0:01

Welcome to Stuff You Missed in History Class,

0:03

a production of iHeartRadio.

0:12

Hello, and welcome to the podcast. I'm Tracy

0:14

V. Wilson and I'm Holly Frye.

0:16

Back at the beginning of May, I read

0:19

an article in the Washington Post called

0:21

how the arrival of iodized salt

0:24

one hundred years ago changed America. And

0:27

I was immediately fascinated by this whole

0:29

thing, And I also wanted to learn more

0:32

than a thousand word newspaper article

0:34

could tell me. I already

0:36

knew, and I think maybe a lot of folks already knew

0:39

from something like elementary school health

0:41

class that iodine is

0:43

added into table salt because our

0:45

bodies need that iodine for thyroid

0:48

reasons. And I also

0:50

knew there are various people who, for

0:53

whatever reason, don't like iodized

0:55

salt or don't want to use it, and

0:57

that was sort of the sum of my knowledge about

0:59

the iodide salt. And

1:01

so reading this Washington Post article, I

1:03

didn't really grasp that adding

1:06

the iodine to the salt was not just

1:08

like a nutritional nice to have. They

1:11

were not like well meaning public

1:13

health people kind of like, wouldn't it be great if

1:15

everybody just had enough iodine, just because

1:18

it was to try to deal with

1:21

a problem that in some parts of the world

1:23

was really serious with chronic iodine

1:26

deficiency. It

1:28

was incredibly widespread in some

1:30

places, and that was causing a range of

1:32

actual health issues, not

1:34

just wouldn't it be great if we all got enough

1:37

iodine.

1:38

So a complete history of salt would

1:40

be its own episode, or perhaps even more

1:42

than one. You could even have the story of salt

1:45

as an entire podcast. I imagine. Of

1:47

course, edible salt or sodium chloride

1:50

makes food more flavorful, and it's

1:52

an electrolyte that our bodies need to function

1:54

correctly. Salt can also

1:57

be used to preserve food through salting,

1:59

curing, brining, or pickling, and

2:01

there are lots of non dietary

2:03

uses for it as well. So for

2:06

those and other reasons, people

2:08

have wanted and needed salt, going

2:10

all the way back to our earliest beginnings,

2:13

cultures all around the world have boiled

2:16

or evaporated salt from water,

2:18

including seawater and water

2:21

from salt lakes or mineral springs.

2:24

Animals besides us, need salt to

2:26

often they get it from licking at salt

2:28

deposits. So people who are living

2:30

farther inland could sometimes find

2:33

sources of salt by just watching what the

2:35

animals were doing, even

2:37

if salt had no other uses.

2:40

Its importance in flavoring and preserving

2:42

food has made it highly sought

2:44

after all over the world for basically

2:47

all of history. Some of the

2:49

world's earliest trade networks were,

2:51

of course, salt roads, and many

2:53

of the earliest governments, established thousands

2:56

of years ago, regulated

2:58

the salt trade and establish salt

3:00

stockpiles. Iodine

3:03

is not nearly as abundant assault,

3:05

but it is similarly critical. People

3:08

and all other vertebrate animals

3:11

need iodine for our bodies to function

3:13

properly. Specifically, the

3:15

body uses iodine to make thyroid

3:17

hormones, and thyroid hormones

3:19

regulate a number of body functions,

3:21

including growth and metabolism, affecting

3:24

virtually every cell in the body. The

3:27

iodine we consume moves from the digestive

3:29

system to the blood and from there to the

3:31

thyroid gland, which produces

3:34

those hormones.

3:35

People only need a little bit

3:37

of iodine. In the United States,

3:39

the recommended daily allowance is only

3:42

one hundred and fifty micrograms

3:44

a day for adults. It's roughly half

3:46

that For babies and children, the

3:49

recommended daily allowance increases

3:51

to two hundred and twenty micrograms during

3:53

pregnancy and two hundred and ninety

3:55

micrograms while lactating. But whether

3:58

people can get that much eye iodine

4:00

without access to fortified

4:02

foods like iodized salt varies

4:06

widely depending on where they live.

4:08

There's iodine in seawater, and

4:11

it's in the Earth's crust, but exactly

4:13

how much iodine there is in a particular

4:15

location depends on things like

4:17

how close it is to the sea and

4:20

geological changes that have taken place

4:22

over thousands and thousands of years.

4:25

The presence of iodine in seawater means

4:28

that various types of seaweed and marine

4:30

animals are also high in iodine,

4:33

so people living in an island nation like

4:35

Japan, where the traditional diet includes

4:38

a lot of seafood and seaweed may

4:40

be able to get enough iodine through their regular

4:42

diet without some kind of supplementation.

