Rickets

Summary

Episode Overview

Podcast: Stuff You Missed in History Class
Hosts: Tracy V. Wilson and Holly Frey
Episode: Rickets (Jan 26, 2026)

In this episode, Tracy and Holly delve into the historical understanding of rickets, a disease caused by vitamin D deficiency. The conversation explores how rickets was identified, named, depicted, and misunderstood before its connection to vitamin D and sunlight was made clear. The hosts bring together archaeology, medical history, and social context to illustrate how both scientific advancement and changing societies shaped our knowledge and treatment of rickets.

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Key Discussion Points and Insights

1. Introduction to Nutritional Deficiencies and Rickets

[02:52] Tracy: The hosts introduce the theme, highlighting that rickets, like scurvy and pellagra, was treated effectively before its actual cause (vitamin D deficiency) was understood.

• Early treatments for deficiency diseases predated modern biochemistry.
• “People figured out two ways to treat [rickets] before we even knew what vitamin D was.” [03:40] Tracy

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2. The Etymology and Naming of Rickets

[04:23] Holly, [05:03] Tracy:

• The origin of the word “rickets” is unclear.
• Possibilities: It might derive from a surname, from the word "rucket" (to breathe with difficulty), or from German/Swedish words meaning twisting/swaying.
• The disease was also known as “rachitis” (Latin/Greek), describing spinal inflammation.

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3. What is Rickets? The Biological Basis

[05:46] Holly, [06:24] Tracy, [06:51] Holly:

• Rickets affects bone growth in children and young animals due to lack of vitamin D, which impairs calcium absorption and bone mineralization.
• Vitamin D comes from two main sources:
  • Diet (egg yolks, certain fish, wild mushrooms)
  • Sunlight (UVB converts cholesterol in the skin to vitamin D)
• “In the body, Vitamin D is converted into a hormone that affects the way calcium is absorbed in the digestive system.” [05:46] Holly

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4. Sunlight, Skin Color, and Vitamin D Synthesis

[07:46] Holly, [08:21] Tracy:

• UVB exposure varies by latitude and can be blocked by glass, clothing, fog, and air pollution.
• Skin melanin reduces vitamin D synthesis; people with more melanin (darker skin) need more sun exposure.

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5. Historical Prevalence of Rickets and Changing Lifestyles

[08:21] Tracy, [09:24] Holly:

• Ancient populations (hunters, gatherers, farmers) spent more time outdoors, limiting rickets.
• In the far north, lower sunlight was offset by diets rich in vitamin D (e.g., from fish).
• Babies are especially vulnerable (breast milk is low in D, swaddling reduces sun exposure).

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6. Archaeological and Early Written Evidence

[10:30] Holly, [11:17] Tracy, [12:01] Holly:

• Archaeological finds (e.g., 5,000-year-old Scottish skeleton, Roman-era bones) show signs of rickets.
• Possible earliest written description: Soranus of Ephesus (~1st–2nd century CE) described infant care practices likely aimed at preventing deformity (“bowed legs and spinal curvatures are two of the most recognizable symptoms of rickets.” [12:01] Holly)

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7. Recognition and Documentation in Early Modern Europe

[16:53] Tracy, [17:37] Holly, [18:43] Holly:

• Rickets becomes widely recognized in the 16th–17th centuries (artwork, medical records).
• Descriptions of children with bow legs or “richetic rosary” (knobs on the ribs) appear in medical accounts.
• Special waters (e.g., St. Willibrord's well) were used to try to treat these ailments.

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8. The Naming and Recording of Rickets

[19:17] Tracy, [19:47] Holly:

• The first written use of “rickets” appears in a Yorkshire family’s medical receipt book (1632).
• The London Bill of Mortality (1634) lists rickets as a cause of death, indicating growing awareness.

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9. Early Medical Theories and Social Implications [22:49–25:29]

• Daniel Whistler’s 1645 thesis: Detailed clinical description, identifies symptoms and speculates about causes (blood clots in viscera, class associations).
• Francis Glisson’s 1650 treatise: So influential, rickets is called “Glisson’s disease” or "English Disease" in parts of Europe.
• Early physicians thought rickets was new and especially common in England, possibly due to environmental changes (Little Ice Age, smog, poor nutrition).

Notable Quote:
“Glisson’s work was so influential that some people started calling rickets Glisson’s disease.” [25:08] Holly

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10. Early (Ineffective) Treatments and the Move Toward Cod Liver Oil and Sunlight

[26:31] Holly, [26:58] Tracy, [27:53] Holly:

• Initial treatments followed humoral medicine, lacked efficacy.
• Cod liver oil emerged in the 18th century as an effective remedy—accidentally discovered as it was used for general malnutrition.
• Sunlight recommended by Polish physician Jedrez Sniadecki (1822) as preventive/cure ("the sun’s action on the body was one of the most efficient methods for the prevention and cure of rickets.” [28:32] Tracy).

