Salt and Forgotten Knowledge

Summary

According to the World Health Organization, iodine deficiencies during pregnancy are the greatest single cause of preventable mental impairment in children.   However, societal trends are leading away from reliable sources of dietary iodine.  In recent decades, nutritional surveys show declining levels of iodine in the population, particularly among women of child-bearing age.  We owe it to the children of the next generation to understand the importance of dietary iodine and provide unborn children with the nutrients they need.

Iodine is a trace nutrient, measured in micro-grams and necessary for the health of adults and children.  Iodine is especially important during pregnancy, when dietary iodine requirements increase by 50%, for a variety of metabolic reasons.  Children born to mothers who are iodine-deficient run the risk of developmental disorders, mental impairment, and increased risk of autism.  Iodine deficiency during pregnancy causes lower IQs in children by about 10 to 15 points, impaired social development, risk of physical development disorders, and increased incidence of autism.  Children born to mothers who are only mildly iodine deficient have an increased risk of lower IQs and autism-spectrum disorders.  

Iodine consumption in the United States and Britain has been decreasing for 40 years.  Iodine consumption has fallen due to increasing use of prepared foods, restaurant foods, and sea-salt, which do not contain iodized salt.  In the United States and Britain, medical surveys show that women of child-bearing age and pregnant women have lower levels of iodine than the general population and are often iodine deficient. 

Salt and Forgotten Knowledge

In 1924, the United States began one of the simplest and most effective public health measures ever taken.   Health authorities encouraged salt manufacturers to make and sell iodized table salt. 

The program was spectacularly successful.  Iodized salt reduced the occurrence of thyroid disorders across the northern United States and eliminated severe mental impairment due to iodine deficiency.  Later studies showed that the program raised the average IQ of citizens living in iodine-deficient areas by about 15 points.  After that, iodized salt became the standard in American homes.  For nearly a century, health issues related to iodine deficiency were regarded as a solved problem, until both the problem and the solution became forgotten knowledge. 

According to the World Health Organization, iodine deficiency is the single most important preventable cause of brain damage in the world.  Since the 1970s, the United Nations has worked to provide iodized salt or other iodine supplements to populations worldwide.   WHO has said that ending iodine deficiency would be on a par with eliminating smallpox.   Iodine deficiency is a really big problem where populations do not receive supplemental dietary iodine.  

Today, the effective use of iodine supplements is declining in the United States and Britain, and iodine deficiency is becoming common, particularly among women of child-bearing age and pregnant women.  The known consequences of mental impairment and thyroid problems in their children are likely to follow.

All public health authorities agree that iodine is an essential nutrient, especially during pregnancy. But there is controversy about the delivery method for iodine.  For every means of obtaining iodine, there is someone offering caution or opposing its use.  Many doctors recommend eliminating the use of table salt.  There is some evidence that iodine supplements in pills are poorly absorbed or ineffective, and some health authorities recommend severe limits on the consumption of fish due to the fear of mercury contamination.  This issue needs attention from public health authorities, and consensus on the best way to obtain dietary iodine.

History of Iodine Supplements in Public Health

We’ve known for over 100 years that iodine is a necessary micro-nutrient for thyroid function.  The initial program to provide supplemental iodine in salt was intended to combat thyroid disorders such as goiter.  Goiter was a common disorder before the 1920s, across a broad swath of the northern United States known as the Goiter Belt.  It was also known that supplemental iodine could prevent the syndrome of cretinism, which is marked by severe mental impairment, problems with motor coordination and physical deformities.  Cretinism is related to iodine-deficient diet in pregnant women. Programs in the United States and Switzerland in the 1920s eliminated cretinism in areas of iodine deficiency.  For the rest of the twentieth century, iodine deficiency was considered a solved problem in the United States. 

By the 1970s, iodine supplements came to be recognized as a core part of international aid programs.   Programs to iodize salt or provide other dietary iodine supplements were implemented in most of the developing world, and today, most of the world has access to dietary iodine.  Still, nearly two billion people are considered to be at risk for iodine deficiency, and international aid programs continue to make progress in bringing iodized salt to iodine-deficient populations. 

Recent Research

Research over the past two decades has reaffirmed the importance of dietary iodine supplements.  A landmark study in Britain, published in 2013 in the medical journal Lancet, shows that even a mild iodine deficiency during pregnancy is a risk to a developing fetus.   The study was careful and comprehensive; accounting for 21 potentially confounding variables, such as socio-economic status.  Children of mothers with mild-to-moderate iodine deficiency were followed until age 8.  Children of mothers with iodine deficiency during pregnancy were more likely to be in the bottom 25% in terms of IQ.    Impairment was most evident in verbal IQ and reading proficiency.  The degree of impairment was proportional to the degree of iodine deficiency; the greatest mental impairment occurred in children whose mothers had the greatest iodine deficiency. 

A meta-analysis of about three dozen studies of iodine supplementation found that prenatal supplementation showed clear benefits in terms of the mental and educational development of children.  Iodine supplementation after birth showed only marginal improvements.  A typical study in the review concluded that for the timing of supplementation during pregnancy, “earlier is better” as a rule.  The meta-analysis is published on a blog without the process of peer review, but nevertheless provides a good overview of recent scientific literature on the topic.

Iodine Deficiency in Britain and the United States

There is no direct way of measuring the iodine sufficiency in an individual.  Iodine sufficiency is generally measured in terms of urinary iodine, which fluctuates daily according to iodine consumption.  Still, the urinary iodine test provides a means to statistically measure iodine consumption across a population and determine whether a group is receiving sufficient iodine or not.

Five recent studies across the UK have shown iodine deficiencies in pregnant women, particularly in the first trimester of pregnancy, which is believed to be the most important.  More than 60 percent of the pregnant women participating in the Lancet study were iodine deficient.   