4:46

Generally speaking, things get trickier

4:48

farther inland. How much iodine

4:51

is available to people and animals depends

4:53

on how much of it is present in

4:55

the soil, so, for example,

4:58

cows grazing on a pasture near the

5:00

sea, where the iodine in the soil

5:02

is replenished by the spray blowing in

5:04

from the ocean, they might get enough iodine,

5:07

and that means there would also be iodine in their

5:09

milk. But high altitudes

5:11

places where there are recurring floods

5:14

or cycles of glaciers melting

5:16

and refreezing, those places

5:18

typically have very little iodine

5:20

in the soil, so without some kind of supplementation,

5:23

people and animals living there cannot

5:25

get enough iodine in their diets.

5:28

This isn't only a problem for humans

5:30

who rely on these animals for food. Iodine

5:33

deficiency in livestock is connected

5:35

to things like still births, the deaths

5:37

of young, and lower production of eggs

5:40

and milk. As a side note,

5:42

in today's world, some of the iodine and milk

5:44

doesn't actually come from what the cows are

5:47

eating. It's from the use of iodine

5:49

as an antiseptic or sterilizer,

5:51

both on the cow's utters and on equipment

5:54

that's used in the dairy industry.

5:56

There are also some things that can interfere

5:59

with the bodies of bil to absorb iodine,

6:02

including compounds found in cassava

6:04

and millet, and some chemical

6:06

pollutants. So a person

6:09

living in an area where the soil is low

6:11

in iodine, or whose diet includes

6:13

a lot of those foods somebody who's

6:15

exposed to these kinds of pollutants. These

6:18

people could have even more difficulty getting

6:20

enough iodine In people.

6:23

Iodine deficiency can lead to a number

6:25

of health issues. As we said

6:27

earlier, the body needs iodine to make

6:29

thyroid hormones. If the thyroid

6:31

gland isn't getting enough iodine to do

6:33

this, it enlarges as it

6:35

tries to filter more iodine from the blood.

6:38

This enlarged thyroid gland is called

6:41

a goiter, and a goiter can put

6:43

pressure on the blood vessels in the neck and

6:45

on the trachea. There are other

6:47

things that can cause goiter, including autoimmune

6:50

disorders like graves disease, thyroid

6:52

nodules, and cancers, but iodine

6:54

deficiency is the most common cause

6:57

of goiter worldwide, and yes, non

6:59

human and animals can also develop

7:01

goiter.

7:02

Without enough iodine.

7:04

The body also can't make enough thyroid

7:06

hormone that leads to hypothyroidism.

7:09

Symptoms and effects of hypothyroidism

7:12

include things like fatigue, listlessness,

7:14

difficulty concentrating, dry

7:17

skin, feeling cold all the time,

7:20

depression, irregular menstrual

7:22

periods, among other things. Iodine

7:25

and thyroid hormones also play an important

7:27

role in brain development in utero.

7:30

Iodine deficiency during pregnancy

7:32

can lead to babies being born with congenital

7:34

iodine deficiency syndrome, which

7:36

a startling number of sources are still

7:39

right now in the year twenty twenty four while

7:41

we record this describing using

7:43

the word cretinism, even though

7:46

at this point that term has deeply insulting

7:48

connotations. Congenital

7:50

iodine deficiency syndrome can lead to developmental

7:53

disabilities, deafness and inability

7:56

to speak, and muscular skeletal

7:58

issues. Treatment with iodine

8:00

can resolve many of the issues associated

8:03

with hypothyroidism, including

8:05

the physical changes in babies born with

8:07

congenital iodine deficiency syndrome,

8:10

but not the damage to the brain

8:12

that takes place during fetal development.

8:15

Iodine wasn't discovered until

8:17

the nineteenth century, but people

8:19

in various parts of the world connected

8:21

foods that are high in iodine

8:24

with the prevention and treatment of goiter thousands

8:26

of years ago. Documents from

8:29

China dating back to about thirty six hundred

8:31

BCE describe a reduction in

8:33

goiter after eating seaweed or burned

8:36

sea sponge. Seaweed and

8:38

sea sponge continued to show up in medical

8:40

texts in Asia, Europe, and Northern

8:43

Africa afterward. Ierveateic

8:45

texts from the Indian subcontinent dating

8:47

back to about fourteen hundred BCE also

8:50

include descriptions of hyperthyroidism

8:53

and hypothyroidism, with

8:55

treatments for hypothyroidism including

8:57

things like milk, various grains, and bladder

9:00

rack, which is a type of seaweed.

9:03

Overall, earlier medical writers

9:05

didn't know exactly what caused goiter.