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11. Urbanization, Industrialization, and Public Health

[29:31] Holly, [30:21] Tracy:

• Industrial Revolution: Crowded cities, indoor labor, coal pollution -> rising rickets rates.
• Dietary changes (reduced fish, whiter flour with alum) may have made the problem worse.

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12. Rickets in Animals and Institutional Research

[31:26] Holly:

• Rickets observed in zoo monkeys living behind glass (blocking UVB); many died of rickets rapidly.
  • “Nearly half of the monkeys in the gardens die rickety.” (John Bland Sutton, 1883)

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13. Sunlight vs. Cod Liver Oil: Divergent Theories

[32:13] Tracy, [33:28] Holly:

• Into the early 20th century, some doctors argued for sunlight while others saw cod liver oil as the solution.
• Theobald Palm attributed low rickets rates in sunny Japan to “abundant sunshine” – missing the role of fish-rich diets.

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14. Discovery of Vitamins and The Science of Rickets

[33:28] Holly, [34:50] Holly:

• 1912: Casimir Funk coins "vitamin," identifies rickets as a deficiency disease.
• Researchers hunt for the “anti-rachitic” (anti-rickets) factor, leading to confusion between vitamin A and D.
• Both cod liver oil and sunlight prove effective, but exact mechanism unclear for a time.

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15. Landmark 20th-Century Studies

[34:50] Holly, [35:23] Tracy, [36:18] Holly:

• UV lamps found to cure rickets (even treating both arms when only one exposed).
• Cod liver oil shown to prevent rickets (not just treat it).
• Historical studies in NYC highlight higher risk among Black children due to less vitamin D synthesis at northern latitude.

Notable Moment:
“Today, this study would not be viewed as ethical, since other studies had already established that cod liver oil could be used to treat rickets.” [36:18] Holly

• Acknowledgment: Prevalence in Black communities was weaponized as racist pseudo-science (“This again was just about melanin and the sun.” [36:47] Tracy)

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16. Isolation and Naming of Vitamin D

[37:06] Holly, [37:40] Tracy:

• Researchers distinguish vitamin D as separate from A; Elmer McCollum names it.
• 1921–22: Harriet Chick’s Vienna study shows both cod liver oil and sunlight prevent and cure rickets in infants—acceptance that both are valid.

Notable Quote:
“This study helped establish that rickets could be treated with both cod liver oil and sunlight. This was not the one or the other situation that a lot of researchers had been thinking that it was.” [39:30] Tracy

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17. Decline and Modern Concerns

[40:04] Holly, [40:23] Tracy:

• Widespread use of cod liver oil, vitamin D supplementation, and fortification led to a sharp decline in rickets.

• Rickets persists for those with absorption disorders (celiac, IBD, cystic fibrosis), or with little sun exposure.

• Modern debate: Does sunscreen use contribute to rickets? Probably not as much as lack of outdoor time.

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Notable Quotes & Memorable Moments

• “People figured out two ways to treat [rickets] before we even knew what vitamin D was.”
  — Tracy V. Wilson [03:40]
• “Bowed legs and spinal curvatures are two of the most recognizable symptoms of rickets.”
  — Holly Fry [12:01]
• “Glisson’s work was so influential that some people started calling rickets Glisson’s disease.”
  — Holly Fry [25:08]
• “Nearly half of the monkeys in the gardens die rickety.”
  — John Bland Sutton (quoted by Holly Fry) [31:30]
• “The sun’s action on the body was one of the most efficient methods for the prevention and cure of rickets.”
  — Jedrez Sniadecki (translated by Tracy) [28:32]
• “This study helped establish that rickets could be treated with both cod liver oil and sunlight. This was not the one or the other situation that a lot of researchers had been thinking that it was.”
  — Tracy V. Wilson [39:30]

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Timestamps for Important Segments

• [02:52] — Topic introduction: nutritional deficiencies and early treatments.
• [05:03] — Etymology and history of the word “rickets.”
• [05:46]–[06:51] — Biological explanation of rickets: causes and sources of vitamin D.
• [08:21] — Discussion on early human populations, skin color, and sun/vitamin D.
• [10:30] — Archaeological and Roman-era evidence.
• [16:53] — Rickets in the Renaissance: early modern Europe and art.
• [19:17] — First written English use of “rickets.”
• [22:49]–[25:29] — Medical treatises and theories of causation.
• [26:58] — Emergence of cod liver oil as a remedy.
• [28:32] — Early advocacy for sunlight as a treatment.
• [31:26] — Victorian zoos and rickets in animals.
• [33:28] — Discovery of vitamins and the anti-rachitic factor.
• [34:50]–[39:30] — Key 20th-century studies and discovery of vitamin D.
• [40:04] — Modern persistence of rickets and concerns about sun exposure.

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Overall Tone and Style

The conversation is consistently enthusiastic, inquisitive, and respectful of the science and social context of rickets. Both hosts use humor and conversational asides to make the dense historical content engaging and relatable. They are careful to acknowledge changing scientific understanding and the effects of social context (like racism and urbanization) on public health.

