Speaker 1: Welcome to Stuff You Missed in History Class, a production
Speaker 1: of iHeartRadio. Hello, and welcome to the podcast. I'm Tracy V.
Speaker 1: Wilson and I'm Holly Frye.
Speaker 2: Back at the beginning of May, I read an article
Speaker 2: in the Washington Post called how the arrival of iodized
Speaker 2: salt one hundred years ago changed America. And I was
Speaker 2: immediately fascinated by this whole thing, And I also wanted
Speaker 2: to learn more than a thousand word newspaper article could
Speaker 2: tell me. I already knew, and I think maybe a
Speaker 2: lot of folks already knew from something like elementary school
Speaker 2: health class that iodine is added into table salt because
Speaker 2: our bodies need that iodine for thyroid reasons. And I
Speaker 2: also knew there are various people who, for whatever reason,
Speaker 2: don't like iodized salt or don't want to use it,
Speaker 2: and that was sort of the sum of my knowledge
Speaker 2: about the iodide salt. And so reading this Washington Post article,
Speaker 2: I didn't really grasp that adding the iodine to the
Speaker 2: salt was not just like a nutritional nice to have.
Speaker 2: They were not like well meaning public health people kind
Speaker 2: of like, wouldn't it be great if everybody just had
Speaker 2: enough iodine, just because it was to try to deal
Speaker 2: with a problem that in some parts of the world
Speaker 2: was really serious with chronic iodine deficiency. It was incredibly
Speaker 2: widespread in some places, and that was causing a range
Speaker 2: of actual health issues, not just wouldn't it be great
Speaker 2: if we all got enough iodine.
Speaker 1: So a complete history of salt would be its own episode,
Speaker 1: or perhaps even more than one. You could even have
Speaker 1: the story of salt as an entire podcast. I imagine.
Speaker 1: Of course, edible salt or sodium chloride makes food more flavorful,
Speaker 1: and it's an electrolyte that our bodies need to function correctly.
Speaker 1: Salt can also be used to preserve food through salting, curing, brining,
Speaker 1: or pickling, and there are lots of non dietary uses
Speaker 1: for it as well. So for those and other reasons,
Speaker 1: people have wanted and needed salt, going all the way
Speaker 1: back to our earliest beginnings, cultures all around the world
Speaker 1: have boiled or evaporated salt from water, including seawater and
Speaker 1: water from salt lakes or mineral springs. Animals besides us,
Speaker 1: need salt to often they get it from licking at
Speaker 1: salt deposits. So people who are living farther inland could
Speaker 1: sometimes find sources of salt by just watching what the
Speaker 1: animals were doing, even if salt had no other uses.
Speaker 1: Its importance in flavoring and preserving food has made it
Speaker 1: highly sought after all over the world for basically all
Speaker 1: of history. Some of the world's earliest trade networks were,
Speaker 1: of course, salt roads, and many of the earliest governments,
Speaker 1: established thousands of years ago, regulated the salt trade and
Speaker 1: establish salt stockpiles. Iodine is not nearly as abundant assault,
Speaker 1: but it is similarly critical. People and all other vertebrate
Speaker 1: animals need iodine for our bodies to function properly. Specifically,
Speaker 1: the body uses iodine to make thyroid hormones, and thyroid
Speaker 1: hormones regulate a number of body functions, including growth and metabolism,
Speaker 1: affecting virtually every cell in the body. The iodine we
Speaker 1: consume moves from the digestive system to the blood and
Speaker 1: from there to the thyroid gland, which produces those hormones.
Speaker 2: People only need a little bit of iodine. In the
Speaker 2: United States, the recommended daily allowance is only one hundred
Speaker 2: and fifty micrograms a day for adults. It's roughly half
Speaker 2: that For babies and children, the recommended daily allowance increases
Speaker 2: to two hundred and twenty micrograms during pregnancy and two
Speaker 2: hundred and ninety micrograms while lactating. But whether people can
Speaker 2: get that much eye iodine without access to fortified foods
Speaker 2: like iodized salt varies widely depending on where they live.
Speaker 2: There's iodine in seawater, and it's in the Earth's crust,
Speaker 2: but exactly how much iodine there is in a particular
Speaker 2: location depends on things like how close it is to
Speaker 2: the sea and geological changes that have taken place over
Speaker 2: thousands and thousands of years.
Speaker 1: The presence of iodine in seawater means that various types
Speaker 1: of seaweed and marine animals are also high in iodine,
Speaker 1: so people living in an island nation like Japan, where
Speaker 1: the traditional diet includes a lot of seafood and seaweed
Speaker 1: may be able to get enough iodine through their regular
Speaker 1: diet without some kind of supplementation.