9:08

For example, those same Aervedic

9:10

texts conclude that goiter was caused

9:13

by edema, and various physicians

9:15

throughout history have blamed goiter on a

9:17

range of illnesses, poisons, and

9:19

even tumors. But there are also

9:22

written records of people making a connection

9:24

between goiter and the symptoms of hypothyroidism

9:27

like fatigue and difficulty concentrating.

9:31

In the tenth century, Arab historian

9:33

and geographer Al mas Udi described

9:35

Europeans as having quote large

9:38

bodies, dull understanding, and

9:40

heavy tongues, which is often

9:42

interpreted as a reference to how many people

9:45

had hypothyroidism. In

9:47

the sixteenth century. Paracelsus

9:49

also made a connection between parents with

9:51

goiter and children born with developmental

9:54

delays and disabilities. People

9:57

started to get a clearer understanding of

9:59

the relationship but between goiter, thyroid

10:01

hormone, and iodine after iodine

10:04

was discovered in the nineteenth century. We'll

10:06

have more on that after a sponsor break.

10:14

In eighteen eleven, French

10:16

pharmacist and chemist Bernon Courtois

10:19

was working with seaweed at his father's

10:21

saltpeter factory. This

10:23

process involved burning the seaweed

10:25

to produce soda ash and then adding sulfuric

10:27

acid to it. One day, by accident,

10:30

he added too much sulfuric

10:32

acid. In the words of Humphrey

10:34

Davy, this produced quote a beautiful

10:37

violet vapor. Courtois

10:40

was not sure what this vapor was, but

10:42

he called it by the Greek word iodes,

10:45

meaning violet. He didn't

10:47

have time to really experiment

10:49

with this, so he gave a sample to Joseph

10:51

Luis Gaerusac.

10:53

We talked about.

10:54

This in our recent episode on Humphrey Davy,

10:56

Davy and Gaelusac each described

10:59

iodine as an element in eighteen

11:01

thirteen. They made those descriptions

11:03

about a week apart, and then they had an argument

11:06

about who should get the credit for it.

11:08

Like so many other newly discovered

11:10

substances, once it had been identified

11:13

and isolated, iodine made

11:15

its way into medicines meant to treat

11:17

all kinds of things. Of

11:19

course, it didn't have an effect on most

11:21

of them, and this experimental iodine

11:23

treatment also carried the risk of what came

11:26

to be known as the yod Basidou

11:28

phenomenon. Yaod is the

11:30

German word for iodine, and Carl

11:32

Adolf von Basidu was the nineteenth

11:35

century German doctor who worked with it.

11:37

He was reportedly the first person to

11:39

describe thyrotoxicosis,

11:42

which occurs when there is too much thyroid

11:44

hormone circulating in a person's body.

11:47

The yod bazidoo effect is thyrotoxicosis

11:50

in response to treatment with iodine.

11:53

As a note, sometimes the terms thyrotoxicosis

11:56

and hyperthyroidism are used interchangeably,

11:59

but they're there are some slight nuances between

12:02

these two terms. Those nuances

12:04

are a little outside the scope of a generalist

12:06

history podcast. Both

12:08

of them however, involve an excess

12:10

of thyroid hormone, they can cause

12:13

things like tremors, weight loss, and low

12:15

blood sugar, as well as a rapid heartbeat,

12:17

and in extreme cases, can be fatal.

12:20

It did not take long for people to realize

12:23

that iodine could have a beneficial effect

12:25

on goiter, though. In eighteen

12:27

twenty one, Swiss physician Jef Freancois

12:29

Quande published a paper detailing

12:32

how he had reduced the size of goiter's

12:34

by administering iodine. But

12:37

Quondai didn't have a perfect process.

12:40

His iodine treatments led to hyperthyroidism

12:43

in some of his patients, and this continued

12:45

to be the case for other researchers through

12:48

much of the nineteenth century. Around

12:50

the same time, French agricultural chemist

12:53

Jean Beausingaul was also suggesting

12:55

that iodine might offer a treatment for goiter

12:58

That was based on a correlation observed

13:00

between the prevalence of goiter and

13:02

how much iodine was in soil samples

13:05

in the eighteen fifties. Another French

13:07

researcher, Caspar Adolf Chattez,

13:10

similarly described a relationship between

13:12

how much iodine was in the air drinking

13:14

water and soil in a particular area

13:17

and the incidence of goiter there.