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Conclusion

The episode traces the fascinating evolution of our understanding and treatment of rickets, from ancient misattributions and ineffective remedies to the eventual recognition that both sunlight and specific foods could prevent and cure the disease. Along the way, Tracy and Holly explore how language, environment, nutrition, and social changes intersect to influence disease and medicine—reminding us how often solutions precede explanations in medical history.

Transcript

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[Holly Fry]

Welcome to Stuff youf Missed in History Class, a production of iHeartradio.

[Tracy V. Wilson]

Hello and welcome to the podcast. I'm Tracy V. Wilson.

[Holly Fry]

And I'm Holly Fry.

[Tracy V. Wilson]

Once again, I'm returning to the realm of nutritional deficiency diseases. I just find them very interesting, especially because people have really figured out how to treat them way before they figured out exactly what was causing them, which has not always been the case with other diseases. Like scurvy is caused by vitamin C deficiency, and people had figured out that some foods, including citrus fruit, could prevent scurvy by the 17th century. So today we know that these foods are good sources of vitamin C. But people made the connection between the food and the scurvy well over a century before Casimir Funk even coined the word vitamin. And that also happened before any individual vitamin had been identified and named. We have an episode on scurvy, and then last year we also did an episode on pellagra, which is caused by niacin deficiency. People were similarly treating pellagra with brewer's yeast decades before we knew what niacin was or that brewer's yeast has a lot of it in there. The discovery and identification of specific vitamins grew in part from people trying to figure out what exactly people were missing with that missing substance making them sick. Nutritional rickets is caused by a vitamin D deficiency, and people figured out two ways to treat it before we even knew what vitamin D was.

[Holly Fry]

So it's a fun word to say, but we don't really know where the word rickets even comes from. English physician Daniel Whistler wrote a thesis on Rickets in 1645 and claimed that it had been named for someone who had supposedly tried to cure it, or from the term to ruck it, which he said was used in parts of England to mean to breathe with difficulty. While there were people whose surname was rickett, there's really no evidence of any of them trying to cure this disease. And it's also not clear whether there is any merit to that rucket idea. Another possibility is that it comes from German or Swedish words meaning twisting or swaying.

[Tracy V. Wilson]

Yeah, I went down a big rabbit hole trying to figure out if in 1645 people in parts of England were using the word to rucket this way. Did not find a good answer. In the 17th century, rickets was also called rachitis, and that came from Latin and Greek words to describe disorders or inflammations of the spinal column. The symptoms of rickets can include spinal pain and unusual spinal curvatures. So it's possible that doctors writing In Latin used the word rachitis because of these symptoms. And then laypeople shifted that pronunciation to rickets. But again, that is all very speculative.

[Holly Fry]

Rickets affects growing animals, not only human beings. In the body, Vitamin D is converted into a hormone. That affects the way calcium is absorbed in the digestive system. And it has other effects on calcium in the body. To put it really, really, Basically, without enough vitamin D. The body cannot absorb the calcium needed for bones to mineralize properly. Rickets usually affects animals during infancy, childhood, and adolescence. When their bones are growing in mineral. Especially during growth spurts. A similar vitamin D deficiency in adults is called osteomalacia.

[Tracy V. Wilson]

Animals get vitamin D from two primary sources. Their food and exposure to the sun. Foods that are naturally high in vitamin D include egg yolks and various types of fish like salmon, tuna, and sardines. Wild mushrooms can also be high in vitamin D. But commercially grown mushrooms that are raised in the dark typically aren't. They aren't getting that sun exposure themselves to have vitamin D today.

[Holly Fry]

Some foods are also fortified with added vitamin D. Although which foods, Whether fortification is voluntary or mandatory for manufacturers. And whether foods are fortified at all Depends on where you live. In the United States. Foods that are most likely to be fortified with vitamin D. Include dairy and non dairy milks or orange juice and breakfast cereals. All of which are associated, of course, with children's diets.

[Tracy V. Wilson]

In terms of sun exposure, Again, very, very basically. UVB radiation converts cholesterol in the skin to cholecalciferol, which is the more formal name for vitamin D.3 this requires direct exposure to the sun. Because UVB is blocked by things like glass. And clothing. Can also be blocked or at least reduced by things like fog and air pollution.

[Holly Fry]

UVB radiation is also affected by the Earth's atmosphere. And the angle at which sunlight reaches the surface of the Earth. Areas at very high latitudes get a lot less UVB light than the tropics do. And since melanin protects the body from UV light. The amount of vitamin D that a person's own body can synthesize. Is affected by how much melanin they have in their skin. People with more melanin, meaning people who are darker skinned. Need more sun exposure. To be able to synthesize enough vitamin D Than people with lighter skin.

