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

Should We Use Supplements For Cardiovascular Health?

Posted July 10, 2018 by Dr. Steve Chaney

Are You Just Wasting Your Money On Supplements?

Author: Dr. Stephen Chaney

 

supplements for cardiovascular health wast moneyYou’ve seen the headlines. “Recent Study Finds Vitamin and Mineral Supplements Don’t Lower Heart Disease Risk.”  You are being told that supplements are of no benefit to you. They are a waste of money. You should follow a healthy diet instead. Is all of this true?

If I were like most bloggers, I would give you a simple yes or no answer that would be only partially correct. Instead, I am going to put the study behind these headlines into perspective. I am going to give you a deeper understanding of supplementation, so you can make better choices for your health.

 Should we use supplements for cardiovascular health?

In today’s article I will give you a brief overview of the subject. Here are the topics I will cover today:

  • Is this fake news?
  • Did the study ask the right questions?
  • Is this a question of “Garbage In – Garbage Out?
  • Reducing Heart Disease Risk. What you need to know.

All these topics are covered in much more detail (with references) in my book “Slaying The Supplement Myths”, which will be published this fall.

 

How Was This Study Done?

supplements for cardiovascular healthThis study (D.J.A. Jenkins et al, Journal of the American College Of Cardiology, 71: 2540-2584, 2018 ) was a meta-analysis. Simply put, that means the authors combined the results of many previous studies into a single database to increase the statistical power of their conclusions. This study included 127 randomized control trials published between 2012 and December 2017. These were all studies that included supplementation and looked at cardiovascular end points, cancer end points or overall mortality.

Before looking at the results, it is instructive to look at the strengths and weaknesses of the study. Rather than giving you my interpretation, let me summarize what the authors said about strengths and weaknesses of their own study.

The strengths are obvious. Randomized control trials are considered the gold standard of evidence-based medicine, but they have their weaknesses. Here is what the authors said about the limitations of their study:

  • “Randomized control trials are of shorter duration, whereas longer duration studies might be required to fully capture chronic disease risk.”
  • “Dose-response data were not usually available [from the randomized control studies included in their analysis]. However, larger studies would allow the effect of dose to be assessed.”

There are some other limitations of this study, which I will point out below.

Is This Fake News?

supplements for cardiovascular health fake newsWhen I talk about “fake news” I am referring to the headlines, not to the study behind the headlines. The headlines were definitive: “Vitamin and Mineral Supplements Don’t Lower Heart Disease Risk.” However, when you read the study the reality is quite different:

  • In contrast to the negative headlines, the study reported:
    • Folic acid supplementation decreased stroke risk by 20% and overall heart disease risk by 17%.
    • B complex supplements containing folic acid, B6, and B12 decreased stroke risk by 10%.
    • That’s a big deal, but somehow the headlines forgot to mention it.
  • The supplements that had no significant effect on heart disease risk (multivitamins, vitamin D, calcium, and vitamin C) were ones that would not be expected to lower heart disease risk. There was little evidence from previous studies of decreased risk. Furthermore, there is no plausible mechanism for supposing they might decrease heart disease risk.
  • The study did not include vitamin E or omega-3 supplements, which are the ones most likely to prove effective in decreasing heart disease risk when the studies are done properly (see below).

Did The Study Ask The Right Question?

Most of the studies included in this meta-analysis were asking whether a supplement decreased heart disease risk or mortality for everyone. Simply put, the studies started with a group of generally healthy Americans and asked whether supplementation had a significant effect on disease risk for everyone in that population.

That is the wrong question. We should not expect supplementation to benefit everyone equally. Instead, we should be asking who is most likely to benefit from supplementation and design our clinical studies to test whether those people benefit from supplementation.

supplements for cardiovascular health diagramI have created the graphic on the right as a guide to help answer the question of “Who is most likely to benefit from supplementation?”. Let me summarize each of the points using folic acid as the example.

 

Poor Diet: It only makes sense that those people who are deficient in folate from foods are the most likely to benefit from folic acid supplementation. Think about it for a minute. Would you really expect people who are already getting plenty of folate from their diet to obtain additional benefits from folic acid supplementation?

The NIH estimates that around 20% of US women of childbearing age are deficient in folic acid. For other segments of our population, dietary folate insufficiency ranges from 5-10%. Yet, most studies of folic acid supplementation lump everyone together – even though 80-95% of the US population is already getting enough folate through foods, food fortification, and supplementation. It is no wonder most studies fail to find a beneficial effect of folic acid supplementation.

The authors of the meta-analysis I discussed above said that the beneficial effects of folic acid they saw might have been influenced by a very large Chinese study, because a much higher percentage of Chinese are deficient in folic acid. They went on to say that the Chinese study needed to be repeated in this country.

In fact, the US study has already been done. A large study called “The Heart Outcomes Prevention Evaluation (HOPE)” study reported that folic acid supplementation did not reduce heart disease risk in the whole population. However, when the study focused on the subgroup of subjects who were folate-deficient at the beginning of the study, folic acid supplementation significantly decreased their risk of heart attack and cardiovascular death.  This would seem to suggest using supplements for cardiovascular health is a good idea.

Increased Need: There are many factors that increase the need for certain nutrients. However, for the sake of simplicity, let’s only focus on medications. Medications that interfere with folic acid metabolism include anticonvulsants, metformin (used to treat diabetes), methotrexate and sulfasalazine (used to treat severe inflammation), birth control pills, and some diuretics. Use of these medications is not a concern when the diet is adequate. However, when you combine medication use with a folate-deficient diet, health risks are increased and supplementation with folic acid is more likely to be beneficial.