In the United States, measured levels of iodine in the population have been falling since the 1970s.  From the 1970s to the 1990s, the measured level of iodine fell by half.  In general, iodine levels in the United States population are considered adequate, but iodine levels in women of childbearing age are consistently lower than the general population, a trend that has persisted since 2001.

Dietary Iodine Requirements

Most foods are low in dietary iodine.  The exceptions are seafood, dairy products, eggs, some vegetables grown in iodine-rich soil, and iodized salt.  The recommended daily intake of iodine for most adults is 150 micrograms per day.   This is roughly the amount that you can receive by eating one serving of baked cod, and one cup of milk.   Other species of fish, such as tuna and salmon, are not as iodine-rich as cod, however.   Alternatively, you might eat one cup of yogurt, two eggs, and a quarter-teaspoon of iodized salt.

The recommended amount of dietary iodine consumption for pregnant women is rising even as the measured level of iodine in the general population is falling.  In 2001, the World Health Organization recommended a diet containing 200 micrograms per day, but in 2007, WHO increased its recommendation of daily intake to 250 micrograms of iodine per day for pregnant women.    Current standards of the U.S. National Institutes of Health recommend 220 micrograms per day for pregnant women, and 290 micrograms for lactating (breast-feeding) women.    This is roughly equivalent to eating two servings of cod plus a cup of milk every day. Alternatively, a pregnant woman could reach the recommended iodine intake with two cups of yogurt, one serving of fish sticks, one serving of shrimp, and one can of tuna every day.

In short, sourcing iodine from diet alone would require a pregnant woman to eat unrealistically large amounts of fish, according to John Lazarus, specialist in hormone disorders and chair of the UK Iodine Group, and Professor Emeritus of Cardiff University.

Rising Iodine Deficiency

Colorful bottles of sea-salt line the shelves of upscale groceries and gourmet shops.   Artisan crafted, in specialty glass with names from distant exotic places, they promise pure and natural ingredients.  But by omission, these products may contribute to a degradation of the mental acuity and health of the next generation. 

Why is iodine deficiency rising in the United States and Britain?   There are several reasons which are obvious, and possibly others that are not so obvious. 

1)      The main reason that iodine levels have been falling for 40 years is decreased preparation of food at home, with the consequent lower consumption of iodized table salt.  Restaurant foods and prepared foods contain a lot of salt, but they do not contain iodized salt.  By some estimates, restaurant and prepared foods now account for 70% to 90% of Americans’ salt consumption, but this does not contribute to dietary iodine.

2)      Another reason for declining iodine sufficiency is the rising prevalence of vegetarian, vegan, and the newer fad of paleo-diet.   Vegetarians and vegans are particularly at risk of iodine deficiency; a 2001 study found that vegans in America are generally iodine deficient. 

3)      Sea salt and kosher salt do not contain significant amounts of iodine.  Among Americans who are not vegetarian, there is increasing use of sea salt, kosher salt, and other non-iodized salt, due to increasing public belief in natural foods and suspicion of additives.  Currently, about 12 percent of table salt sold in America is sea salt. 

4)      The medical community is complicit in the broad declines in iodine sufficiency.  Medical authorities, focused on cardiac health, blood pressure, and fluid retention issues during pregnancy, declared a “War on Salt” about thirty years ago.  Even today, official advice letters encourage pregnant mothers to “put away the salt shaker”, without concern or comment about pre-natal health or iodine deficiency.

5)      There is a possible decrease in the use of iodine disinfectants in the dairy industry, which might lead to a decreased concentration of incidental iodine in milk products.

Sources of Dietary Iodine

Seaweed is by far the richest source of dietary iodine.  But the amount of iodine in a bit of seaweed varies widely and up to dangerous levels.  According to the NIH, a gram of seaweed can contain between 16 and 2984 micrograms of iodine.  Other references indicate that ¼ gram of seaweed can contain 4600 micrograms of iodine.  Since 1100 micrograms is considered the safe upper limit for daily iodine consumption, routine consumption of seaweed as an iodine source is not recommended.

Seafood is by far the best general source of iodine, including fish, shrimp, and shellfish.   Salt-water white fish such as cod are the best sources, while tuna and salmon are less concentrated.  Dairy products, particularly from cows eating iodine-fortified feed, can be a good source of iodine.  Eggs and meat can contribute to iodine sufficiency, but are likely to be inadequate without supplementation.

Organic milk is known to be about 40% lower in iodine content than regular milk. 

A few select sources of iodine are given in the table below, from the National Institutes of Health.

Food	Approximate Micrograms (mcg) per serving	Percent DV*
Seaweed, whole or sheet, 1 g	16 to 2,984	11% to 1,989%
Cod, baked, 3 ounces	99	66%
Yogurt, plain, low-fat, 1 cup	75	50%
Iodized salt, 1.5 g (approx. 1/4 teaspoon)	71	47%
Milk, reduced fat, 1 cup	56	37%
Fish sticks, 3 ounces	54	36%
Bread, white, enriched, 2 slices	45	30%
Fruit cocktail in heavy syrup, canned, 1/2 cup	42	28%
Shrimp, 3 ounces	35	23%
Ice cream, chocolate, 1/2 cup	30	20%
Macaroni, enriched, boiled, 1 cup	27	18%
Egg, 1 large	24	16%
Tuna, canned in oil, drained, 3 ounces	17	11%

Table from the National Institutes of Health

https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/

Supplemental Dietary Iodine

In the United States, iodized salt has been the primary means of providing supplementary iodine to the population.  In Great Britain, supplementary iodine is provided in grain and in milk products, through the introduction of supplemental iodine in cattle feed.  In both countries, incidental iodine supplementation occurred through the use of iodine disinfectants in the dairy process. 