Speaker 2: Generally speaking, things get trickier farther inland. How much iodine
Speaker 2: is available to people and animals depends on how much
Speaker 2: of it is present in the soil, so, for example,
Speaker 2: cows grazing on a pasture near the sea, where the
Speaker 2: iodine in the soil is replenished by the spray blowing
Speaker 2: in from the ocean, they might get enough iodine, and
Speaker 2: that means there would also be iodine in their milk.
Speaker 2: But high altitudes places where there are recurring floods or
Speaker 2: cycles of glaciers melting and refreezing, those places typically have
Speaker 2: very little iodine in the soil, so without some kind
Speaker 2: of supplementation, people and animals living there cannot get enough
Speaker 2: iodine in their diets.
Speaker 1: This isn't only a problem for humans who rely on
Speaker 1: these animals for food. Iodine deficiency in livestock is connected
Speaker 1: to things like still births, the deaths of young, and
Speaker 1: lower production of eggs and milk. As a side note,
Speaker 1: in today's world, some of the iodine and milk doesn't
Speaker 1: actually come from what the cows are eating. It's from
Speaker 1: the use of iodine as an antiseptic or sterilizer, both
Speaker 1: on the cow's utters and on equipment that's used in
Speaker 1: the dairy industry.
Speaker 2: There are also some things that can interfere with the
Speaker 2: bodies of bil to absorb iodine, including compounds found in
Speaker 2: cassava and millet, and some chemical pollutants. So a person
Speaker 2: living in an area where the soil is low in iodine,
Speaker 2: or whose diet includes a lot of those foods somebody
Speaker 2: who's exposed to these kinds of pollutants. These people could
Speaker 2: have even more difficulty getting enough iodine In people.
Speaker 1: Iodine deficiency can lead to a number of health issues.
Speaker 1: As we said earlier, the body needs iodine to make
Speaker 1: thyroid hormones. If the thyroid gland isn't getting enough iodine
Speaker 1: to do this, it enlarges as it tries to filter
Speaker 1: more iodine from the blood. This enlarged thyroid gland is
Speaker 1: called a goiter, and a goiter can put pressure on
Speaker 1: the blood vessels in the neck and on the trachea.
Speaker 1: There are other things that can cause goiter, including autoimmune
Speaker 1: disorders like graves disease, thyroid nodules, and cancers, but iodine
Speaker 1: deficiency is the most common cause of goiter worldwide, and yes,
Speaker 1: non human and animals can also develop goiter.
Speaker 3: Without enough iodine.
Speaker 2: The body also can't make enough thyroid hormone that leads
Speaker 2: to hypothyroidism. Symptoms and effects of hypothyroidism include things like fatigue, listlessness,
Speaker 2: difficulty concentrating, dry skin, feeling cold all the time, depression,
Speaker 2: irregular menstrual periods, among other things. Iodine and thyroid hormones
Speaker 2: also play an important role in brain development in utero.
Speaker 2: Iodine deficiency during pregnancy can lead to babies being born
Speaker 2: with congenital iodine deficiency syndrome, which a startling number of
Speaker 2: sources are still right now in the year twenty twenty
Speaker 2: four while we record this describing using the word cretinism,
Speaker 2: even though at this point that term has deeply insulting connotations.
Speaker 2: Congenital iodine deficiency syndrome can lead to developmental disabilities, deafness
Speaker 2: and inability to speak, and muscular skeletal issues. Treatment with
Speaker 2: iodine can resolve many of the issues associated with hypothyroidism,
Speaker 2: including the physical changes in babies born with congenital iodine
Speaker 2: deficiency syndrome, but not the damage to the brain that
Speaker 2: takes place during fetal development. Iodine wasn't discovered until the
Speaker 2: nineteenth century, but people in various parts of the world
Speaker 2: connected foods that are high in iodine with the prevention
Speaker 2: and treatment of goiter thousands of years ago. Documents from
Speaker 2: China dating back to about thirty six hundred BCE describe
Speaker 2: a reduction in goiter after eating seaweed or burned sea sponge.
