The Dangers of Iodine Deficiency During Pregnancy

Written by Dr. Steve Chaney on . Posted in Iodine Deficiency During Pregnancy

Does Your Prenatal Contain Enough Iodine?

Author: Dr. Stephen Chaney

 

iodine deficiency during pregnancyA 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?

iodine deficiency pregnant womenHere 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?

iodine deficiencyThe 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

dangers of iodine deficiency during pregnancyIodine 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 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.

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Comments (1)

  • Richard O Brouse

    |

    Dr. Chaney,
    What an excellent article on iodine and the need in pregnancy.

    Reply

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Latest Article

Can Plant-based Diets Be Unhealthy?

Posted September 10, 2019 by Dr. Steve Chaney

Do Plant-Based Diets Reduce Heart Disease Deaths?

Author: Dr. Stephen Chaney

 

plant-based diets vegetablesPlant-based diets have become the “Golden Boys” of the diet world. They are the diets most often recommended by knowledgeable health and nutrition professionals. I’m not talking about all the “Dr. Strangeloves” who pitch weird diets in books and the internet. I am talking legitimate experts who have spent their life studying the impact of nutrition on our health.

Certainly, there is an overwhelming body of evidence supporting the claim that plant-based diets are healthy. Going on a plant-based diet can help you lower blood pressure, inflammation, cholesterol and triglycerides. People who consume a plant-based diet for a lifetime weigh less and have decreased risk of heart disease, diabetes, and cancer.

But, can a plant-based diet be unhealthy? Some people consider a plant-based diet to simply be the absence of meat and other animal foods. Is just replacing animal foods with plant-based foods enough to make a diet healthy?

Maybe not. After all, sugar and white flour are plant-based food ingredients. Fake meats of all kinds abound in our grocery stores. Some are very wholesome, but others are little more than vegetarian junk food. If you replace animal foods with plant-based sweets, desserts, and junk food, is your diet really healthier?

While the answer to that question seems obvious, very few studies have asked that question. Most studies on the benefits of plant-based diets have compared population groups that eat a strictly plant-based diet (Seventh-Day Adventists, vegans, or vegetarians) with the general public. They have not looked at variations in plant food consumption within the general public. Nor have they compared people who consume healthy and unhealthy plant foods.

This study (H Kim et al, Journal of the American Heart Association, 8:e012865, 2019) was designed to fill that void.

 

How Was The Study Done?

plant-based diets studyThis study used data collected from 12,168 middle aged adults in the ARIC (Atherosclerosis Risk in Communities) study between 1987 and 2016.

The participant’s usual intake of foods and beverages was assessed by trained interviewers using a food frequency questionnaire at the time of entry into the study and again 6 years later.

Participants were asked to indicate the frequency with which they consumed 66 foods and beverages of a defined serving size in the previous year. Visual guides were provided to help participants estimate portion sizes.

The participant’s adherence to a plant-based diet was assessed using four different well-established plant-based diet scores. For the sake of simplicity, I will include 3 of them in this review.

  • The PDI (Plant-Based Diet Index) categorizes foods as either plant foods or animal foods. A high PDI score means that the participant’s diet contains more plant foods than animal foods. A low PDI score means the participant’s diet contains more animal foods than plant foods.
  • The hPDI (healthy plant-based diet index) is based on the PDI but emphasizes “healthy” plant foods. A high hPDI score means that the participant’s diet is high in healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) and low in animal foods.
  • The uPDI (unhealthy plant-based diet index) is based on the PDI but emphasizes “unhealthy” plant foods. A high uPDI score means that the participant’s diet is high in unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) and low in animal foods.

For statistical analysis the scores from the various plant-based diet indices were divided into 5 equal groups. In each case, the group with the highest score consumed the most plant foods and least animal foods. The group with the lowest score consumed the least plant foods and the most animal foods.

The health outcomes measured in this study were heart disease events, heart disease deaths, and all-cause deaths. Again, for the sake of simplicity, I will only include 2 of these outcomes (heart disease deaths and all-cause deaths) in this review. The data on deaths were obtained from state death records and the National Death Index. (Yes, your personal information is available on the web even after you die.)

 

Do Plant-Based Diets Reduce Heart Disease Deaths?

plant-based diets reduce heart deathsThe participants in this study were followed for an average of 25 years.

The investigators looked at heart disease deaths over the 25 years and compared people with the highest intake of plant foods to people with the highest intake of red meat and other animal foods. The results were:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

What Else Did The Study Show?

The investigators made a couple of other interesting observations:

  • The association of the overall diet with heart disease and all-cause deaths was stronger than the association of individual food components. This underscores the importance of looking at the effect of the whole diet on health outcomes rather than the “magic” foods you hear about on Dr. Strangelove’s Health Blog.
  • Diets with the highest amount of healthy plant foods were associated with higher intake of carbohydrates, plant protein, fiber, and micronutrients, including potassium, magnesium, iron, vitamin A, vitamin C, folate, and lower intake of saturated fat and cholesterol.
  • Diets with the highest amount of unhealthy plant foods were associated with higher intake of calories and carbohydrates and lower intake of fiber and micronutrients.

The last two observations may help explain some of the health benefits of plant-based diets.

 

Can Plant-Based Diets Be Unhealthy?

plant-based diets unhealthy cookiesNow, let’s return to the question I asked at the beginning of this article: “Can plant-based diets be unhealthy?” Although some previous studies have suggested that unhealthy plant-based diets might increase the risk of heart disease, this study did not show that.

What this study did show was that an unhealthy plant-based diet was no better for you than a diet containing lots of red meat and other animal foods.

If this were the only conclusion from this study, it might be considered a neutral result. However, this result clearly contrasts with the data from this study and many others showing that both plant-based diets in general and healthy plant-based diets reduce the risk of heart disease deaths and all-cause deaths compared to animal-based diets.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

There is one other subtle message from this study. This study did not compare vegans with the general public. Everyone in the study was the general public. Nobody in the study was consuming a 100% plant-based diet.

For example:

  • The group with the highest intake of plant foods consumed 9 servings per day of plant foods and 3.6 servings per day of animal foods.
  • The group with the lowest intake of plant foods consumed 5.4 servings per day of plant foods and 5.6 servings per day of animal foods.

In other words, you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet.

 

The Bottom Line

A recent study analyzed the effect of consuming plant foods on heart disease deaths and all-cause deaths over a 25-year period.

When the investigators looked at heart disease deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

A more subtle message from the study is that you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet. The people in this study were not following some special diet. The only difference was that some of the people in this study ate more plant foods and others more animal foods.

For more details on the study, 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.

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