[Tracy V. Wilson]

We don't really know whether rickets was a widespread problem during early human history. But it might not have been early hunters and gatherers. And then later on, early farmers. Would have been spending a lot of time outside in the sun. In the tropics, where in the long ago past, more people had more melanin in their skin, the sun was also a lot more direct, so they would have been getting more UVB exposure. Of course, those things are interconnected, the UV light and the melanin. Conversely, in the far north, for example, people had less exposure to sunlight, since even during the long days of the summer, the sun's rays just aren't as direct. And people also tended to wear more clothing because it was colder. But these indigenous peoples have also historically had a diet that is rich in vitamin D. People still living in the same places that their ancestors did, following the same traditions and life ways, are probably getting a lot of their vitamin D the same ways today.

[Holly Fry]

At the same time, it is possible, and maybe even likely, that people around the world did historically go through periods when they weren't getting enough vitamin D, especially in the winter or during times of famine. But this might not have been an ongoing problem problem, since most people would have been spending more time outside again in the spring.

[Tracy V. Wilson]

One big exception here, at least in theory, is babies. Because breast milk alone does not provide infants with enough vitamin D. It would take a lot of vitamin D supplementation for a person to produce breast milk that was really rich in vitamin D, like way beyond what someone would get through ordinary food and sunlight. So throughout history, babies who were breastfed and then also swaddled or covered up or kept out of the sun could be susceptible to rickets. Today, various health organizations around the world recommend that breastfed babies be given a vitamin D supplement, especially if they are exclusively breastfed.

[Holly Fry]

We do have some evidence of rickets in the archaeological record. In 2013, archaeologists in Scotland announced the discovery of a 5,000-year-old skeleton that showed evidence of rickets. That is the oldest example discovered so far. Prior to this discovery, the oldest skeletons known to have signs of rickets were from the Roman era. And there's some evidence to suggest that it may have been more widespread in the Roman Empire. For example, in 2018, researchers from Historic England and McMaster University in Canada surveyed Roman era skeletons from cemeteries from what's now northern England down to southern Spain. And they found evidence of rickets in more than one in 20 children with babies most often affected.

[Tracy V. Wilson]

What may be the earliest written description of rickets also comes from the Roman era. Soranus of Ephesus wrote a treatise on gynecology around the first or second century ce. It includes a section about the care of newborns. And in this section, he advises loosening a baby's swaddling clothes only after their body has become reasonably firm so that it does not become distorted. Siranas also recommends not letting babies try to sit up too early or for too long because that could cause them to become hunchbacked. And he says if a baby is allowed to try to walk too early, their legs can become distorted.

[Holly Fry]

Bowed legs and spinal curvatures are two of the most recognizable symptoms of rickets, so this is often interpreted as a description of the condition. There is some debate about whether that's really what he's talking about, but serranus is generally more accepted as the first description of rickets than some earlier but even more vague possibilities.

[Tracy V. Wilson]

Yes, sometimes it's a brief sentence that sort of seems like maybe someone's leg was growing in a strange way. Could that have been rickets? Maybe. Of course, rickets is definitely not caused by unswaddling a baby too early. It is not caused by letting babies try to stand up too soon after they're born. And we really don't have any way to know if what Sirrannis is describing in this passage is something that he also would have recognized in the children from that 2018 study we mentioned, or if the children in that study were seen as having some kind of illness or condition relating to their bones or while they were alive.

[Holly Fry]

Rickets was not recognized as a disease with a name until the early modern period, and we're going to get into that after we pause for a sponsor break.

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[Tracy V. Wilson]

Rickets seems to have been a more widespread problem in parts of Europe in the 16th and 17th centuries. Or at least that is when it seems to start showing up more in artwork and in written records. In 1509, German painter Hans Borchmeier the Elder painted a version of the Virgin and Child in which the infant Jesus appears to have bowed legs and other possible signs of rickets. In 1532, German physician Hieronymus Reusner described a disease that occurred only in children whose symptoms included weakness, bowed legs, and chest malformations. Roizner said this disease was common in Holland and Switzerland.

[Holly Fry]

In 1554, Theodosius of Bologna described a child who was very pale and had an unusual spinal curvature which could have been rickets. Other accounts in the late 16th century described children whose bones were bent and who seemed to have some kind of wasting disease.

[Tracy V. Wilson]

In 1614, a visitor to a monastery in the Netherlands, which was at the time part of the Dutch Republic, described children being treated with water from a well dedicated to St. Willibrord. These children were described as having St. Willibord's infirmity, or the ailment of St. Willibrord. One of the symptoms was a series of knobs on the children's ribs, described as being like pinheads or rosary beads or something of a similar size. Some of these children were also described as having the ailment of St. Machetus, in which their legs appeared as though they were sitting cross legged. It was possible for a child to have both of these ailments at once.

[Holly Fry]

As we said earlier, bowed legs are one of the most recognizable signs of rickets. Another is called richitic rosary. These are knobs that develop where each rib connects to the costal cartilage on the front of a person's rib cage, and they're named for their resemblance to a string of rosary beads. So it seems likely that at least some of these children that Tracy was just talking about had rickets. There were also other Willebrord wells and springs around the Netherlands, and their water was similarly used to try to treat children who had these conditions.