13:20

In areas with more iodine,

13:23

goiter was less common. He

13:25

also published works suggesting that chronically

13:28

low iodine levels could cause

13:30

chronic goiter, but his conclusions

13:33

really weren't widely accepted because

13:35

people questioned whether the minute

13:38

amounts of iodine that he was describing

13:40

really could have such a pronounced impact

13:42

on a person's body. In

13:44

eighteen ninety five, German chemist

13:47

Eugen Bauman pinpointed the presence

13:49

of iodine in the thyroid glands

13:52

and isolated a physiologically

13:54

active substance from within the

13:56

glands, but he didn't get far on

13:58

figuring out exactly what the substance

14:00

was or how it functioned within the body,

14:03

and he died the following year at the age of

14:05

forty nine. In the early

14:07

twentieth century, David Marine

14:10

published work demonstrating a clear

14:12

connection between iodine levels

14:14

and thyroid function, but at first this

14:17

was not in humans. He was

14:19

studying other animals, including farmed

14:22

brook trout. These brook

14:24

trout seemed to be prone to some kind of

14:26

thyroid dysfunction. Before

14:28

Marine carried out these experiments, the

14:30

swellings and lesions on these trout's

14:33

thyroid glands were believed to be a form

14:35

of carcinoma. He concluded

14:37

that in a lot of cases this was an ordinary

14:40

goiter except in a fish, and

14:43

that it could be resolved just by adding

14:45

iodine to their water supply. Marine

14:48

started publishing this work in nineteen oh seven,

14:50

and within about a decade he was studying the

14:52

connection between iodine and

14:54

goiter in humans. He

14:56

carried out the first controlled human

14:59

experiment to t this in Akron, Ohio.

15:02

The test subjects included more than four

15:04

thousand schoolgirls, with half

15:06

of them receiving small doses of iodine

15:09

and the other half not. Only

15:11

five of the girls receiving iodine

15:14

developed some kind of thyroid condition,

15:16

but that number in the group who didn't receive

15:19

iodine was four hundred and seventy

15:21

five. His book on the subject,

15:23

titled The Prevention of Simple Goiter in

15:25

Man, was published in nineteen seventeen.

15:29

The Akron experiment started in nineteen

15:32

sixteen, and it ran in parallel

15:34

to some work on goiter prevention that was going

15:36

on in two places where goiter was

15:39

highly prevalent was the country

15:41

of Switzerland and the state of Michigan.

15:44

Although these are on two different continents, both

15:47

of them have very low levels of iodine

15:49

in the soil. The work

15:51

in Switzerland started just a bit earlier.

15:54

In some areas of the country, goiter wasn't

15:57

particularly prevalent, but according

15:59

to a survey published by doctor Heinrich Bircher

16:01

in eighteen eighty three, in one

16:04

suburb of the capital city of Bern, ninety

16:07

four percent of men had goiters. In

16:09

the early twentieth century, as many as

16:11

ten percent of babies born in Switzerland

16:14

showed signs of congenital thyroid deficiency

16:17

syndrome, and according to death certificates,

16:19

goiter was the cause of death for more

16:21

than fifteen hundred people there between

16:24

nineteen eleven and nineteen twenty.

16:26

Another four hundred sixty three people

16:28

died of thyroid cancer during that period.

16:32

Researchers had proposed various ideas

16:34

to explain why so many people

16:36

in Switzerland had goiter and

16:39

why it was so much more prevalent

16:41

in some places in Switzerland than in others.

16:44

Some of these ideas involved eugenics

16:46

and the idea that people who had goiter

16:49

or the symptoms of hypothyroidism

16:51

must have had bad breeding. Heinrich

16:54

Hunziker proposed that Switzerland's

16:56

rates of goiter were caused by a lack

16:59

of iodie.

17:00

In nineteen fourteen.

17:02

There was again a lot of opposition to his ideas

17:04

of iodine supplementation, due to fears

17:07

that that supplementation might poison people.

17:10

Even so, at least one person

17:13

tried to test out Hunsicker's ideas.

17:15

That was Auto Bayard, from the town of Valet.

17:18

He mixed iodine into salt at

17:21

five different concentrations and distributed

17:23

it to five families who were living

17:25

in a remote area where the train only

17:27

ran in the warmer months. About

17:30

seventy five percent of the children living in

17:32

this area reportedly had in large

17:34

thyroid glands. In addition

17:37

to providing salt to these families, Bayard

17:39

supplied salt for the village's animals

17:42

and to the bakery. He delivered

17:44

the salt before the train shut down for the

17:46

winter of nineteen eighteen.

17:48

When he returned there in the spring, he found

17:50

that people's thyroid glands had dramatically

17:53

improved, and nobody

17:55

seemed to have been harmed by the iodine

17:58

that had been added to the salt. Biard

18:00

heard about the Akron experiment not long

18:02

after this, and he repeated his experiment

18:05

on a larger scale with the help of the Swiss

18:07

Health Authority. Byard

18:09

was invited to present his research to

18:11

the Swiss Goiter Commission on January

18:14

twenty first, nineteen twenty two.

