Iodine and Child Brain Development – PediaCast 524

Show Notes


  • Dr Liz Zmuda, Dr Elizabeth Pearce and Marina Chaparro visit the studio as we consider iodine deficiency as a cause of intellectual disability in children. Learn the nature of this relationship and steps we can take to prevent it from occurring. We hope you can join us!


  • Iodine Deficiency
  • Hypothyroidism
  • Child Brain Development
  • Intellectual Disability




Announcer 1: This is PediaCast.




Announcer 2: Welcome to PediaCast, a pediatric podcast for parents. And now, direct from the campus of Nationwide Children's, here is your host, Dr. Mike.


Dr. Mike Patrick: Hello, everyone, and welcome once again to PediaCast. It is a pediatric podcast for moms and dads. This is Dr. Mike, coming to you from Nationwide Children's Hospital. We're in Columbus, Ohio.


It's Episode 524 for September 6, 2022. We're calling this one "Iodine and Child Brain Development". I want to welcome all of you to the program.




So, we have a really important topic for you today as we raise awareness about the dangers of iodine deficiency especially in pregnant moms, babies, and children. And it's important because iodine deficiency is the leading preventable cause of intellectual disability in children. And when intellectual disability occurs because of iodine deficiency, the damage is irreversible.


We also know that intellectual disability can impact quality of life and future success with education, jobs, and relationships. So, there's a cause to iodine deficiency at the individual family and community level, which means prevention of iodine deficiency is something all care about because we care about our friends and neighbors. And we want every child to have the best shot of thriving right out of the gate.


Now, this is not to say that those with intellectual disabilities are not able to have a great quality of life and achieve success, but it certainly is more difficult, right? There are more challenges, more barriers, and of course, more cost to that success.




And so, we want to prevent intellectual disability when we can, but we also want 100% support those impacted by iodine deficiency and its effect on child brain development.


Now, you may be wondering why is it that iodine is important for child brain development and how does it prevent intellectual disability. We're going to explore the science of these relationships. And we’ll also consider the scope of the problem.


But I will give you a hint, iodine deficiency is pretty common even in developed countries like the United States. So how does iodine deficiency occur? How is it treated? And better yet what can we do to prevent it. And we'll have answers to all of these questions and more, as we explore iodine and its impact on child brain development and intellectual disability.


Of course, in our usual PediaCast fashion, we have three terrific guests joining us for the discussion. Dr. Liz Zmuda is a pediatrician and a director of Medical Education at Doctor's Hospital, which is part of the Ohio Health System here in Central Ohio.




Dr. Elizabeth Pearce is an endocrinologist and professor of Medicine at Boston University College of Medicine.


And Marina Chaparro is a registered pediatric dietician and founder of Nutrichicos, which is a bilingual dietary practice for young patients and their families


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So, let's take a quick break. We'll get our expert guests connected to the studio and then we will be back to talk about iodine deficiency and child brain development. It's coming up right after this.






Dr. Mike Patrick: Dr. Liz Zmuda is a pediatrician and director of Medical Education for Doctor's Hospital which is part of the Ohio Health System here in Central Ohio. Dr. Elizabeth Pearce is an endocrinologist and Professor of Medicine at Boston University School of Medicine. And Marina Chaparro is a registered pediatric dietician and founder of Nutrichicos which is a bilingual dietary practice for young patients and their families.


All three have a passion for raising awareness about the importance of iodine and its role in preventing intellectual disabilities in children. That's what they're here to talk about, iodine and child brain development. But first let's give a warm PediaCast welcome to our guests, Dr. Liz, Dr. Elizabeth, and Marina. Thank you all for stopping by today.


Marina Chaparro: It's so nice to be here. Thank you, Dr. Mike, for inviting us.


Dr. Elizabeth Pearce: It's a pleasure to be with you.


Dr. Elizabeth Zmuda: Thanks. I'm excited for the conversation, too.




Dr. Mike Patrick: Yeah, I'm really excited and so glad that the three of you were able to take time out of your very busy schedules to join us and talk about iodine.


I think a great place to start with, Dr. Pearce, what exactly is iodine? I think it's something like a chemical. I think most people have heard of it before. But give us some more information about iodine.


Dr. Elizabeth Pearce: Iodine is a trace element. It's found naturally in seawater and in the earth's crust and much of the world. But there are many regions of the world where there is really not enough iodine in the soil. So that if foods are grown in those regions, the food products that are produced in those areas will be low in iodine. And therefore, humans who are eating those foods will also wind-up being iodine deficient.


Dr. Mike Patrick: So, this is a chemical that we have to get outside of our body. It's not naturally inside, right?


Dr. Elizabeth Pearce: Correct, correct.


Dr. Mike Patrick: And so, if we're not getting that in our diet or through some kind of supplementation, then we're going to have an iodine deficiency. And so, as we think about medicine, what role does iodine play in the body? Why is it important for us to get it?




Dr. Elizabeth Pearce: Well, it plays only one role at the body, as far we know, but it's actually quite an important role. So, iodine is needed for the production of thyroid hormone. And thyroid hormone is needed in turn to regulate how the body uses energy. In early life, it's particularly important for regulating growth and development.


Dr. Mike Patrick: So, we have iodine, as a trace element, coming in through food products. And if we have enough of it, we can make enough thyroid hormone. And if we don't have enough iodine in our diet or through supplementation of some kind, then we're not going to be able to make enough thyroid hormone.


And so then, we would have a condition that we would call hypothyroidism. So, less thyroid hormone than your body needs. What are some of the symptoms of hypothyroidism? So, iodine deficiency could cause that through the means of not having enough thyroid hormone.