Speaker 2: Seaweed and sea sponge continued to show up in medical
Speaker 2: texts in Asia, Europe, and Northern Africa afterward. Ierveateic texts
Speaker 2: from the Indian subcontinent dating back to about fourteen hundred
Speaker 2: BCE also include descriptions of hyperthyroidism and hypothyroidism, with treatments
Speaker 2: for hypothyroidism including things like milk, various grains, and bladder rack,
Speaker 2: which is a type of seaweed. Overall, earlier medical writers
Speaker 2: didn't know exactly what caused goiter. For example, those same
Speaker 2: Aervedic texts conclude that goiter was caused by edema, and
Speaker 2: various physicians throughout history have blamed goiter on a range
Speaker 2: of illnesses, poisons, and even tumors. But there are also
Speaker 2: written records of people making a connection between goiter and
Speaker 2: the symptoms of hypothyroidism like fatigue and difficulty concentrating. In
Speaker 2: the tenth century, Arab historian and geographer Al mas Udi
Speaker 2: described Europeans as having quote large bodies, dull understanding, and
Speaker 2: heavy tongues, which is often interpreted as a reference to
Speaker 2: how many people had hypothyroidism. In the sixteenth century. Paracelsus
Speaker 2: also made a connection between parents with goiter and children
Speaker 2: born with developmental delays and disabilities. People started to get
Speaker 2: a clearer understanding of the relationship but between goiter, thyroid hormone,
Speaker 2: and iodine after iodine was discovered in the nineteenth century.
Speaker 2: We'll have more on that after a sponsor break. In
Speaker 2: eighteen eleven, French pharmacist and chemist Bernon Courtois was working
Speaker 2: with seaweed at his father's saltpeter factory. This process involved
Speaker 2: burning the seaweed to produce soda ash and then adding
Speaker 2: sulfuric acid to it. One day, by accident, he added
Speaker 2: too much sulfuric acid. In the words of Humphrey Davy,
Speaker 2: this produced quote a beautiful violet vapor. Courtois was not
Speaker 2: sure what this vapor was, but he called it by
Speaker 2: the Greek word iodes, meaning violet. He didn't have time
Speaker 2: to really experiment with this, so he gave a sample
Speaker 2: to Joseph Luis Gaerusac.
Speaker 3: We talked about.
Speaker 2: This in our recent episode on Humphrey Davy, Davy and
Speaker 2: Gaelusac each described iodine as an element in eighteen thirteen.
Speaker 2: They made those descriptions about a week apart, and then
Speaker 2: they had an argument about who should get the credit
Speaker 2: for it.
Speaker 1: Like so many other newly discovered substances, once it had
Speaker 1: been identified and isolated, iodine made its way into medicines
Speaker 1: meant to treat all kinds of things. Of course, it
Speaker 1: didn't have an effect on most of them, and this
Speaker 1: experimental iodine treatment also carried the risk of what came
Speaker 1: to be known as the yod Basidou phenomenon. Yaod is
Speaker 1: the German word for iodine, and Carl Adolf von Basidu
Speaker 1: was the nineteenth century German doctor who worked with it.
Speaker 1: He was reportedly the first person to describe thyrotoxicosis, which
Speaker 1: occurs when there is too much thyroid hormone circulating in
Speaker 1: a person's body. The yod bazidoo effect is thyrotoxicosis in
Speaker 1: response to treatment with iodine.
Speaker 2: As a note, sometimes the terms thyrotoxicosis and hyperthyroidism are
Speaker 2: used interchangeably, but they're there are some slight nuances between
Speaker 2: these two terms. Those nuances are a little outside the
Speaker 2: scope of a generalist history podcast. Both of them however,
Speaker 2: involve an excess of thyroid hormone, they can cause things
Speaker 2: like tremors, weight loss, and low blood sugar, as well
Speaker 2: as a rapid heartbeat, and in extreme cases, can be fatal.
Speaker 2: It did not take long for people to realize that
Speaker 2: iodine could have a beneficial effect on goiter, though. In
Speaker 2: eighteen twenty one, Swiss physician Jef Freancois Quande published a
Speaker 2: paper detailing how he had reduced the size of goiter's
Speaker 2: by administering iodine. But Quondai didn't have a perfect process.
Speaker 2: His iodine treatments led to hyperthyroidism in some of his patients,
Speaker 2: and this continued to be the case for other researchers
Speaker 2: through much of the nineteenth century. Around the same time,
Speaker 2: French agricultural chemist Jean Beausingaul was also suggesting that iodine
Speaker 2: might offer a treatment for goiter That was based on
Speaker 2: a correlation observed between the prevalence of goiter and how
Speaker 2: much iodine was in soil samples in the eighteen fifties.
Speaker 2: Another French researcher, Caspar Adolf Chattez, similarly described a relationship
Speaker 2: between how much iodine was in the air drinking water
Speaker 2: and soil in a particular area and the incidence of
Speaker 2: goiter there. In areas with more iodine, goiter was less common.
Speaker 2: He also published works suggesting that chronically low iodine levels
Speaker 2: could cause chronic goiter, but his conclusions really weren't widely
Speaker 2: accepted because people questioned whether the minute amounts of iodine
Speaker 2: that he was describing really could have such a pronounced
Speaker 2: impact on a person's body. In eighteen ninety five, German
Speaker 2: chemist Eugen Bauman pinpointed the presence of iodine in the
Speaker 2: thyroid glands and isolated a physiologically active substance from within
Speaker 2: the glands, but he didn't get far on figuring out
Speaker 2: exactly what the substance was or how it functioned within
Speaker 2: the body, and he died the following year at the
Speaker 2: age of forty nine. In the early twentieth century, David
Speaker 2: Marine published work demonstrating a clear connection between iodine levels
Speaker 2: and thyroid function, but at first this was not in humans.