18:17

He and the Commission were not completely sure

18:19

why adding iodine to the salt was

18:21

so effective at treating goiter, but

18:23

it definitely seemed to work, so the Commission

18:26

wanted to try implementing it nationally.

18:29

We mentioned up at the top of the show that governments

18:32

around the world had regulated

18:34

salt for centuries, and that was

18:36

the case in Switzerland. Switzerland

18:39

is more formally known as the Swiss

18:41

Confederation. Today it comprises

18:43

twenty six member states known

18:45

as cantons. In the nineteeneens

18:48

that number was slightly smaller, but each

18:50

of these cantons had a monopoly

18:52

on the sale of salt there going

18:55

all the way back to the medieval period, so

18:57

it wasn't possible for Switzerland

19:00

and as a nation, to just mandate

19:02

the sale or use of iodized salt

19:04

across the whole country, or to make

19:06

national changes to the salt supply. They

19:09

had to advocate for doing this with each

19:11

of the cantons individually. Hans

19:14

Eggenberger, chief doctor in the town of

19:16

Harrisau, became a vocal advocate

19:18

for the use of iodized salt, spearheading

19:21

efforts both within the government and as

19:23

a public relations campaign. By

19:25

June of nineteen twenty two, the Goiter Commission

19:28

had recommended the use of iodized salt

19:30

to all of the cantons, and the first

19:32

deliveries of iodized salt took place

19:35

at November. Michigan

19:37

was facing really similar rates of goiter

19:39

to Switzerland. In the early twentieth century,

19:42

this part of the United States had been

19:44

nicknamed the goiter Belt due

19:46

to the prevalence of goiter and thyroid

19:49

disease in Michigan and surrounding

19:51

states. In nineteen eighteen,

19:54

as Otto Bayard was working on his

19:56

salt experiment, doctor Simon

19:58

Levin was conducting physicals

20:01

in Houghton County, Michigan. Levin

20:03

reported that thirty percent of

20:05

the men that he examined had an

20:08

enlarged thyroid. It was

20:10

estimated that more than twenty thousand

20:12

men in northern Michigan alone

20:14

were ineligible for military service because

20:17

of their goiters and an enlarged

20:19

thyroid. Gland was the most common

20:21

reason for medical disqualification

20:24

from military service in this part of the United

20:26

States. Since the United

20:28

States was involved in World War One, this

20:30

was seen as an urgent issue.

20:33

Health officials in Michigan expanded

20:35

their focus beyond military physicals

20:37

and conducted a follow up study in two

20:39

towns in Houghton County for people

20:41

aged one to sixty one.

20:44

They found that more than sixty four percent of the

20:46

people examined had some kind of goiter.

20:49

Almost half of school children showed

20:51

some evidence of thyroid dysfunction.

20:54

Canadian American physician David Murray

20:56

Cowie was the first professor of pediatrics

20:59

at the Universe of Michigan. He

21:01

had learned about the Swiss efforts to add iodine

21:04

to salt, and he recommended a similar

21:06

program to the Michigan State Medical Society.

21:09

In nineteen twenty two, the

21:11

Society established an advisory

21:13

committee in its Pediatric section to

21:15

focus on this project. This would

21:17

lead to the first widespread use of a fortified

21:20

food product in the United States. We're

21:23

going to talk more about that after we paused

21:25

for a sponsor break. There

21:36

were a lot of reasons behind the decision

21:38

to add iodine to salts. Rather

21:40

than trying some other strategy to get

21:43

iodine into people's diets. Various

21:45

experiments involving iodine supplements

21:48

in the late nineteenth and early twentieth century

21:50

hadn't been really successful, Like there

21:52

were iodine syrups that tasted disgusting

21:55

so children didn't want to take them,

21:58

or these were supplements that only needed to be administered

22:00

every few months, so people would just

22:02

forget about them. Meanwhile, salt

22:05

was something that virtually everyone used

22:07

in cooking, and its use didn't really

22:10

vary much from season to season, unlike

22:13

in earlier eras where the salt trade

22:15

could involve long and arduous journeys,

22:18

which I mean, I guess it still could in the early

22:20

twentieth century, but most people

22:22

had access to salt at a local store

22:24

at a reasonable price, and unlike

22:27

today, there wasn't a big public health focus

22:29

on reducing salt intake

22:31

due to sodium's connection to high blood

22:33

pressure. Salt wasn't

22:35

the only thing that people tried adding iodine

22:38

to in the US, though. In Rochester,

22:41

New York, there was a plan to add ionine to the

22:43

drinking water that started on April

22:45

twenty fourth, nineteen twenty three.

