In the early 1900s, an epidemic hit the American South. Called pellagra — Italian for “sour skin” — the disease caused a leprosy-like outbreak of skin lesions on the afflicted, as seen here. Pellagra had struck other societies as well: Spain, in the mid-1700s and in Italy, sometime thereafter. Pellagra struck approximately 100,000 Southerners in 1916 (although only a fraction died from it). In South Carolina alone, over 1,000 people died from pellagra the year prior.

The prevailing theory at the time was that dirty, germ-ridden conditions caused pellagra — but there was little science to back this up. To combat this disease, the Surgeon General of the United States asked a physician, Joseph Goldberger (above), to figure out what was going on.

Goldberger’s exploration used, by modern standards, extreme tactics.

First, he went to some of the more unkempt places in the South: prisons, orphanages, and mental institutions. Pellagra was definitely more common there than elsewhere, suggesting that dirty conditions were the cause. However, Goldberger observed that the staff at those institutions — who were better fed — were not developing pellagra. To further disprove the notion that grime was pellagra’s cause, Goldberger’s team — and, his wife — engaged in “filth parties,” ingesting the scabs, feces, blood, and other bodily fluids of pellagra plaintiffs. No one on Goldberg’s team developed pellagra (although it’s almost certain that they ended up getting a bevy of other maladies.).

Goldberger was convinced: something in the diet of the typical Southerner was causing the disease. At the time, the Southern staples were three “M”s — meat, molasses, and meal — cornmeal. Corn was the first food he tested. He found 11 prisoners to volunteer for an experiment. The prisoners — who were granted pardons for participation in the experiment — were separated from the rest of the prison population and put in a house which was cleaned daily. For a few days before the experiment, the prisoners were fed a balanced diet. But after that, for a two week period, their diets consisted only of corn. And then came the sickness. First headaches and loss of appetite. Then pellagra struck seven of the 11 volunteers. Goldberger returned them all to the more healthful, balanced diet. The seven diseased prisoners recovered. Something in the corn was killing people.

Kind of. More accurately, something not in the corn was killing them. Goldberger died of kidney cancer in 1929, without discovering what biochemist Conrad Elvehjem, continuing Goldberger’s work (in a modern, traditional manner) would later conclude.  It turns out that pellagra is caused by a chronic lack of niacin (vitamin B3) — a nutrient that corn happens to not have.

So, why weren’t people in Mexico and South America dying from pellagra? As early as 1500 BCE, ancient civilizations in South America developed something called “nixtamalization” — a process by which corn is boiled in water containing lime (calcium hydroxide, not the fruit). This made raw corn kernals tastier and easier to digest. (As seen in the picture here, the treated corn, right, looks more like the stuff we eat today.)

As it turns out, nixtamalization has another benefit: it adds niacin to the corn. Most likely unbeknownst to the Mayans, Incans, and Aztecs who employed nixtamalization, they were turning their food staple from poison to gold.

Bonus fact: The world’s largest corn maze is 45 acres large and is located in Dixon, California.  (There is an aerial picture of it here.)  Like virtually everything else these days, it has a Starbucks.

From the Archives: Laughing to Death: Another strange disease, with laughter as a key symptom.

Related: A really creepy statute of corn with a really creepy face on it.