Speaker 2: He was studying other animals, including farmed brook trout. These
Speaker 2: brook trout seemed to be prone to some kind of
Speaker 2: thyroid dysfunction. Before Marine carried out these experiments, the swellings
Speaker 2: and lesions on these trout's thyroid glands were believed to
Speaker 2: be a form of carcinoma. He concluded that in a
Speaker 2: lot of cases this was an ordinary goiter except in
Speaker 2: a fish, and that it could be resolved just by
Speaker 2: adding iodine to their water supply. Marine started publishing this
Speaker 2: work in nineteen oh seven, and within about a decade
Speaker 2: he was studying the connection between iodine and goiter in humans.
Speaker 2: He carried out the first controlled human experiment to t
Speaker 2: this in Akron, Ohio. The test subjects included more than
Speaker 2: four thousand schoolgirls, with half of them receiving small doses
Speaker 2: of iodine and the other half not. Only five of
Speaker 2: the girls receiving iodine developed some kind of thyroid condition,
Speaker 2: but that number in the group who didn't receive iodine
Speaker 2: was four hundred and seventy five. His book on the subject,
Speaker 2: titled The Prevention of Simple Goiter in Man, was published
Speaker 2: in nineteen seventeen. The Akron experiment started in nineteen sixteen,
Speaker 2: and it ran in parallel to some work on goiter
Speaker 2: prevention that was going on in two places where goiter
Speaker 2: was highly prevalent was the country of Switzerland and the
Speaker 2: state of Michigan. Although these are on two different continents,
Speaker 2: both of them have very low levels of iodine in
Speaker 2: the soil. The work in Switzerland started just a bit earlier.
Speaker 2: In some areas of the country, goiter wasn't particularly prevalent,
Speaker 2: but according to a survey published by doctor Heinrich Bircher
Speaker 2: in eighteen eighty three, in one suburb of the capital
Speaker 2: city of Bern, ninety four percent of men had goiters.
Speaker 2: In the early twentieth century, as many as ten percent
Speaker 2: of babies born in Switzerland showed signs of congenital thyroid
Speaker 2: deficiency syndrome, and according to death certificates, goiter was the
Speaker 2: cause of death for more than fifteen hundred people there
Speaker 2: between nineteen eleven and nineteen twenty. Another four hundred sixty
Speaker 2: three people died of thyroid cancer during that period. Researchers
Speaker 2: had proposed various ideas to explain why so many people
Speaker 2: in Switzerland had goiter and why it was so much
Speaker 2: more prevalent in some places in Switzerland than in others.
Speaker 2: Some of these ideas involved eugenics and the idea that
Speaker 2: people who had goiter or the symptoms of hypothyroidism must
Speaker 2: have had bad breeding. Heinrich Hunziker proposed that Switzerland's rates
Speaker 2: of goiter were caused by a lack of iodie.
Speaker 3: In nineteen fourteen.
Speaker 2: There was again a lot of opposition to his ideas
Speaker 2: of iodine supplementation, due to fears that that supplementation might
Speaker 2: poison people.
Speaker 1: Even so, at least one person tried to test out
Speaker 1: Hunsicker's ideas. That was Auto Bayard, from the town of Valet.
Speaker 1: He mixed iodine into salt at five different concentrations and
Speaker 1: distributed it to five families who were living in a
Speaker 1: remote area where the train only ran in the warmer months.
Speaker 1: About seventy five percent of the children living in this
Speaker 1: area reportedly had in large thyroid glands. In addition to
Speaker 1: providing salt to these families, Bayard supplied salt for the
Speaker 1: village's animals and to the bakery. He delivered the salt
Speaker 1: before the train shut down for the winter of nineteen eighteen.
Speaker 2: When he returned there in the spring, he found that
Speaker 2: people's thyroid glands had dramatically improved, and nobody seemed to
Speaker 2: have been harmed by the iodine that had been added
Speaker 2: to the salt. Biard heard about the Akron experiment not
Speaker 2: long after this, and he repeated his experiment on a
Speaker 2: larger scale with the help of the Swiss Health Authority.
Speaker 2: Byard was invited to present his research to the Swiss
Speaker 2: Goiter Commission on January twenty first, nineteen twenty two. He
Speaker 2: and the Commission were not completely sure why adding iodine
Speaker 2: to the salt was so effective at treating goiter, but
Speaker 2: it definitely seemed to work, so the Commission wanted to
Speaker 2: try implementing it nationally. We mentioned up at the top
Speaker 2: of the show that governments around the world had regulated
Speaker 2: salt for centuries, and that was the case in Switzerland.