22:48

This involved adding sodium iodide

22:50

to the inflow of the city's reservoir in a

22:52

project overseen by doctor George

22:54

W. Goehler, who was Rochester's

22:56

health officer. He had his

22:58

own backstory that we not getting into,

23:01

including apparently opposing pasteurization

23:04

because he had seen such a reduction in milk

23:06

boorn illnesses through his own inspection

23:08

program. This effort

23:11

to add iodine to the water was relatively

23:13

effective, but it had some challenges

23:15

like the amount of iodine that could

23:18

be added to the reservoir was not enough

23:20

to keep the average person's thyroid

23:22

working well, at least

23:25

not if they drank a typical amount

23:27

of water, so people were advised

23:29

to drink more tap water, as

23:31

much as three times more than they

23:33

were typically drinking. The level

23:36

of iodine in the tap water also

23:38

dropped really quickly after it was

23:40

added to the reservoir.

23:42

A lot of people also objected to the

23:44

idea of something being added to their drinking

23:46

water, including other water authorities.

23:49

For example, a write up by the British Water

23:51

Works Association set in part quote,

23:54

it is contrary to ordinary medical

23:56

teaching to force a whole population to

23:59

drink doped water to the benefit of

24:01

the minority. There were also

24:03

several fires that appeared to be arson

24:05

and threats that there would be more fires

24:07

if this program was not stopped. Although

24:11

the rate of goiter in and around Rochester

24:13

did decline while this program was going

24:15

on, it ended during the Great Depression,

24:18

after a round of budget cuts and Goaler's

24:20

retirement to return to Michigan.

24:23

There was a proposal to pass a state

24:25

law mandating the addition of iodine

24:28

to salt, but there were a number

24:30

of worries, in my opinion, well

24:33

founded worries that people would object

24:35

to a legal mandate that required

24:38

something to be added to their food. So

24:40

instead, health authorities in Michigan started

24:43

a campaign of public education and

24:45

a sort of industry pr

24:47

campaign similar to what had happened

24:50

in Switzerland, to convince all of the cantons

24:52

to sell idise salt. This

24:54

involved almost two hundred public

24:57

health lectures that were carried out all over the

24:59

state and work with the Michigan

25:01

Salt Producers Association and

25:04

outreach to the presidents of all the individual

25:06

salt producers that were selling their products

25:09

in Michigan. These folks

25:11

were nicknamed the Saltmen.

25:13

This became a.

25:14

Huge cooperative effort between Michigan's

25:17

public health workers and the salt industry,

25:19

with David Marie Cowie being a major

25:22

presence in all of it. Officials

25:24

had to convince the salt industry that adding

25:26

iodine wouldn't affect the quality of their

25:28

product. They even brought in William Hale

25:31

of Dow Chemical Company to demonstrate

25:33

that it would not change the salt's flavor or

25:35

function. They worked at a process

25:38

for adding the iodine at a step into process

25:40

when magnesia was already being

25:42

added to keep the salt free flowing, and

25:45

that cut down on the costs involved.

25:47

They also had to do some outreach within

25:50

the medical community to try to reassure

25:52

doctors that adding iodine

25:54

to the salt would not just flip

25:57

the situation and cause an epidemic

25:59

of hype thyroidism instead

26:01

of hypothyroidism. That

26:04

bit is a little more complicated. The

26:07

amount of iodine that was to be

26:09

added to the salt was nowhere near

26:11

enough to cause hyper thyroidism in

26:13

somebody whose thyroid was actually

26:15

working properly, but it

26:17

was enough to cause problems in people

26:19

who were already experiencing serious

26:22

thyroid dysfunction. According

26:24

to a paper published in the Journal of the European

26:27

Economic Association in twenty seventeen.

26:30

Iodization may have contributed

26:32

to as many as ten thousand deaths

26:34

in the United States between nineteen twenty five

26:36

and nineteen forty two, primarily

26:39

among people who had been chronically

26:41

iodine deficient for a very long

26:43

time like many years. Officials

26:46

in Michigan also wanted to be able to

26:48

clearly document whether this whole effort

26:50

was working, so they set up a research

26:53

program to evaluate the effects

26:55

of iodized salt. This

26:57

started with a baseline survey of the

26:59

rates of guaiter and other thyroid issues

27:01

before iodized salt became available

27:04

in stores, with follow ups

27:06

to see how things changed after people

27:08

had access to iodized salt. A

27:10

lot of this was happening in late nineteen twenty

27:13

three, and on March fifteenth, nineteen

27:15

twenty four, the Michigan State Medical

27:17

Society publicly endorsed the use

27:19

of salt that contained zero point

27:21

zero one percent sodium iodide.