Maternal vitamin supplements are the most certain source of supplemental iodine for pregnant women.  Maternal vitamins SHOULD BE TAKEN WITH GREAT CARE, and only a single daily dose of vitamins taken, because some vitamins can become toxic or damaging to the unborn baby at higher levels than the dosage provided.   The vitamin should be checked for iodine content.  Despite the known importance of iodine during pregnancy, as of 2011, only about 50% of maternal vitamins contained supplemental iodine.   The usual dosage is about 150 micrograms, leaving the mother to acquire about 100 micrograms of iodine daily from other dietary sources (e.g. two eggs and a cup of yogurt, or fish sticks and a cup of milk). 

A single study found no benefit from supplementary iodine in maternal vitamins.  The study did not follow children past one year of age, and may have been too short to find meaningful results.  The study may also indicate that not all means of iodine supplementation are equal.  In contrast to vitamin supplements, iodized salt has a long-established track record in effectively providing iodine supplementation during pregnancy and early childhood.

Dietary Fish

When I was a child, children would tell each other that fish was “brain food”.  It turns out that the children’s myth is correct.  Studies from around the world show that eating fish at any point in life can improve IQ and memory.  But eating fish is particularly important during pregnancy.  Numerous studies have found that mothers who regularly eat fish during pregnancy will have children with higher IQs and a lower risk of autism.

Photo Credit El Segundo Fish Company.  Used without permission, but with thanks.

The mental benefits of eating fish are generally attributed to omega-3 fatty acids.  But some researchers also noted that fish represent an excellent source of iodine, which is also known to provide benefits during pregnancy and afterwards. 

It is important to note that health authorities are divided on the recommended amount of fish to eat.  United States’ dietary guidelines recommend that pregnant women consume no more than 12 ounces of fish per week, due to concerns about mercury in fish.  European guidelines recommend up to 21 ounces (600 grams) of fish per week. 

A recent study in Spain found that every 10 grams of increased fish consumption was correlated with higher IQs.  Researchers also found decreased incidence of autism in children from mothers who ate the most fish.  The study found that even at 21 ounces of fish per week, there was no indication of mercury having a negative effect on child development.   An earlier study in Britain also found that consuming fish during pregnancy led to high IQs among children.  Researchers found beneficial effects for children from mothers who ate more than 12 ounces of fish per week.  The researchers in this study found no protection against adverse outcomes among mothers who ate less than 12 ounces of fish per week.  According to the authors, the risk from inadequate nutrients was greater than the risk of exposure to trace contaminants due to eating fish.

The conclusion should be that expectant mothers should regularly include fish as part of a pregnancy diet, to increase the mental abilities and social development of their children, while decreasing the risk of autism-spectrum disorders.  Mothers should avoid the kinds of fish which are likely to contain unhealthy concentrations of mercury.   Swordfish, shark, king mackerel, ahi tuna and albacore tuna should be avoided.  In general, smaller fish contain less mercury than large fish.  Short-lived fish like salmon, cod, and pollack contain less mercury than long-lived fish like rockfish. 

Dietary Advice for Pregnancy

Dietary advice of any kind is maddening; dietary advice for pregnancy is especially so. 

Any woman planning to become pregnant, or who might become pregnant, should consult with a doctor about diet and lifestyle choices in order to have a healthy baby.  This post is not intended to take the place of that advice, but rather to raise the awareness of nutrition requirements, in particular the need for iodine and folic acid.   There are a couple of important points to put first.

1)       A developing baby needs a lot of protein – 70 to 100 grams a day.   In a practical sense, it is very difficult to obtain that much protein, and the necessary variety of amino acids, without eating meat.  Many reference sites recommend 3 servings of meat, poultry, eggs, fish or seafood per day.  Other sources, including dairy, legumes, nuts, and soy are also important.

2)      A dietary supplement designed for pregnancy is generally recommended.   It is important to only use one supplement.  High doses of some vitamins, particularly vitamin A, are toxic, and can lead to birth defects.  The dietary supplement should include iodine and folic acid.

3)      Regular consumption of fish, particularly salt-water fish, provides natural iodine, omega-3 fatty acids, and protein.  Avoid species associated with high mercury content, and eat plenty of fish.

4)       Iodine is a necessary micro-nutrient in pregnancy and early childhood.  For nearly a century, it has been known that serious iodine deficiency during pregnancy can cause life-long mental impairment.  Recent research in Britain now shows that even mild to moderate iodine deficiencies also causes significant mental impairment.  Further, surveys in Britain and the United States show that many pregnant women and women of child-bearing age are deficient in iodine.  Iodized salt has a clear track record in effectively delivering dietary iodine; ¼ to ½ teaspoon of salt daily is enough.

5)      Folic acid is another very important nutrient during pregnancy.   Folic acid is found in “leafy green vegetables” and various artificially fortified foods.  Deficiency in folic acid is the cause of many, if not most, birth defects, including spina bifida.  Like iodine, it is difficult to obtain sufficient folic acid through diet alone.  To obtain the required amount of folic acid from one of the richest sources, it would be necessary to eat five cups of broccoli a day.  Although there is evidence that synthetic folic acid is slow to convert to useful forms in the body, folic acid supplements have been shown to reduce birth defects such as spina bifida, cleft palates, congenital heart defects, limb defects and urinary tract abnormalities.  Many breads and cereals are also good sources of supplemental folic acid.

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Iodized Salt References

Iodine in Public Health

https://en.wikipedia.org/wiki/Iodised_salt

Iodization of salt may be the simplest and most cost-effect public health measure available.

Iodine deficiency affects two billion people, and is the leading cause of intellectual and developmental disabilities.

