that they convert to vitamin A. So this is important from a public health standpoint. It means that you could put as much provitamin A in that maize as you have in carrots and it's not going to make a difference. They will not go vitamin A toxic based on how much they eat because your body will co-regulate it. Here are supplements. You give a dose, vitamin A goes up in the liver, but within four months it's gone. You give another supplement, goes up, comes down, goes up, comes down. It prevents blindness in children that are at risk, but it is not the best way for people to get the vitamin A that they need on a daily basis. Here's more data. This is the Guatemalans. Here we go. Vitamin A with a high sugar intake. Here you have a diabetic person that can't eat sugar. Low intake of sugar. Biofortified maize, a low intake will not get you out of vitamin A deficiency but a high intake will, and that sort of asymptotes and you will never become vitamin A toxic. It's a visible trait. It is going to take nutrition education for these people to change the color of food that they eat. White rice. White sweet potato. White potatoes. White maize. It's as engrained into all cultures. For some reason, we have gravitated toward white staple foods. So convincing them that orange maize is more nutritious is going to be extremely important. And I think we need to focus on children and expectant mothers, and it can make a difference. It's going to take lots of social marketing. And also, you need to convince the farmers to grow these biofortified foods. Why? Well it's their bottom dollar, right? And not only do they eat what they grow, they are also selling it in many instances. So why do we go around and do what we do? Well, we think it's very important to assist programs to improve the vitamin A status of both women and children in the world, and I think biofortified crops is a good way to go right now because it is difficult to get them to switch to eating vegetables. The bottom line is they want to fill their stomachs, and staple foods do that. The high energy and the high calorie is what they need in order to feel satiated when we're talking about a poor rural community. So if we can make those staple crops more nutritious, in the long run, everybody will be better off. It takes time. Remember, I told you it took 600 years to go from yellow and purple carrots to orange and red carrots. Why do we have orange carrots in the United States, the predominant one? It's because that's the color that the Europeans decided to bring over many, many years ago. And so, that's why orange carrots predominated instead of red carrots. But there are countries that eat red carrots. Indians are one of them. And so, there are other types of carrots around. Purple carrots are in Afghanistan. Yellow carrots are often fed to animals in Europe. And, believe it or not, you now see all of these different carrots at different venues in Wisconsin. Why? Because I came here about 14 years ago, and we started showing that nutritionally these carrots, all different colors, can enhance nutrient status, not only in gerbils, but also in humans. One hundred years later, we are still trying to prove maize can solve the vitamin A problem. So, even though extracts of maize prevented vitamin A deficiency in rats a hundred years ago, we need to get the levels up just a little bit more so that we can prevent a marginal status in people who will adopt these crops. But that's a whole other ball game. We need to have people change the color of the way they eat. And that is no small task. But nutrition education becomes extremely important. With that, I would like to thank you for your attention. This was our first group of kids, and some of those kids repeated the study in 2012. So, thank you for your attention.

APPLAUSE