27:24

Six different companies selling salt in

27:27

Michigan had their iodized products

27:29

ready to go that May. Morton

27:31

was something of a latecomer. There were executives

27:34

who had concerns about producing

27:37

iodized salt for only a couple of states

27:39

if that salt was not also being used

27:41

in all of the other states.

27:44

Morton started selling iodized salt

27:46

a few months after everyone else, and by

27:48

the fall of that year, iodized salt

27:50

was available in stores all across the United

27:53

States. In most places

27:55

in the US, iodized and non

27:58

iodized salt were both sold into stores,

28:01

but thanks to extensive public education

28:03

campaigns and advertising on the part

28:05

of the salt companies, most people

28:07

who had access to iodized salt

28:10

bought it. Follow Up studies

28:12

in Michigan showed that once iodized salt

28:14

was widely available, incidents

28:16

of enlarged thyroids dropped by up

28:18

to ninety percent. By nineteen

28:21

thirty two, between ninety and ninety

28:23

five percent of salt sold in Michigan

28:25

was iodized, so by the mid

28:27

nineteen twenties, it was clear that

28:30

iodine had an effect on the prevalence

28:32

of goiter and on hypothyroidism,

28:35

and that salt was an effective way to

28:37

get enough iodine into people's diets,

28:40

but people still didn't fully understand

28:42

why this worked, including within the

28:44

medical community. An international

28:47

conference on goiter was held and burned

28:49

in nineteen twenty seven, and causes

28:51

for goiter that were proposed at this conference

28:54

included intestinal parasites,

28:56

poor hygiene, bad food, and

28:59

contaminated drinking water. A

29:01

lot of the experts cited these

29:03

as the cause of goiter. While agreeing

29:06

that the addition of iodine

29:08

to the salt worked to treat that goiter, they

29:11

concluded, though, that the iodine was killing

29:14

the parasites or destroying whatever

29:16

was contaminating the food or water. Even

29:19

in nineteen thirty three, an article in Public

29:21

Health Reports still characterized

29:23

the cause of endemic goiter as

29:26

the subject of speculation and

29:28

of divergence of opinion.

29:31

David Murray Cowie died on January

29:33

twenty seventh, nineteen forty, after

29:36

a coronary thrombosis. At

29:38

that point, he had been working toward a national

29:40

campaign for iodized salt. His

29:43

replacement, Frederick B. Minor, continued

29:46

toward that goal and helped establish

29:48

an iodized Salt Committee at the American

29:50

Public Health Association. Although

29:53

bills were introduced to mandate iodized

29:55

salt nationwide, none of them

29:57

ever passed.

29:59

Today, laws and standards

30:01

around iodized salt vary

30:04

widely from one country to another,

30:06

but an estimated eighty eight percent

30:09

of people around the world have access

30:11

to iodized salt. For the

30:13

most part, once a nation's salt iodization

30:15

program is well established, people

30:18

typically still have access to iodized

30:20

salt even when war or

30:22

some kind of other unrest disrupts

30:24

other public health measures like vaccine

30:27

programs. But that still

30:29

means that around the world, more than nine hundred

30:31

million people don't have access to

30:33

iodized salt, and an estimated

30:36

fifty million people have enlarged thyroid

30:38

glands and possibly other concerns.

30:40

Because of this, researchers

30:42

have also looked for other ways to distribute

30:44

iodine in places where iodized salt

30:47

isn't practical for some reason or where there's

30:49

some other issue going on.

30:51

One example is the use of iodinated

30:54

poppyseed oil in highland areas

30:56

of New Guinea where iodine deficiency

30:59

is particularly or

31:01

adding iodine to irrigation water

31:03

or animal feeds so that it makes its way into

31:05

other foods. Interestingly,

31:08

the twenty one nations that are currently reported

31:10

as having insufficient iodine intake

31:13

are scattered all over the world in a way that looks

31:16

pretty random on a globe. This

31:18

includes both rich and poor countries.

31:20

In Europe, Asia, Africa, and

31:23

Central America, and there

31:25

are thirteen countries that have too

31:27

much iodine, either from already

31:29

abundant iodine in their diets or

31:32

over iodization of the salt.

31:34

Here in the United States, dietary

31:37

iodine intake has been declining since

31:39

the nineteen seventies. Some

31:41

of this is because of concerns about the connection

31:44

between sodium intake and hypertension,

31:47

although the biggest sources of sodium

31:49

in the typical American diet are processed

31:52

foods that are not usually made

31:54

with iodized salt, not the

31:56

iodized table salt that people

31:59

might be avoiding. But another

32:01

reason is just an increasing preference

32:03

for things like sea salt and kosher

32:06

salt and Himalayan pink salt.

32:08

These are typically not iodized, although

32:11

there are some brands that do carry

32:13

iodized versions of these products.