[Tracy V. Wilson]

The first known use of the word rickets in writing was a couple of decades after this visitor report. Unlike most of the first uses in writing we've talked about before, this was not in published material. It was a handwritten receipt book belonging to the Fairfax family of Yorkshire, England. People used to call recipes receipts and the word Receipt could also apply specifically to the ingredients and methods used to make medicinal preparations.

[Holly Fry]

This particular receipt book had belonged to Mary Cholmondeley, who married the Reverend Henry Fairfax in 1626. The book remained in the family, with people recording recipes for things like foods, medicines and household preparations into the late 18th century. Some of the entries were attributed to well known physicians of the day, and others came from relatives or friends. An entry for February 25, 1632, includes five remedies for rickets in children attributed to the Reverend's cousin, Lady Fairfax of Steaton. There are also various recipes labeled for the rickets and one marked for a child that is weak or lame in her joints.

[Tracy V. Wilson]

None of these remedies would have been effective in treating rickets. They included things like ointments made of herbs minced into butter, and drinks being made of things like herbs or dried fruit boiled in water or ale. But this suggests that by the first quarter of the 17th century, people in England knew about a disease that they were calling rickets and that they were trying to figure out ways to treat it.

[Holly Fry]

The first use of the word rickets in published material was in the Annual Bill of Mortality of the City of London in 1634. This was only the fifth year that the annual Bill of Mortality included causes of death. This information was gathered by people called searchers who were described as elderly matrons.

[Tracy V. Wilson]

Made a lot of sense for older women to be doing this job, since they were typically involved in laying out the dead and preparing people's bodies for burial. Good fit for them to also be the people determining cause of death. Since older women often cared for sick people, people also thought they might have some protection from whatever illness a person might have died of. And that experience could also theoretically help them identify and describe a person's cause of death.

[Holly Fry]

At the same time, these women typically didn't have access to a formal education. Most of them could not read or write. So they gave their reports to the clerk orally. And that means we don't have any details or notes about how they determine the causes of death. So at the time, these searchers were seen as knowledgeable and respected members of their community who were doing important work. But today, their reports are not really seen as an accurate accounting of what people were dying of.

[Tracy V. Wilson]

All of that said, in 1634, the annual bill of Mortality of the City of London reported that 14 people died of rickets out of almost 11,000 total deaths in the city. And while no English medical treatises have been unearthed that mention rickets before this point, it seems like it must have been something the medical community would have been aware of, otherwise how would it be reported as a cause of death in this official document?

[Holly Fry]

The first known clinical description of rickets was written by Daniel Whistler in his MD thesis at the University of Leiden in the Netherlands. That is where a lot of people from Britain and Ireland went to study medicine. And this was written in Latin and its title translated to concerning the Disease of English Children, which in English it is called rickets. Whistler defended this thesis on October 18, 1645, and he would eventually go on to be the president of the College of Physicians.

[Tracy V. Wilson]

In this work, Whistler described rickets as common in England. He listed a series of symptoms including enlargements at the ends of the bones, weakness, deformities of the limbs, unusually flexible joints, delayed emergence of the teeth, decay in the teeth once they had emerged, and chest malformations. All of these very physically recognizable signs of rickets. He also listed some other symptoms that were not related to the skeletal system, like cough, fever, irregular pulse and digestive distress. Some of these can occur in severe cases of rickets. He speculated that rickets was caused when blood clots form in the viscera. And he said that the disease was often fatal, especially in children who were affected with it from birth.

[Holly Fry]

Whistler also described rickets as something that was most frequent in England's wealthiest people, with the next most affected group being the poor. He thought that as a group, people in the middle were the least affected by rickets. He attributed the rate of rickets among the wealthy to the use of wet nurses, and when it came to poor people, he blamed, quote, the intemperance of parents.

[Tracy V. Wilson]

Other works on rickets soon followed. One was a book chapter by Arnold Boot, which was printed as part of a book on medicine that came out in 1649. Boot was born in Holland and practiced medicine in Ireland. Then in 1650, English physician Francis Glisson printed the longest and best known 17th century treatise on rickets. Its title translated to A Treatise of the Rickets Being a Disease Common to Children.

[Holly Fry]

Glisson's work was so influential that some people started calling rickets Glisson's disease. And in some other parts of Europe it was known as English Disease. All these works were written in Latin, which was the shared language of the European medical community. But most of them used the English word rickets for the name of the disease.

