Iodine Deficiency During Pregnancy Archives - Health Tips From The Professor

Prenatal Supplements Strike Out Again

May 9, 2023 by Dr. Steve Chaney

Is It Three Strikes And You Are Out?

Author: Dr. Stephen Chaney

If you are pregnant, you want the best for your unborn baby. Your doctor has recommended a prenatal supplement, but do the prenatal supplements on the market meet your needs? A few months ago, I shared two studies that concluded that most prenatal supplements on the market are woefully inadequate.

In fact, the authors said, “[Our] analysis found that prenatal supplements vary widely in content, often only contain a subset of essential vitamins, and the levels were often below…recommendations.”

In other words, their study found that most prenatal vitamins on the market may not be adequate to support your needs and the needs of your child through pregnancy and breastfeeding.

Now, a third study on the topic has been published (KA Saunders et al, American Journal of Clinical Nutrition, 117: 823-829, 2023. It differs from the previous studies in that:

1) The previous two studies took a comprehensive approach, while this study focused on 6 key nutrients.

The previous studies included all nutrients important for a healthy pregnancy including choline, iodine, and vitamin K, which have only recently been shown to be important for a healthy pregnancy.

This study focused on 6 nutrients, vitamin A, vitamin D, folic acid, calcium, iron, and omega-3 fatty acids, which have long been recognized as essential for a healthy pregnancy.

2) The previous two studies focused on prenatal supplements, while this study focused on all supplements that might be taken by pregnant women.

3) The previous two studies asked whether supplements provided recommended amounts of all nutrients needed for a healthy pregnancy. This study took a “Goldilocks approach” and asked whether levels of these 6 essential nutrients were appropriate (“just right”). The study:

Started by determining the intake of these 6 key nutrients by American women. The authors of the study then added the amount of each nutrient provided by the supplements in their study to the amount of that nutrient in the diet of American women and:

- Calculated the minimum amount of each nutrient that would be needed to assure that 90% of American women taking a particular supplement would meet the recommended intake for pregnant and lactating women.

- Calculated the maximum amount of each nutrient provided by supplements in their study to assure that that 90% of American women taking that supplement would not get potentially toxic amounts of that nutrient.

In other words, for each of the 6 nutrients they calculated a supplemental dose range that was neither too low nor too high. They called this the “appropriate dose range” for each nutrient. Goldilocks would have called it “just right”.

I’m sure you are anxiously waiting to learn what their study found. But before we go there, I will describe how the study was done.

How Was The Study Done?

For the dietary intake portion of the study, the authors used dietary intake data previously collected from the Environmental Influences on Child Health Outcomes (ECHO) study.

The ECHO study is a consortium of 69 medical centers across multiple states. It is an observational study of mothers and their offspring designed to understand the effects of early life exposures on child health and development.

The current study analyzed dietary intake data for 2450 participants from 6 medical centers across 5 states in the ECHO study. The women in this study were diverse with respect to ethnicity, education, and weight.

All pregnant women in the current study completed at least one 24-hour dietary recall between 6-week gestation until delivery (24% completed one dietary recall. 76% completed two or more dietary recalls). Dietary intake was generally assessed with an expert interviewer and included all foods and beverages consumed in the previous 24 hours.

For the supplement portion of the study, the authors used the NIH Dietary Supplement Label Database because it is the most complete listing of supplements in the US. The authors selected 20,547 supplements that contained at least one of the 6 essential nutrients from this database.

To determine which of the 20,547 supplements contained appropriate levels of the 6 nutrients (vitamin A, vitamin D, folic acid, calcium, iron, and omega-3 fatty acids) selected for this study, the authors used the process described in the introduction above. Briefly:

The authors added the amount of each nutrient provided by the supplements in their study to the amount of that nutrient in the diet of American women and:

Calculated the minimum amount of each nutrient that would be needed to assure that 90% of American women taking a particular supplement would meet the recommended intake for pregnant and lactating women.

Calculated the maximum amount of each nutrient provided by supplements in their study to assure that that 90% of American women taking that supplement would not get potentially toxic amounts of that nutrient.