Dr. Elizabeth Pearce: So, iodine deficiency, it causes hypothyroidism, truly low thyroid hormone levels, only in regions of severe iodine deficiency. So, that's going to be a manifestation. You're not going to see in places where levels of iodine intake are only mildly low.


Hypothyroidism can manifest as fatigue and cold intolerance, constipation, kind of foggy thinking, people just by brain fog, irregular periods, infertility in women. So, whole host of symptoms.


But the consequences of iodine deficiency are broader than that. Because iodine deficiency causes hypothyroidism really only is the tip of the iceberg and there are lots of other manifestations.


Dr. Mike Patrick: So, you have to have really low levels of thyroid hormone to have hypothyroidism and those symptoms that you had mentioned. But even if you have just a relative iodine deficiency, it's a less than is ideal. And so, you're still making some thyroid hormone but perhaps not enough thyroid hormone to cause other consequences.




Dr. Elizabeth Pearce: Right. It causes stress for the thyroid when there's not enough iodine to manufacture thyroid hormone. And that can cause enlargement of the thyroid of goiter or thyroid nodules once within the thyroid. And we'll talk about this, obviously, quite a bit more, but critically important for brain development in very early life. And so even miles degree of iodine deficiency can be associated with impairments of intellectual development in children.


Dr. Mike Patrick: So, mom with a baby inside may have enough iodine, that got enough thyroid hormone that she's not hypothyroid, but it still could affect the baby in terms of their brain development.


Dr. Elizabeth Pearce: That's correct, yeah.


Dr. Mike Patrick: Okay. And so, Liz, I want to bring you into the conversation. It would seem then the iodine is going to be really particularly important during the prenatal period when the brain is first developing if the thyroid hormone is needed for proper brain development.




Dr. Elizabeth Zmuda: Absolutely. So, in addition to the fact we know that there are women walking around that are iodine deficient, we know that the demand for iodine actually increases by up to 50% during pregnancy and lactation. So, depending on where they start from that can, obviously, have a different impact on different women. And mom's the only source of iodine for that infant.


And so initially, before the baby has their own thyroid that's functioning, they're reliant on the mom's thyroid hormones for their well-being. But then sometime around mid-gestation, their own thyroid starts to work in, so that iodine is also important for the development of their thyroid hormone.


Dr. Mike Patrick: Yeah, that makes sense. And so, as you mentioned, a lot of moms are sort of relatively iodine deficient to begin with going into pregnancy. And then, you're not only providing iodine for yourself, you need it for the baby as well. And as you said, that need increases by 50% or more during pregnancy. And yeah, a lot of women enter into pregnancy sort of deficient in iodine to begin with. So that's a problem.




Dr. Elizabeth Zmuda: Exactly. I mean, we know that kids, their diet around middle school, probably even before that, is really representative of what they're going to be when they're entering those prenatal time period. And so, it's not just about catching them when they're thinking about becoming pregnant. It's really about that lifelong education and support for the proper nutrition for children and for women specifically in this case.


Dr. Mike Patrick: And we're going to talk more about this, but I just want to introduce this concept that if you don't have enough iodine and enough thyroid hormone during those early months of development inside mom, during that prenatal period, that can lead to irreversible what we call neurocognitive defects, which is really lower IQ, lower ability to think, intellectual disabilities, right?




Dr. Elizabeth Zmuda: Right. So, iodine deficiency is the most preventable cause of intellectual disability in the world. And I think whenever I say that I have to sit for a minute because that is really astounding to me, that the thyroid hormones are crucial for brain development and things like cell migration, differentiation, myelination of never fibers.


All of these things that are happening at this really critical time point for brain development. It's such a period of rapid growth. And the interesting thing about the brain is that more complicated processes rely on the successful completion of the previous ones. And so, it builds upon itself and it's really important to get it right from the beginning. And that's why you can see an impact on IQ and intellectual function later.


Dr. Mike Patrick: Yeah, because it's just so important for brain development for that to be in place. And so, we really want to combat iodine deficiency wherever we can. And as you said, not just targeting moms who may become pregnant but really everyone because you don't know when you become pregnant.




And you don't have to have such low iodine that there is hypothyroidism disease to clue you in. It could really be anyone who feels fine and yet their iodine deficient. And that could impact their child's brain development and their intellectual powers later in life.


Dr. Elizabeth Zmuda: Absolutely. And this can really be complicated but things like food and security can even play a role in that and understanding access to appropriate nutrition, and what that means for socioeconomic classes and ultimately, the function and the IQ of that community. So, it's really an important point for us to be focusing on as a medical profession.


Dr. Mike Patrick: Yeah, absolutely. What about women who are breastfeeding? So, I would suspect that babies get some of their iodine through breastmilk. And so, it would be important not only during pregnancy, but also after pregnancy in terms of the child's brain development, really making sure that lactating moms also are not iodine deficient. Correct?




Dr. Elizabeth Zmuda: From the standpoint of brain development, absolutely. But I am going to turn this one over to Dr. Pearce and ask her to answer some of the specifics about excretion of iodine and how all of that looks in that postnatal time period.


Dr. Elizabeth Pearce: Yeah. So, women who are breastfeeding actively secrete iodine into breastmilk. It's concentrated in breastmilk at levels 20 to 50 times higher than what's circulating in the blood. Abd that's important because for a breastfeed infant, that mom's breastmilk is going to be the only source of iodine nutrition.


So, women who have maintained their optimal iodine state all through pregnancy will continue to have higher iodine requirements until they've done breastfeeding.




Dr. Mike Patrick: So really important to think about iodine. And since the only way that we get it in is through what we are eating and/or supplementation, I wanted to bring Marina, who's our dietician on board here. What are some good sources of iodine? What should we be eating in order to prevent iodine deficiency?