[Tracy V. Wilson]

Most of the people writing about rickets in the mid 17th century thought it was a new disease that had only been seen for the previous couple of decades. It's possible that this was just connected to growing awareness and more doctors starting to look for this disease. But it's also possible that rickets was becoming a bigger issue. This was during the period of regional cooling known as the Little Ice Age, when parts of the world, including parts of Europe, were generally cooler and wetter and cloudier. This could have affected how much sunlight people got. It also led to poor harvests and food shortages that could have led to other nutrient deficiencies that people might have mistaken for rickets. And it's also possible that in major cities, air pollution was becoming a factor. London, in particular, was described as being blanketed in a cloud of smog that could be seen from miles away. We will be talking about that more in a future episode.

[Holly Fry]

It is likely that people were experiencing rickets in other parts of the world as well. But most of the writing about it is from northern and western Europe. And at this point, there was no effective treatment being used in Europe. The idea of four humors was still a very big part of medicine. So most of the proposed treatments were influenced by that. In general, they did not include any vitamin D. No.

[Tracy V. Wilson]

We will get to the first effective treatments for rickets after a sponsor break. The first effective treatment for rickets was cod liver oil, which we know today is high in vitamin D. As that name suggests, this is an oil made from the liver of Atlantic code that Atlantic cod live in coastal waters in the northern Atlantic Ocean. By the 1700s, people who lived in areas that were home to a lot of cod fishing had started using cod liver oil for a range of medicinal purposes, including as a treatment for arthritis, sciatica, tuberculosis, and scrofula, which is a swelling of the lymph nodes in the neck that is typically caused by tuberculosis.

[Holly Fry]

The discovery of cod liver oil as a rickets treatment may have been an accident. A lot of children who had rickets also had other conditions, such as tuberculosis, and some were more generally malnourished. So in the 18th century, doctors and hospitals were using cod liver oil to treat a range of ailments and as a source of fat and calories for malnourished children. And people started noticing improvements in children who were recognized as having rickets, and children who weren't diagnosed with rickets, but were just seen as small and sick started growing more and faster than could be explained simply by getting more food to eat.

[Tracy V. Wilson]

By the early 19th century, another proposed treatment for rickets was sunlight. Polish physician Jedrez Sniadecki proposed sunlight as A cure for rickets. As early as 1822, he wrote a book whose title translates to on the Physical Education of Children, and it had a chapter on the English disease. In that chapter, he said that if parents were financially able, they should take their children to the country to keep them in the dry, open air. And he said it was particularly important that they be in the sun, because the sun's action on the body was one of the most efficient methods for the prevention and cure of rickets. I do not know how he came to that conclusion, but it was correct.

[Holly Fry]

It may have just been that general fresh air and the great outdoors is good for kids.

[Tracy V. Wilson]

There was a lot of fresh air and sunlight focus. So it just might have been that.

[Holly Fry]

Snowdecki cited densely populated English towns as places where rickets was common. He described such towns as having narrow streets and poorly lit dwellings, places where people would not get a lot of sun. And starting in the 18th century, in the UK and in other parts of the world, more and more people were living this way. In the wake of the Industrial Revolution, more people were moving from the country to towns and cities and were working indoors in factories, and this included children. The air pollution problems that had already been observed back in the 17th century were also getting worse because many of those factories were powered by burning coal. Soon rickets was being associated with the urban poor, particularly in the uk, but in other industrialized nations as well.

[Tracy V. Wilson]

It's possible that there may have also been some dietary changes involved in this as people moved to the cities, especially if, for example, they moved from the coast where they were eating a lot of fish to somewhere farther inland where they were not. One potential factor in London was also the use of alum to whiten poor quality flour. Physician John Snow, most famous today for tracing the source of a cholera outbreak in London, understood that rickets was a disease that affected the mineralization of bone. In 1857, he published a paper arguing that alum was binding to phosphorus in the intestines of people who ate a lot of cheap bread and that kept their bones for mineralizing. People did already know what phosphorus was. Hennig Brand had figured that out after boiling huge amounts of urine, just enormous amounts of urine way back in 1669. We have scheduled that as an upcoming Saturday classic.

[Holly Fry]

I got 1500 gallons of urine in.

[Tracy V. Wilson]

My it's the Pee Guy workshop.

[Holly Fry]

You want to come see? In the 19th century, people also started noticing rickets in other animals, including animals that were living in the gardens and of the London Zoological Society, for example, surgeon John Bland Sutton described rickets as extremely frequent in the monkeys living in the garden. In 1883, he wrote a paper titled on the Diseases of Monkeys in the Society's Gardens, in which he said nearly half of the monkeys in the gardens die rickety. That is his direct quote, and that healthy monkeys that arrived in the gardens were dead of rickets within four months. These monkeys lived in a fully glassed in enclosure that would have blocked the UV light.

[Tracy V. Wilson]

By the late 1890s, two schools of thought had evolved around one that it could be cured with cod liver oil and the other that it could be cured with sunlight. And a lot of doctors really thought it was one or the other, not both, or they focused mainly on one and not on the other. For example, physician Theobald Adrian Palm wrote a letter to the British Medical Journal in 1888 in response to a report on rickets that had made the quote, want of light sound unimportant. Palm was objecting to that dismissiveness. He had worked in Japan for almost 10 years and described rickets there as, quote, conspicuous by its absence. Since he attributed this to Japan's abundant sunshine, he speculated that a worldwide study would find that rickets is directly related to an absence of sunshine. He advocated the use of sun baths as treatment. He did not, at least in this piece, seem to make any connection with cod liver oil and the fact that the Japanese diet included a lot of fish.