In other words, for each of the 6 nutrients they calculated a supplemental dose range that was neither too low nor too high. They called this the “appropriate dose range” for each nutrient.

Why Are The 6 Nutrients Included In This Study Important?

Dietary Intake Is Often Inadequate

The diet analysis of pregnant American women in this study found:

42% were at risk of inadequate vitamin A intake.

96% were at risk of inadequate vitamin D intake.

45% were at risk of inadequate folic acid intake.

55% were at risk of inadequate calcium intake.

93% were at risk of inadequate iron intake.

67% were at risk of inadequate omega-3 intake.

The percentage of women at risk for inadequate intake of these nutrients varied with age, ethnicity, and income levels. But the overall message is clear. Most American women are not getting enough of these essential nutrients from their diet alone.

The Risk of Inadequate and Excessive Intake Of These Nutrients

These 6 nutrients were chosen in part because reviews by the Cochrane Collaboration have concluded that inadequate intake of these nutrients are associated with complications during pregnancy and delivery. They can also adversely affect the health and normal development of the baby.

This is important because the Cochrane Collaboration is considered the Gold Standard of clinical studies. You can find a more detailed description of Cochrane Collaboration studies and why they are the Gold standard here.

[Note: The Cochrane Collaboration has not yet evaluated choline, iodine, and vitamin K for pregnant women, but their inclusion in prenatal supplements is supported by multiple clinical studies.]

In addition, excess intake of all these nutrients except omega-3s can harm both the fetus and the mother. The is why the Food and Nutrition Board has set ULs (Upper Limits – the level above which toxicity can occur) for 5 of the 6 nutrients. This is important because previous studies have suggested that up to 25% of women may be getting toxic levels of one or more of these nutrients when you consider both their dietary intake and their prenatal supplement.

Summary

In other words, both too little and too much of these nutrients can harm the mom and her baby. It is critical that prenatal supplements get the dosing right.

It is for that reason that the authors of this study have set an “appropriate dose range” (high enough that 90% of women have enough of each nutrient to prevent deficiency and low enough that 90% of women do not exceed the UL for each nutrient) as the standard for evaluating the adequacy and safety of supplements for pregnant women.

Prenatal Supplements Strike Out Again

Of the 20,547 supplements (421 labeled as prenatal supplements) available on the US market as of December 31, 2022, the investigators reported that:

Only 69 (0.3%) supplements contained all 6 nutrients considered essential for a healthy pregnancy.

Only 1 supplement contained all 6 nutrients at the appropriate doses, and it wasn’t even labeled as a prenatal supplement.

In addition:

One supplement containing all 6 nutrients put 100% of the women in their study at risk for excessive intake of folic acid.

Another supplement containing all 6 nutrients put 46% of the women in their study at risk of inadequate calcium intake.

The authors concluded, “Almost no US dietary supplements provide key nutrients in the doses needed for pregnant women. Affordable and convenient products that fill the gap between food-based intake and estimated requirements of pregnancy without inducing excess intake are needed to support pregnant women and their offspring.”

In short, the conclusion of this study can be summed up as, “Prenatal Supplements Strike Out Again”.

[Note: It sometime takes a while for supplement labels to be posted in the NIH Dietary Supplement Label Database. The authors acknowledged that this study may not include supplements introduced or reformulated in the last quarter of 2022.]

Is It Three Strikes And You Are Out?

If you are pregnant or thinking of becoming pregnant, this should be a wake-up call.

70% of pregnant women in this country take prenatal supplements, usually based on recommendations by their health care provider. They assume the prenatal supplements meet their needs and the needs of their unborn baby.

Yet three studies evaluating the adequacy of prenatal supplements have been published in the past few months. They took very different approaches in evaluating the supplements. But all three studies concluded that the vast majority of prenatal supplements on the market are woefully inadequate.

You may be wondering, “Is it three strikes, and you are out?” Are there no decent prenatal supplements on the market? The answer to those questions is, “No. There are good prenatal supplements on the market.”