32:16

At this point, a lot of people in the US

32:18

are getting more of their iodine from dairy

32:20

products than from table salt, which

32:22

means the rising preference for non dairy

32:25

milks is playing a part in this story as

32:27

well. Whether a plant based

32:29

milk contains iodine depends on what

32:31

it is made of. Some of them use

32:33

thickeners made from seaweed, although the

32:36

iodine and the seaweed might not make

32:38

it through the manufacturing process.

32:40

In the United States, nutrition labels

32:43

typically only list iodine content

32:45

if that was added into the product, not

32:47

if the iodine occurs naturally, and

32:50

that can make it tricky to know how much

32:52

iodine a person is actually getting, and

32:54

this affects people who are trying to get enough

32:57

iodine as well as people who need

32:59

to avoid iodine. For

33:01

example, people who are getting radioactive

33:03

iodine treatment are typically advised

33:06

to avoid iodine in their diets.

33:09

Since we have a whole episode on the

33:11

history of radio iodine treatment, we're

33:13

gonna run that as a Saturday Classic because

33:15

it overlaps with this.

33:16

A little bit. Do you also

33:19

have listener mail for us? I do have

33:21

listener mail for us. It is from Jody.

33:24

Jody wrote, Hi, Holly and Tracy.

33:27

Usually I listened to your podcast weekday

33:29

mornings when getting ready for work, but when I saw

33:31

this week's lineup was food themed,

33:34

I decided to spend my Saturday afternoon

33:36

with you. What caught my eye

33:38

was banana ketchup. This came

33:41

on my radar a few years ago after I moved

33:43

from the Florida Keys to Las Vegas,

33:45

Nevada, where there's a much larger Filipino

33:47

population. I'm also a

33:49

canner and had to figure out what

33:52

to do with the fifteen ish pounds

33:54

of bananas that showed up with an Instacart

33:57

order instead of the one bunch

33:59

I was exp This was

34:01

during the pandemic, so another quick

34:03

sweetbread was out of the question. I

34:06

look forward to reading more about Maria Rosa's

34:09

story using your references as a guide.

34:11

As for how my banana ketchup turned

34:13

out, it was interesting.

34:15

Lol.

34:16

Here's the safe canning recipe I used.

34:18

There's a link to a recipe for banana

34:21

ketchup. A Filipino co worker

34:23

tasted it and approved, but my brain

34:25

had trouble making sense of the color and

34:28

I couldn't eat it with fries. But I do

34:30

make a beat ketchup that gets

34:32

gobbled up, so I know that's just in my head.

34:35

That being said, I do try to run a

34:37

zero waste kitchen, so I use it

34:39

as a base for barbecue sauce for grilled

34:42

ribs, and my guests kept trying to figure

34:44

out what the secret flavor was while licking

34:46

their fingers attached for cat

34:48

tacks are picks of our ten year old spicy

34:51

cat Ella and almost four year

34:53

old goofball Jazzber. My

34:55

husband is a jazz musician, so Ella

34:57

is named after Ella Fitzgerald, and Jazz

35:00

has not stopped purring since we adopted him

35:02

from a shelter. His eyes looked like green

35:04

jasper. This

35:10

cat's I like this. I'm looking

35:12

at a picture of a black cat with a

35:14

very startled expression. I

35:19

don't know if this kitty cat is

35:21

actually startled, but

35:23

that's that's the way that it struck me. And then there's

35:26

also other kitty cat, so I'm

35:28

guessing this one is Ella.

35:29

Ella is on a bookshelf.

35:32

Posed in such a way that at first

35:34

I thought this was like a cat

35:37

figurine.

35:38

No, it is the real cat on the bookshelf.

35:41

Thank you so much.

35:42

I'm so interested about number

35:44

one hearing the that

35:47

you know, somebody just needed

35:49

to make some banana ketchup at home because of all of these

35:51

extra bananas. And then it also reminded me of

35:53

experience I had in

35:55

the early pandemic years

35:58

when I had an order from

36:01

like a place that sold locally

36:04

grown fruits

36:06

and vegetables and things, and the

36:09

it was described as a pound of halapeno

36:12

peppers, and I was like, I don't think

36:14

that can be right, don't I don't think I'm gonna

36:16

get a whole pound of halapeno peppers.

36:18

I did, so

36:21

I made a bunch of infused vodka

36:23

with because that was more holopenos

36:25

than I needed at that moment. Uh

36:28

So, thank you so much for that email. If

36:31

you would like to send us a note about this or

36:33

any other episode, where at History Podcasts

36:35

at iHeartRadio dot com, and

36:38

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36:40

the iHeartRadio app and anywhere

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36:50

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