Speaker 2: Switzerland is more formally known as the Swiss Confederation. Today
Speaker 2: it comprises twenty six member states known as cantons. In
Speaker 2: the nineteeneens that number was slightly smaller, but each of
Speaker 2: these cantons had a monopoly on the sale of salt
Speaker 2: there going all the way back to the medieval period,
Speaker 2: so it wasn't possible for Switzerland and as a nation,
Speaker 2: to just mandate the sale or use of iodized salt
Speaker 2: across the whole country, or to make national changes to
Speaker 2: the salt supply. They had to advocate for doing this
Speaker 2: with each of the cantons individually. Hans Eggenberger, chief doctor
Speaker 2: in the town of Harrisau, became a vocal advocate for
Speaker 2: the use of iodized salt, spearheading efforts both within the
Speaker 2: government and as a public relations campaign. By June of
Speaker 2: nineteen twenty two, the Goiter Commission had recommended the use
Speaker 2: of iodized salt to all of the cantons, and the
Speaker 2: first deliveries of iodized salt took place at November. Michigan
Speaker 2: was facing really similar rates of goiter to Switzerland. In
Speaker 2: the early twentieth century, this part of the United States
Speaker 2: had been nicknamed the goiter Belt due to the prevalence
Speaker 2: of goiter and thyroid disease in Michigan and surrounding states.
Speaker 2: In nineteen eighteen, as Otto Bayard was working on his
Speaker 2: salt experiment, doctor Simon Levin was conducting physicals in Houghton County, Michigan.
Speaker 2: Levin reported that thirty percent of the men that he
Speaker 2: examined had an enlarged thyroid. It was estimated that more
Speaker 2: than twenty thousand men in northern Michigan alone were ineligible
Speaker 2: for military service because of their goiters and an enlarged thyroid.
Speaker 2: Gland was the most common reason for medical disqualification from
Speaker 2: military service in this part of the United States. Since
Speaker 2: the United States was involved in World War One, this
Speaker 2: was seen as an urgent issue.
Speaker 1: Health officials in Michigan expanded their focus beyond military physicals
Speaker 1: and conducted a follow up study in two towns in
Speaker 1: Houghton County for people aged one to sixty one. They
Speaker 1: found that more than sixty four percent of the people
Speaker 1: examined had some kind of goiter. Almost half of school
Speaker 1: children showed some evidence of thyroid dysfunction.
Speaker 2: Canadian American physician David Murray Cowie was the first professor
Speaker 2: of pediatrics at the Universe of Michigan. He had learned
Speaker 2: about the Swiss efforts to add iodine to salt, and
Speaker 2: he recommended a similar program to the Michigan State Medical Society.
Speaker 2: In nineteen twenty two, the Society established an advisory committee
Speaker 2: in its Pediatric section to focus on this project. This
Speaker 2: would lead to the first widespread use of a fortified
Speaker 2: food product in the United States. We're going to talk
Speaker 2: more about that after we paused for a sponsor break.
Speaker 2: There were a lot of reasons behind the decision to
Speaker 2: add iodine to salts. Rather than trying some other strategy
Speaker 2: to get iodine into people's diets. Various experiments involving iodine
Speaker 2: supplements in the late nineteenth and early twentieth century hadn't
Speaker 2: been really successful, Like there were iodine syrups that tasted
Speaker 2: disgusting so children didn't want to take them, or these
Speaker 2: were supplements that only needed to be administered every few months,
Speaker 2: so people would just forget about them. Meanwhile, salt was
Speaker 2: something that virtually everyone used in cooking, and its use
Speaker 2: didn't really vary much from season to season, unlike in
Speaker 2: earlier eras where the salt trade could involve long and
Speaker 2: arduous journeys, which I mean, I guess it still could
Speaker 2: in the early twentieth century, but most people had access
Speaker 2: to salt at a local store at a reasonable price,
Speaker 2: and unlike today, there wasn't a big public health focus
Speaker 2: on reducing salt intake due to sodium's connection to high
Speaker 2: blood pressure. Salt wasn't the only thing that people tried
Speaker 2: adding iodine to in the US, though. In Rochester, New York,
Speaker 2: there was a plan to add ionine to the drinking
Speaker 2: water that started on April twenty fourth, nineteen twenty three.