You may be wondering how I can say that in the face of such overwhelming negative data. That’s because while all 3 studies were very good studies, they each had “blind spots”:

1) Each of the studies used very stringent criteria for identifying adequate prenatal supplements. In some cases, their criteria were stricter than the RDA recommendations and the recommendations of the American College of Obstetrics and Gynecology for pregnant and lactating women. It could be argued that their criteria were too stringent.

2) In the case of the current study, it could also be argued that evaluating only 6 nutrients is not a good criterion for evaluating the adequacy of prenatal supplements. For example, I looked up the one supplement rated as adequate in this study. It does provide appropriate doses of the 6 nutrients this study focused on. It also provides appropriate doses of vitamin K and iodine. But it does not provide choline. It is a very good supplement for women, but it is not the perfect prenatal supplement.

So, what can you do? How can you find the best prenatal supplement for you? Unfortunately, you cannot rely on advice from your friends or your health professional. You cannot rely on advertisements. That is a good place to start, but you have to do your own sleuthing.

With that in mind, I have listed 7 simple rules for selecting the best possible prenatal supplement in my article about the first two studies. Use these rules for evaluating every prenatal supplement you come across. Happy sleuthing.

The Bottom Line

A recent study evaluated all 20,547 supplements on the US market to see if they met the needs of pregnant women in this country.

They focused on 6 nutrients (vitamin A, vitamin D, folic acid, calcium, iron, and omega-3s) known to be essential for a healthy pregnancy.

They determined the dietary intake for all 6 nutrients in a cross section of pregnant women in the US.

They added the amount of the 6 nutrients in each of the 20,547 supplements to the dietary intake of those nutrients by pregnant women.

They then asked which supplements provided the “appropriate dose” of all 6 nutrients. They defined “appropriate dose” as the dose range that was.

- High enough to prevent deficiency of that nutrient in 90% of pregnant women taking the supplement…and…

- Low enough to prevent toxicity from that nutrient in 90% of pregnant women taking the supplement.

In other words, for each of the 6 nutrients they calculated a supplemental dose range that was neither too low nor too high.

Of the 20,547 supplements (421 labeled as prenatal supplements) available on the US market:

Only 69 (0.3%) supplements contained all 6 nutrients they considered essential for a healthy pregnancy.

Only 1 supplement contained all 6 nutrients at the appropriate doses, and it wasn’t even labeled as a prenatal supplement.

If you are pregnant or thinking of becoming pregnant, this should be a wake-up call.

Yet three studies evaluating the adequacy of prenatal supplements have been published in the past few months. And all three studies concluded that the vast majority of prenatal supplements on the market are woefully inadequate.

You may be wondering how I can say that in the face of such overwhelming negative data. That’s because while all 3 studies were very good studies, they each had “blind spots”:

For more details on this study and 7 tips on finding the best prenatal supplement for you, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

____________________________________________________________________________

My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

My answer is, “Yes, as long as you share only the article without any additions or alterations. In particular, you should avoid adding any mention of your company or your company’s products. If you were to do that, you could be making what the FTC and FDA consider a “misleading health claim” that could result in legal action against you and the company you represent.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

The Perils Of Iodine Deficiency For Women

May 10, 2022 by Dr. Steve Chaney

Where Can You Get The Iodine You Need?

Author: Dr. Stephen Chaney

It shouldn’t be happening. The introduction of iodized salt in the 1920s virtually eliminated iodine deficiency in this country. However, in just the past twenty years the incidence of iodine deficiency has increased 3-8-fold in women of childbearing age. Recent studies have estimated that today 30-40% of women of childbearing age are iodine deficient.

How did that happen?

We have been told to cut back on sodium. Many Americans have responded by throwing away the (iodized) salt shaker. Unfortunately, we still get a lot of salt from processed foods, and that salt is usually non-iodized.

When we do add salt to our foods it is usually the “healthier” designer salts. First it was sea salt. Now it is trendy versions like Pink Himalayan Salt. While sea salt might have some iodine naturally, the trendier versions are non-iodized.