[Holly Fry]

Meanwhile, advocates of cod liver oil and other fish oils were bolstered by the work of Casimir Funk. In 1912, he coined the term vital amines or vitamins to describe compounds necessary for life. He theorized that a lack of vital amines could cause what he called deficiency diseases, including scurvy, pellagra and rickets. The first vitamin to be isolated and named was vitamin A a few years later, followed by vitamins B and C.

[Tracy V. Wilson]

They were named that because that's the order of the Alphabet. The search for vitamins was partly rooted in a search for nutrients that could prevent these diseases. When it came to vitamin C, that disease was of course, scurvy. And the search was for a substance with antiscorbutic properties, meaning the ability to fight off scurvy. So with these developments, researchers were also looking for a compound with anti rickets properties. When cod liver oil was found to be a good source of vitamin A, after vitamin A was isolated, people started wondering if that was the anti rakytic component. And this led to some confusion and some like kind of overlapping research about why exactly cod liver oil was an effective Treatment for rickets.

[Holly Fry]

As that vitamin research was going on, there were also ongoing efforts to study the use of both UV light and cod liver oil to treat rickets. In 1918 and 1919, a Dr. Holchinsky successfully demonstrated the use of UV lamps to treat rickets in children. He also noted that using the UV lamp on one arm treated rickets in both arms. And he speculated that the UV light was causing the synthesis of some kind of compound that could then circulate all throughout the body.

[Tracy V. Wilson]

At around the same time, American doctors Alfred Hess and Lester Unger were testing cod liver oil as a treatment and preventative for scurvy in black children in New York City. As we noted earlier, people with darker skin are at greater risk for rickets because of the amount of melanin in their skin compared to these strength of the sun at that latitude, just not as much direct sunlight in New York than in parts of Africa. For example, cod liver oil treatments either prevented the onset of rickets or led to its resolution in 92% of infants who were treated for six months, and in more than half of the infants who were treated for four months. Sixteen infants in the control group were not given any cod liver oil, and nearly all of them had rickets by the end of six months.

[Holly Fry]

Today, this study would not be viewed as ethical, since other studies had already established that cod liver oil could be used to treat rickets. What wasn't as well established was whether cod liver oil could prevent rickets, not just treat it, and this study was the first to show that it could. The Henry Street Settlement House, which was involved with this study, also became a rickets screening and treatment center for the community more broadly as it was going on.

[Tracy V. Wilson]

Also, we should take a moment to note that the prevalence of rickets among black people living in North America was used to justify racism, with racists arguing that it signaled some kind of inherent weakness in their bodies. This again was just about melanin and the sun.

[Holly Fry]

Vitamin D was isolated and named not long after this study. Multiple people contributed to its discovery, some of them through their previous work on vitamin A. In 1919, Edward Melanby wrote about a fourth vitamin, the absence of which could cause rickets, concluding that it was either vitamin A or another fat soluble vitamin that's found in a lot of the same foods as vitamin A. Elmer McCollum, who had helped discover vitamin A, differentiated the two, and he was the one who coined the name vitamin D. In.

[Tracy V. Wilson]

1922, bacteriologist Harriet Chick of the Lister Institute of Preventive Medicine in London led a team from the British Medical Research Council to Vienna to study rickets there. They had been invited by Charles Perquet, director of the University of Vienna's Kinder Clinic. This was an unusual research team for the time because most of its members, including Chick, were women.

[Holly Fry]

They divided the babies into two groups. Group one continued on the Kinder Clinic's regular diet, which included local cow's milk and sucrose, while group two had full cream dried milk with some added sugar supplemented with cod liver oil. They assessed the babies for rickets using X rays. Half of the babies in group one developed rickets, while none of the babies in group two did.

[Tracy V. Wilson]

This study took place over the course of 1921 and 1922, and the results were different based on the season. Babies in group one who had showed signs of rickets early in the year seemed to improve in the spring and summer, so the team did further research to narrow down whether this had something to do with the quality of the local milk changing seasonally, or if it was the fact that the babies were being placed outside on balconies as soon as the weather was warm enough.

[Holly Fry]

Eleven babies from group one were kept strictly indoors for about three months and developed rickets, and they all rapidly improved after being brought outdoors when the weather allowed it. Babies also improved after being exposed to light from a mercury vapor lamp. The babies in group one who had developed rickets also rapidly improved once cod liver oil was added to their food.