Speaker 2: This involved adding sodium iodide to the inflow of the
Speaker 2: city's reservoir in a project overseen by doctor George W. Goehler,
Speaker 2: who was Rochester's health officer. He had his own backstory
Speaker 2: that we not getting into, including apparently opposing pasteurization because
Speaker 2: he had seen such a reduction in milk boorn illnesses
Speaker 2: through his own inspection program. This effort to add iodine
Speaker 2: to the water was relatively effective, but it had some
Speaker 2: challenges like the amount of iodine that could be added
Speaker 2: to the reservoir was not enough to keep the average
Speaker 2: person's thyroid working well, at least not if they drank
Speaker 2: a typical amount of water, so people were advised to
Speaker 2: drink more tap water, as much as three times more
Speaker 2: than they were typically drinking. The level of iodine in
Speaker 2: the tap water also dropped really quickly after it was
Speaker 2: added to the reservoir.
Speaker 1: A lot of people also objected to the idea of
Speaker 1: something being added to their drinking water, including other water authorities.
Speaker 1: For example, a write up by the British Water Works
Speaker 1: Association set in part quote, it is contrary to ordinary
Speaker 1: medical teaching to force a whole population to drink doped
Speaker 1: water to the benefit of the minority. There were also
Speaker 1: several fires that appeared to be arson and threats that
Speaker 1: there would be more fires if this program was not stopped.
Speaker 1: Although the rate of goiter in and around Rochester did
Speaker 1: decline while this program was going on, it ended during
Speaker 1: the Great Depression, after a round of budget cuts and
Speaker 1: Goaler's retirement to return to Michigan. There was a proposal
Speaker 1: to pass a state law mandating the addition of iodine
Speaker 1: to salt, but there were a number of worries, in
Speaker 1: my opinion, well founded worries that people would object to
Speaker 1: a legal mandate that required something to be added to
Speaker 1: their food. So instead, health authorities in Michigan started a
Speaker 1: campaign of public education and a sort of industry pr
Speaker 1: campaign similar to what had happened in Switzerland, to convince
Speaker 1: all of the cantons to sell idise salt. This involved
Speaker 1: almost two hundred public health lectures that were carried out
Speaker 1: all over the state and work with the Michigan Salt
Speaker 1: Producers Association and outreach to the presidents of all the
Speaker 1: individual salt producers that were selling their products in Michigan.
Speaker 1: These folks were nicknamed the Saltmen.
Speaker 3: This became a.
Speaker 1: Huge cooperative effort between Michigan's public health workers and the
Speaker 1: salt industry, with David Marie Cowie being a major presence
Speaker 1: in all of it. Officials had to convince the salt
Speaker 1: industry that adding iodine wouldn't affect the quality of their product.
Speaker 1: They even brought in William Hale of Dow Chemical Company
Speaker 1: to demonstrate that it would not change the salt's flavor
Speaker 1: or function. They worked at a process for adding the
Speaker 1: iodine at a step into process when magnesia was already
Speaker 1: being added to keep the salt free flowing, and that
Speaker 1: cut down on the costs involved. They also had to
Speaker 1: do some outreach within the medical community to try to
Speaker 1: reassure doctors that adding iodine to the salt would not
Speaker 1: just flip the situation and cause an epidemic of hype
Speaker 1: thyroidism instead of hypothyroidism. That bit is a little more complicated.
Speaker 1: The amount of iodine that was to be added to
Speaker 1: the salt was nowhere near enough to cause hyper thyroidism
Speaker 1: in somebody whose thyroid was actually working properly, but it
Speaker 1: was enough to cause problems in people who were already
Speaker 1: experiencing serious thyroid dysfunction. According to a paper published in
Speaker 1: the Journal of the European Economic Association in twenty seventeen.
Speaker 1: Iodization may have contributed to as many as ten thousand
Speaker 1: deaths in the United States between nineteen twenty five and
Speaker 1: nineteen forty two, primarily among people who had been chronically
Speaker 1: iodine deficient for a very long time like many years.
Speaker 1: Officials in Michigan also wanted to be able to clearly
Speaker 1: document whether this whole effort was working, so they set
Speaker 1: up a research program to evaluate the effects of iodized salt.
Speaker 1: This started with a baseline survey of the rates of
Speaker 1: guaiter and other thyroid issues before iodized salt became available
Speaker 1: in stores, with follow ups to see how things changed
Speaker 1: after people had access to iodized salt. A lot of
Speaker 1: this was happening in late nineteen twenty three, and on
Speaker 1: March fifteenth, nineteen twenty four, the Michigan State Medical Society
Speaker 1: publicly endorsed the use of salt that contained zero point
Speaker 1: zero one percent sodium iodide. Six different companies selling salt
Speaker 1: in Michigan had their iodized products ready to go that May.
Speaker 1: Morton was something of a latecomer. There were executives who
Speaker 1: had concerns about producing iodized salt for only a couple
Speaker 1: of states if that salt was not also being used
Speaker 1: in all of the other states.