The New-Age Whole Food diets often ban salt from the diet. That increases the probability of becoming iodine deficient. For example, a recent study reported that women who followed the Paleo diet for two years became iodine deficient (S. Manousi et al, European Journal of Clinical Nutrition, 72: 124-129, 2018).

The consequences of iodine deficiency, especially among women of childbearing age, are alarming. In a previous issue of “Health Tips From the Professor” I reported that iodine is essential for bone and neural development during fetal development and infancy.

This study (JL Mills et al, Human Reproduction, doi: 10.1093/humrep/dex379, 2018) reports that iodine deficiency also reduces a woman’s chances of becoming pregnant.

How Was The Study Done?

This study recruited 501 couples (ages 18-40) from 16 counties in Michigan and Texas. The women had all discontinued conception within the previous two months with the intention of becoming pregnant and were followed for an additional 12 months. Women with known thyroid disease were excluded from the study.

Urine samples were collected from each woman at the beginning of the study to determine iodine and creatine levels. The women used fertility monitors to time intercourse relative to ovulation (Basically, that means they optimized their chances of becoming pregnant). They then used digital home pregnancy monitors on the day of expected menstruation to identify pregnancies.

Finally, 90% of the women took either a multivitamin or a prenatal vitamin during the study (The significance of this will be discussed later).

The Perils Of Iodine Deficiency For Women

The results of the study were:

44.3% of the women in the study were iodine deficient (defined as iodine-creatine ratios of <100 mcg/g). This was further broken down to:

- 21.8% were mildly iodine deficient (50-99 mcg/g).

- 20.8% were moderately iodine deficient (20-49 mcg/g).

- 1.7% were severely iodine deficient (<20 mcg/g).

That is a total of 22.5% who had moderate to severe iodine deficiency.

Women who had moderate to severe iodine deficiency had a 46% decrease in the chance of becoming pregnant over each menstrual cycle compared to the iodine sufficient group.

A simple way of reporting those data would be to say that their chances of becoming pregnant were reduced by 46%, but that would not convey the whole picture. Most of the women did become pregnant during the 12-month study. However, it took the women with moderate to severe iodine deficiency twice as long to become pregnant. Iodine deficiency did not prevent pregnancy from occurring, but it delayed it.

The authors concluded: “In summary, our data show that groups of women with iodine concentrations in the moderate to severe deficient range experience a significantly longer time to pregnancy…The US and European countries where iodine deficiency is common should evaluate the need for programs to increase iodine intake for women of childbearing age, particularly those trying to become pregnant.”

And the increased difficulty in becoming pregnant is just the tip of the iceberg. As I mentioned above, the consequences of iodine deficiency among women of childbearing age, can be devastating.

Iodine is essential for bone and neural development during fetal development and infancy. The American Academy of Pediatrics, The National Institutes Of Health, and the World Health Organization have all declared that mild iodine deficiency during pregnancy can prevent normal cognitive development and reduce IQ levels in children.

Because the consequences of iodine deficiency during pregnancy are so detrimental, if iodine deficiency also reduced the chances of a woman becoming pregnant, it could be considered a good thing. It could be part of Nature’s Plan. Unfortunately, this study suggests that iodine deficiency only delays pregnancy. It doesn’t prevent it.

Where Can You Get The Iodine You Need?

Since iodine is so essential for a healthy pregnancy, the important question becomes: “Where can you get the iodine you need?”

You could start by using old-fashioned iodized salt rather than designer salts in your salt shaker. However, I am reluctant to recommend anything that would increase sodium intake. We get far too much from processed foods already.

Seafood (or seaweed, if you are a vegetarian) are the best food sources of iodine. However, our oceans are so contaminated I would recommend consuming those foods only occasionally.

You will often see bread and dairy mentioned as good food sources because iodine was used in the preparation of those foods. However, iodine has largely been replaced by other agents, so those foods should no longer be considered good sources. For example:

- Iodine in commercial breads has traditionally come from the use of iodate as a dough conditioner. Today iodate has largely been replaced with bromide in commercial bread making. Not only does this trend decrease the amount of iodine available in our diet, but bromide also interferes with iodine utilization in our bodies

- Iodine in milk has traditionally come from the use of iodine-containing disinfectants to clean milk cans and teats. However, they have largely been replaced with other disinfectants

Fruits and vegetables are a variable source of iodine, depending on where they were grown. That is because iodine levels in the soils vary tremendously from region to region.