Marina Chaparro: And I think, Dr. Mike, you brought up an important point, initially. They were like, "Okay, iodine" like "What is iodine?" Right?


And so, I think I did this very non-randomized poll in my Instagram and just really asking everyday moms. It's like, "tell me about iodine? What do you know about iodine? Where you ever talked about iodine when you were pregnant?"


And I think most of them, and including myself when I was pregnant, we really have very little clue on iodine. Maybe we've seen it in salt and that's kind of how we associate it. But I think that's not the recommendation, right?


I think we want to focus not just on using iodized salt. We can get a little into that, but really how can we optimize iodine through iodine-rich foods.




And so, that's where really dairy food, eggs, and fish come into play. Really those are key sources of natural iodine. And the new dietary guidelines really emphasize that, in particular, woman who do not consume dairy foods, eggs, seafood or use iodized table salt are really at risk.


And so, I think there's various problems or risks. I think the fact that pregnant women and lactating women need more iodine. I think that the rise of vegan diets, plant-based diets, where they might be missing some of these key foods.


And also, we talked about the rise of the non-iodized salt. You go to a neighbor's house, and you ask them, "What type of salt do you have?" They might have pink salt, Himalayan salt. All these kind of fancier to a lot of people maybe healthier type of salt while they're not actually providing the iodine that our body needs.




And so, I think it's multifactorial issue. But it's simply, if we consume three sources of dairy, you're going to get enough iodine. And what I like especially is that really, it's 20 cents per serving of dairy. So, it's really economical. It's really affordable. It's accessible.


So, my whole concept is it doesn't need to be fancy. It doesn't need to be complicated. It's really about meeting our moms and our patients where they are and just providing practical solutions that are going to work for pregnant women.


Dr. Mike Patrick: Sometimes, especially as we think about healthy eating, those foods that you mentioned, milk, cheese, eggs, get kind of a bad rap a little bit in terms of fat content.




And so, we hear over and over, we need to lower the saturated fat in our diet. Maybe not so much for little kids, but as we’re thinking about pregnant moms, they may have heard the message that I need to really watch my fat intake. How can we be smart getting dairy foods, cheese, milk, eggs in but maybe not having all the added fat content?


Marina Chaparro: And I think when it comes down to is education, right? I think one of my biggest challenges is really to myth bust a lot of the messages that we hear that are really not evidence based. And so, when it comes to fat, there's multiple.


That's a good part about dairy, that there's many varieties. There are many ways of consuming it from a 2% from a full fat, from a zero-percent fat milk. And so same concept goes to lactose intolerance, right?


I might deal with family that say that they can't tolerate some type of milk. And so, there are lactose-free options as well, which are the real deal. They're still going to provide the same iodine amount as regular milk. They just don't have the lactose.




So, I think a big part of my job is to kind of understand, "Okay, why is it that you're doing what you're doing?" Right? So, my job, I always say, is not to be the food police. It is not to tell them this is what you need to do. But rather, "Okay, listen first. You're worried about the fat content, okay, let's talk. Let's find out other sources, other alternatives."


And I think that's where the education comes into play, that there's numerous ways of getting iodine whether it's through dairy, through eggs, through fish. It's just finding ways that fit them.


Dr. Mike Patrick: Yeah, absolutely. And like you mentioned, you can definitely choose a lower fat milk whether that's 2% or skim milk. And that's still going to have the same amount of iodine in it, correct?




Marina Chaparro: Absolutely. And I will point out that, unfortunately, a lot of the plant-based or soy milks do not provide iodine compared to the dairy. And so, that's a really key factor when we're dealing with vegan moms or vegetarian moms that are not consuming dairy products.


It's again, first understanding why you are doing what you're doing, respecting that, but providing them the appropriate support and appropriate resources to say "This is really something that you are missing. How can we find other alternatives, so you're not at risk or your baby is not at risk?" Or you name it.


Dr. Mike Patrick: And I want to underscore, again, that we're only talking about cow's milk, right? So, if you are talking soy milks, almond milks, oat milks, there's a lot of them out there now. Those are not going to have good iodine content compared to cow's milk.


Marina Chaparro:  Exactly. So, I believe one cup of cow's milk provides about maybe 70, I think it's 88 micrograms of iodine versus the other one provides less than 1. So, it's really a huge comparison.




Dr. Mike Patrick: Eggs are a great source. How many eggs would you need to eat a day to get a good iodine in?


Dr. Elizabeth Pearce: So, the iodine's in the egg yolk. And you would need to eat, for number of eggs to get your iodine only from eggs, it's maybe about 30 micrograms per egg yolk.


Dr. Mike Patrick: Okay, so that may not be a practical way. Eggs only is off the table.


Marina Chaparro: So, we know, for example, that cod, so 3 ounces of cod actually provides one of the highest amounts of iodine with 158 milligrams of iodine. So that's really good source of iodine as well.


Dr. Mike Patrick: Yeah, we didn't mention fish yet. And I think this is another one where you really have to take the person into consideration, right, because pregnant women are also hearing that you want to stay away from too much mercury. And so, there are certain fishes that like tuna, for example, can have high mercury content. What about cod? Is that safe from a mercury standpoint?




Marina Chaparro: That's a lower mercury fish. So, we know even, for example, a canned tuna to some people might think all type of canned tuna might have the same amount of mercury. But actually no, albacore tuna and white tuna that is canned are different. White canned tuna tends to have a lower mercury amount than let's say an Albacore, but they're considered medium.


So, I think again, just when counseling my pregnant women, there are so many things to consider, whether it's food safety, whether it's exercise, whether it's the mercury, whether it's the iodine. So, I think it's just a matter of making it simple and making it real.