Speaker 2: Morton started selling iodized salt a few months after everyone else,
Speaker 2: and by the fall of that year, iodized salt was
Speaker 2: available in stores all across the United States. In most
Speaker 2: places in the US, iodized and non iodized salt were
Speaker 2: both sold into stores, but thanks to extensive public education
Speaker 2: campaigns and advertising on the part of the salt companies,
Speaker 2: most people who had access to iodized salt bought it.
Speaker 2: Follow Up studies in Michigan showed that once iodized salt
Speaker 2: was widely available, incidents of enlarged thyroids dropped by up
Speaker 2: to ninety percent. By nineteen thirty two, between ninety and
Speaker 2: ninety five percent of salt sold in Michigan was iodized,
Speaker 2: so by the mid nineteen twenties, it was clear that
Speaker 2: iodine had an effect on the prevalence of goiter and
Speaker 2: on hypothyroidism, and that salt was an effective way to
Speaker 2: get enough iodine into people's diets, but people still didn't
Speaker 2: fully understand why this worked, including within the medical community.
Speaker 2: An international conference on goiter was held and burned in
Speaker 2: nineteen twenty seven, and causes for goiter that were proposed
Speaker 2: at this conference included intestinal parasites, poor hygiene, bad food,
Speaker 2: and contaminated drinking water. A lot of the experts cited
Speaker 2: these as the cause of goiter. While agreeing that the
Speaker 2: addition of iodine to the salt worked to treat that goiter,
Speaker 2: they concluded, though, that the iodine was killing the parasites
Speaker 2: or destroying whatever was contaminating the food or water. Even
Speaker 2: in nineteen thirty three, an article in Public Health Reports
Speaker 2: still characterized the cause of endemic goiter as the subject
Speaker 2: of speculation and of divergence of opinion.
Speaker 1: David Murray Cowie died on January twenty seventh, nineteen forty,
Speaker 1: after a coronary thrombosis. At that point, he had been
Speaker 1: working toward a national campaign for iodized salt. His replacement,
Speaker 1: Frederick B. Minor, continued toward that goal and helped establish
Speaker 1: an iodized Salt Committee at the American Public Health Association.
Speaker 1: Although bills were introduced to mandate iodized salt nationwide, none
Speaker 1: of them ever passed.
Speaker 2: Today, laws and standards around iodized salt vary widely from
Speaker 2: one country to another, but an estimated eighty eight percent
Speaker 2: of people around the world have access to iodized salt.
Speaker 2: For the most part, once a nation's salt iodization program
Speaker 2: is well established, people typically still have access to iodized
Speaker 2: salt even when war or some kind of other unrest
Speaker 2: disrupts other public health measures like vaccine programs. But that
Speaker 2: still means that around the world, more than nine hundred
Speaker 2: million people don't have access to iodized salt, and an
Speaker 2: estimated fifty million people have enlarged thyroid glands and possibly
Speaker 2: other concerns. Because of this, researchers have also looked for
Speaker 2: other ways to distribute iodine in places where iodized salt
Speaker 2: isn't practical for some reason or where there's some other
Speaker 2: issue going on. One example is the use of iodinated
Speaker 2: poppyseed oil in highland areas of New Guinea where iodine
Speaker 2: deficiency is particularly or adding iodine to irrigation water or
Speaker 2: animal feeds so that it makes its way into other foods. Interestingly,
Speaker 2: the twenty one nations that are currently reported as having
Speaker 2: insufficient iodine intake are scattered all over the world in
Speaker 2: a way that looks pretty random on a globe. This
Speaker 2: includes both rich and poor countries. In Europe, Asia, Africa,
Speaker 2: and Central America, and there are thirteen countries that have
Speaker 2: too much iodine, either from already abundant iodine in their
Speaker 2: diets or over iodization of the salt. Here in the
Speaker 2: United States, dietary iodine intake has been declining since the
Speaker 2: nineteen seventies. Some of this is because of concerns about
Speaker 2: the connection between sodium intake and hypertension, although the biggest
Speaker 2: sources of sodium in the typical American diet are processed
Speaker 2: foods that are not usually made with iodized salt, not
Speaker 2: the iodized table salt that people might be avoiding. But
Speaker 2: another reason is just an increasing preference for things like
Speaker 2: sea salt and kosher salt and Himalayan pink salt. These
Speaker 2: are typically not iodized, although there are some brands that
Speaker 2: do carry iodized versions of these products.
Speaker 1: At this point, a lot of people in the US
Speaker 1: are getting more of their iodine from dairy products than
Speaker 1: from table salt, which means the rising preference for non
Speaker 1: dairy milks is playing a part in this story as well.
