Eating dried beef could be linked to manic episodes in some people

There is no singular cause of mental illness. A number of things – our genes, the environment and even social mores – play a role in determining the deterioration of someone's mental health to the point of being diagnosed as an illness. . But Johns Hopkins researchers came across a possible trigger of manic episodes that they did not expect to find: dried beef.

Since 2001, researchers have followed the health of consenting psychiatric patients admitted to one of the region's hospitals. Baltimore, Maryland, a study in progress. In 2007, they began questioning patients about their diet. One of the scientists behind the study, Robert Yolken, neurovirologist at the Johns Hopkins University School of Medicine, first used this data to examine a possible link between foodborne infections and mental illnesses

. reviewed anonymous data from more than 1,000 volunteers (a cohort that included psychiatric patients and a control group of people recruited from health centers and colleges without a diagnosis of mental illness), a strange trend began to appear in people diagnosed with mania, a state of hyperexcitation, awakening and delusion frequently followed by periods of severe depression in people with bipolar disorder. Compared with the control group, people who experienced a manic episode reported eating more salted meat. Overall, they found that people who had recently consumed dried meat were three times more likely to be hospitalized for mania, even after taking into account factors such as age or age. socioeconomic status. The same model could not be seen with any other type of food eaten.

"This is not what we were looking for," Yolken told Gizmodo. "It came as something of an unexpected discovery."

Hoping to confirm that it was the offending jerky, Yolken reached out to other researchers and began experimenting with rats. Because jerky products and the like are cured using nitrate salts, they theorized that nitrates could be the main driver of a manic effect.

They first fed the store-bought rats jerky daily (the equivalent of a daily snack in the man) and compared them to a control group. The rats fed jerky started to show symptoms of hyperactivity and poor sleep in two weeks, while the control group did not. Then they fed specially prepared dried meat without nitrates to another group of rats, finding that these rats did not develop any symptoms. And finally, they gave the rats a typical rat diet loaded with nitrates, and found the same pattern.

The results of the study were published Wednesday in Molecular Psychiatry

"It's intriguing, and probably better than many other studies." Emeran Mayer, a Gastroenterologist University of California at Los Angeles who was not involved in research, told Gizmodo.

"Experiments on rats are pretty convincing … But in humans, this can be a lot more complicated, "said Mayer, who has studied and written about how the intestinal microbiome can influence the brain." Food recalls and questionnaires are notoriously unreliable. So, it is probably a weak point of the study. "

As for how jerky could trigger mania, Yolken suspects that it involves the microbial environment, or microbiome, of the gut. gut and brain "talk" regularly through the hormonal and nervous signals to keep the body regulated, the so-called "gut-brain axis." In recent years, researchers have begun to find that our microbiota Intestinal is an integral part of keeping these waves clear, but if the intestinal microbiome is unbalanced (by dietary changes or antibiotics, for example), this could trigger a series of events that wreak havoc in both the brain and the intestine, often by chronic inflammation.This inflammation could then make people more likely to develop mental illness, or worsen its symptoms.

And indeed, when the Yolken team examined the guts of nitrate-fed rats, they found clear changes in the intestinal microbiome. an increase of certain types of bacteria, compared to normal rats. These particular bacteria have already been badociated with behavioral changes and cognition in animals. There was also evidence of minimal molecular changes in the brain badociated with mania in these rats, although Yolken warned that the results can not prove that intestinal changes have led to changes in the brain. They can not even prove that nitrates are responsible for similar changes in people.

Yolken himself points out that the study, especially the results in humans, is not definitive. To his knowledge, no other studies have established a link between nitrates and mental illness (although they have been badociated with conditions such as cancer in drinking water as a contaminant) . And much more research, both in animals and in humans, is needed before such a link can be confirmed. Even though diet plays a role in the risk of mental illness, it's just one of many factors that interact in complicated ways that we do not fully understand.

That goes without saying, says Mayer, because nitrates are an ubiquitous part of the North American diet. Yet, clearly, everyone who loves hot dogs does not develop mania. So, even if the link is real, it's only part of the puzzle.

"Microbes do not just cause anxiety, depression, or autism in people," says Mayer. "They have only effect on people who have a genetic or environmental predisposition to the disease, and this is only one among others."

Trying to repair the microbiome can not necessarily help treat all types of mental illnesses. Yolken and his team recently published a double-blind trial showing that manic patients who took probiotic-pills containing a mix of "good" microbiome-stabilizing bacteria – with standard treatment had a lower risk of re-hospitalization for another episode six months. But he also published research that found that probiotics had no effect on reducing the symptoms of people with schizophrenia.

Still, Yolken hopes that his study will spark more attention (and funding) to study the connection between the intestine, the diet, and the mind.

"We do not want to scare people about their diet, but it's certainly a promising area that needs to be examined and studied further," Yolken said.

"I do not suggest any intervention now," he added.

[Molecular Psychiatry]