[Tracy V. Wilson]

This study helped establish that rickets could be treated with both cod liver oil and sunlight. This was not the one or the other situation that a lot of researchers had been thinking that it was. By 1925, this was generally accepted within the medical community. And then over the 1920s and 30s, researchers figured out how to produce vitamin D, allowing it to be added to things like infant formula and other food. That led to a sharp decline in rates of rickets in some parts of the world.

[Holly Fry]

Rickets continues to be an ongoing issue, though. In addition to the things that we've talked about, people who have other conditions that affect their absorption of nutrients can certainly develop rickets. This includes celiac disease, inflammatory bowel disease, and cystic fibrosis, among others.

[Tracy V. Wilson]

In more recent years, there have also been concerns that advice to wear sunblock to prevent skin cancer has led to a rise in rickets. This seems to be complicated in lab studies. Unquestionably, sunblock keeps the skin from being able to synthesize vitamin D, but in real world situations, it is not nearly as clear. Most people just don't apply sunblock perfectly or often enough or use enough of the product so at least some sun exposure is still happening. It's possible that a bigger factor than wearing sunblock is just the fact that some people don't go outside much at all. Like if a child is being driven to school and then does not have recess at school and then comes back home and reads and plays video games and goes to bed. Not a lot of opportunity there for direct sun exposure.

[Holly Fry]

Yeah, I'm having a flashback to our episode where we talked about sunscreens.

[Tracy V. Wilson]

I'm not knocking reading and playing video games. Those are two of my favorite pastimes.

[Holly Fry]

Or using sunscreen.

[Tracy V. Wilson]

I am an advocate of sunscreen.

[Holly Fry]

All of these things are important, but you must get vitamin D.

[Tracy V. Wilson]

Do you.

[Holly Fry]

Have listener mail for us?

[Tracy V. Wilson]

I do have listener mail. This is from Cherilyn who wrote hi both. I've been listening for over a decade. My now ex wife used to refer to you as the Ladies because you were and still are my food prep companions. I really appreciate the years of company as well as the reflective and sometimes self reflective way you address your work. I grew up half an hour south of Boston so hearing bits of Tracy's life is like fragments from home. I now live in Wales and my first bit of Welsh history from you years before I moved here it was the Abervan disaster and living in the Welsh valleys as I do, understanding the mining history is an important culture point. I have been to the graves of the children who died in the Abervan disaster which is absolutely heartbreaking. I almost took this last line out because I cried writing it and I can picture Holly trying not to cry reading it. But the personal connection to history and this bridge this podcast has been is part of the point on two Iguanodons in between Boston and Wales. In between Boston and Wales I lived not far from Crystal palace, which is an area of London in addition to a park, so I really enjoyed hearing about the creation of the park. My shorthand for the statues has always been what the Victorians thought dinosaurs looked like, so it was interesting to hear the background to them. I too was sad to think of the people working on it, seeing them already be incorrect because of new discoveries, but they are still fun to visit. I recommend them to anyone wanting something a little more offbeat in London. The larger park is also lovely and the train station is now part of the tube network. It was also interesting to hear that they demolished the Ping mansion for the park as Ping is now an area down the road slash hill for a pet tax. I've attached my 8 year old cat Willow. Her pet sitter got this scratching pad for Christmas and he was instantly appreciative. Thank you for all you do, especially as it gets harder to access resources. You are my podcast staple and the one I most often recommend to others. All the best Cherilyn. We have a picture of a black cat. My computer does not want to open it at full size at the moment, but oh, there we go. As soon as I said that and tried to close the window it appeared we have a black cat on a Christmas tree shaped one of those cardboard like scratching pads. Super cute. I in my house have a cardboard Halloween house that was bought at the pet store on impulse a couple of years ago and became one of Opal's favorite things. It is still in good enough shape to still be in the house. I'm always wondering how much longer though until like the bottom is all the way shredded through. How I don't know even the right word for a person's first bit of Welsh history before moving to Wales being the Abervan disaster. One of the saddest episodes we have ever done.

[Holly Fry]

Listen while you were reading I was hoping she was gonna say it was the Merrillide.

[Tracy V. Wilson]

It was gonna be horse skeletons of the holidays, but no.

[Holly Fry]

Alas, no.

[Tracy V. Wilson]

Yeah, no. It's so sad that I kind of erased it from my memory for a while after we recorded it and when someone asked about what are some of the saddest episodes you've ever done? I didn't mention it and somebody else was like what about the Abervan? Well, I blocked it out of my head is that's what hard same.

[Holly Fry]

I had some that we had talked about that were really harrowing come up in recent research and I was like I forgot we did these. I think my brain did that on purpose.

[Tracy V. Wilson]

Yeah, can only hold so much. So thank you again Sherilyn for this lovely email. I'm glad you enjoy visiting the Crystal Palace Park. Perhaps one day I will make it and see them myself. If you would like to send us a note, our email address is historypodcastheartradio.com and you can subscribe to the show on the iHeartRadio app or anywhere else you'd like to get your podcasts. Stuff you missed in history class is a production of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows. This is an iHeart podcast. Guaranteed Human.