Dr. Mike Patrick: Yeah, absolutely. This is why every medical practice needs a dietician in the office to help their patients because we don't know this stuff, right, Liz? Well, you do, Elizabeth, because you're an iodine expert but for us normal pediatricians, we don't learn a lot about this stuff. Right, Liz?




Dr. Elizabeth Zmuda: Right. That's actually what I was going to comment on is we don't have to be experts. We need to understand the importance and we need to understand generally speaking what are the foods. And I think if we are able to counsel our patients and our families from the standpoint of really focusing on variety.


I mean, obviously, we're not just going to eat eggs all day long go get our iodine. But if we have some dairy, some eggs, and some fish and it's incorporated into the diet on a regular basis, probably, things are going to work out just fine. And I think that's where I come from when I'm counseling patients, it's just really flexibility, variety, understanding the importance and then when you understand the importance, it drives the decision.


And if we are uncertain, somebody is high risk or food insecure or unable to have those foods for whatever reason, either choice or allergy, that's when it's really important to engage the dietician because it's going to become a little bit more complicated.




So, I agree it's hard to know everything and the recommendations for physicians change all the time. So, their best bet is to really partner with the dietician.


Dr. Mike Patrick: Yeah, absolutely. So, the key take-home here is going to be dairy food, cow's milk, cheeses, yogurts. We didn't mention yogurts but those are an excellent source as well. With less lactose, right, than cow's milk?


Marina Chaparro: Correct.


Dr. Mike Patrick: And then, eggs, we mentioned and seafood and in particular, cod is a really good one if you're looking for a lot of iodine.


Dr. Elizabeth Pearce: And I would add to that list, really importantly, don't add extra salt to the diet. But if you're going to be using salt in cooking or at the table, make sure it's iodized salt. That's an easy thing to do.


Dr. Mike Patrick: And it should be clearly on the label. If you don't find it saying iodized or iodine on the label, you should assume it does not have iodine in it.


Dr. Elizabeth Zmuda: That's correct.




Dr. Mike Patrick: Now, a lot of processed foods, soups, for example, you look at the sodium content and they're quite high in salt. But that's not necessarily iodized salt either, correct?


Dr. Elizabeth Pearce: Yeah, unfortunately, salt iodization has never been mandated in the United States. It's always been voluntary. And by and large, the food processors in the United States are not using iodized salt in their products.


So, even though the vast majority of sodium that we ingest in America is coming from commercially processed food. That's, unfortunately, not necessarily going to be a good source of iodine.


Dr. Mike Patrick: I wonder if there was a mandate and all of that salt was iodized, could you get too much iodine? Can you have iodine toxicity?


Dr. Elizabeth Pearce: Only if we are not doing a good job as a public health nutrition community, that we monitor the salts concentration of iodine. We regulate that and we monitor the population iodine status. So, it's perfectly possible, for example, as country's work to reduce sodium intakes to improve cardiovascular outcomes to just alter the amount of iodine in salt to keep things stable as sodium intake shift.




Dr. Mike Patrick: Got you. So, in other words, you may have to go down a little on how much iodine that goes into the iodized salt or up a little depending on the community salt.


Dr. Elizabeth Pearce: Exactly right, but it's actually fairly straightforward to adjust.


Dr. Mike Patrick: Good to know. Just people have to talk. The industries have to talk together, right?


Dr. Elizabeth Pearce: Well, that's always the problem. There are lots of efforts ongoing on the world to harmonize these decisions.


Dr. Mike Patrick: Yeah, absolutely. What about multivitamins? Iodine is a trace element. Other elements like calcium, for example, are present in multivitamins. And we have prenatal vitamins that moms can take. Is there iodine present in those vitamins? Or is that something that you have to also look for in the label?


Marina Chaparro: So, I think this is something really important for moms and practitioners because I think they get all sorts of recommendations. Some of them might not even contain DHA. So, I think it's really important, again, the education piece because about half of the prenatal supplements do not contain iodine.




And so, this is something to note, that when you are looking for a multivitamin to know. And so, when I went to my pharmacy, I started looking, right? And so, it's fairly easy. You will just find iodine.


And so those simple education pieces are going to be really important because they might not be containing it. And again, it's not just important when they are pregnant, but rather the three months prior or that prenatal, that planning phase. That's where it's going to be really important for them to know, am I taking the right supplement?


Dr. Mike Patrick: Yeah, really good point.


Dr. Elizabeth Pearce: I might also just make a couple points that I think are helpful here. One is that for whatever reason, the prenatal multivitamins that are marketed in the US that are sold by prescription only rather than over the counter are actually much less likely to contain iodine than the over-the-counter ones. And you can't look at the label and know what's in there.




So, the recommendation by and large is for looking for those over-the-counter supplements, and the amount of iodine you're looking for in them is 150 micrograms a day.


Dr. Mike Patrick: How does that compare to the RDA? Next to all these micronutrients right there on the label, it will give you the percentage of the recommended daily allowance. Those 150 micrograms, what is that? Would that be a 100%?


Dr. Elizabeth Pearce: It would be a 100% if you're not pregnant. It's less than that in pregnancy, the RDA is 220 micrograms a day. And in breastfeeding, it's actually up to 290 micrograms a day.


Dr. Mike Patrick: So, you're going to need more than a 100% if you're pregnant or you're breastfeeding?


Dr. Elizabeth Zmuda: Right.


Dr. Elizabeth Pearce: Main assumption is that people would be getting some in diet, as well as some supplements.


Dr. Mike Patrick: Yeah, got you. And then, there are some other medications that I have read that could be an issue with drug interactions. If you have too much iodine, that one time like ACE inhibitors and potassium-sparing diuretics which you used to treat high blood pressure, anti-thyroid medications.