Residents of the northern United States were subject to widespread iodine deficiency prior to the 1920s.  After the introduction of iodized salt, IQs in the region increased by 15 points on average.

http://blogs.discovermagazine.com/crux/2013/07/23/how-adding-iodine-to-salt-boosted-americans-iq/#.Vw31g_krLZ4

Iodized Salt in 1914 raised IQ in iodine across most of the northern United States by 15 points, according to military recruiting records.   The sudden introduction of iodized salt resulted in about 10,000 thyroid-related deaths over several decades.

http://www.dailymail.co.uk/news/article-2377052/How-adding-iodine-salt-America-smarter.html

https://www.devex.com/news/how-to-raise-the-world-s-iq-taken-with-a-grain-of-salt-87203

The World Health Organization has said that ending iodine deficiency would be on a par with the elimination of smallpox.

Iodine deficiency can lead to a 13 point reduction in IQ. 

http://www.ign.org/about.htm

Iodine Global Network,  an NGO dedicated to improving iodine nutrition worldwide.

http://www.nytimes.com/2008/12/04/opinion/04kristof.html?_r=2

Nicholas Kristof on World Iodine supplementation.

http://www.who.int/nutrition/publications/en/idd_assessment_monitoring_eliminination.pdf

Date: 2001

WHO, UNICEF, and ICCIDD (4) recommend that the daily intake of iodine should be as follows: n 90 µg for preschool children (0 to 59 months); n 120 µg for schoolchildren (6 to 12 years); n 150 µg for adults (above 12 years); and n 200 µg for pregnant and lactating women.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2453047/

Iodine in Pregnancy: Is Salt Iodization Enough?

Iodine deficiency affects more than 2.2 billion individuals worldwide (38% of the world’s population). Decreases in maternal T₄ associated with even mild iodine deficiency may have adverse effects on the cognitive function of offspring (1,2), and iodine deficiency remains the leading cause of preventable mental retardation worldwide. It has recently been suggested that mild iodine deficiency may also be associated with attention-deficit and hyperactivity disorders in offspring (3).

WHO optimal range of UI is 150 – 259 mg/l.    WHO recommendation for dietary iodine is 200 – 300 mg/day (2007).  Endocrine society recommends dietary iodine intake of 220 mg/day. 

American Thyroid Association recommends supplements of 150 mg/d for women during pregnancy and lactation.

http://www.thyroid.org/iodine-deficiency/

An equivalence between dietary iodine and urinary iodine can be established.  The level of urinary iodine, in micrograms of iodine per liter of creatine, is about two-thirds of dietary iodine consumption per day.    For instance, dietary iodine of 150 micrograms/day will correspond with UI of 100 micrograms/liter.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3509517/

The association of iodine deficiency with goiter was made in the mid-to-late 1800s.

Urinary iodine levels declined 50% from the 1970s to the 1990s, and has since stabilized (article date 2012). 

http://www.iccidd.org/newsletter/idd_aug13_growth_and_iq.pdf

Iodized salt introduction in Switzerland in 1922 resulted in a decrease in goiter and the elimination of cretinism.

Maps and graphs. 

https://en.wikipedia.org/wiki/Iodine_deficiency

Iodine deficiency during pregnancy typically results in mental handicaps, with reductions of 10 to 15 IQ points.

http://ajcn.nutrition.org/content/83/1/108.full

Iodine supplementation improved cognitive and motor performance of iodine deficient children.

http://www.ghanaweb.com/GhanaHomePage/health/Iodized-salt-s-miracle-in-the-village-of-idiots-220824

Anecdotal evidence from Chinese village

Iodine Deficiency

http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(13)60436-5/abstract

Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children: results from the Avon Longitudinal Study of Parents and Children (ALSPAC), Bath et al, 2013.

Iodine deficiency in pregnancy was correlated to deficits in verbal IQ, reading accuracy and reading comprehension at age 8.   The deeper the iodine deficiency during pregnancy, the worse the children’s reading and IQ scores were at age 8.

Children of women in the group with less than 150 mg/l of iodine/creatinine were more likely to score in the bottom quartile in verbal IQ and reading proficiency.

The study took into account and corrected for 21 potentially confounding variables.

https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/

According to the WHO, a median urinary iodine concentration of 150–249 mcg/L indicates adequate iodine nutrition during pregnancy, while values less than 150 mcg/L are considered insufficient [3,7]. Analyses of NHANES datasets covering time periods from 2001 to 2008 indicate that a substantial portion of pregnant women in the United States are iodine insufficient. Median urinary iodine concentrations for pregnant women participating in NHANES surveys were 181 mcg/L in 2003–2004 [21] and 153 mcg/L in 2001–2006 [26], and only 125 mcg/L in 2005–2008 [25]. Further, 56.9% of pregnant women surveyed during 2005–2008 had a median urinary iodine concentration <150 mcg/L [25]. In a study published in 2004, the median urinary iodine concentration of 100 healthy pregnant women in Boston was 149 mcg/L and 49% of the women had values below the WHO cutoff for sufficiency [27]

Pregnant women who do not consume dairy products are particularly at risk for iodine deficiency.

According to NHANES 2001–2006 data, pregnant women who consumed no dairy products in the previous 24 hours had a median urinary iodine concentration of only 100 mcg/L, compared with 163 mcg/L among consumers of dairy [26].

Chronic iodine deficiency in children reduces IQ by 12 to 13.5 points.   Mild to moderate maternal iodine deficiency is associated with increased risk of hyperactive attention deficit disorder.

http://www.theguardian.com/lifeandstyle/2015/dec/07/pregnant-mothers-and-the-dangers-of-iodine-deficiency

Up to 60% of mothers in one study had iodine deficiency; their children had greater risk of low IQs.

Five recent studies of pregnant women in Britain showed substantial iodine deficiency.