That leaves multivitamins and prenatal vitamins as your best source. However, you do need to read labels. You should look for supplements that provide 150 mcg of iodine. Unfortunately, only 50% of prenatal supplements in the United States even contain iodine. Remember, 90% of the women in this study took either a multivitamin or prenatal supplement and 44.3% of them were iodine deficient.

The Bottom Line

The introduction of iodized salt in the 1920s virtually eliminated iodine deficiency in this country. Now, almost 100 years later, iodine deficiency is back. Recent studies estimate that 30-40% of women of childbearing age are iodine deficient. This is concerning. Previous studies have shown iodine deficiency affects mental development during fetal development and infancy. A recent study suggests that iodine deficiency may also make it more difficult for women to become pregnant. Specifically, the study reported:

44.3% of the women in the study were iodine deficient. This was further broken down to:

- 21.8% were mildly iodine deficient.

- 20.8% were moderately iodine deficient.

- 1.7% were severely iodine deficient.

That is a total of 22.5% with moderate to severe iodine deficiency.

Women who had moderate to severe iodine deficiency had a 46% decrease in their chance of becoming pregnant over each menstrual cycle compared to the iodine sufficient group.

For more details about why iodine deficiency has reemerged in this country and where we can get the iodine we need, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Your Chances of Getting Pregnant Reduced by Iodine Deficiency?

February 12, 2018February 6, 2018 by Dr. Steve Chaney

Your Chances Of Getting Pregnant Could Be Cut In Half

Author: Dr. Stephen Chaney

Are your chances of getting pregnant reduced by iodine deficiency?

How did that happen?

We have been told to cut back on sodium. Many Americans have responded by throwing away the (iodized) salt shaker. Unfortunately, we still get a lot of salt from processed foods, and that salt is usually non-iodized.
When we do add salt to our foods it is usually the “healthier” designer salts. First it was sea salt. Now it is trendy versions like Pink Himalayan Salt. While sea salt might have some iodine naturally, the trendier versions are non-iodized.
The New-Age Whole Food diets often ban salt from the diet. That increases the probability of becoming iodine deficient. For example, a recent study reported that women who followed the Paleo diet for two years became iodine deficient (S. Manousi et al, European Journal of Clinical Nutrition, 72: 124-129, 2018 ).

The consequences of iodine deficiency, especially among women of childbearing age, are alarming. In a previous issue of “Health Tips From the Professor,” The Dangers of Iodine Deficiency During Pregnancy, I reported that iodine is essential for bone and neural development during fetal development and infancy. I also reported that the American Academy of Pediatrics, The National Institutes Of Health, and the World Health Organization have all declared that mild iodine deficiency during pregnancy can prevent normal cognitive development and reduce IQ levels in children.

This study (JL Mills et al, Human Reproduction, doi: 10.1093/humrep/dex379, 2018 ) reports that iodine deficiency also reduces a woman’s chances of becoming pregnant. [I might add, this almost seems to be part of Nature’s plan. If the consequences of iodine deficiency during pregnancy are so detrimental, the fact that iodine deficiency also reduces the chances of a woman becoming pregnant could be considered a good thing.]

How Was The Study Done?

This study recruited 501 couples (ages 18-40) from 16 counties in Michigan and Texas. The women had all discontinued contraception within the previous two months with the intention of becoming pregnant and were followed for an additional 12 months. Women with known thyroid disease were excluded from the study.

Finally, 90% of the women took either a multivitamin or a pre-natal vitamin during the study (The significance of this will be discussed later).

Are Your Chances of Getting Pregnant Reduced by Iodine Deficiency?