Genetic Predisposition: The best known genetic defect affecting folic acid metabolism is MTHFR. MTHFR deficiency does not mean you have a specific need for methylfolate. However, it does increase your need for folic acid. Again, this is not a concern when the diet is adequate. However, when you combine MTHFR deficiency with a folate-deficient diet, health risks are increased and supplementation with folic acid is more likely to be beneficial. I cover this topic in great detail in my upcoming book, “Slaying The Supplement Myths”. In the meantime, you might wish to view my video, “The Truth About Methyl Folate.”

Diseases: An underlying disease or predisposition to disease often increases the need for one or more nutrients that help reduce disease risk. The best examples of this are two major studies on the effect of vitamin E on heart disease risk in women. Both studies found no effect of vitamin E on heart disease risk in the whole population. However, one study reported that vitamin E reduced heart disease risk in the subgroup of women who were post-menopausal (when the risk of heart disease skyrockets). The other study found that vitamin E reduced heart attack risk in the subgroup of women who had pre-existing heart disease at the beginning of the study.

Finally, if you look at the diagram closely, you will notice a red circle in the middle. When two or three of these factors overlap, that is the “sweet spot” where supplementation is almost certain to make a difference and it may be a good idea to use supplements for cardiovascular health.

Is This A Question Of “Garbage In, Garbage Out”?

supplements for cardiovascular health garbage in outUnfortunately, most clinical studies focus on the “Does everyone benefit from supplementation question?” rather than the “Who benefits from supplementation?” question.

In addition, most clinical studies of supplementation are based on the drug model. They are studying supplementation with a single vitamin or mineral, as if it were a drug. That’s unfortunate, because vitamins and minerals work together synergistically. What we need are more studies of holistic supplementation approaches.

Until these two things change, most supplement studies are doomed to failure. They are doomed to give negative results. In addition, meta-analyses based on these faulty supplement studies will fall victim to what computer programmers refer to as “Garbage In, Garbage Out”. If the data going into the analysis is faulty, the data coming out of the study will be equally faulty. It won’t be worth the paper it is written on. If you are looking for personal guidance on supplementation, this study falls into that category.

 

Should We Use Supplements For Cardiovascular Health?

 

If you want to know whether supplements decrease heart disease risk for everyone, this meta-analysis is clear. Folic acid may decrease the risk of stroke and heart disease. A B complex supplement may decrease the risk of stroke. All the other supplements they included in their analysis did not decrease heart disease risk, but the analysis did not include vitamin E and/or omega-3s.

However, if you want to know whether supplements decrease heart disease risk for you, this study provides no guidance. It did not ask the right questions.

I would be remiss, however, if I failed to point out that we know healthy diets can decrease heart disease risk. In the words of the authors: “The recent science-based report of the U.S. Dietary Guidelines Advisory Committee, also concerned with [heart disease] risk reduction, recommended 3 dietary patterns: 1) a healthy American diet low in saturated fat, trans fat, and meat, but high in fruits and vegetables; 2) a Mediterranean diet; and 3) a vegetarian diet. These diets, with their accompanying recommendations, continue the move towards more plant-based diets…” I cover the effect of diet on heart disease risk in detail in my book, “Slaying The Food Myths”.

 

The Bottom Line

 

You have probably seen the recent headlines proclaiming: “Vitamin and Mineral Supplements Don’t Lower Heart Disease Risk.” The study behind the headlines was a meta-analysis of 127 randomized control trials looking at the effect of supplementation on heart disease risk and mortality.

  • The headlines qualify as “fake news” because:
    • The study found that folic acid decreased stroke and heart disease risk, and B vitamins decreased stroke risk. Somehow the headlines forgot to mention that.
    • The study found that multivitamins, vitamin D, calcium, and vitamin C had no effect on heart disease risk. These are nutrients that were unlikely to decrease heart disease risk to begin with.
    • The study did not include vitamin E and omega-3s. These are nutrients that are likely to decrease heart disease risk when the studies are done properly.
  • The authors of the study stated that a major weakness of their study was that that randomized control studies included in their analysis were short term, whereas longer duration studies might be required to fully capture chronic disease risk.
  • The study behind the headlines is of little use for you as an individual because it asked the wrong question.
  • Most clinical studies focus on the “Does everyone benefit from supplementation question?” That is the wrong question. Instead we need more clinical studies focused on the “Who benefits from supplementation?” question. I discuss that question in more detail in the article above.
  • In addition, most clinical studies of supplementation are based on the drug model. They are studying supplementation with a single vitamin or mineral, as if it were a drug. That’s unfortunate, because vitamins and minerals work together synergistically. What we need are more studies of holistic supplementation approaches.
  • Until these two things change, most supplement studies are doomed to failure. They are doomed to give negative results. In addition, meta-analyses based on these faulty supplement studies will fall victim to what computer programmers refer to as “Garbage In, Garbage Out”. If the data going into the analysis is faulty, the data coming out of the study will be equally faulty. It won’t be worth the paper it is written on. If you are looking for personal guidance on supplementation, this study falls into that category.
  • If you want to know whether supplements decrease heart disease risk for everyone, this study is clear. Folic acid may decrease the risk of stroke and heart disease. A B-complex supplement may decrease the risk of stroke. All the other supplements they included in their analysis did not decrease heart disease risk, but they did not include vitamin E and/or omega-3s in their analysis.
  • If you want to know whether supplements decrease heart disease risk for you, this study provides no guidance. It did not ask the right questions.
  • However, we do know that healthy, plant-based diets can decrease heart disease risk. I cover heart healthy diets in detail in my book, “Slaying The Food Myths.”

 

For more details, 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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