Professor John Lazarus, Chair of the UK Iodine Group and a specialist in hormone disorders,  Sourcing it from the diet alone “would require a woman to eat unrealistically large amounts of fish.

http://health.gov/dietaryguidelines/dga2015/comments/uploads/CID54_Reference_4.pdf

Iodine Status of the U.S. Population, National Health and Nutrition Examination Survey, 2005–2006 and 2007–2008

Kathleen L. Caldwell, Amir Makhmudov, Elizabeth Ely, Robert L. Jones, and Richard Y. Wang. Thyroid. April 2011, 21(4): 419-427. doi:10.1089/thy.2010.0077.

The median U.S population UI was 164 micrograms/liter in 2005 – 2008.  However, the median UI of all pregnant women surveyed was 125 mg/l.    57% of pregnant woman had UI levels under 150 mg/l.   UI levels were lower in the black population.  

The UI concentrations were consistently lower in women of childbearing age compared with the general population, a relationship that has been observed since 2001.   In the general population, UI levels were the lowest in the age group of 20 – 29.   UI levels were also very low in the black population.

The median UI concentration for the general U.S. population in NHANES 2009–2010 was significantly lower than the levels found during NHANES 2007–2008.

https://www.gwern.net/docs/iodine/2012-zimmerman.pdf

The Effects of Iodine Deficiency in Pregnancy and Infancy, M. B. Zimmermann, 2012, Paediatric and Perinatal Epidmilogy, doi: 10.1111/j.1365-3016.2012.01275.x

Iodine supplementation eliminates new cases of cretinism, increases birthweight, reduces rates of perinatal and infant mortality, and generally increases developmental scores in children by 10%-20%.  Mild maternal iodine deficiency can cause thyroid dysfunction, but whether it impairs IQ is unknown.  In nearly all areas with iodine deficiency, salt iodisation is the most cost-effective way to deliver iodine and improve maternal and infant health.

http://www.drweil.com/drw/u/QAA400874/Why-Buy-Iodized-Salt.html

Don’t depend on processed foods for iodine: the salt used to prepare them is not iodized.   Iodine intakes in the United States have declined from about 250 micrograms per day to about 157 mg per day.   [Figures also cited in the Salt Institute Paper, also without dates.]  Pregnant women need to consume more for the health of their babies.   Consumption of up to 1100 mg is considered safe for adults and children over the age of 4.

http://www.whfoods.com/genpage.php?tname=nutrient&dbid=69

Seaweed is the most concentrated source of dietary iodine.   Shellfish are a large source, followed by certain fish.  Eggs and milk can be minor sources of iodine.

Iodine deficiency in the United States is on the rise.  Levels of urinary iodine have fallen by half since the 1970s.  Although there is a lot of salt in pre-packaged foods, the salt in these foods is not necessarily fortified with iodine.  There are indications that the average pregnant woman in the United States has substandard iodine nutrition.  This is absolutely a concern, because iodine is necessary for proper development for the development of the brain and nervous system.

Iodine is necessary for proper thyroid function. 

A 2011 study found that vegans in America are generally iodine deficient.

https://www.bda.uk.com/foodfacts/Iodine.pdf

Recent research has shown mild iodine deficiency in schoolgirls and pregnant women. There is now concern that many adult women may not be getting enough iodine, particularly in pregnancy

Adults need 150 micrograms of iodine per day.

Pregnant and Breastfeeding women need 250 micrograms of iodine each day.

Organic milk has a 40% lower iodine content than conventional milk.

Adult intakes should not exceed 600 micrograms per day.

Vegetarians and vegans are particularly at risk of iodine deficiency.

It can be difficult to meet the higher recommendations for iodine during pregnancy, especially if you do not consume rich sources of iodine.

http://www.modernreaders.com/listeria-cdc-warns-public-avoid-raw-milk-products/42478/ed-jones

Organic milk contains 30% less iodine than standard milk. 

“Iodine deficiency ought to be a health problem from the past. But unless this situation is carefully monitored, we risk sleepwalking into a new health crisis in the 21st century”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3074887/

About iodine deficiency

http://stacks.cdc.gov/view/cdc/30824

CDC article summarizing salt sales in the United States.  Data summarized in the next reference.

http://www.ign.org/newsletter/idd_may15_iodized_salt_in_the_u.s..pdf

Summary of US iodized and non-iodized table salt sales.  Only 57 of 1117 brands are iodized, but represent 53% of sales.   Salt blends (seasoned salt) is not iodized.   Only about 12% of American salt consumption comes from table salt or cooking; 88% of salt consumption is from non-iodized salt in pre-packaged or restaurant foods.

https://www.seasalt.com/wholesale/press-releases/saltworks-posts-record-sales

Saltworks, incorporated doubled sales from $5 million to $10 million from 2006 to 2007.

The 2006 figure represented 10 million pounds of salt.

https://www.seasalt.com/

A website for a commercial seasalt provider.

http://www.health.harvard.edu/heart-health/cut-salt-it-wont-affect-your-iodine-intake

Harvard medical letter recommends against getting your iodine from salt.  They recommend sea food, milk products, and “vegetables raised in iodine-rich soil”.   Not that the consumer is going to know what kind of soil their vegetables were raised in.   To get all of your iodine from salt, you would need a half-teaspoon of iodized salt every day. 

Americans receive 70% to 90% of their sodium from restaurants, processed and prepared foods which do not contain iodized salt.

http://www.todayifoundout.com/index.php/2012/06/why-iodine-is-added-to-salt/

Iodized Salt has a shelf life of about 5 years.   According a study at the University of Texas, about half of the iodized salt prepared in this country lacks sufficient iodine to meet daily requirements.

http://paleoleap.com/iodine-getting-enough/

The combination of a Paleo diet and the modern food environment can unintentionally create a dangerously low dietary iodine intake.

Urinary levels of iodine have declined for 40 years.

Pregnant women are often mildly iodine deficient, even in the United States.

The top three iodine sources in the modern diet are artificial.

