Then the researchers discovered the unusual truth: Fungi in the human digestive system turn carbohydrates into alcohol – a rarely diagnosed condition known as "auto-brewing syndrome".
In people with the syndrome, fermenting fungi or bacteria in the intestine produce ethanol and may cause patients signs of drunkenness. The condition, also known as bowel fermentation syndrome, can occur in otherwise healthy people, but is more common in patients with diabetes, obesity or Crohn's disease.
"One is intoxicated by this fermenting yeast, and it's a terrible disease," said Barbara Cordell, a researcher of the auto-brewing syndrome and author of "My Intestine Makes Alcohol."
The condition is rarely studied and rarely diagnosed. Researchers at the University of Richmond Medical Center in New York, however, wrote in BMJ Open Gastroenterology that they thought the syndrome was underdiagnosed.
The situation made news in 201
4, when the driver of a truck spilled 11,000 salmon on a highway claimed to have auto-brewing syndrome. The following year, a New York woman was charged with driving under the influence after registering a blood alcohol level that is more than four times the legal limit, CNN reported. A judge dismissed the charges after being shown evidence that she had a brewery syndrome.
A man from a University of Richmond study whose identity has not been released began taking antibiotics in 2011 for traumatic injury to his thumb. It was then that the strange symptoms began: depression, memory problems and aggressive behavior, which was rare for him.
"Everybody thought he was a liar, he was a drinker in the closet," said Fahad Malik, a doctor and lead researcher for the study.
Following his arrest on drunk driving charges, his aunt's aunt remembered a similar situation addressed by a doctor in Ohio. She bought her nephew a breathing apparatus to check his blood alcohol levels and persuaded him to go to Ohio for treatment.
Doctors there gave the man a heavy carbohydrate diet and watched the blood alcohol level rise to 0.57. He left strict orders not to eat carbohydrates – often found in bread, pasta and beer, among other foods, but soon began to grow again. When his intoxication at one point made him fall and suffer from brain bleeding, the doctors again refused to believe that he did not drink.
The man contacted the authors of the study, published in August. He was prescribed an antifungal drug that would get rid of his symptoms until he recurred from eating pizza and drinking soda. In the end, doctors discovered a combination of treatments that, in combination with regular checks on his blood alcohol level, allowed a person to stick to a normal diet without showing symptoms.
People with auto-brewing syndrome may smell of alcohol or feel too tired to work or spend time with family. Some patients are unemployed because of the condition, Malik said, while others skip meals to stay sober for longer periods.
Nick Hess, 39, states that his auto-brewing syndrome causes him to oscillate every day between intoxication and hangovers. He said he had to leave college because of his symptoms and appealed the DUI verdict. He suffers from vomiting, headache and other symptoms every day.
Hes, Columbus, Ohio, stated that his wife did not believe he did not drink when he began to show symptoms. At one point, he said, she began recording it to make sure he hadn't run out of alcohol. What he saw, only Hess said, was just him playing video games all day.
"She would watch me wake up and sit on this couch from the moment I woke up to the moment I fell asleep and progressively get drunk more and more," he said.
Cordell said her husband had had auto-brewing syndrome for six years before discovering why he sometimes misled his words and lost coordination. If he ate heavy carbs at night like ice cream, Cordel says, he usually shows signs of intoxication until the next afternoon.
Auto-brewing syndrome appears to be caused by the use of antibiotics that alter the fungal growth of humans, but Cordel said researchers do not know why few people who take antibiotics contract this condition. Other medicines, environmental toxins or food preservatives can also cause auto-brewing syndrome, disrupting the normal balance of bacteria in the body.
Early symptoms of auto-brewing syndrome may be changes in mood, brain fog and delirium, rather than signs of intoxication according to a Richmond study. Some symptoms of auto-brewing syndrome can mimic other conditions or medical events, such as hypoglycemia or stroke, Cordell said. She recommends that people who are suspected of having a brewery syndrome get a breathing apparatus so that they can test their blood alcohol levels when symptoms occur.
If one becomes severely intoxicated with auto-brewing syndrome, Cordel recommends first seeking treatment for potential alcohol poisoning, blood alcohol levels in people with auto-brewing syndrome can reach five times the legal border, she said. Antifungal drugs, probiotics and low carb diets can cure the condition.
Cordell leads a support group for about 200 people with auto-brewing syndrome and said that about 500 people from around the world have contacted her for the state of 2015.  "I think they suffer a lot more people than we even know, "she said.