Processed Meats Linked to Mania Disorders
“We looked at a number of different dietary exposures and cured meat really stood out. It wasn’t just that people with mania have an abnormal diet.” – Dr. Robert Yolken
(Baltimore, MD) – An analysis of more than 1,000 people with and without psychiatric disorders has shown that nitrates—chemicals used to cure meats such as beef jerky, salami, hot dogs and other processed meat snacks—may contribute to mania, an abnormal mood state. Mania is characterized by hyperactivity, euphoria and insomnia.
The findings of the Johns Hopkins Medicine study, which was not designed to determine cause and effect, were published July 18 in Molecular Psychiatry. Specifically, it found that people hospitalized for an episode of mania had more than three times the odds of having ever eaten nitrate-cured meats than people without a history of a serious psychiatric disorder.
Experiments in rats by the same researchers showed mania-like hyperactivity after just a few weeks on diets with added nitrates.
While a number of genetic and other risk factors have been linked to the manic episodes that characterize bipolar disorder and may occur in other psychiatric conditions, those factors have been unable to explain the cause of these mental illnesses, and researchers are increasingly looking for environmental factors, such as diet, that may play a role.
The researchers say that their new study adds to evidence that certain diets and potentially the amounts and types of bacteria in the gut may contribute to mania and other disorders that affect the brain.
“Future work on this association could lead to dietary interventions to help reduce the risk of manic episodes in those who have bipolar disorder or who are otherwise vulnerable to mania,” says lead author Robert Yolken, M.D., the Theodore and Vada Stanley Distinguished Professor of Neurovirology in Pediatrics at the Johns Hopkins University School of Medicine.
Mania, a state of elevated mood, arousal and energy that lasts weeks to months, is generally seen in people with bipolar disorder, but can also occur in those with schizoaffective disorder. Manic states can lead to dangerous risk-taking behavior and can include delusional thinking, and most of those affected experience multiple hospitalizations in the course of their psychiatric illness.
Bipolar disorder affects an estimated 1 to 3 percent of the population of the United States and costs an estimated $25 billion a year in direct health care costs, according to a study in the Journal of Affective Disorders.
Yolken, trained as an infectious disease expert, was originally interested in whether exposure to infections such as viruses transmitted through food might be linked to any psychiatric conditions. Between 2007 and 2017, as part of an ongoing study, he and colleagues collected demographic, health and dietary data on 1,101 individuals aged 18 through 65 with and without psychiatric disorders. Approximately 55 percent of the participants were female and 55 percent were Caucasian, with 36 percent identifying as African-American.
Those with psychiatric disorders were recruited from patients receiving care at the Sheppard Pratt Health System in Baltimore. Individuals with no history of psychiatric disorders were recruited from posted announcements at local health care facilities and universities in the region.
A study of their records between 2007 and 2017 showed that, unexpectedly, among people who had been hospitalized for mania, a history of eating cured meat before hospitalization were approximately 3.5 times higher than the group of people without a psychiatric disorder. Cured meats were not associated with a diagnosis of schizoaffective disorder, bipolar disorder in people not hospitalized for mania or in major depressive disorder. No other foods about which participants were queried had a significant association with any of the disorders, or with mania.
“We looked at a number of different dietary exposures and cured meat really stood out,” says Yolken. “It wasn’t just that people with mania have an abnormal diet.”
Nitrates have long been used as preservatives in cured meat products and have been previously linked to some cancers and neurodegenerative diseases, so Yolken suspected they may also explain the link to mood states such as mania.
The dietary survey did not ask about frequency or time frame of cured meat consumption, so the researchers couldn’t draw conclusions about exactly how much cured meat boosts one’s risk of mania, but Yolken hopes future studies will address this.
To get at the roots of the association, Yolken collaborated with researchers studying the impact of nitrates on rats.