Claims that milk contains iodine only because of the iodine used as a disinfectant on cows udders and on milk containers. 

http://www.sun-sentinel.com/health/fl-suzy-cohen-080215-20150729-column.html

Columnist Suzy Cohen from the South Florida Sun-Sentinel  makes many important points about dietary iodine.  However, she advocates “natural” iodine, rather than iodized salt.  Cohen doesn’t understand that humans rarely consume elemental iodine, and that most forms of consumable iodine are in molecules, in the form of iodide or iodate.

Paleo Slow Cooking, Molly Pearl, 2014

The book Paleo Slow Cooking advocates replacing iodized salt with kosher salt or sea salt.

Thyroid Disease, Dr. Alan Christianson, Hy Bender, 2011

Fast food restaurants, processed and prepared foods do not use iodized salt.

Sources of Iodine

https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/

Table 1: Recommended Dietary Allowances (RDAs) for Iodine [2]
Age	Male	Female	Pregnancy	Lactation
Birth to 6 months	110 mcg*	110 mcg*
7–12 months	130 mcg*	130 mcg*
1–3 years	90 mcg	90 mcg
4–8 years	90 mcg	90 mcg
9–13 years	120 mcg	120 mcg
14–18 years	150 mcg	150 mcg	220 mcg	290 mcg
19+ years	150 mcg	150 mcg	220 mcg	290 mcg

* Adequate Intake (AI)

The World Health Organization (WHO), United Nations Children's Fund (UNICEF), and the International Council for the Control of Iodine Deficiency Disorders (ICCIDD) recommend a slightly higher iodine intake for pregnant women of 250 mcg per day [3,7].

Table 2: Selected Food Sources of Iodine [10,11,12]
Food		Approximate Micrograms (mcg) per serving	Percent DV*
Seaweed, whole or sheet, 1 g		16 to 2,984	11% to 1,989%
Cod, baked, 3 ounces		99	66%
Yogurt, plain, low-fat, 1 cup		75	50%
Iodized salt, 1.5 g (approx. 1/4 teaspoon)		71	47%
Milk, reduced fat, 1 cup		56	37%
Fish sticks, 3 ounces		54	36%
Bread, white, enriched, 2 slices		45	30%
Fruit cocktail in heavy syrup, canned, 1/2 cup		42	28%
Shrimp, 3 ounces		35	23%
Ice cream, chocolate, 1/2 cup		30	20%
Macaroni, enriched, boiled, 1 cup		27	18%
Egg, 1 large		24	16%
Tuna, canned in oil, drained, 3 ounces		17	11%
Corn, cream style, canned, 1/2 cup		14	9%
Prunes, dried, 5 prunes		13	9%
Cheese, cheddar, 1 ounce		12	8%
Raisin bran cereal, 1 cup		11	7%
Lima beans, mature, boiled, 1/2 cup		8	5%
Apple juice, 1 cup		7	5%
Green peas, frozen, boiled, 1/2 cup		3	2%
Banana, 1 medium		3	2%
Table 3: Tolerable Upper Intake Levels (ULs) for Iodine [2]
Age	Male	Female	Pregnancy	Lactation
Birth to 6 months	Not possible to establish*	Not possible to establish*
7–12 months	Not possible to establish*	Not possible to establish*
1–3 years	200 mcg	200 mcg
4–8 years	300 mcg	300 mcg
9–13 years	600 mcg	600 mcg
14–18 years	900 mcg	900 mcg	900 mcg	900 mcg
19+ years	1,100 mcg	1,100 mcg	1,100 mcg	1,100 mcg

http://bembu.com/iodine-rich-foods

http://draxe.com/top-10-iodine-rich-foods/

Top 10 Iodine Rich Foods List

1) Dried seaweed
¼ oz: 4500 mcg (over 100% DV)

2) Cod fish
3 oz: 99 mcg (66% DV)

3) Yogurt
1 cup: 87 mcg (58% DV)

4) Turkey breast
3 oz: 34 mcg (23% DV)

5) Navy beans
½ cup: 32 mcg (21% DV)

6) Tuna
3 oz: 17 mcg (11% DV)

7) Eggs
1 large: 12 mcg (8% DV)

8) Baked potato
1 medium: 60 mcg (40% DV)

9) Strawberries
1 cup: 13 mcg (8.6% DV)

10) Cranberries
1 oz 90 mcg (60% DV)

http://consumer.healthday.com/cognitive-and-neurological-health-information-26/brain-health-news-80/low-prenatal-iodine-may-affect-child-s-brain-development-676664.html

Low Prenatal Iodine May Affect Child's Brain Development

Mothers with deficiency had kids with lower IQs and reading ability, researchers say

1 cup of yogurt contains 75 micrograms of iodine; 1 cup of milk contains 56 micrograms of iodine.

3 ounces of baked cod contains 99 micrograms of iodine.

Recommendations for Iodine Consumption

https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/

Iodine has not been part of the public health agenda in the UK for the past 50 years; iodine requirements for pregnancy and lactation are outdated, population monitoring has been absent, and advice to pregnant women has not included information about iodine intake.  WHO guidelines recommend iodine intake for pregnant women of 250 micrograms per day.

http://apps.who.int/iris/bitstream/10665/43781/1/9789241595827_eng.pdf

Long and very informative technical paper by UNICEF and WHO, 2007.   Recommended daily consumption levels and supplements included.  Recommendation for pregnant and lactating women of 250 micrograms/day. 

Dietary Fish

http://www.livescience.com/53611-eating-fish-during-pregnancy-benefits.html

Study in Spain, 2016, showed that eating three to four servings of fish per day during pregnancy resulted in higher IQs in offspring.   No negative effects from mercury were noted.  Higher consumption of fish also correlated with a consistent reduction of autism-spectrum disorders in children.

