Medieval friars had fresh food and clean water. So why were they riddled with gut parasites?

In medieval times, you could do a lot worse than being a friar.

Friars lived in stone complexes, with lush gardens full of fresh fruits and vegetables to enjoy — far healthier than the mushy, boiled porridge concoctions the average peasant ate for dinner every night.

They also had access to proper latrines with running water, while peasants relieved themselves in bowls or outdoor cesspits.

And yet, a new study published in the International Journal of Paleopathology has found medieval friars were riddled with gut parasites — almost twice as many as those of everyday folks.

“That really surprised us,” lead author Piers Mitchell, a University of Cambridge archeologist, told As It Happens guest host Susan Bonner.

“The basic levels of sanitation and cleanliness in a typical friary or monastery should, in theory, have been a lot better than we would find in the peasants who were living in the town.”

You are what you eat

For the study, Mitchell and his colleagues examined the remains of 19 people unearthed at a medieval Augustinian friary in Cambridge, UK, and compared them to 25 bodies buried in a nearby parish cemetery.

But instead of studying the bones directly, the researchers examined the soil on and around the pelvises, where intestines would have once been.

“When they decompose, any intestine or parasitic worms that would have been in those intestines, their eggs would still be left in the soil that we can study using microscopy,” Mitchell said.

Two skeletons lie side by side in the dirt, their hands resting on their chests.  Both are well preserved, although the one on the left has a large hole in its skull.  A man in a hard hat and gloves crouches over one skeleton, performing excavation work with a tool of some kind.  Ziploc bags and archeology tools are scattered about in the dirt.
A member of the Cambridge Archaeological Unit excavates the remains of medieval Augustinian friars. (Cambridge Archaeological Unit)

Of those buried in the parish cemetery, 32 percent had intestinal parasites — specifically roundworms and whipworms — which Mitchell says is about on par with what experts would expect for medieval populations in Europe. But among the Augustinians, 58 percent had intestinal worms.

Even those numbers are likely an underestimation. The study notes some traces of worm eggs in the pelvic sediment would have been destroyed over time by insects and fungi.

“If it’s to do with sanitation, and if the monks and the friars had toilets and better sanitary setup, then it may be the way they were manoeuvring their crops that would explain it,” Mitchell said.

Mitchell and his colleagues theorize the friars would have used their own feces to fertilize their vast crops, as was common practice at the time, thereby regularly re-infecting themselves again and again with parasites.

The average peasant, by contrast, would have only had a small garden plot — if they were lucky enough to have any agriculture at all.

What’s more, medieval Europe’s poorest people, he said, most commonly ate a food called pottage — a kind of stew or porridge of grains, cereals, herbs and root vegetables boiled into a mush and served with bread.

The friars, on the other hand, were munching on fresh salads full of uncooked produce.

“And so cooking … is much more likely to kill off parasites than if you were to have fresh fruit and fresh vegetables and salads and so on,” Mitchell said.

They didn’t know what they didn’t know

Nowadays, the World Health Organization recommends that human feces used as fertilizer be composted for six months beforehand. That way, most parasites will die off.

But, of course, medieval friars would have no way of knowing that.

A balding man smiles for the camera.  He is wearing a blue plaid collared shirt with the top two buttons unbuttoned.  Gold and stone objects can be seen in the background.
Piers Mitchell is an archeologist at the University of Cambridge. (Submitted by Piers Mitchell)

Mitchell says there’s plenty of evidence that people in medieval times knew they had gut parasites. Medical texts from that period describe them in detail. What they didn’t know, he said, is where they came from.

“They had no idea that feces could spread parasitic worms. They thought these worms were spread or created by an imbalance of the four humors that people had in their bodies, as they understood medicine at that time — phlegm, black bile, yellow bile and blood. And if they were out of balance or had too much of one of those, then diseases happened,” he said.

Lessons for the present

Findings like these, he says, not only shed light on how people used to live, but also help us “understand the benefits of all the modern health care that we have today.”

“A lot of people take health for granted and say, ‘Oh, we don’t need vaccinations or we don’t need hand-washing and I don’t need to bother washing myself or cleaning my teeth,’ or this kind of stuff,” he said.

“If you study populations in the medieval period… you start to see evidence for all these diseases that we take for granted as being really rare or not affecting us today. And it does highlight the importance of taking those basic things to keep yourself healthy, not only at home, but also when you travel to parts of the world that don’t have the luxuries of good sanitation that we’re all used to.”


Written by Sheena Goodyear. Interview produced by Kate McGillivray.

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