The results of the study were:

3% of the women in the study were iodine deficient (defined as iodine-creatine ratios of <100 mcg/g). This was further broken down to:
8% were mildly iodine deficient (50-99 mcg/g).
8% were moderately iodine deficient (20-49 mcg/g).
7% were severely iodine deficient (<20 mcg/g).
That is a total of 22.5% who had moderate to severe iodine deficiency.
Women who had moderate to severe iodine deficiency had a 46% decrease in the chance of becoming pregnant over each menstrual cycle compared to the iodine sufficient group.

Where Can You Get The Iodine You Need?

The important question becomes: “Where can you get the iodine you need?”

You could start by using old-fashioned iodized salt rather than designer salts in your salt shaker. However, I am reluctant to recommend anything that would increase sodium intake. We get far too much from processed foods already.
Seafood (or seaweed, if you are a vegetarian) are the best food sources of iodine. However, our oceans are so contaminated I would recommend consuming those foods only occasionally.
You will often see bread and dairy mentioned as good food sources because iodine was used in the preparation of those foods. However, iodine has largely been replaced by other agents, so those foods should no longer be considered good sources. For example:
Iodine in commercial breads has traditionally come from the use of iodate as a dough conditioner. Today iodate has largely been replaced with bromide in commercial bread making. Not only does this trend decrease the amount of iodine available in our diet, but bromide also interferes with iodine utilization in our bodies
Iodine in milk has traditionally come from the use of iodine-containing disinfectants to clean milk cans and teats. However, they have largely been replaced with other disinfectants
Fruits and vegetables are a variable source of iodine, depending on where they were grown. That is because iodine levels in the soils vary tremendously from region to region.
That leaves multivitamins and prenatal vitamins as your best source. However, you do need to read labels. You should look for supplements that provide 150 mcg of iodine. Unfortunately, only 50% of prenatal supplements in the United States even contain iodine. Remember, 90% of the women in this study took either a multivitamin or prenatal supplement and 44.3% of them were iodine deficient.

The Bottom Line

3% of the women in the study were iodine deficient. This was further broken down to:
8% were mildly iodine deficient.
8% were moderately iodine deficient.
7% were severely iodine deficient.
That is a total of 22.5% with moderate to severe iodine deficiency.
Women who had moderate to severe iodine deficiency had a 46% decrease in their chance of becoming pregnant over each menstrual cycle compared to the iodine sufficient group.

For more details about why iodine deficiency has reemerged in this country and where we can get the iodine we need, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

The Dangers of Iodine Deficiency During Pregnancy

December 6, 2016 by Dr. Steve Chaney

Does Your Prenatal Contain Enough Iodine?

Author: Dr. Stephen Chaney

A recent study (S.M. O’Kane et al, British Journal of Nutrition, doi.org/10.1017/S0007114516003925) concluded that 2/3 of Irish women had no idea that iodine was important during pregnancy. In fact, 57% of the women had no idea what iodine was, and 41% were unable to name any health problem related to iodine deficiency. The authors of the study considered this ignorance about iodine to be alarming. I’ll discuss why below.

First, let’s consider the situation in the United States. I suspect ignorance about the importance of iodine is just as widespread in the United States as it is in Ireland. Think about the nutrients we have been told are essential for healthy pregnancy outcomes.

We have heard about the importance of iron and calcium for decades.

The importance of folic acid and other B vitamins has been widely publicized over the last 20 years.

In recent years, we have learned about the importance of omega-3s, especially DHA.

But who has been telling us about the importance of iodine? Almost nobody.

What Are The Recommendations For Iodine Intake?

The RDAs for iodine are:

150 ug/day for adults
220 ug/day for pregnant women
290 ug/day for breastfeeding women

How Common Is Iodine Deficiency During Pregnancy?

Here are some quick facts about iodine deficiency in the US from a recent American Academy of Pediatrics position paper and the National Institutes of Health Consumer information site:

Approximately 1/3 of pregnant and lactating women in the United States are at least marginally iodine deficient.
To meet their RDA requirements for iodine during pregnancy and lactation the American Thyroid Association, The National Academy of Sciences, and The American Academy of Pediatrics all recommend pregnant and lactating women take supplements containing 150 ug of iodine.
Although most pregnant and lactating women take supplements:
- Only 50% of prenatal supplements in the United States contain iodine.
- Even worse, only 15% of the supplements pregnant and lactating women take contain iodine (some pregnant and lactating women take multivitamins rather than prenatal supplements).
Labeling can be deceptive. Most multivitamins and prenatal supplements specify the amount of potassium iodide in the supplement, not iodine. It requires at least 197 ug of potassium iodide to provide 150 ug of iodine.

