Nav: Home

Beef jerky and other processed meats associated with manic episodes

July 18, 2018

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.

Kellie Tamashiro, Ph.D., associate professor of psychiatry and behavioral sciences, and M.D./Ph.D. student Seva Khambadkone, both of Johns Hopkins, and others divided a group of otherwise healthy rats into two groups: one received normal rat chow, and the other received both normal chow and a piece of store-bought, nitrate-prepared beef jerky every other day. Within two weeks, the rats receiving the jerky showed irregular sleeping patterns and hyperactivity.

Next, the team worked with a Baltimore-based beef jerky company to create a special nitrate-free dried beef. They repeated the experiment, this time giving some rats the store-bought, nitrate-prepared jerky and others the nitrate-free formulation. The animals that ate the nitrate-free meat behaved similarly to a control group, while the animals that consumed the nitrates once again showed sleep disturbances and hyperactivity similar to that seen in patients with mania--increased activity during normal sleep times and in new environments.

The results were then replicated with a specially formulated rat chow that had either nitrate added directly to the chow, or no nitrate.

Importantly, the amount of nitrate being consumed on a daily basis by the rats¾when scaled up to the size of a human--was equivalent to the amount a person might eat for a daily snack, such as one beef jerky stick or hot dog.

"We tried to make sure the amount of nitrate used in the experiment was in the range of what people might reasonably be eating," says Yolken.

When the group analyzed the gut bacteria of the different groups of rats, they found that animals with nitrate in their diet had different patterns of bacteria living in their intestines than the other rats. Moreover, the animals had differences in several molecular pathways in the brain that have been previously implicated in bipolar disorder.

While the team also cautions that it's too early to take any clinical messages from the results, and occasional cured meat consumption is unlikely to spur a manic episode in most of the population, Yolken says the findings add to evidence of the multiple factors that contribute to mania and bipolar disorder.

"It's clear that mania is a complex neuropsychiatric state, and that both genetic vulnerabilities and environmental factors are likely involved in the emergence and severity of bipolar disorder and associated manic episodes," says Khambadkone. "Our results suggest that nitrated cured meat could be one environmental player in mediating mania."

Yolken's group recently published results of a separate study showing that when people with bipolar disorder are given probiotics--which can change the composition of gut bacteria--after a manic episode, they are less likely to be rehospitalized in the following six months. "There's growing evidence that germs in the intestines can influence the brain," says Yolken. "And this work on nitrates opens the door for future studies on how that may be happening."
-end-
Other authors on the paper include Zachary Cordner, Emily Severance, Emese Prandovszky, Mikhail Pletnikov, Jianchun Xiao, Ye Li, Gretha Boersma, C. Conover Talbot Jr., and Timothy Moran of the Johns Hopkins University School of Medicine; Faith Dickerson of the Sheppard Pratt Health System; Wayne Campbell and Christian S. Wright of Purdue University; and C. Evan Siple of Mobtown Meat Snacks.

This work was supported by a National Institute of Mental Health Silvio O. Conte Center grant (MH-94268) and by the Stanley Medical Research Institute.

Johns Hopkins Medicine

Related Bipolar Disorder Articles:

Is bipolar disorder associated with increased risk of Parkinson's disease?
This study, called a systematic review and meta-analysis, combined the results of seven studies with 4.3 million participants to examine a potential association between bipolar disorder with a later diagnosis of Parkinson's disease of unknown cause.
Bipolar disorder may be linked to Parkinson's disease
People who have bipolar disorder may be more likely to later develop Parkinson's disease than people who do not have bipolar disorder, according at a study published in the May 22, 2019, online issue of Neurology®, the medical journal of the American Academy of Neurology.
Probiotics could help millions of patients suffering from bipolar disorder
About 3 million people in the US are diagnosed every year with bipolar disorder, a psychiatric condition characterized by dramatic shifts in mood from depression to mania.
Novel intervention for anxiety symptoms among people with Bipolar Disorder
Psychologists at Lancaster University have devised a novel psychological intervention to address Anxiety in Bipolar Disorder (AIBD).
Mutation links bipolar disorder to mitochondrial disease
Mutations in the gene ANT1 may confer a risk for bipolar disorder through a complex interplay between serotonin and mitochondrial signaling in the brain.
A new path into bipolar disorder comes to light
A new article authored by an international group of researchers reveals a novel potential drug target for bipolar disorder and offers new insights into the underlying biology of this lifelong and devastating mental illness.
After searching 12 years for bipolar disorder's cause, U-M team concludes it has many
Nearly 6 million Americans have bipolar disorder, and most have probably wondered why.
Simple EKG can determine whether patient has depression or bipolar disorder
A groundbreaking Loyola Medicine study suggests that a simple 15-minute electrocardiogram could help a physician determine whether a patient has major depression or bipolar disorder.
Gene breakthrough on lithium treatment for bipolar disorder
Genes linked to schizophrenia in psychiatric patients suffering from bipolar disorder are the reason why such patients don't respond to the 'gold standard' treatment for bipolar -- the drug lithium -- according to international research led by the University of Adelaide.
Shared genetics in schizophrenia and bipolar disorder
A genetic variant associated with multiple psychiatric disorders drives changes in a brain network that may increase an individual's risk of developing bipolar disorder and schizophrenia, finds a study published in JNeurosci.
More Bipolar Disorder News and Bipolar Disorder Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.