Speaker 1: Whether a plant based milk contains iodine depends on what
Speaker 1: it is made of. Some of them use thickeners made
Speaker 1: from seaweed, although the iodine and the seaweed might not
Speaker 1: make it through the manufacturing process.
Speaker 2: In the United States, nutrition labels typically only list iodine
Speaker 2: content if that was added into the product, not if
Speaker 2: the iodine occurs naturally, and that can make it tricky
Speaker 2: to know how much iodine a person is actually getting,
Speaker 2: and this affects people who are trying to get enough
Speaker 2: iodine as well as people who need to avoid iodine.
Speaker 2: For example, people who are getting radioactive iodine treatment are
Speaker 2: typically advised to avoid iodine in their diets. Since we
Speaker 2: have a whole episode on the history of radio iodine treatment,
Speaker 2: we're gonna run that as a Saturday Classic because it
Speaker 2: overlaps with this.
Speaker 1: A little bit. Do you also have listener mail for us?
Speaker 1: I do have listener mail for us. It is from Jody.
Speaker 1: Jody wrote, Hi, Holly and Tracy. Usually I listened to
Speaker 1: your podcast weekday mornings when getting ready for work, but
Speaker 1: when I saw this week's lineup was food themed, I
Speaker 1: decided to spend my Saturday afternoon with you. What caught
Speaker 1: my eye was banana ketchup. This came on my radar
Speaker 1: a few years ago after I moved from the Florida
Speaker 1: Keys to Las Vegas, Nevada, where there's a much larger
Speaker 1: Filipino population. I'm also a canner and had to figure
Speaker 1: out what to do with the fifteen ish pounds of
Speaker 1: bananas that showed up with an Instacart order instead of
Speaker 1: the one bunch I was exp This was during the pandemic,
Speaker 1: so another quick sweetbread was out of the question. I
Speaker 1: look forward to reading more about Maria Rosa's story using
Speaker 1: your references as a guide. As for how my banana
Speaker 1: ketchup turned out, it was interesting.
Speaker 3: Lol.
Speaker 2: Here's the safe canning recipe I used. There's a link
Speaker 2: to a recipe for banana ketchup. A Filipino co worker
Speaker 2: tasted it and approved, but my brain had trouble making
Speaker 2: sense of the color and I couldn't eat it with fries.
Speaker 2: But I do make a beat ketchup that gets gobbled up,
Speaker 2: so I know that's just in my head. That being said,
Speaker 2: I do try to run a zero waste kitchen, so
Speaker 2: I use it as a base for barbecue sauce for
Speaker 2: grilled ribs, and my guests kept trying to figure out
Speaker 2: what the secret flavor was while licking their fingers attached
Speaker 2: for cat tacks are picks of our ten year old
Speaker 2: spicy cat Ella and almost four year old goofball Jazzber.
Speaker 2: My husband is a jazz musician, so Ella is named
Speaker 2: after Ella Fitzgerald, and Jazz has not stopped purring since
Speaker 2: we adopted him from a shelter. His eyes looked like
Speaker 2: green jasper. This cat's I like this. I'm looking at
Speaker 2: a picture of a black cat with a very startled expression.
Speaker 2: I don't know if this kitty cat is actually startled,
Speaker 2: but that's that's the way that it struck me. And
Speaker 2: then there's also other kitty cat, so I'm guessing this
Speaker 2: one is Ella.
Speaker 3: Ella is on a bookshelf.
Speaker 2: Posed in such a way that at first I thought
Speaker 2: this was like a cat figurine.
Speaker 3: No, it is the real cat on the bookshelf. Thank
Speaker 3: you so much.
Speaker 2: I'm so interested about number one hearing the that you know,
Speaker 2: somebody just needed to make some banana ketchup at home
Speaker 2: because of all of these extra bananas. And then it
Speaker 2: also reminded me of experience I had in the early
Speaker 2: pandemic years when I had an order from like a
Speaker 2: place that sold locally grown fruits and vegetables and things,
Speaker 2: and the it was described as a pound of halapeno peppers,
Speaker 2: and I was like, I don't think that can be right,
Speaker 2: don't I don't think I'm gonna get a whole pound
Speaker 2: of halapeno peppers. I did, so I made a bunch
Speaker 2: of infused vodka with because that was more holopenos than
Speaker 2: I needed at that moment. Uh So, thank you so
Speaker 2: much for that email. If you would like to send
Speaker 2: us a note about this or any other episode, where
Speaker 2: at History Podcasts at iHeartRadio dot com, and you can
Speaker 2: subscribe to the show on the iHeartRadio app and anywhere
Speaker 2: else you'd like to get your podcasts. Stuff you Missed
Speaker 2: in History Class is a production of iHeartRadio. For more
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Speaker 2: wherever you listen to your favor shows.