In short, many pregnant and lactating women in this country are not getting enough iodine from their diet and the supplements they are taking may not provide the iodine they need.

Why Are So Many Americans Deficient In Iodine?

The best and most reliable natural sources of iodine are seaweeds and ocean fish. Meats, dairy, and grains can be moderate sources of iodine, but their iodine content is highly variable. It depends on the iodine content of the soil in which they were produced and how they were processed.

Because the soil in the interior of this country is very low in iodine, crops and animals raised in much of our country are also low in iodine. That lead to widespread iodine deficiency in this country prior to the introduction of iodized salt in the 1920s. Iodized salt largely eliminated iodine deficiency in the 1920s. However, since the 1970s, iodine deficiency has been gradually returning to this country for many reasons.

In the 1920s most of our food was prepared at home, so most of the salt in our diet was iodized. However, today:

Processed foods are replacing home-cooked meals, and the salt used in processed foods is not iodized.

Much of the salt we use today is “gourmet” salt that is not iodized. Even sea salt often contains far less iodine than iodized salt.

Seaweed has never been considered a delicacy in this country, and increasingly, Americans are avoiding ocean fish because of concerns about our polluted oceans.

Iodine in commercial breads has traditionally come from the use of iodate as a dough conditioner. Today iodate has largely been replaced with bromide in commercial bread making. Not only does this trend decrease the amount of iodine available in our diet, but bromide also interferes with iodine utilization in our bodies.

Iodine in milk has traditionally come from the use of iodine-containing disinfectants to clean milk cans and teats. However, they have largely been replaced with other disinfectants.

Together these trends have combined to create the “perfect storm”. Iodine deficiency has, once again, become a major health concern in the US and other developed countries.

The Dangers Of Iodine Deficiency During Pregnancy

Iodine is an essential component of the thyroid hormone. Accordingly, inadequate iodine intake leads to hypothyroidism. Thus, you might expect iodine deficiency to be associated with symptoms like fatigue, sensitivity to cold, dry skin, and unexpected weight gain.

However, you may not have known that thyroid hormone is also essential for bone and neural development during fetal development and infancy. Because of that, thyroid hormone production increases dramatically during pregnancy and lactation (Hence, the increase in iodine requirement for pregnant and lactating women).

I can’t emphasize strongly enough the consequences of iodine deficiency during pregnancy and lactation. Here is what the experts say:

The American Academy of Pediatrics says: “…mild iodine deficiency can affect cognitive development of the child”

The National Institutes of Health says: “[Mild] iodine deficiency can cause lower than average IQ in infants and children…”

The World Health Organization says: “Iodine deficiency is the single greatest cause of preventable intellectual disability in children worldwide.”

The Bottom Line

Iodine is important for bone and neural development during both fetal development and infancy. Because of this, iodine requirements are significantly higher during pregnancy and breastfeeding.

The iodine content of the American diet has decreased significantly since the 1970s. Today approximately 1/3 of pregnant and lactating women in the United States are at least marginally iodine deficient.

The National Institutes of Health, the American Academy of Pediatrics, and the World Health Organization all warn that even mild iodine deficiency during pregnancy and lactation can result in cognitive impairment in children.

Because of this, the American Thyroid Association and the American Academy of Pediatrics recommend that pregnant and lactating women take a supplement providing 150 ug of iodine. That corresponds to at least 197 ug of potassium iodide (the unit shown on most supplement labels).

Only 50% of prenatal supplements and 15% of multivitamin supplements contain iodine. Many that do contain iodine do not provide the recommended 197 ug of potassium iodide.

In short, many pregnant and lactating women in this country are not getting enough iodine from their diet; the consequences of even mild iodine deficiency are significant; and the supplements they are taking may not provide the iodine they need.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.