The article cited a 2004 study from Denmark, that noted negative effects from high fish consumption during pregnancy, due to mercury contamination.  “Many other studies” have linked eating fish during pregnancy with better outcomes in children.

http://www.medicalnewstoday.com/releases/241036.php

During Pregnancy, Consuming Fish Improves Offspring's Cognitive Development And Prosocial Conduct

University of Grenada study showed that eating fish during pregnancy raises the IQ of offspring.   2012

http://www.life-enhancement.com/magazine/article/1094-scottish-iq-study-confirms-cognitive-value-of-fish-oil

Higher IQ in seniors (age 64) correlated with fish-oil consumption.

http://timesofindia.indiatimes.com/life-style/health-fitness/health-news/Eating-fish-makes-you-smarter-Study/articleshow/4249308.cms

Consumption of fish related to high IQs among teenagers in India.

http://www.nutraingredients.com/Research/Fish-intake-linked-to-higher-IQ-in-offspring

Fish intake linked to higher IQ in offspring

By Stephen Daniells, 16-Feb-2007

Eating more than 340 grams of omega-3-rich seafood per week during pregnancy was associated with higher verbal intelligence quotient (IQ) scores in the children, says a new study.

The study found that fish consumption of less than 340 grams (12 ounces, or 4 servings) per week did not protect children from adverse outcomes.   Improvements in child development were recorded from mothers who ate more than 340 grams (12 ounces) of fish per week.  According to the researchers, the risk from the loss of nutrients was greater than the risk of exposure to trace contaminants in 340 grams (21 ounces) of seafood eaten weekly.

http://www.albanydailystar.com/health/according-to-study-sea-food-consumption-during-pregnancy-leads-boost-babys-iq-history-of-technology-15543.html

Spanish study, 2016, found that consumption of fish during pregnancy increased the IQ of children, up to 600 grams (21 ounces, or seven servings) of fish per week.  No further gains were noted beyond that level.  European guidelines allow up to 600 grams of fish consumption per week; by comparison, U.S. guidelines recommend no more than 340 grams (12 ounces, or four servings) of fish per week.   Each 10 gram increase in fish consumption was tied to higher IQ scores at age 5.  Higher amounts of fish consumption correlated with lower incidence of autism.

http://esfishco.com/fish/

El Segundo Fish Company

Benefits of eating fish, with photo credit.

Iodine Supplements

https://www.gwern.net/Iodine

Supplementation by iodine in the form of salt, water, or oil can raise IQ scores in deficient areas by up to 13 points.   Cooking may reduce iodine content in iodized salt.   The window for iodine intervention may close rapidly during pregnancy, and be closed post-birth.

Meta-analysis of many studies seems to show little improvement in iodine-deficient children.  Studies of pregnancy support the idea that “earlier is better” for iodine supplementation.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4377875/

57 out of 1117 salt products were iodized.   Iodized salt represents 53% of the total volume of salt sales in the United States (2015).  A historical estimate

Adequate intake of iodine, a trace element, plays a key role in regulating human growth, development, and metabolic functions. It is estimated that, worldwide in 2011, 1.88 billion people were iodine deficient [1,2]. Iodine deficiency can result in goiter, neurocognitive impairment, hyperthyroidism, and hypothyroidism [3]. During pregnancy, severe iodine deficiency can cause cretinism, congenital anomalies, and increased neonatal and infant mortality [2], with recent evidence from observational studies suggesting mild to moderate deficiency during pregnancy can lead to reduced IQ and educational achievement among offspring [4,5]. While iodine status is sufficient for most Americans, certain subsets of the population, including pregnant women, may be at risk for mild to moderate iodine deficiency [6,7,8]. Iodizing salt is a global public health strategy for addressing iodine deficiency [9], yet limited data exist on the proportion of salt that is iodized in the United States.

http://www.saltinstitute.org/news-articles/iodized-salt/

“IDD is the single greatest cause of preventable mental retardation. Severe deficiencies cause cretinism, stillbirth and miscarriage. But even mild deficiency can significantly affect the learning ability of populations. Scientific evidence shows alarming effects of IDD. Even a moderate deficiency, especially in pregnant women and infants, lowers their intelligence by 10 to 15 IQ points, with incalculable damage to social and economic development of nations and communities. Today over 1 billion people in the world suffer from iodine deficiency, and 38 million babies born every year are not protected from brain damage due to IDD. These 38 millions, or nearly 30 percent of the world’s newborns, come from families that are the least educated, most isolated and economically disadvantaged. The mark of a civilized society is how well it takes care of its most vulnerable and deprived communities. If we continue to fail to reach these newborns, we will be consigning them to an inter-generational cycle of poverty and injustice.”

Salt producers are a key partner in combating Iodine Deficiency Disorders (IDD) today throughout the world. Many people erroneously assume that because salt iodization was first implemented nearly a century ago, that the problem no longer exists. Tragically, that’s wrong. In 1990, only about 20% of the world’s households had access to iodized salt and were protected against Iodine Deficiency Disorders. After a major push, access now exceeds 70%.

Average Iodine intakes have declined from over 250 micrograms per day to 157 micrograms per day.    Health authorities recommend 150 micrograms per day for adults, particularly for expectant mothers. 

Over 1 billion people in the world suffer from iodine deficiency, and 38 million babies a year, or about 30 percent of the world’s newborns, are not protected from iodine deficiency.   In 1990, only 20% of the world’s households had access to iodized salt, but currently iodized salt is accessible to 70% of households. 

Salt used in processed foods are not iodized.

Iodized salt is prepared by spraying a solution of potassium iodide on salt, in a conveyor belt process.  Treated salt contains 0.002% to 0.004%, or 2 to 4 parts potassium iodide per 100,000 parts salt.

Iodine deficiency impairs fetal brain development, and imposes a lifetime intellectual deficit equivalent to 10 to 15 IQ points.