So, you do want to talk to your doctor if you're on other medicines to make sure that too high of iodine might not be an issue with the other medicines you're taking? Am I right about that or off base?




Dr. Elizabeth Pearce: Probably not a huge issue, to be honest. The one group I'd probably would be careful about would be people taking anti-thyroid drugs usually for hyperthyroidism, often for Graves' disease. They could get in trouble from excess iodine, although the levels of iodine in prenatal supplement are not typical enough to trigger worsened hyperthyroidism in that group.


Dr. Mike Patrick: So really, the benefit of extra iodine in the diet is going to far outweigh any risk for the vast majority of folks?


Dr. Elizabeth Pearce: Correct, yeah.


Dr. Mike Patrick: So then, how common is iodine deficiency. We've kind of said it's common. Can you put some numbers on just how common this problem is?


Dr. Elizabeth Pearce: Well, a hundred years ago, this would have been incredibly common in most of the globe and certainly in the United States. A century ago, the whole upper portion of the United States, including especially the area around the Great Lakes and the Pacific Northwest was known as the Goiter Belt. Goiter being thyroid enlargement.




So, a part of the country where school children had visible thyroid enlargement. Up to 70% of school-aged kids had enlarged thyroids because of inadequate iodine intake.


So, a very prevalent and very visible public health problem a hundred years ago. What changed was that in the 1920s, we started introducing salt iodization as a way to prevent that goiter. And that effectively eliminated our US goiter belts by about the 1940s.


So, around the globe in the last 30 years, there's been a huge push to try and eliminate iodine deficiency disorders by salt iodization. So, we've gone from 30 years ago, the majority of countries around the world really having low iodine intakes to currently, I believe, only 21 countries that are believed to be iodine deficient overall.




But that's not quite the whole story, because when you're looking at the whole country iodine status, it's obscuring the fact that there may be regions of country where things are still low or particularly vulnerable populations. And because the pregnant women and the lactating women need more iodine than the rest of us, in a lot of the world, even where iodine nutrition overall has been optimized, the pregnant women still remain mildly to moderately iodine deficient. And we worry then about effects on child brain development.


Dr. Mike Patrick: Yeah, absolutely. I want to go back to something you had said on the 1920s, is when salt iodization really took off. And it was really meant as a public health effort to prevent iodine deficiency. So that we don't see intellectual disabilities in kids and problems with child brain development, particularly for pregnant moms and moms that are breastfeeding.




And I would just say that it seems that we ought to study this really well of what worked, because I feel like today, if there was an effort to add iodine to salt, that we would have all of the naysayers on social media saying this is a conspiracy theory and iodine's going to kill you and cause cancer. It just seems this is an example of a public health measure of adding an element to salt that actually works.


Dr. Elizabeth Pearce: It works beautifully. It's sort of an undersang, underknown public health triumph. Although I will say it's not quite straightforward as I may think. And we still have only voluntarily salt iodization in the US because efforts to try and mandate in the 1940s failed.


Dr. Mike Patrick: Yeah, just like fluoride in the water and COVID vaccines and all the other things. Okay, but we will not digress into that territory.


So, we've kind of mentioned that pregnant women and lactating moms because they have a higher need of iodine, that they are definitely at risk for a relative iodine deficiency. Who else is at risk for this problem?




Dr. Elizabeth Pearce: Probably depends on where you live. So, this varies a lot with geography. And so, thinking globally, if you're in that part of the world that does not have salt iodization and that historically has low iodine in the soil, you're going to be at risk.


So, it's basically about where you live. And then, if you're living in the part of the world that does have sources of iodine, are you getting adequate ones in the diet? So, when the US have already touched on the groups that are known to be iodine, it's women who are pregnant, primarily.


But probably also people with very restricted diet. There are some evidence in the US and elsewhere for example that people who follow a vegan diet are at risk for iodine deficiency. Mostly, probably because they're not getting dairy.


Dr. Mike Patrick: Great. So really important, really, I think ask your medical provider because if you're in an area that is at higher risk for iodine deficiency, hopefully, your medical provider knows this since they're taking care of that population. So that may be a good person to ask, "Hey, how's the iodine? Is this an issue for our area, correct?"




Dr. Elizabeth Pearce: Yes, although, I have to say in the US, as a country, we're considered iodine sufficient. And providers may not really know this.  A great resource for this is actually the website of something called the Iodine Global Network or IGN, which works with the World Health Organization to create global maps that are updated annually that show what countries have adequate iodine and where people might be at risk for iodine intakes are low.


Dr. Mike Patrick: Great. And we will put a link to that. We'll put the link to that site in the show notes over at for this episode, which is 524, so folks can find the resource easily. We have some other resources and links which we'll talk about in a little bit.


So then, we talked about the consequences of iodine deficiency. And in particular, if it's severe hypothyroidism, but even when there's sort of mild deficiency, we can see neurocognitive defects if young babies during development are exposed to an iodine-deficient diet.




And I would suspect if you had intellectual disabilities and neurocognitive defects, that could result in lower IQ, which then really can perpetuate poverty cycles and make it more difficult for folks to be successful in terms of academic work and then careers. And all of these things can really be tied into iodine deficiency. Am I overstating the problem?


Dr. Elizabeth Pearce: Not at all. Has huge impacts on whole region's economies and society at large. It's not just sort of an individual health outcome that gets affected.


Dr. Elizabeth Zmuda: And it really highlights the importance for the physician or the medical provider that look at the person or the family. And if we're in the United States and we're iodine sufficient but it's a vegan family, or it's a food insecure family. It's really about looking at those components that makes somebody higher risk that I think would help us to focus and target that population to prevent this.


Dr. Mike Patrick: Yeah, that's a really good point. So, the higher risk is not only where you live but also what you eat. And so, if you are a person who is avoiding dairy products or you are a vegan, you don't have many fish in your diet, then you are also going to be at risk. And again, you would want to talk to your medical provider about that.




I also want to mention since you might not have hypothyroid symptoms to know that you are iodine deficient. How do you diagnose this? Like how would an individual mom who may be in early pregnancy, how does she know if she's iodine deficient?


Dr. Elizabeth Pearce: And this is where things got a little bit tricky. You can't. There's not an individual biomarker for iodine nutrition that we can use urine iodine concentrations at the population level, just looking at median amounts to assess population as a whole. That's why we know for example that pregnant women in the US as a group are not getting adequate iodine nutrition.


But urine iodine concentrations fluctuate hour to hour, day to day. And it's been estimated that you need 10 or 12 spot or ideally 24-hour urine collections to measure iodine to understand somebody's ongoing intake with even 20% precision. So effectively, it's not completely impractical.




So, we don't have any marker for a patient to go into her provider and get tested and know if she's iodine deficient or not. So really, it's about all the clues that we've been discussing. What part of the world is this?  Are there recommendations for iodine supplementation in specific groups in that part of the world? Is there anything about this particular patients or their family's diet that might put them at higher risk?


Dr. Mike Patrick: Yeah, so it's a really great point. And I think a lot of people would think, "Oh, I can just go in and get my blood ran and see what my iodine level is." But it doesn't work that way.


Dr. Elizabeth Pearce: Sadly, no.


Dr. Mike Patrick: Why is that?


Dr. Elizabeth Pearce: Again, because…


Dr. Mike Patrick: You can check the sodium level but not amount of iodine.


Dr. Elizabeth Pearce: Yeah, most of the iodine in our bodies is in the thyroid gland. It's not necessarily circulating in the blood. So, we really can't get a good sense of iodine stores or whole-body iodine or a chronic intake because it just fluctuates so much in the blood or in the urine at any given moment.




Dr. Mike Patrick: So that makes sense. Thank you. It really does. So, in other words, when you take iodine in, it gets concentrated in the thyroid because that's where it's going to get used. And so, unless you took a thyroid sample, which is not a good idea, then the level of iodine in the blood is not really going to tell you how much is in the thyroid, which is what the important thing is.


Dr. Elizabeth Pearce: Exactly right.


Dr. Mike Patrick: And so, we can combat that by just saying everybody should get more iodine in their diet. Make sure that you're eating dairy foods on a daily basis. And if you're not a fish eater, try cod. Cod is great.


Dr. Elizabeth Pearce: And maybe just as a follow up to that, that we're really focused on getting the right amount of iodine nutrition, but as for more nutrient, more is not always better. So just because we worry most as a public health issue about intakes that are too low, too much is not healthy either and also disrupts thyroid function.


So, you don't really have any need to ingest more than the RDA. And it's recommended against ingesting more than somewhere between 500 and 1100 micrograms on a daily basis, particularly in pregnancy.




Dr. Mike Patrick: Okay, so you can get too much, either.


Dr. Elizabeth Pearce: Yes.


Dr. Mike Patrick: So, you want to be careful about that.


So, Liz, I want to bring you back in as a primary care pediatrician. Just tell us, we have a lot of this particular podcast is really geared for parents and families. But we do have a lot of pediatricians and other pediatric primary care providers who listen.


What do you see the role of us, providers, being for helping kids and families and pregnant women and lactating women to really raise awareness and make sure that folks are getting enough iodine but not too much iodine? How do you handle that in your practice?


Dr. Elizabeth Zmuda: I think this is where it comes back to just being all about the balance and really trying to support the family and keeping it from becoming too complicated. So, you have a mom who's maybe pregnant and she's trying to figure out what she should have. And she has some other children and what should they have and how much, "I don't want to get too much." 




And I think there's a lot of things that Dr. Pearce has mentioned that are just really beautiful about this, where a breastfeeding mom, we know that the iodine is concentrated in breastmilk. And that's probably for a purpose and that serves that young infant. But if the mom is getting some of these foods, eggs, cheese, milk, any form of dairy, cheese, getting her sufficient iodine and if she's feeding her children the same thing, they probably are, too.


And so, to me, this is really about us being aware, educating families about the importance of it and really making it practical and not too complicated. Because otherwise, I think people will freeze and they don't know what to do with it.


Dr. Mike Patrick: You have come up with something that has been published called The Iodine Action Plan. Tell us about that.




Dr. Elizabeth Zmuda: Well, it's very similar. We've had all these other public health measures that we've done. Everybody knows about folic acid. Nobody questions it. There's no conspiracy theory over folic acid. We know it's important for neural tube development.


And so, if this is important for brain development, then really this is just about educating and screening. And it's no different than anything else that we do as providers. So, to me, this is really, after the education, then ask the questions.


So, is this a family that has a special dietary need? Is there food insecurity? We should be asking those questions, anyway.


Is it an access issue? Is it a cost issue? What is the issue for the family so we can support them?


Maybe it's an education issue where they are fearful about something. And then, it would be about linking them with a dietician to really spend the time with a family about what makes sense for them, what they can feel comfortable with.


Just ask about the foods that they eat. If you hear that they're giving their child milk three times a day or they're incorporating some of these things into the diet, then we can educate around it but maybe be a little bit less concerned.




Checking those prenatal vitamins. So, until this all came out, I didn’t realize that prescription prenatal vitamins didn't always have iodine. So, asking where they're getting them and checking and making sure they're getting the right thing.