Iodine deficiency is the single greatest cause of preventable mental retardation, and even a moderate deficiency can cause intellectual impairment of 10 to 15 IQ points.

http://www.fasebj.org/content/29/1_Supplement/272.3

The first comprehensive survey of iodized salt sales in the United States was published in April, 2015.

53% of US dietary salt is iodized; figures as reported elsewhere.

http://www.medscape.com/viewarticle/840056

American Thyroid Association recommends that pregnant women take a supplement with at least 150 mg of iodine each day.  Pregnant women actually need more iodine, for a variety of metabolic reasons.

Worldwide, about 2 billion people are iodine-deficient.  A National Health and Nutrition survey found that half of all American pregnant women show levels of iodine below the recommended level of 150 micrograms. 

In 2009, only 51% of pregnancy vitamin supplements contain iodine, and tested samples showed that the actual dosage of iodine did not match values on the labeling.

http://www.who.int/elena/titles/iodine_pregnancy/en/

Iodine supplementation in pregnant and lactating women

Most foods are relatively low in iodine content. To ensure that everyone has a sufficient intake of iodine, WHO and UNICEF recommend universal salt iodization as a global strategy.

http://www.who.int/nutrition/publications/micronutrients/iodine_deficiency/WHO_NUT_96.13/en/

Universal salt iodization is the recommended intervention for preventing and correcting iodine deficiency; substantial experience has been gained in the last decade in implementing this strategy and in assessing its impact on iodine deficiency disorders (IDD). A major achievement is the spectacular reduction of IDD in countries that have adopted appropriate measures.

http://www.techinsider.io/sea-salt-mining-iodine-table-salt-processed-minerals-2015-8

This article identifies table salt as the principle source of iodine, but only discusses thyroid issues, not neurological development.

http://www.mirror.co.uk/lifestyle/health/pregnant-women-damaging-iq-babies-5761966

A survey in Britain found that 84 percent of British women were unaware of the importance of iodine-rich foods during pregnancy.   Only 12 percent were aware of iodine-specific dietary advice.

https://www.newscientist.com/article/dn28026-iodine-supplements-might-raise-the-uks-iq-but-jury-still-out/

Article sounds a cautionary note about artificial iodine supplement, references the following study.

http://aje.oxfordjournals.org/content/177/9/944

Paradoxically found that 150 microgram iodine supplements were associated with decrease in motor skills at age 1.

http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/sea-salt/faq-20058512

This article notes in passing that table salt contains iodine, as an essential nutrient, important to thyroid function, but does not say anything about neurological development.

Recommended Salt Intake during Pregnancy

http://www.whattoexpect.com/pregnancy/salt-in-diet/

Up to a teaspoon— 2400 milligrams of sodium, or 6 grams of salt, the same for all adults and pregnant women, except for those with hypertension.   1500 milligrams for people with hypertension.  According to USDA and HHS.

http://www.parents.com/pregnancy/week-by-week/14/sodium-intake/

Intake should be limited to 2400 milligrams of sodium (6 grams, or one teaspoon of salt per day.)  “Take the salt shaker off the table during pregnancy.”

http://www.livestrong.com/article/493914-how-much-sodium-is-too-much-for-pregnant-women/

Institute of Medicine has set the adequate daily intake of sodium to 1.5 grams, which is the same for non-pregnant adults – this is equivalent to 3.8 grams of salt per day, as salt is only 40% sodium.  The tolerable upper limit is 5.8 grams of salt per day. 

Folic Acid and Protein

http://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/pregnancy-nutrition/art-20045082?pg=2

Protein and protein sources.

http://trace.lib.utk.edu/assets/Kuney/HostessBrands/WonderBreadNutritionalInformationLIVESTRONG.pdf

Wonder bread contains 9 of the essential vitamins and minerals needed for good health and children’s development.

8 percent of riboflavin, 10 percent of vitamin D, thiamine, niacin, folic acid, zinc, iron, vitamin E, vitamins B6 and B12 and 30 percent of calcium

http://www.webmd.com/vitamins-supplements/ingredientmono-1017-folic%20acid.aspx?activeingredientid=1017&

Folic acid is necessary during pregnancy.  Although there is evidence that synthetic folic acid is slow to convert to useful forms in the body, folic acid supplements have been shown to reduce birth defects such as spina bifida, cleft palates, congenital heart defects, limb defects and urinary tract abnormalities.  It is also a cancer preventative, and necessary for a number of adult health functions.

https://en.wikipedia.org/wiki/Folate_deficiency

Folate deficiency may contribute to low birth weight, as well as other deficiencies.

https://www.nlm.nih.gov/medlineplus/folicacid.html

Folic acid occurs naturally in leafy green vegetables, fruits, beans and nuts.  Folic acid can also be obtained from fortified breads and cereals.

http://www.cdc.gov/ncbddd/folicacid/quiz.html

Women should consume adequate quantities of folic acid before becoming pregnant.

You would need to eat 5 cups of broccoli to obtain the minimum daily requirement for folate, which is generally available in a single bowl of fortified cereal.

https://en.wikipedia.org/wiki/Spina_bifida

Between 5% to 20% of people have spina bifida occulta (hidden).  Although the condition is generally benign, it may contribute to back pain throughout life.

http://www.cdc.gov/ncbddd/spinabifida/data.html

Folic acid supplementation has been shown to prevent an estimated 1300 cases per year of spina bifida.  The introduction of folic acid supplementation caused a 28% reduction in cases of anencephaly and spina bifida.

http://www.cdc.gov/ncbddd/birthdefects/data.html

Overt birth defects occur in about one in 33 births, and account for about 20% of infant deaths.

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5701a2.htm

IN a study in Atlanta from 1978 to 2005, the rate of birth defects was stable.  The incidence of birth defects was lower among black and Hispanic mothers than among white mothers.   The overall incidence of spina bifida and anencephaly may represent fortification of grains with folic acid and increased use of folic acid supplements.