So, to me, this is about the same things that we do in every other area of medicine. Just ask the questions, educate on the why and then support them in the how.


Dr. Mike Patrick: That totally makes sense. And asking about salt intake as well and what kind of salt do, they use at home and how much. And there’s an opportunity to talk about whether it's enough salt and also the problems of too much salt, too.


Dr. Elizabeth Zmuda: Right. Especially for pregnant women, there's concern of high blood pressure and pre-eclampsia. And this is not about adding salt into the diet where it wasn't already existing. It would be if you're using it, what kind are you using. And then, educating around that family and that need and whatever that looks like at the time.




Dr. Mike Patrick: Marina, from a dietician standpoint, what sort of advice do you have for your young patients in the families that you counsel in terms of screening for iodine deficiency and the recommendations that you have to prevent that from occurring?


Marina Chaparro: So, I always say that we don't eat nutrients. We eat food, right? And so, I think when we kind of stop thinking about nutrients, nutrients, nutrients but rather focus on food, on the concept of family meals in real life. So, I think a lot of the times, as providers and practitioners, we're really excited about the theory and the importance and all the science. But then, it comes to real life and it's a mom who's working, who's busy, who has other kids, who has to deal with a lot of other issues. How do we make it feasible to this mom?


And I'll echo a lot of what Dr. Liz said. It's about listening. It's about educating them. Like you said, are they not eating fish because of the mercury?




Are they not consuming dairy because of the lactose, and they were consuming some other type of dairy when in fact they could just consume it lactose-free?


And a lot of it comes down to really focusing on those nutrient dense foods that we either way will want. So, we know that dairy, we know that eggs and seafood are really, really critical for brain development. And so, they're going to work in conjunction. Again, it's not just about one single nutrient for those meals.


And so, a lot of the times, what I see is moms and families, we just want ideas. Like, give me ideas. Tell me what this means in real life. And so, it's sometimes just coming down to "Okay, tell what you're having for breakfast." "How can we change your breakfast?"


And say, "Okay, let's do it the night before." Let's do a little meal prep. Let's do some overnight oats with some Greek yogurt. Because the Greek yogurt will also have the calcium, the vitamin D that you'll also going to want. And guess what some of the prebiotics that your guts will definitely want.




And so, thinking about snacks, right? So pregnant women are very into snacks and snacks as a way to optimize nutrition. It's asking, right, what type of salt do you use? And sometimes, I do this with every one of my friends. And I'm surprised of the amount of non-iodized salt that I'm seeing more and more.


If you are vegetarian, if you are vegan, okay, tell me more. And maybe we need to start using some type of supplements.


So, it's focusing on iodine-rich foods. It's focusing on getting the right supplement. And if you are using some type of salt, making sure it is iodized. So again, support is huge for moms.


Dr. Mike Patrick: Yeah, absolutely. If you had to give one generic piece of advice that would really help improve iodine intake in the whole population, what would your advice be?




Marina Chaparro: I mean, eggs, fish, and dairy. And not just because of the iodine, if you really think about it. But it's because of the other key nutrients that they will also provide, the omega 3's, the choline, the vitamin D.


Again, it's so hard to just say, just eat one food. Because it's never one food. It's rather one meal, one habit. And so, it really comes down to those three main food groups. The dairy, the eggs, and then the fish are key for brain function, cognitive health and they provide other benefits beyond just the iodine.


Dr. Mike Patrick: That's three servings a day? Would that be adequate of those things?


Marina Chaparro: Three servings of dairy a day, you're perfect. And again, it could be anywhere from a string cheese. It could be a Greek yogurt or a kefir for breakfast that you're having in a milk, in a smoothie. It could be a little bit of cheese that you put on some pasta.




So, it's simple ways of doing it. It's some enchiladas that you're doing a little bit of fish, a little bit of queso fresco. And so, there are multiple ways and also very unique and culturally relevant ways of also incorporating dairy into our population, into pregnant women.


Dr. Mike Patrick: Great. So, milk, cheese, yogurt, eggs, fish. And cod is like the super iodine fish, right?


Marina Chaparro: Yes, cod is abundant list. But it doesn't need to be cod if that is not your preference. I'm not going to force a pregnant woman to consume cod if they're especially nauseous. But they can consume other things. Maybe a smoothie would work even better for them. Maybe some overnight oats with a little bit of Greek yogurt or a frozen popsicle.




So again, that's where meeting with a registered dietician and I'm glad you're both saying it because louder for the people in the back.


Dr. Mike Patrick: Yeah, absolutely. When you said popsicle, you mean like a frozen yogurt?


Marina Chaparro: Exactly.


Dr. Mike Patrick: There's still got to be dairy in the popsicle.


Marina Chaparro: Exactly. But it's still providing that key nutrition. Maybe a little chia seeds, some flax seeds, some extra omega 3's. We're boosting it up in very simple ways.


Dr. Mike Patrick: Yeah, absolutely. Liz, I know that you have a particular passion for looking at this iodine deficiency really as a public health concern. Tells us why we should all, obviously, I'm not ever going to be a pregnant woman or nursing. So why is it important for me just as a citizen to think about iodine deficiency in the community?


Dr. Elizabeth Zmuda: I look at this at this and I say that building healthy and productive communities begins within the first thousand days. And that is my pediatrician heart. It is everything about that preconception period to that second birthday that is really the critical time point.




It's not that these things aren't important. After that, we know our brain develops throughout life. And it has this plasticity that makes us so wonderful. But the time here that is most critical is that first thousand days.


So, making sure that women that are entering pregnancy are sufficient and well-nourished. And then, continuing that throughout the lifetime is really going to change the productivity of that community. They're going to have high IQs. They're going to have less risk in lot of different social areas.


So, it is a simple way for us to have a huge impact on multiple socioeconomic classes. It's critical. So, when we look at outcomes in all different measures, that first thousand days is important and including this one.




Dr. Mike Patrick: Yeah, absolutely. So, when we think about the community as a whole and the success of the community, obviously, having as few intellectual disabilities as possible is going to be important.


Dr. Elizabeth Zmuda: Oh, absolutely. But I think we look at this as intellectual disability. But really, when I look at this, it's brain development. It is reinforcing those patterns over and over that we know are important. And the right patterns then build, and you got more complicated patterns and that person becomes more productive in different ways.


And this is very pediatric, right? When parents come into the office, they're asking. They talk about eating and pooping and what milestones the child is achieving.


And this is a way for us to explain the science behind what the parents are seeing. And really, also empowering them to make sure that they're getting good nutrition.


And like Dr. Pearson and Marina were just saying, it's not just iodine. It's all of the things. But iodine is one component that we know has a huge impact in it, something that lot of people aren't aware of.




So put that in the context of all the other education that we’re providing. And that has a huge impact on that child. And therefore, it's family and ultimately, it's community.


Dr. Mike Patrick: Elizabeth, tell us how communities can come together then to really combat this problem.


Dr. Elizabeth Pearce: I think it's really about awareness. As Liz has just noted, that 100 years ago in America, people knew about this problem. People have forgotten.


But it's important still in our country, it's important internationally to really continue to understand how important this is. Because basically, it's an easy, it's an inexpensive thing to do to make sure everybody's getting adequate iodine. And that effectively allows people to live up to their full potential.


Dr. Mike Patrick: So really an important thing for all of us to consider, not just at the individual and family levels but at the community level. And that's why we're dedicating an entire episode of PediaCast to iodine and the problem of iodine deficiency and how that relates to brain development, and ultimately into intellectual success for individual's families and communities. All really really important.




We are going to have several resources for you in the show notes over at, Episode 524, including that regional map where you can look at see what areas of the world are deficient in natural iodine.


We also have one. This is a terrific resource. I know, Liz, you are a part of putting this together called The Importance of Iodine in Prenatal Brain Development, published by the National Dairy Council. And we'll put a link to that in the show notes as well.


And then, the Proceedings of the Nutrition Society, if you're interested in little more science-y stuff, The Role of Iodine in Brain Development. If you want to dig deeper how iodine is involved in brain development, you can check that out.


And there's another article in food, science and nutrition called Iodine Consumption and Cognitive Performance.


Again, just want to reassure folks that all of the things that we're talking about is evidence based. And if you'd like to see some of the evidence, check out the show notes over at And we will have links to that evidence for you.




So once again Marina Chaparro with the Nutrachicos and a registered pediatric dietician, also Dr. Elizabeth Pearce, endocrinologist at Boston University School of Medicine, and Dr. Liz Zmuda, Director of Medical Education at Doctor's Hospital, the Ohio Health System, thank you all so much for being here today.


Marina Chaparro: Thank you for having us.


Dr. Elizabeth Pearce: Thanks for having us. This is a real pleasure.


Dr. Elizabeth Zmuda: Thank you.






Dr. Mike Patrick: We are back with just enough time to say thanks once again to all of you for taking time out of your day and making PediaCast a part of it. Really do appreciate that. Also, thanks again to our guests this week, Marina Chaparro, registered pediatric dietitian, Dr. Elizabeth Pearce, endocrinologist at Boston University School of Medicine, and Dr. Liz Zmuda, Director of Medical Education at Doctor's Hospital with the Ohio Health System here in Central Ohio.


After we got done recording, we had our usual sort of post-recording conversation. And Dr. Liz actually brought up a really good point that I wanted to share with all of you. And that is, as you're introducing new foods to your baby, and we're a lot less strict about that than we used to be. It used to be you'd wait till about four to six months of age and then you'd start the cereals and then vegetables and then fruits and then, finally, meats. And we worried about food allergies of all sorts.




And really, the change of thought has been that now, around closer maybe to six months, breast milk is best if you can up to about six months of age. And then, it's kind of more of a free-for-all really in terms of just introducing things. You want to make sure that it's nothing that they can choke. But you really can introduce a lot of different foods between 6 months and 12 months of age.


Again, you don't want stuff they can choke on. But as long as it's smooth and soft and easy for babies to swallow, it's all fair game.


And the exception, of course, is if you have a child with severe eczema or there's peanut allergy history in the family, or they have a lot of wheezing, a lot of allergic type disorder, then there are some rules for introduction of peanut product which you can talk to your medical provider about.


But the point is, the food that we've been talking about in this podcast in terms of being rich in iodine, things like milk and cheese and yogurt and eggs, and of course, fish as well, these are things that you could introduce early, and should introduce early and really make it a part of their regular diet. So then, you don't have to worry about iodine deficiency as much.




And the eating habits that begin in infancy really do continue on into childhood and into the teenage years and then into adulthood. So, by really focusing in on a well-balanced diet, which includes dairy products and fish because these things adequate amounts of iodine, starting in infancy and then into childhood, really sets them up even into adulthood, to hopefully not have to deal with the impact of iodine deficiency.


So really important to start good eating habits right out of the gate. And we were just talking about that as pediatricians and dieticians amongst ourselves after the recording. And I wanted to share that with you.


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Thanks again for stopping by. And until next time, this is Dr. Mike saying stay safe, stay healthy and stay involved with your kids. So, long, everybody.




Announcer 2: This program is a production of Nationwide Children's. Thanks for listening. We'll see you next time on PediaCast.

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